Car stalls:What else could it be

[usp55]

I have been battling a stalling problem for weeks now with no luck.

Problem: from a stop when i go to apply pressure to the gas the car hesitates, then goes. sometimes so bad that it stalls and other times it wont do it at all.
When i come to a stop and put it into neutral the rpm's go up ad hold at 1300-1500 for a few seconds then return to 900-1100 ( normal idle). Most of thetime if i put it in drive it will stall after being in neutral.

Things ive changed that i thought might have been the problem.
-fuel pump(fixed the hard starts-back check valve on old one)
-TPS
-cleaned idle air control (thinking i should buy a new one)
-new sparkplugs
-new wires
-

I cleaned the IAC really good with carb cleaner and most of the carbon buildup came off. What else could it possibly be?


oh and when it stalls, i cant get it to fire back up. very hard start. have to floor it once it fires up.





any thoughts?

[cam98aro]

Re: Car stalls:What else could it be

that really sounds like a bad IAC or your engine is flooding out

take your iac sensor out, and put the key to "on" and see if the IAC moves in and out

[ne0hisda0ne]

Re: Car stalls:What else could it be

codes?

[usp55]

Re: Car stalls:What else could it be

that really sounds like a bad IAC or your engine is flooding out

take your iac sensor out, and put the key to "on" and see if the IAC moves in and out

what would cause it to flood?

im gona pick up a new iac tomorrow, was really hoping it wasnt that cause thats an expensive sensor and im dumping all my money into my 71 firebird build.

no codes

[cam98aro]

Re: Car stalls:What else could it be

what would cause it to flood?

im gona pick up a new iac tomorrow, was really hoping it wasnt that cause thats an expensive sensor and im dumping all my money into my 71 firebird build.

no codes

bad FPR maybe.. or bad injectors

im not saying that is the reason, but those are exact symptoms of getting too much fuel

what did the spark plugs look like before you replaced them, if they wernt black, i would say IAC

[z38camaro]

Re: Car stalls:What else could it be

hey man.



i have the ANSWER.


my car did the EXACT SAME THING a few weeks ago.



here is a thing that will save loads of time.



1st step.
(take maf sensor out) "clean it with maf cleaner or break parts cleaner."
2nd step.
(put it back in {after its dry}) and then turn the car on.


take a screw driver. and lightlY with the plastic handle. (with the car running in park at idle) lightly tap the top of the maf sensor and if the idle changes. or the cars sounds different or anything for that matter.


that means the maf sensor is basically...."screwed"
(replace it if that happens)



and if not then your tps sensor is malfunctioning.

if both of those things are NOT broken and work fine.


MAKE SURE the moisture is out of the connecting boots of ALL the sensors on the throttle body.





last but not least.

if you do alllllll that and its stilll not running right.




buy a chemical called SEA FOAM and run it through your break booster line.


that should clear up all the carbon build up in your combustion chambers and clean out your whole top end.



if allllllllllll that doesent work,

then you got some problems lol haha


hope everything works out man

[ne0hisda0ne]

Re: Car stalls:What else could it be

sounds like an ICM or a coil....

[tkoforpresident]

Re: Car stalls:What else could it be

3.4's don't have a MAF....

[usp55]

Re: Car stalls:What else could it be

ok just put the new iac on and same problem. now even when coasting the idle seams high. also pulled into my driveway and the idle was around 1500 and it held till i put it into neutral then reverse and it stalled.


what s the sensor on the elbow of the intake? only one i havent changed


oh, plugs looked good. they had about 30k on them and had proper color and gap.

any way to test coils?

oh and what should the fuel pressure be?

[cam98aro]

Re: Car stalls:What else could it be

thats the IAT sensor

its possible for it to be bad, and the car is dumping fuel into the engine.. but you say the plugs looked fine

i dont think it is a coil, usually a coil would cause a misfire, and i have never heard of a misfire causing the engine to have higher rpm's.. but i think you just use a DMM and check the resistance of the coil to see if it is within spec

fuel pressure should be between 41-47psi with the key in the on position and car not running, and should decrease by 3-10psi after you start it up

[usp55]

Re: Car stalls:What else could it be

ok changed the IAT and it was idle better but still after a 5 min drive, i still had a hesitation problem. fuel pressure is right at 40 so maybe ill bump it up a little.

running out of ideas

[nimrod.sixty9]

Re: Car stalls:What else could it be

Clogged CAT?

[Mighty Thor]

Re: Car stalls:What else could it be

I'm almost willing to beat that IAC is the culprit.

I didn't know 3.4 doesn't have a MAF. My 2.8 has it.

[z38camaro]

Re: Car stalls:What else could it be

did you even try any of my suggestions?

[ssms5411]

Re: Car stalls:What else could it be

3.4's don't have a MAF....

LOL, Yes they do not. I would check for vacuum leaks or EGR if you have one on the 3.4's since it sounds like it is acting up when it is in open loop any codes? Can you scan for your O2's to see if one has taken a dump or any exhaust leaks in engine or down at the Y pipe or the crossover pipe from the headers , since you replaced the IAC, TPS. What scanning can you do on your 3.4?