I have the timing set at 40 degree advanced and right when it hits 4 lbs of boost it backfires through the intake. The causes of most engine backfires fall into two categories: gases explosively expelled through the intake manifold, or explosions that take place within the exhaust system. backfires , catalatic converters glow red. veh verry hard to start exsessive cranking runs fine at idle as soon as you touch accelerator backfire through intake i have already replaced module,check cam sensor adjustment,42lbs fuel pressure coil pack ohm's ok crank signal ok fuel trim at idle only 128 iac counts normal but runs so poorly when trying to rev enine under load or in park cannot get any stable readings. If it's popping back through the intake you have only 2 possible causes. You can just keep that disconnected and plugged till you get the engine running right. I installed a 95 5. On the intake side, regular backfires can lead to engine damage. Down stream there will be a metering needle, which is the pilot screw and eventually a passageway leading to the four tiny holes and into the main. I tried fuel system cleaners with no luck. A bent or not properly seated intake valve will cause your trouble too. Rough Idle and Backfiring Engine with Check Engine Light Problem Description The 3. Now if it is backfiring through the intake, you have other issues. Engine backfire is the result of incomplete combustion inside the combustion chamber. as the one guys said before, backfire is a pop through the intake. All your responses are afterfire and are good diagnosis of the probable cause. Combination Effects are Complex A nitro-methanol fuel mixture up to about 87-percent nitro, with increased richness, is less prone to detonation. Regards, Robin. That definitely should be replaced. Backfires and loud explosion-like sounds are common when an antilag system is present and active. What I don't understand is how popping/backfiring can be indicative of a lean condition. The thread from the air cleaner wing nut were still on the stud. For engines to run efficiently, the spark plugs have to ignite the air and fuel at the right time. Holley products for GM's popular LS engine are dominating the LS scene as well. Since the intake valve needs to provide the engine with a proper balance of fuel and air, a backfire occurs when that balance fails. If the fuel mixture is too lean (not enough fuel) you may have a backfire in the intake, or too rich (too much fuel) you may get a backfire out of the exhaust system. Engine wont Start and is backfiring through the carbs - PMA, rephased 277, Pamco ign Discussion in 'The Garage' started by NorthParkMC, Jul 24, 2014. Anywho, I'm sure Paul can describe this better than I, but when decelerating, above a certain speed, the fuel injectors are doing nada, shut off. The good thing is that a vacuum leak is not hard to identify if you have the right tools and the right knowledge. Incorrect timing can lead to the fuel being ignited before the manifold intake valve closes, causing a backfire through the carburetor or exhaust. These all causes help you to understand what problems influenced in your intake and you can get rid out from this for next time. RE: Odd miss and backfiring thru intake IP: Logged Message: Wadak, My Dakota just passed 40k miles on it, and no, the O2 sensor has not been replaced. Do you experienced engine backfire when you are cruising along a busy highway and hears a loud bang from your exhaust? That's what usually happens to older cars where an explosion can occur in the air intake or the exhaust system instead of the combustion chamber. The causes of most engine backfires fall into two categories: gases explosively expelled through the intake manifold, or explosions that take place within the exhaust system. You may have a worn cam lobe. "Backfiring" is usually caused by a spark plug "sparking" when it isn't its turn and the exhaust valve is open. A fuel level fluctuation could cause both problems. When she drives I get a pop through the exhaust and a pop through the intake. A second function of the PCV valve is to protect the engine in case of a backfire, which causes a sudden high-pressure pulse in the intake manifold. It sounds like the engine is temporarily flooded on hard accel. If you let his car warm up for a minute, and then take off for the end of the subdivision, it won't backfire; but once you come to a stop at the exit and take your turn it starts to cut out and backfire and act like it is going to die. The engine stalls at idle and takes a little to get turned over, if the pedal is held steady the engine will only backfire now and then. When it does it during cranking, it's probably timing related. a smog pumps or AIS) can cause a backfire through the intake. Backfires through the intake are generally related to problems with ignition timing, and backfires through the exhaust are usually related to fuel mixture problems. Ever since I put this engine together it has had a problem with backfiring through the intake below 2500 rpm. I thought 6* was the stock timing but I dont have my Haynes manual anymore so I couldnt remember for sure. Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. sounds like your ignition timming is off. com A faulty ignition system is a possible cause of a engine backfire. Combination Effects are Complex A nitro-methanol fuel mixture up to about 87-percent nitro, with increased richness, is less prone to detonation. I taped it up a little to see if it would stop backfiring and it helped a little. During the time of valve overlap, when both the intake and the exhaust valves are open, the burning exhaust gases can ignite the fresh fuel-air charge being taken into the cylinder through the intake valve. 045, and a 224/228,. Consequently this will cause a severe jerk or shock in the operation of the engine (the engine may even backfire through the air intake system, producing a loud “pop”). This explosion is what causes the infamous nerve-wrecking sound many have heard when riding their ATVs. Timing is good, Fuel pressure is 5 lbs. Engine starts, then dies within a few seconds. firing order, cam timing, bent valve, these are typically the things that you would look for. In some engines, an intake manifold can corrode or crack causing either vacuum or coolant leaks. and leaving it. It's still a 28 oz balancer ! The engine has been apart before from the signs of different gaskets that are not stock and signs of silicon being used. The backfiring is in sequence with RPM. What can cause backfire in the intake along with sputtering during acceleration? Fine when it is in park. (it's leaning out). Valve problems can cause exhaust and intake back-fires depending which valve is causing the problem. Combination Effects are Complex A nitro-methanol fuel mixture up to about 87-percent nitro, with increased richness, is less prone to detonation. Afterfire tends to happen when unburned fuel is ignited in the exhaust. Really listening to it, it sounds like it's backfiring through the wastegate and not the intake like it sounded like before. If the valves are operating properly and the compression is still low, worn rings or bore are best fixed by installing a rebuild kit, shortblock or complete replacement engine. The excess air and fuel mixture can travel to the intake manifold or through the exhaust manifold and detonate prematurely, causing a backfire. Project is not road worthy yet so only been running in back yard for now. CarComplaints. What causes backfire through the intake???? I was looking at some pictures of cars I know that spray nitrous and see fire come out of the hood scoops what causes this?? And how can it be prevented??. I guess it's just because the power assist wasn't working, but I was standing on the pedal and could barely get the car to stop. The datalog you are looking at is with that carb, and it is backfiring through the intake on this engine. Mine does it a little tooevery once in a while isn't a big deal, but it can get annoying, lol. That term is used somewhat loosely. I have a FG50 with a Nissan TB45 propane engine that periodically backfires through the intake blowing the air cleaner cap off. If this timing is mis-adjusted it can cause low power, poor gas mileage, engine detonation (pinging) and backfiring through the intake or exhaust system. what exactly causes it to backfire and are engine backfire. A cracked manifold must be replaced if it cannot be safely repaired. This only occurs under high revs when lifting,never when travelling. Afterfire is in the exhaust system,usualy an air fuel mixture problem. One caveat is in order here, Do not waste time trying to listen for a leak in the exhaust pipe with the engine running, You won’t hear it. veh verry hard to start exsessive cranking runs fine at idle as soon as you touch accelerator backfire through intake i have already replaced module,check cam sensor adjustment,42lbs fuel pressure coil pack ohm's ok crank signal ok fuel trim at idle only 128 iac counts normal but runs so poorly when trying to rev enine under load or in park cannot get any stable readings. 588, 114LSA cam. If the engine has been recently rebuilt, and you are having trouble getting it to. Although it is impossible to have been damaged by the squirrels without notice to the plastic covers, not much of a reason to be popping back through the intake unless there is a problem in this area. Did this problem just start or have you been having problem right on. Ignition or valve timing? Ignition If the spark is directed to the wrong plug it will backfire because an intake valve is open when the spark is sent to the wrong spark plug. Sounds to me like it's misfiring part of the time, and the resultant unburned fuel being passed is later igniting downstream, in the exhaust system - causing the "sloppy, farty" sound, backfiring and red-hot exhaust pipe. Re: Intake backfire What actually happened to my engine when it done this was a valve push rod came unseated and was laying inside the valve cover. Bad engine timing is often the issue behind intake backfires, but they can also cause exhaust backfires. This explosion is what causes the infamous nerve-wrecking sound many have heard when riding their ATVs. A defective or malfunctioning PCM can make the entire powertrain and chassis system seem like it's packed with defective components. A pop in the exhaust is called a misfire. Re: Is your 2-stroke BACKFIRING? This could help good to know did a rebuild and was at