420a Idle problems??? help please

[x4g63x]

ok ive done the reserch and cant find anything usefull but my 96 talon esi when i starting jumps up pretty high like in the 3-4000 range and then slowly dies back down to idle at 8-900 but when i just rev it back up to 4000 it takes forever to come back down to idle??? and now for the seconed prob that i encountered today my car shut off when i came to a stop and did it again like 4 times after that??? what would randomly make it do this??? i have an idea of the possible problems and one could be that my battery isnt the strongest and i was wondering if it could be an ISC or vac leak or the idle pulley or something else minor i just put msd wires on it so i dont know if that would have anything to do with it? not a real big 420a genius more of a 4g63 guy unfortunitly i sold my 91 tsi and now i have to deal with an esi but any help would be greatly appreciated, thanks

 

[95TalonOwner]

If you sold your 91 4g63 then change your profile so people don't get confused.

Anyways, you prob have a bunch of vacuum leaks and that's why it takes forever for your idle to come down. It could also be your intake gasket.

 

[poonman]

my car does the same crap bro, after going to shops and useing my buddies 3000 dollar machine we both found out that AFTER changing the IAC motor and replacing the PCV valve along with EVERY sensor under the hood that its the ECU, I bet you have the p0505 Cel dont ya?

 

[x4g63x]

i havnt checked but i probably did through the the cel code p0505 so you think its the ecu all together and not an IAC or anything else?

and as for the 95talonmember i havnt been on here for a few months so i didnt have a chance to change anything for my car info yet but thanks for your input

 

[poonman]

see the thing is, is that the IAC is controlled by the ECU and nothing else, if your IAC is moving and your still getting the p0505 code then check your risistance from the ECU to the IAC and if all your signals are good then yes your ECU is done for.

Im acually finding out latley that there is a big issue with the ECU and IAC's on alot of ppls cars.

it even screws up the ms pulse on my injectors., Ecu is expensive so what works for me is i just hold the pedal down about 1/8 when starting and left off and it stays idling fine it just has a slight lope to it but hey thats fine, sounds like i have cams

 

[Locke]

i havnt checked but i probably did through the the cel code p0505 so you think its the ecu all together and not an IAC or anything else?

and as for the 95talonmember i havnt been on here for a few months so i didnt have a chance to change anything for my car info yet but thanks for your input

see the thing is, is that the IAC is controlled by the ECU and nothing else, if your IAC is moving and your still getting the p0505 code then check your risistance from the ECU to the IAC and if all your signals are good then yes your ECU is done for.

Im acually finding out latley that there is a big issue with the ECU and IAC's on alot of ppls cars.

it even screws up the ms pulse on my injectors., Ecu is expensive so what works for me is i just hold the pedal down about 1/8 when starting and left off and it stays idling fine it just has a slight lope to it but hey thats fine, sounds like i have cams

A lot of people do seem to have idle problems with the 420a, and the '95 ECU's are more likely to go bad than on other years. ECU's aren't cheap, and most often are not the reason for people experiencing high and holding idles.

First, check for vacuum leaks, second pull the IAC and clean it. It often gums up, which causes it to react very slowly. You can also test it, 38-52 ohms between 1-4 and also between 2-3. Third, while you are cleaning and testing the IAC, you will want to clean the TB plate and bore. There can be deposits here that allow air to get past the plate when closed, and it may take a short moment for the IAC to compensate.

Start with those most common problems, then go from there.