Smart guys, come in please

[cmb91LX]

Alright guys, I have been having a problem with the 99 lately. Whenever I get in and drive for a while and say, stop at a store for gas, a drink, etc. the car will crank right up when I get back in but it hunts for an idle and many times will die altogether until I hold the throttle for a few seconds to steady it. IAC is good. I have an "EVAP CONTROL VALVE" code along with several O2 sensor codes coming from the processor. Could these be the culprit? The car starts fine the first start every morning BUT after a short drive and cut off, it doesnt want to hold an idle. TPS is at .98. I dont get it, could the above mentioned codes be causing this? Help me out guys

c

 

[Cali03Boss]

friend had a similar issue on his SS. It was the butterfly, it wasn't opening and shutting correctly. I'd take off ur CAI or whatever intake thing you have and check the butterfly.

 

[cmb91LX]

butterfly=throttle blade?

What kind of fix can I do for that. Lubricate?

 

[Cali03Boss]

butterfly=throttle blade?

What kind of fix can I do for that. Lubricate?

yea the butterfly is the little blade that turns when you give it gas. Anyway, my friend and I fixed his car by replacing the spring that controled it. Apparently Chevy did a bad job and when you floor it a lot it can bend the spring out, leaving free movement of the butterfly during idle. You can do one of two things, check the spring and replace it, or take it to the delor. I'd replace the spring for starters, then also make sure the butterfly stopper is still in place. If it's not in place the butterfly will close completely and kill the engine

 

[RysRed96GT]

i doubt it's your butterfly...mine never got loose like that.

what are the codes you're getting for the O2 sensors? u sure the IAC is good? got a vacume leak around the plenum? does it hesitate under load/WOT?

 

[cmb91LX]

i doubt it's your butterfly...mine never got loose like that.

what are the codes you're getting for the O2 sensors? u sure the IAC is good? got a vacume leak around the plenum? does it hesitate under load/WOT?

I am getting front and rear bank O2 codes, like 8 of them. No hesitation with throttle at all. Only a hunting idle when started after a short drive. 2nd IAC since I have had the car since 99, it is good for sure, different symptoms, it will run fine after a minute BUT as soon as it cranks the RPMS go to about 1500 RPM and immediately drop to 1-200RPMs and sometimes surge back up but mostly try to die until I hold the RPMs steady for a minute. ????

 

[StangLou]

That still sounds a lot like its a bad IAC. Bad 02 sensors can cause a bit of a rough idle, but it should be a maintained rough idle, not clear up after a few minutes. That just screams IAC if its clearing up after your on the gas a bit. How do you know your IAC is "good?" The only other thing I could think of would be your mass air meter. If you recently oiled your air filter, oil could be getting on the sensor and making it act all wacky.

Just read that its your 2nd IAC. Sadly that doesnt mean squat man. I had 3 on mine within 6 months. 1st one was the stock IAC, ford replaced it, next day ford replaced that IAC since it was bad from them. A few months later I had the same problem, went back and they replaced it again.

Mustangs seem to eat up IAC's

 

[cmb91LX]

Maybe, I have been misled. I was under the impression that if you could shake the IAC and the valve moved freely on the shaft, then it was good. Besides wouldnt the car do the same thing on cold starts if it was the IAC? It should do it at every start if that was bad, right?

 

[RysRed96GT]

i never heard mine shake before. it's an electric motor that opens and closes a valve. mine did it randomly before too. sometimes it would open fine, but other times it would be stuck from the dirt that it would take a vacume from opening the throttle to pull the iac valve open.

 

[cmb91LX]

Hmmmmmmm.......

It doesnt shake while installed, rather when taken off the intake and shaken by hand I can hear it slide up and down with no sticking

 

[jbrown]

try spraying some tb cleaner into the tb with the car running after you take off your air intake. Check your tps too.

 

[cmb91LX]

TPS is at .98. Will cleaning the TB solve the warm start problem? It only does it after it has been running for a bit.

 

[RysRed96GT]

try spraying some tb cleaner into the tb with the car running after you take off your air intake. Check your tps too.

cant remove the intake hose while the car's running, it'll stall. remvoe the TB and just clean it by hand with carb cleaner or degreaser.


also, im assuming you're getting a p1443 code? this is the evap control failure one. this has to do with the purge system. either check your purge valve sensor (follow the hose coming off the rearof the plenum, you'll come to a black L-shaped sensor with a plug, that's it). but since you're having more problems (such as start-up issues), it might be the purge canistor or valve. now im not sure exacltly where this is (i had this code before and it was only the sensor going bad), but both are pretty cheap. do a google search for the location of this canistor and valve. but im pretty sure they're somewhere on that hose if you follow it back further. this problem would also effect your idle.