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Probationary Member
From: Buffalo, Missouri
Registered: May 2006
Reputation: 
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Persistant Idle Issues. Won't idle at start, high idle at times. Check engine light.
Please note that I'm discussing the 420a engine, not the 4G63 turbo motor. Thanks!
Good day all,
I've been "living" with this problem for some time now, and have done numerous searches here on the forums in hopes of gleaning some information to help me resolve it. I haven't had much luck as of yet.
I've got a 1996 Eagle Talon ESi, 420a non-turbo 2.0L engine, manual transmission.
I can't remember exactly how it started, or even how it acted initially, but I'll describe what happens currently, and what I've done to try and fix it to this point.
Please keep in mind, these symptoms happen intermittently. No 2 days seem to bring the same behavior, and weather does affect it.
If outside temperatures are 55+ degrees Fahrenheit, the car will usually start just fine, and idle around 900-1100rpm. If outside temperatures are colder, say, 35 degrees Fahrenheit or colder, the car will more often than not just start and stall immediately. This will necessitate me having to hold the throttle open for a few minutes, and then gradually let off, hoping the engine doesn't stall out. Sometimes this works, sometimes not. In the instances where it doesn't, I generally give it a bit to warm up, then just drive.
Now, once the engine is up to operating temperature, several different things can, and do happen. Sometimes, the idle will hover in the 1,500 - 2,000rpm range when coming to a stop, with the tranny in neutral. Once you come to a full stop, the idle will then slowly drop down to the 1,100 - 900rpm range. However, sometimes it won't, and it will just continue to hover in that higher range. I've had many trips where the idle will just "stick" in that 2,000rpm range, no matter what I do. Sometimes, I can blip the throttle quickly a few times, and the idle will drop. Other times, I do the same blip, and the idle will go higher, say, 3,000rpm, and then hang there.
Needless to say, this is frustrating.
The "Service Engine Soon" light has been on during this entire time as well. I do not have a scan tool to see what codes exist, and the light does come back on even after a long term battery disconnect. So, I know there's an issue, I just can't pinpoint it. I had a friend who has a shop attempt to get the codes with his Snap-On scan tool, but when connected to the diagnostic port, he merely gets a "no communication" message. He's told me to check for blown fuses, which I have, but all are good. One item to note, is that I have disconnected the SRS module from the wiring harness, due to having an aftermarket steering wheel installed, and having the driver's airbag removed. Is it possible that having the SRS module unplugged could be causing the rest of the system to become unreadable via the diagnostic port inside?
As I've said earlier, I've done a ton of searches on this forum, and other sites, and some common suggestions have been to; a) check for vacuum leaks, b) check and clean the throttle body, c) check and clean the IAC motor, d) check the IAC motor for worn spots on the tip. I've done all of the above, with the following results; a) no vacuum leaks were found, b) I cleaned the throttle body on the vehicle with the solvent spray, which caused the engine idle to stick at 4,000rpm until I took the car for a drive, while constantly working the throttle. It eventually went back to "normal", but the 4k idle freaked me out. c) I pulled the IAC, found it dirty, and installed a replacement. This had zero effect on the symptoms. I checked the resistances on the IAC, and the resistance on the pins was within spec (about 35-50ohms). d) was handled with the changing of the IAC, which has not fixed the condition.
The last item that has been mentioned in my searches on this issue, relates to issues with the ECU. Many have said the ECU controls the IAC, and this could ultimately be my issue. ECU's can be had on eBay, and via local scrapyards, but before I go that route, I wanted to see if you all had any further suggestions for me.
What have I missed? What have I done wrong? What else can I try?
Thanks for your assistance!
Last edited by uncooldude; 12-07-2011 at 09:14 AM.
Reason: Adding 420a engine note.
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