a loss for parts to replace with something major, was thinking a bad install but knew myself better than that. Considering it only pops at off idle and infrequently, its gotta be in the idle or transfer circuit. A rule of thumb is a backfire through intake means running rich, backfire through exhaust means running lean. 0L Backfire; Thread: Mine will backfire through the intake just like yours, but mine will do it when its cold or warm. starts at about 2000 rpmanyone have any ideas please > email me Intake manifold leak? I had that happen on the Torino stupid cheap gasket got sucked down and caused a leak between the manifold head. pressure regulator can cause backfiring. Although there are many problems that can cause the intake system to backfire, the overall effect is the same. In case you are facing a frequent backfiring issue in your car, its best to get the engine checked as soon as possible, before an intake valve side explosion causes major damage. Re: 99 V6 no power, popping through intake? I have the same engine in my 99 windstar 3. replaced both upstream o2 sensors ( this killed the backfire issue ). Here 1g4hr52k5xh403208 VIN number is decoded. In my how-to video I will walk you through the basic principles and fundamentals of what you are adjusting and how it will impact your bike's response. As of right now, it keeps fouling spark plugs. Poor or unregulated engine timing is often a cause of intake backfires, but can also be responsible for exhaust backfires. For some reason backfiring has become a popular issue lately on forums I visit. Use a vacuum gauge connected to any convenient spot on the intake manifold. Ordinarily, backfiring in the intake is an overlean condition. Best Answer: The same thing that causes backfiring on a car or any other vehicle or object that uses an internal combustion engine: running too rich - unburned fuel in the exhaust. 7? Backfiring is usually an indication of a lean condition. (it's leaning out). Backfires can cause it to rip. If the compression checks OK makes sure the vales are opening fully. Common problems with intake manifolds include vacuum, coolant or oil leaks, reduced flow due to carbon build-up and issues with the intake tuning valves. To be picky though, a backfire happens when the air and fuel mixture ignites in the intake; the fires goes backwards through the intake manifold, carburetor or throttle body and air filter. Since your engine has 100k plus miles, I would suggest (especially on a Ford 6 of this period - been there, done that!), that your backfire is much more likely to be a burned/stuck intake valve. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power. The valves are adjusted too tight. Engine wont Start and is backfiring through the carbs - PMA, rephased 277, Pamco ign Discussion in 'The Garage' started by NorthParkMC, Jul 24, 2014. Initial Startup - Backfiring Through Throttle Body If this is your first visit, be sure to check out the FAQ by clicking the link above. Another thing that I noticed was the brakes were VERY hard to apply. A leaking, burned, cracked, or stuck valve could be the cause. The backfiring can be eliminated by using the governor's valve limiter to limit the carburetor butterfly valve to a position that limits the intake manifold air pressure below 17 to 20ish PSIA, but this will also limit the engine speed. One of the most common causes of an engine misfire condition is the tune up parts. the rest are the one im stuck on now. It's a lot more subtle, now. The datalog you are looking at is with that carb, and it is backfiring through the intake on this engine. You just do not want lean in the power bandthat would be a no no. When you have the spark plug against the engine block go ahead and hit the starter button. I replaced the seals on the fuel injectors and cleaned them. The PV is inside the primary fuel bowl and requires disassembly of the carb for replacement. This is a very common problem with cars today and the fix can be very easy and often times performed at home. Valve problems can cause exhaust and intake back-fires depending which valve is causing the problem. Backfiring through the carb can mean that at the time of the explosion, the intake valve isn't fully closed; i. Sounds like you might have a burned intake valve. Mind you, explosions are normal occurrences in engines, but they ought to ignite in the combustion chamber only. The datalog you are looking at is with that carb, and it is backfiring through the intake on this engine. On the older engines with points I would see a condenser going out, or be loose on the connections and cause backfiring; but you don't see those old. What causes a small engine (&s) to backfire when trying to start it? - Answered by a verified Technician We use cookies to give you the best possible experience on our website. If you need more information, send another email and include the model number of the tractor. Engine Uses Too Much Oil · Find and correct oil leaks. the rest are the one im stuck on now. To be picky though, a backfire happens when the air and fuel mixture ignites in the intake; the fires goes backwards through the intake manifold, carburetor or throttle body and air filter. 