Espey16 Posted February 25, 2023 Share Posted February 25, 2023 Hey guys I'm back. My 89 GL used to not idle at all upon cold start. After finally replacing the MAF it would idle. It would idle high upon startup then drop down to normal once the car was warm. I recently pulled the engine to replace the clutch among other things, but now it doesn't idle high anymore on a cold start. I did the work in September if I remember correctly, and I've been daily driving it since. It runs well just won't warm up in the mornings. Is there anything you can think of that maybe I missed or need to replace? Quote Link to comment Share on other sites More sharing options...
Espey16 Posted February 25, 2023 Author Share Posted February 25, 2023 I was thinking of throwing my timing light back on it to make sure that's perfect, and also re calibrating my TPS. I just did that recently though. Quote Link to comment Share on other sites More sharing options...
el_freddo Posted February 26, 2023 Share Posted February 26, 2023 Check for vacuum leaks. Cheers Bennie Quote Link to comment Share on other sites More sharing options...
Espey16 Posted February 26, 2023 Author Share Posted February 26, 2023 Just spray some starting fluid around the motor while it's running? Quote Link to comment Share on other sites More sharing options...
el_freddo Posted February 26, 2023 Share Posted February 26, 2023 I’d go with something less or not flammable such as WD40, but yes, with the engine running spray it around any joints in the manifold, injectors/carb, vacuum lines etc. Cheers Bennie Quote Link to comment Share on other sites More sharing options...
Espey16 Posted February 26, 2023 Author Share Posted February 26, 2023 Ok, I didn't think WD would work. I'll check that out in a little bit. Quote Link to comment Share on other sites More sharing options...
Steptoe's photos Posted February 27, 2023 Share Posted February 27, 2023 High idle for cold starts comes from air bypassing the throttle plate by electro means - a solenoid air valve. The early mpfi EA82 used a bimetal spring control device that needed ign voltage to start it up. Is yours a spfi beast? If so, I know zip about them. Quote Link to comment Share on other sites More sharing options...
DaveT Posted February 28, 2023 Share Posted February 28, 2023 Check the CTS and wiring for it. Its the 2 wire sensor on the lower thermostat housing. Quote Link to comment Share on other sites More sharing options...
robm2 Posted February 28, 2023 Share Posted February 28, 2023 Coolant Temperature Sensor (CTS) or Idle Air Controller (IAC). LIke DaveT says, check the wiring on the CTS. Same goes for the IAC. Another thing to try: The IAC has a stepper motor that opens and closes to provide the correct idle speed. Shoot it full of carb cleaner, let it soak a bit, and turn the engine on and off a few times to work it. Quote Link to comment Share on other sites More sharing options...
Espey16 Posted March 1, 2023 Author Share Posted March 1, 2023 I replaced the CTS back before I found out the MAF was faulty, it's the one with the green plug. And the IAC was cleaned out when IL pulled the engine to reseal it and do the clutch swap. I'll check both of those again though this weekend. Quote Link to comment Share on other sites More sharing options...
Espey16 Posted March 1, 2023 Author Share Posted March 1, 2023 Yeah, it's spfi Quote Link to comment Share on other sites More sharing options...
Steptoe's photos Posted March 3, 2023 Share Posted March 3, 2023 If only we had a central reference for all these items - in Ohms readings for the operation range. I made notes somewhere of the Ohms of the CTS from cold to op temp, partly to know what to look for and expect and maybe to bypass a dud CTS with a known resistance for op temp to see if problems resolve. If you knew all the inputs the ECU likes, give it what it likes manually to see if problem goes away - you found your problem. More auto electrical bible publication stuff not exposed to general public on the internet Quote Link to comment Share on other sites More sharing options...
el_freddo Posted March 3, 2023 Share Posted March 3, 2023 I believe @DaveT did this with the CTS for the SPFI system years ago. Maybe Dave can dig up his post on this info? Cheers Bennie 1 Quote Link to comment Share on other sites More sharing options...
DaveT Posted March 3, 2023 Share Posted March 3, 2023 Here is my collection of CTS info - 1 Quote Link to comment Share on other sites More sharing options...
Steptoe's photos Posted March 5, 2023 Share Posted March 5, 2023 Oh....mine were a bit different. I think I recorded the Ohm reading every 10 degrees or so as displayed on my digital gauge with sensor on the thermostat bolt Quote Link to comment Share on other sites More sharing options...
Espey16 Posted March 11, 2023 Author Share Posted March 11, 2023 Hey guys, I apologize for no updates yet. I've been busy with a couple projects around the house and haven't had a chance to get to the car. I appreciate the replies and information you've given. Quote Link to comment Share on other sites More sharing options...
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