occasional pop after acceleration
#1
07-17-2009, 06:30 AM
occasional pop after acceleration
Since installing the wizaird CAI and zzp 3 inch down pipe with high flow cat, I've been noticing a slight backfire on occasion after I let off the gas after moderate to hard acceleration. Its not very loud and can't be heard with windows up but I know it wasn't there before. I know a backfire through the exhaust usually means a rich condition, but the new parts were meant to increase air. Check engine lights not on, no stored codes and it runs great and has plenty of power and gas mileage is still good. Is this backfire something to worry about, or just a side effect of a bigger downpipe? I plan on borrowing a tech 2 from work tonight to see if the occasional 1 KR is gone after the new parts were installed, should I check any other data while I have the scan tool?
I haven't installed copper plugs yet so I'm still running the factory platnums, but I did buy a set of new, colder plugs and will hopefully install them tonight. Could the platnum plugs cause it? Another thing is I've never cleaned the MAF and I know its probably never been done so I'm going to clean that as well. Thank you for any input
I haven't installed copper plugs yet so I'm still running the factory platnums, but I did buy a set of new, colder plugs and will hopefully install them tonight. Could the platnum plugs cause it? Another thing is I've never cleaned the MAF and I know its probably never been done so I'm going to clean that as well. Thank you for any input
#2
07-17-2009, 06:43 AM
Below found on Web Search.
Hopefully our Expert Member Tech will add/comment
to your Post Question. Good Luck & let us know what
your tech advises.
To me it sounds like a air flow sensor ?
I hope the below infor helps or gives you some idea's on
your prob...
Backfire in an automobile engine typically results from various malfunctions related to the air to fuel ratio. Usually, backfiring occurs in carbureted engines that are running lean where the air fuel mixture has insufficient fuel. ("Running lean" is typically a sign of mal-adjusted carburetors or fuel injection where there is not enough fuel for the amount of air). Afterfire occurs in engines that have an emission system malfunction (air injection system diverter valve), exhaust leak or unburnt fuel in an exhaust system in which the catalytic converter has been removed. When a driver shifts up and lets off the accelerator, the engine has a moment of running rich or with insufficient oxygen. This causes an incomplete burn which causes the fumes to explode in the exhaust system. The leak itself is the most dangerous aspect. Without it, the mixture would cool enough not to explode. 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.
Common causes of backfires are:
Timing – If car is distributor-less
Timing – If a two stroke engine is backfiring every other stroke.
Fuel pressure, fuel filter and pump – leaks and corrosion could cause lack of fuel during the fuel injection event.
Bad wiring in ignition – ..if car won't run for more than a few moments.
In older engines, backfiring may be considered normal. Backfire is rare in modern cars with fuel-injection and computer-controlled fuel mixtures.
Common causes of back fires in the intake manifold are bad spark timing, or incorrect (usually lean) fuel ratio.
When starting an engine, timing that is too advanced will fire the spark plug before the intake valve is closed. The flame front will travel back in to the intake manifold, igniting all of that air and fuel as well. The resulting explosion then travels out of the carburetor and air cleaner. A common air filter will allow the gases to escape, but will block the flame front. On many small marine engines, no air filter is used, but a screen is placed over the intake of the carburetor as a flame arrestor to prevent these flames from escaping the intake, and potentially igniting fuel, or fuel vapors in the enclosed sump or bilge of the boat and causing a fire or explosion. Improperly adjusted carburetors that create a lean condition during acceleration can cause the air fuel mixture to burn so slowly, that combustion is still taking place during the exhaust stroke, and even when the intake valve opens. The flame front can then travel up the intake and cause a backfire.
#3
07-17-2009, 11:21 AM
Thank you kidspace, thats some good information. I was leaning towards the airflow sensor. I'm gonna clean it today when I put in the new plugs and then take it for a ride with the tech 2 and watch KR and fule trim. I was talked into getting ngk v-power coppers that are colder then the stock plugs and are suppose to be really good. They were only $1.50 each so if I'm not happy with them I'll get a set of autolites
#5
07-24-2009, 11:26 AM
I guess I was wrong, id didn't go away, I heard it a few times yesterday. I'm just confused as to what it could be. Nothing looks unusual as far as data goes, fuel trims are normal, no KR, there's no codes and gas mileage is great. I know the pop is not normal but I guess I won't worry about it until I start getting other symptoms, like gas mileage problems or a check engine light, unless someone knows of anything else I can look for
#6
07-24-2009, 12:12 PM
Timing used to be a issue on late 90's distributor less cars, but it was top dead timing or base timing. probably have to do more info but I would suggest checking if it needs to be adjusted after upgrades.
When i get my high flow cat I'll ask then also just for info.
When i get my high flow cat I'll ask then also just for info.
#9
07-24-2009, 07:51 PM
to adjust it you may be able to do it with computer, but i would check with the manufacturer of the upgrades and see what they recommend.
other then that you have to look up how to use a jumper to set it back to default, while thats done it will run odd and then adjust with the diag tool as necessarily.
again i would check before trying to adjust it, fk it up and things can go bad
other then that you have to look up how to use a jumper to set it back to default, while thats done it will run odd and then adjust with the diag tool as necessarily.
again i would check before trying to adjust it, fk it up and things can go bad
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