588, 114LSA cam. I would first pull the valve covers and make sure all your valvetrain is in good order, no broken valve springs, all the pushrods are straight and are in the rocker arm. Backfiring in the exhaust system: Backfiring occurs in the exhaust system under two conditions of operation. I have a 2000 silverado z71, with 288K, recently replaced fuel pump and filter about 3 weeks ago, was running great, until last week when it started to hesitate bad and back fire under acceleration, it ran good in idle and underload until is warmed up then when you tried to accelerate it would bog down bad and start popping like tiny backfires and the more gas you give it the engine falls flat. 045, and a 224/228,. this thing it will backfire and start the inside of the carb on fire. Compression seems good, fresh gas, and replaced mag and carb with ones off a running tractor. Incorrect timing can lead to the fuel being ignited before the manifold intake valve closes, causing a backfire through the carburetor or exhaust. Hope you will enjoy our guide and it will solve your problems. Afterfire tends to happen when unburned fuel is ignited in the exhaust. If it is an exhaust valve, it will backfire through the tailpipe. If the timing is advancing too much, the mixture is ignited and has time to burn off while the intake valve is still slightly open. Common problems with intake manifolds include vacuum, coolant or oil leaks, reduced flow due to carbon build-up and issues with the intake tuning valves. On older engine's ignition timing is set at a specific degree in relationship to the crankshaft. The backfire is produced when unburned fuel ignites inside the intake or exhaust manifold instead of a cylinder. Mind you, explosions are normal occurrences in engines, but they ought to ignite in the combustion chamber only. was created by syllinx22 I have an issue with my truck that has been happeing over a year now and it will not throw a code. In fact, a backfire creates an explosion in the exhaust or intake of your engine. The Cam is a Factory HO roller cam. It sounds like it is coming from in the dash. It was 200hp nitrous pill and no enrichment. When she drives I get a pop through the exhaust and a pop through the intake. I replaced the seals on the fuel injectors and cleaned them. I'm just trying to understand why/how a lean mix can cause idle backfiring. Is it possible the manifold or manifold gasket failed and would cause it to backfire?. When the intake manifold gaskets have an issue, they can cause drivability problems and even engine overheating. Ordinarily, backfiring in the intake is an overlean condition. What Causes My Motorcycle to Backfire Thru the Exhaust What causes a motorcycle to backfire through the exhaust is generally an airflow problem. It is also possible to have and intermittant electical problem that can cause backfiring out the exhaust. While the cylinder is pressurized, rotate the engine through its strokes and see if you have any leaks other than your intake and exhaust stroke. When I run this car through first, it makes it all the way through happily. The most common occurrence is the somewhat irregular backfiring that occurs when the engine is being motored (driven by the propeller) with the throttle closed. 4 L V6 Firebird, and foolishly ran out of gas on the way to the fill up station (the engine died about 1/4 mi away, lol). i even got it on video so i’ll upload a link to it. All of the symptoms you describe could very well be caused by a weak or intermittent spark. Car backfiring is not alarming as long as it involves only screeching sounds. the rest are the one im stuck on now. Another possibility is incorrect engine timing. backfiring through the intake means the sparkplug sparks before the intake valve has closed the cylinder draws in a charge on the intake stroke, the piston comes up on the compression stroke and the sparkplug sparks before the inlet valve is closed which implies the timing is advanced way too far. Lean mixture can cause higher than normal cylinder temps, but the fact that the engine runs OK when cool discounts mixture as being a primary issue. I got it in the car last year and it ran good until one day I was coming back from a car show and it started running bad and finally quit. i have timed several motors and im super anal about making sure it all lines up right. So what is a backfire, what causes it, and how can you stop your lawn mower engine from backfiring? What is a backfire?. i have timed several motors and im super anal about making sure it all lines up right. with a 18. There are varying degrees of backfires, from a small fire to a fully involved fire or explosion. Sticking valves: If a intake valve is bent, has a bad spring or is misadjusted, the engine will sometimes backfire through the intake. Then when I tried to start it,it backfired through the intake. what will cause my 2002 impala with 3. I pulled the shroud and pull start off and am using a drill to crank the engine as pull start was killing my arm. rcx6 said: Two years ago mine was experiencing the same symptoms and it was one of the coil packs was bad. Hunted high and low and couldn't find out what the problem was. comA backfire that you hear in your tail pipe isA backfire back out through your intake. The biggest