Backfire problem when at high RPMS?? - Performance Forum

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Backfire problem when at high RPMS??
Thursday, July 20, 2006 12:24 PM
Well this started last year before i put the car away for storage, When i gave it all she has and the car got up to 5500-6000rpms it would like all of a sudden make a loud backfire pop noise ( very embarassing) So I swapped new 8mm Accell wires and new AC delcos gapped to .040-.045 since thats what my Haynes manual told me to do. Those ones that were in there were at .030??? but low and behold that cured the problem. Now after storing the car for 6mos, its doing the same @!#$ again. I now have Nology hot wires and MSD igniton coil pacs on there brand new just installed this spring and plugs look fine and are still gapped where i put them. So this has got me stumped now...

Only things that do seem odd are.. My gas milage sucks major ass. I am at like 60 miles and just a smidge on the good side of 1/2 tank which is really bad. But i am thinking thats because 3/4 of the gas in the tank is 11mos old with fuel stabilizer in it and 1/4 fresh gas from mobil. I'm waiting to kill this tank to empty and fill it up with some fresh 93 octane and super concentrated fuel injector cleaner.

Anyone suggest anything else?




Re: Backfire problem when at high RPMS??
Thursday, July 20, 2006 12:40 PM
id guess that its the fuel, since its old it might be causing the motor to act funny, if all the ignition parts are new(er) then that shouldnt be it... wait untill you get rind of this old gas and give it some fresher fuel and see if its still acting up.
Re: Backfire problem when at high RPMS??
Thursday, July 20, 2006 2:18 PM
o2 sensor?



Re: Backfire problem when at high RPMS??
Thursday, July 20, 2006 2:45 PM
when the engine is cold and you crank it when it hits the rpm limiter(fuel cutoff), its going to make poping sounds. if you have an automatic its hitting the limiter somhow.



Re: Backfire problem when at high RPMS??
Thursday, July 20, 2006 4:55 PM
Its does seem like its hittening the rev limiter actually, because when it does that it then goes into the next gear. Its like POP.. and then it shifts. It does seem like the car takes awhile to shift actually. Because the car hits the power band and pulls like she should, but then around 5500 and up it dogs a bit. and dosn't really seem to do much. But the car is still climbing in RPMS and speed, just don't feel it in my Butt-o-meter. With in the next month, i should have my full new exhaust installed with 4-1 header which hopefully will take care of that slump in the power band up top. I will probably also replace both o2 sensors since they are seven years old anyways.

Any idea why I would be hitting my rev limiter?

I'm not breaking traction either.


Edited 1 time(s). Last edited Thursday, July 20, 2006 4:59 PM


Re: Backfire problem when at high RPMS??
Friday, July 21, 2006 8:21 AM
get your tranny checked out. it might be the clutches inside the tranny.
Re: Backfire problem when at high RPMS??
Friday, July 21, 2006 12:23 PM
slasherz24 wrote:get your tranny checked out. it might be the clutches inside the tranny.


Well i will try the easy things to check out first and see if those cure the problem first. I do have 1 year left on my cars extended warrenty... ( however its going to be fun to deal with the dealership now that my car is in this condition)



Re: Backfire problem when at high RPMS??
Friday, July 21, 2006 1:25 PM
missed the edit by 1-2 mins..

edit - Well i just took her out for a spin and it only did it once. So its a freak thing thats only happening once and a while. The transmission shifts really smoothly... So i am thinking its either o2 sensors, or something is dumping too much fuel or who knows. But i will start with those and maybe some Denso Iridium plugs.



Re: Backfire problem when at high RPMS??
Friday, July 21, 2006 3:54 PM
Ask someone with a motorcycle what they do with their bike when they store it for the winter. Sounds to me, like you have bad gas (which will start going bad after about a month) and when you get the car running with the crappy gas, you foul out the plugs. (i had it happen on my bike).

Get some Sta-Bil. It's a fuel stabalizer, inteanded for storing your car. Also, when you put the car away, you want it to have as full of a tank as possible. That way you dont have a chance of getting moisture in the tank.





Re: Backfire problem when at high RPMS??
Friday, July 21, 2006 7:54 PM
SHOoff wrote:Ask someone with a motorcycle what they do with their bike when they store it for the winter. Sounds to me, like you have bad gas (which will start going bad after about a month) and when you get the car running with the crappy gas, you foul out the plugs. (i had it happen on my bike).

Get some Sta-Bil. It's a fuel stabalizer, inteanded for storing your car. Also, when you put the car away, you want it to have as full of a tank as possible. That way you dont have a chance of getting moisture in the tank.


I did just that man... added a couple ounces for 15 gallons and stored her with a full tank, pulled the plugs and shot some fogging oil into the cylanders and turn it over a couple times. Started up just fine man on the first crank actually... But i am sure its a mix of bad gas or some thing.



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