General Maintenance & Repairs - Backfiring...but no SES light

Alright, my car has been making a slight knockingish noise for awhile now, but recently it seems to have gotten louder, especially since I installed my LM1 exhaust. I thought it was the driveshaft, but my dad says he's 100% sure it's a backfire, and he knows a lot more than me. Backfiring would explain why it got louder with the LM1.

It makes this noise when I let off the gas, usually going down a hill, and it seems to be louder and more frequent the higher the speed of the car. It does it with the shifts, never at idle or in OD. The only thing is, I have never gotten a service engine soon light on it.

For the record, I saw the other thread about backfiring, but didn't want to hijack it, plus I'm guessing the root of the problem is different since there's no SES light coming on for me.

Thanks.

clean your maf sensor.
i had a dirty maf and ran super rich and missed like crazy.
clean it and run the car for awhile.

Should I just wipe it down with a towel? Perhaps some WD40? The previous owner descreened it, so I'm betting it's pretty dirty.

Should I just wipe it down with a towel? Perhaps some WD40? The previous owner descreened it, so I'm betting it's pretty dirty.


Very gently with a Q-tip and alcohol. Bend the Q-tip and clean the front of the 02 sensor strips in the maf. A couple wipes up and down both sensors should do it. Be careful, don't break them.

Get a scan though, it's probably a bad 02 sensor.


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scan your computer. You can have a miss and not throw a SSE light. Also when you clean the maf. Do as they say above. Just be very very very gentle.

Very gently with a Q-tip and alcohol. Bend the Q-tip and clean the front of the 02 sensor strips in the maf. A couple wipes up and down both sensors should do it. Be careful, don't break them.



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I think that it would be better if you were to spray the MAF with a quailty spray cleaner designed especialy for that task. Don't rub those little wires in the sensor. They are quiet sensitive. The spray cleaner would be your better choise.

Cleaned the MAF with some alcohol, and sanded down some of the ground connections (one really needed it), but still no luck. I'll get a scan it when I find my scanner. People have been telling me that a little backfiring is normal on performance cars, but I haven't heard of any LS1 guys saying that.

Mine would backfire if I let it go to negative engine load (i.e. foot off throttle, car in gear) and just barely touch back on the gas when the cutout is open but not when it's closed.

It mostly went away with tuning but still happens sometimes when it's cold out.

BTW: Are you running cats or no? That will make a difference.

My car does it also when the car is in negative load... I have the loudmouth exhaust as well and i've heard that it's more of a norm when having that exhaust. I wouldn't worry too much about it unless the car is totally running like crap. But mine has done that ever since i installed the exhaust so...

I've still got my cats.

I ran a scan and came up with nothing. It's not really that bad, and I plan to keep slowly modding it, so a tune isn't a great idea right now. I'm not going to worry about it untill there are flames shooting out my tips, and even then...that would be pretty cool.