backfire blew up the air filter box! As AFV Tech pointed out, a backfire in the intake side of the engine typically indictates a lean fuel mixture engine condition, and a backfire in the exhaust system would typically indicate a rich fuel mixture engine condition. A worn camshaft lobe or bad timing chain could also be at fault. If the backfiring only happens under a large load, like climbing a grade, and stops when he backs off the gas, its most likely fuel pressure related. This reaction is combined with the vehicle running roughly. A rule of thumb is a backfire through intake means running rich, backfire through exhaust means running lean. Issues in fuel system Whenever you find a problem in fuel system then it will be biggest cause of backfire through intake. Only during acceleration. If this gasket starts leaking, it would spell trouble for your engine. 150/250 and CN 250 Helix involves a backfire through the exhaust on sudden deceleration. I did all the FI tests timing is at reccomended 8 deg btdc at 800 rpm, checked for vac leaks, fuel press at constant 32 spikes briefly when reved to 40 and holds 30 for a. net/tdbyjn/psjdd. Engine stumbled when new once or twice a weekend, but wouldn't die. Backfires can cause it to rip. Backfiring through the carb can mean that at the time of the explosion, the intake valve isn't fully closed; i. why? Post by c4mo » Fri Dec 30, 2011 3:28 am The engine is fresh, just got done with the cam Breakin, I used Valvoline racing 20w-50 with Lucas Breakin for 20 min at 2000 rpm, once started it down not pop, except at high rev it will pop out the exhaust. The backfire is through the exhaust not the carb and happen when the throttle is opened up from idle (roughy 800 rpms) This started to happen after I changed the plugs, plug wires and removed the header to get the plugs. Backfire is often a result of unburnt fuel in the exhaust side, so unless you've jumped timing a backfire in and of itself will not likely cause any engine damage - might blow out a baffle, though. I have brought the boat into my local mercruiser dealer and we have not been able to overcome the problem, even with tech support from Mercruiser. If it's truly a backfire through the exhaust it's usually due to a lean condition. A strong explosion, though, can cause severe damage, like cracking an exhaust manifold. Hey gang, my amc 304 recently started backfiring through the intake and exhaust. A true backfire emanates from the engine compartment and is caused by unburnt fuel being ignited in the intake manifold. That term is used somewhat loosely. Since the intake and exhaust mods have caused the engine to run too lean, I have also installed an O2 Modifier to get rid of both problems, to no avail. what will cause my 2002 impala with 3. Another thing that I noticed was the brakes were VERY hard to apply. It won't, but a leaking intake valve will cause backfire through the intake. My engine is running great now. Can lack of sufficient fuel cause a backfire in the intake? I have a new fuel pump to put on, but how to check for fuel pressure on a carbureted engine? I don't think it is fuel pressure because after sitting at a light at idle it will pop and sputter trying to gain speed. It runs fine at low rpm but once I get over 2000 closer to 2500 rpm the boat will backfire. The C8's intake manifold has a volume of 14. Intake valves are almost always burnt if getting intake firing, but more than likely it's out of time (and isn't starting) if youre getting intake firing. Backfires get their etymology from firearms parlance when explosive force is released through the breech instead of the muzzle of an unreliable firearm. Valve adjustment (rocker arms actually). Turn it clockwise until it lightly seats (till it stops) - count how many times you've turned it (so you can put it back to it's initial setting if necessary). A hot muffler and gasoline with a high alcohol content may cause the engine to backfire, also. The backfiring is in sequence with RPM. replaced both upstream o2 sensors ( this killed the backfire issue ). com > Ford Diesels > Power Strokes 1994-1997 General > How and why does a diesel backfire?. 7? Backfiring is usually an indication of a lean condition. Now, Holley EFI products power these cars and are dominating the performance world. If adjusted too tight and valve barely seating could cause a miss. The regulator is on the back of the TBI unit and can be reached by taking the torx head screws of the top of the TBI unit. In fact, a backfire creates an explosion in the exhaust or intake of your engine. If the line is clean fuel can easily pass through the bike's engine and there will be no imbalance of air-fuel inside the engine to cause backfire. Ignition problems get worse during acceleration and valvetrain problems would do it all the time, no mater what. A strong explosion, though, can cause severe damage, like cracking an exhaust manifold. Did it backfire through the carb when it was bucking?. This type of spitting usually caused by the sparking in the spark plug as it is not turned on and also there is an open valve in the exhaust. Issues in fuel system Whenever you find a problem in fuel system then it will be biggest cause of backfire through intake. Timing set