car hesitates/backfires under acceleration

jorge mr · Nov 30, 2008, 08:30 AM

hey guys been doing a search for awhile and still cant figure it out!
during the summer my car runs great no problems, but its getting cold again so this problem keeps happening. at wide open throttle during 3rd or 4th gear, around 4500 rpms the car will back fire or hesitate while my foots on the gas pedal and whenever this happens, its a pretty aggressive hesitation!!
sounds weird but it only happens in the winter time noticed it when i installed the greddy profec b spec 2. switched it out for an ams mbc and its still doing it

my car is an 06 mr.
turbo back, fmic, lower ic pipe, mbc, k&n filter all by ams

any help would be appreciated cause this sucks!!!

Evoryder · Nov 30, 2008, 08:34 AM

1. is your car tuned?
2. changed your plugs or even checked them?
3. Clean your maf sensor.
4. I don't think you REALLY searched.

Mellon Tuning · Nov 30, 2008, 08:36 AM

sounds like he's hitting fuel cut, needs to be tuned

wevo1985 · Nov 30, 2008, 08:44 AM

Quote:

Originally Posted by Mellon Tuning

sounds like he's hitting fuel cut, needs to be tuned

+1, i had that problem with my black evo, cool air and anything above 20psi will do this

Sharkbite2000 · Nov 30, 2008, 08:46 AM

Check your plugs first and then your boost

cthcky5 · Nov 30, 2008, 08:58 AM

listen to these guys. they hit the nail on the head

gsrboi80 · Nov 30, 2008, 09:01 AM

Probably seeing a tad more boost cause of the colder air.

Has the car been tuned cause if not theres you problem. PM the third guy in this thread

jorge mr · Nov 30, 2008, 09:17 AM

plugs were changed 6k miles ago, my boost level is at 23 psi then tapering off to 20 yesterday i did see 24 no too much difference just a little, my car has had a miled tune as well as he has logged my car while doin a small tune cause this occured with him in he car the reason for the miled tune over an aggersive one was for the fact that my wideband has not yet shown up cant really do a aggresive tune without a wideband apprecitae all advise and am hoping my wideband shows up to see if this will fix the problem

braizedtofu · Nov 30, 2008, 02:30 PM

wow, what kind of tuner is tuning your car without a wideband? Sorry its annoyign me that you keep saying miled... its mild.... like mild salsa... anyway post some logs, if you are knocking hardcore its possible your car will pull back timing or fuelcut. If you can get to 4500 and your boost sounds okay then most likely your turbo is okay and it is your tune. imho wait till you get the wideband you cheap/impatient/lazy ass, and redo the tune

Why risk gaining a few hp at the risk of blowing/wearing things out

apagan01 · Nov 30, 2008, 02:35 PM

Quote:

Originally Posted by Mellon Tuning

sounds like he's hitting fuel cut, needs to be tuned

i was going to say Mellon, maybe lean condition because when cold he is over boosting pulling timming.

agreed need to be re-tunned

Evoryder · Nov 30, 2008, 02:38 PM

i was thinking boost cut also. Back to: 1. are you tuned? Looks like not very well.
With the cooler ambient temps your maf is passing more air through it just like upping the boost would create more airflow.
To combat this issue your tuner has to tweak the boost limit area or you will have to lower the boost 1 turn down to stay within your current *boost limit* range.

Contact mellon for further assistance for questions vs creating threads that have been made before.