Ok just one more idle problem question

[DMAN302]

Ok car runs fine but with spring and tune up time I decide to run a can of throttle body cleaner through the intake to see if I can clean out any junk. Now comes the problems..since then when I start the car cold the idle imediately drops to 1000 rpm which I think is a bit low for warm up, then when hot and driven idle will hang a bit around 1500 when I come to a stop and eventually find it's way down to about 1100 and stick or surge about 100-200 but never under 1100 rpm. So I remove my Iac and clean it out, put it back in and same..unplug it and idle settles down on the surging but still at about 1100 rpm...WTF!.sorry just some frustration, Then behold I find a broken plastic vac line off the tree marked AC so I figure tada i'm a brilliant mechanic so I plug the line cause it's for A/C and A/C is not here any more..and tada..no frigin change???????????? Someone help me out!!did I damage the IAC when spraying the TB cleaner while running the car?? or was it likely on its way out..or am I missing something all together different.??

 

[grippper]

did you try resetting the computer?

 

[DMAN302]

Update is new IAC and reset tps to .988, idle has much less surge and has good elevated idle at cold start but still wants to hang about 1100-1300 when warm..come on guys help me out here, no vac leak found.

 

[KDK1988GT]

Update is new IAC and reset tps to .988, idle has much less surge and has good elevated idle at cold start but still wants to hang about 1100-1300 when warm..come on guys help me out here, no vac leak found.

Idle screw on the throttle body? Set that.

 

[DMAN302]

Don't like playing with the screw it's not an idle screw it is actually a throttle stop and computer will not adapt to changes made there long term...thanks anyways, do tps go bad cause the raised idle with new iac after cleaning TB leaves me thinking tps may have gone out of spec even though it's reading .98 I wonder if it could be bad.

 

[KDK1988GT]

Don't like playing with the screw it's not an idle screw it is actually a throttle stop and computer will not adapt to changes made there long term...thanks anyways, do tps go bad cause the raised idle with new iac after cleaning TB leaves me thinking tps may have gone out of spec even though it's reading .98 I wonder if it could be bad.

does it look chewed up at all ?? I can't see it going bad from the new IAC and from cleaning the TB. I guess you could try a new TPS

 

[DMAN302]

I think it is cause the idle seems stumble a bit when it's leveled out around 1100 like the car is missing but then will calm down, then surge a bit then rough idle, and the rev's will hang at times during shifts...but I'll take input from anyone and KDK I do appreciate it.

 

[KDK1988GT]

NEW TPS

I think it is cause the idle seems stumble a bit when it's leveled out around 1100 like the car is missing but then will calm down, then surge a bit then rough idle, and the rev's will hang at times during shifts...but I'll take input from anyone and KDK I do appreciate it.

With the rev's coming up when you go to shift it sounds like the TPS is bad that would casue it to do this I had the same prob. The TPS sounds like it might be sticking a bit, not turning very smooth when the throttle is pressed in. I would get a new TPS

 

[RacinChris]

I think it is cause the idle seems stumble a bit when it's leveled out around 1100 like the car is missing but then will calm down, then surge a bit then rough idle, and the rev's will hang at times during shifts...but I'll take input from anyone and KDK I do appreciate it.

Updates? Were you able to get it fixed, DMAN?

 

[DMAN302]

Well I ended up pulling the upper intake when I found 2 stripped bolts on my Edelbrock upper to lower, the coner bolt hole on the lower was cracked!! So I put in new helicoils on the bad holes and pluged her all back together (HOPING THAT WAS IT). Then found throttle body butterfly was not closing all the way, removed it cleaned it. All done and said I had removed and replaced the IAC, TPS, EGR and selenoid not cause I like throwing money at problems but they were 16years old and beat pretty bad. Put it all back together..no vac leaks and reset the idle as per corral instructions and ....BAM perfect idle. Next day started car perfect idle, hit the gas and Idle jumped to 1500 and still hung during shifts...VERY VERY ANGRY..decided to drive the car some and found the idle to start to settle in better, I honestly don't know if problem is completely solved but car pulls no codes and seems to be learning to idle as I drive it if that is possible..bottom line is I will live with it cause I have done everything I can untill new motor goes in in september, and I want to drive the &ucken car tired of playing shade tree mechanic. To note I just picked up my new 3.73 set and rebuild kit which is going in monday!!!!I'll keep you posted on the install if you want.

 

[RacinChris]

Well I ended up pulling the upper intake when I found 2 stripped bolts on my Edelbrock upper to lower, the coner bolt hole on the lower was cracked!! So I put in new helicoils on the bad holes and pluged her all back together (HOPING THAT WAS IT). Then found throttle body butterfly was not closing all the way, removed it cleaned it. All done and said I had removed and replaced the IAC, TPS, EGR and selenoid not cause I like throwing money at problems but they were 16years old and beat pretty bad. Put it all back together..no vac leaks and reset the idle as per corral instructions and ....BAM perfect idle. Next day started car perfect idle, hit the gas and Idle jumped to 1500 and still hung during shifts...VERY VERY ANGRY..decided to drive the car some and found the idle to start to settle in better, I honestly don't know if problem is completely solved but car pulls no codes and seems to be learning to idle as I drive it if that is possible..bottom line is I will live with it cause I have done everything I can untill new motor goes in in september, and I want to drive the &ucken car tired of playing shade tree mechanic. To note I just picked up my new 3.73 set and rebuild kit which is going in monday!!!!I'll keep you posted on the install if you want.

Wow man, that sounds like a lot of stuff. Is it still hanging during shifts, even as it's learning to idle? During this entire time that you've been trying to fix the problem, did you ever just drive it around with the IAC disconnected? That's what I'm doing until I can get it fixed. Also, did you have a "Check Engine" light before you pulled codes, or does it not need to be on for you to pull codes? Maybe I should pull some codes, with the IAC connected.

 

[DMAN302]

I have no check engine light so I pulled the codes and came up with erg and related problems so I just replaced it and the selenoid mostly cause I don't want to have to worry about it after the new motor goes in, first sensors lasted 16years so I figure just prevent headaches down the road by starting fresh, maybe not the best idea but since I want a strong RELIABLE vehicle I have no problem spending a little to prevent future headaches. Having IAC unpluged works but doesn't solve the problem...unfortunately these damn cars are not always cooperative when it comes to idle..if it wasn't for the deeeeep love of my car I swear I would have dumped it long ago.

 

[lubeboy]

...i found my map sensor to be causing similar probs with my idle...and is your ac cutoff relay in good shape...i have an 88 gt as well...

 

[RacinChris]

...i found my map sensor to be causing similar probs with my idle...and is your ac cutoff relay in good shape...i have an 88 gt as well...

Interesting, somebody on a different Mustang forum told me to check the vacuum line to the MAP sensor, as it's usually the first to crack and fail. What was wrong with yours? What did you do to fix it?

I'll have to check mine when I get a chance.

 

[ironheart1]

Kinda unrelated, but since I'm having the exact same issues on my '88 I figured I'd ask.. Where are the IAC and MAP sensors located? Before reading this thread I was going to try the TPS but that seems like it may or may not be the problem. I love this car to death, or I too would have dumped it.