at 10 BTDC without spout. So does that alone cause the backfire?. When you say backfire, is it threw the exhaust or the intake? Its not real easy to check fuel pressure on these trucks but they are very sensitive to it not being right. Mind you, explosions are normal occurrences in engines, but they ought to ignite in the combustion chamber only. It can be very difficult to find the exact cause of a backfire as there are often multiple causes, and at times more than one cause occurs at the same time. Also, an explosion in the inlet manifold, carburetor/throttle body, or air cleaner of an internal combustion engine can occur when the intake valves are not shut prior to fuel combustion. This is due to the way diesel engine must introduce fuel into the engines. Because the mid-engine Vette situates its engine so low in the chassis, Chevy had more space above the engine block. I am thinking that the ignition, which is still being controlled by the Megasquirt, is too noisy and when the RPM's are going haywire that is when it backfires through the intake. 150/250 and CN 250 Helix involves a backfire through the exhaust on sudden deceleration. 3 Mercruiser backfires @ 4000rpm and above Is it backfiring through the carb or the exhaust? If through the carb I would first check for a vacuum leak you can do this by pushing the choke closed by hand. There are several small mechanical problems in the engine intake or exhaust system that may cause it. I taped it up a little to see if it would stop backfiring and it helped a little. It should die quickly if the engine speeds up and then dies you have a leak. what causes a fuel injected engine to backfire through the intake? i have an engine thats got gremlins! 3. If the valves are operating properly and the compression is still low, worn rings or bore are best fixed by installing a rebuild kit, shortblock or complete replacement engine. I've searched the internet and it looks like the cause could be anything: Lean condition at low engine speeds (pilot jet problem). A fuel-injected engine may backfire if an intake leak is present (causing the engine to run lean), or a fuel injection component such as an air-flow sensor is defective. You did not send a model number, so I don't know if the information I am sending you will be helpful. Once u pass that point it will take the throttle and run fine. Diesel fuel needs compression to ignite it and there is no compression in the manifold. - Off-Road Forums & Discussion Groups. Real backfiring is actually the bike "spitting up" in a sense, backwards through the carburetor or intake. The engine starts and runs fine, when I leave for or from work. I turned up the idle screw a bit and it stopped backfiring, unless you tried to choke it, then it would backfire. When you go to give it some throttle though, it starts spitting back through the carb and missing. Does your engine back fire and you don't know why? What causes a car to backfire? Here are five of the most common reasons why your car backfires. pressure regulator can cause backfiring. Valve problems can cause exhaust and intake back-fires depending which valve is causing the problem. I would first pull the valve covers and make sure all your valvetrain is in good order, no broken valve springs, all the pushrods are straight and are in the rocker arm. If it is an exhaust valve, it will backfire through the tailpipe. I didn't even really drive it, the engine hasn't been above 2K RPM, I am at a loss. #928607 Mon cause of your backfiring. The backfiring of an engine through the carburetor is known popularly as coughing or spitting. Show example Dodge Grand Caravan Engine is backfiring Inspection prices Engine is backfiring Inspection Service Engine backfires are one of the most obvious symptoms of car trouble, and they are annoying and potentially damaging to the car's exhaust and catalytic mechanisms. Project is not road worthy yet so only been running in back yard for now. Installed a new after market intake/exhaust manifold. of an intake or vacuum leak, however. Deceleration popping occurs when you close the throttle. Valve adjustment (rocker arms actually). GMC Jimmy Misfiring, Backfiring, Spark Plugs. Backfiring through the carb alone, besides being an ignition timing or timing chain issue, can be a burnt intake valve, or weak springs at higher RPM’s. It turned out to be the module in the Mallory Unilite distributor. While a backfire through the intake can be a camshaft position or crankshaft position sensor issue, a variety of other problems can cause a backfire. Then when I tried to start it,it backfired through the intake. So why is fuel igniting at that time? First thought would be timing has changed. Do you experienced engine backfire when you are cruising along a busy highway and hears a loud bang from your exhaust? That's what usually happens to older cars where an explosion can occur in the air intake or the exhaust system instead of the combustion chamber. It is often said that for an engine to run you need fuel, air, and spark. rcx6 said: Two years ago mine was experiencing the same symptoms and it was one of the coil packs was bad. Here are pics of a worn cam lobe and a relatively good lobe [2006 Volkswagen Jetta TDI, Engine/Propulsion Photo] [2006 Volkswagen Jetta TDI, Engine/Propulsion Photo] The car in question actually drove in with almost 1/4 inch of lift missing from an exhaust lobe and was backfiring into the intake when given throttle. But you also need compression and the correct spark timing. I would check base timing and then check timing fully advanced to see if something is retarding timing. Engine starts OK, idles OK, runs OK around the suburbs, etc. This causes the LIM’s carrier plate to weaken near the bottom of the air intake holes, allowing the large air pressure difference between the cylinder intake passage and the engine valley to suck the sealant bead around the air intake hole into the cylinder intake passage, as shown in this figure. The backfire problem is cured and there is not the slightest bit of doubt in my mind that the cause was as I have explained. So I figure the correct adjustment of the fuel mixture screw should help with the problem. Hey all, I am in a tough spot right now. The fix, involving replacement of the upper plastic (composite) intake manifold, gaskets, and peripherals is costly; but much less expensive than replacing the engine, which will have to be done if this repair is not completed. The more people who do, will cause B&S to look into this problem. Intake manifold air leak: A lean condition due to an intake manifold air leak can cause backfiring. no idea is this related, but last time I had any engine that backfired through the carb/throttle body, it was because the cam was shot. It was dead on I then checked the valves and the exhaust valves were a little too tight. If fuel pressure holds, then your coil may be weak in the secondary. You can just keep that disconnected and plugged till you get the engine running right. The Jeep Technical Service Manual recommends that, when you do this, you cover the air cleaner with a piece of plexiglass since the engine can backfire through the carb and a flame can shoot out. First thing that came to mind was a partially sheared flywheel key, causing the engine to be a little out of time. A pop in the exhaust is called a misfire. At the very least dirt is likely to get into the engine through that hole (both through the intake ductwork and through the valve cover). The boat has developed a backfiring problem above 2600-2700 rpms. net/tdbyjn/psjdd. The burning of the raw fuel is the source of your carbon. How do I diagnose this? Best regards, Kris. If it does not work, look down your carb (with the engine off) and see if it's shooting gas when you work the throttle. Exhaust can't leave to combustion chamber so it exits through the intake. An engine is not supposed to backfire and, when it is persistent, It could be harmful to the engine. Fiat was kind enough to partially refund my money spent ( less mileage can you believe it ? ) and i said i wouldn't bring a lemon law case up. I am just wondering myself! A diesel cannot backfire like a petrol engine. 7? Backfiring is usually an indication of a lean condition. Engine backfire is the result of incomplete combustion inside the combustion chamber. A worn camshaft lobe or bad timing chain could also be at fault. Backfire may cause an objectionable popping noise with possible loss of power and forward motion. Causes of afterfire, and how to fix them. The excess air and fuel mixture can travel to the intake manifold or through the exhaust manifold and detonate prematurely, causing a backfire. Due to strain from heat and the resulting contraction and expansion the gasket can get cracked. The PCV valve can act as a check-valve in these situations. Organize the links coming through your Twitter feed by site, topic and tweeter. 4: Backfires in Exhaust Note: It is normal for many high performance exhaust systems to moderately backfire or pop when the throttle is closed from mid-to-high rpm. I guess it's just because the power assist wasn't working, but I was standing on the pedal and could barely get the car to stop. Open Loop – The ECM monitors sensors positioned on the intake side of the engine and does not monitor the end result of internal combustion at the exhaust. sometimes it will crank right up but most of the time it requires very slight opening of the throttle,and sometime it cranks it butt off, backfires and caries on like the distributer is 180 out. So what's filling the hose and manifold is a nice mix of air and fuel vapor, so any hint of backfire might be enough to make that do what it'll do. Backfiring through the carb is one symptom of valve trouble. backfiring on acceleration possible cause The last few days, my KMD 150 GY6 would start dying at intersections and give an every-now-and-then backfire. Note: Backfire and afterfire through the carburetor will not harm the engine at all! Find out the most common causes and possible fixes for engine backfire and afterfire. CarComplaints. Second has VERY subtle backfires and bucking, but 3rd and 4th are the most prominent. While the cylinder is pressurized, rotate the engine through its strokes and see if you have any leaks other than your intake and exhaust stroke. The engine backfire through the exhaust ONLY and not all the time either ! Backfire through the driver side on the number 5-6-7-8 cylinders. (it's leaning out).