Tabiji Posted September 23, 2012 Report Share Posted September 23, 2012 92 Lumina 3.4 Euro automatic. The car has been doing great all summer. Now that we have cooler mornings, I am having problems with the idle. When I start the car, it will rev up to 3k and bounce between 2.5k and 3k. If I put it in gear, it will start shuddering and die. It will do this several times before it will continue to run. It will continue to run fast until the engine is warm and if I turn it off and on once warm, it will run normal. It will also return to normal after running for a bit after warm and not having to turn it off. I have replaced the TPS and the air charge temp until to no avail. Also replaced were the gaskets that go between the plenum and what ever is below it. Any help would be great since I'll have to go through this every morning for the next 6 months. Terry Quote Link to comment Share on other sites More sharing options...
pitzel Posted September 23, 2012 Report Share Posted September 23, 2012 ECT perhaps? Do you have access to any sort of data acquisition tool? That would probably help out a lot here, just to read what the ECU is seeing. I presume you've also removed the IAC, cleaned the passages of accumulated gunk with an appropriate solvent spray, etc. Because its a mechanical actuator, they have been known to wear out Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted September 24, 2012 Report Share Posted September 24, 2012 i second all three suggestions. if you don't have a vacuum leak, then a coolant temp based high idle is something ECM controlled and if you can see the data the ECM is using to command idle speed from, you can make good decisions as to what are causing it. Quote Link to comment Share on other sites More sharing options...
Tabiji Posted September 24, 2012 Author Report Share Posted September 24, 2012 i second all three suggestions. if you don't have a vacuum leak, then a coolant temp based high idle is something ECM controlled and if you can see the data the ECM is using to command idle speed from, you can make good decisions as to what are causing it. I am not sure what to use to see the ECM data, I thought this was an OBD-I device and I was limited to flashes of the check engine light once jumper'd correctly.. What device can I get to do this? Yes, I took out the idle air valve thing. Cleaned it the best I could and the passages as well. Terry Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted September 24, 2012 Report Share Posted September 24, 2012 you could check out this thread here for some ideas. http://www.w-body.com/showthread.php/74972-new-datalogger or this: http://www.w-body.com/showthread.php/51487-OBD1-ALDL-Cables Quote Link to comment Share on other sites More sharing options...
White93z34 Posted September 24, 2012 Report Share Posted September 24, 2012 There is an airleak somewhere. check for any vacuum leaks. check/change the IAC. it sounds like a broken intake gasket but considering you say you already changed those... Quote Link to comment Share on other sites More sharing options...
Tabiji Posted September 25, 2012 Author Report Share Posted September 25, 2012 When I replaced the brake booster, I took the plenum off because it was easiest to get it out. The gaskets were replaced then. I also replaced some of the vacuum tubes because they were broken. There certainly could be more broken ones as well as I just goofed putting it back together. I ordered the scan tool yesterday and it hopefully will be here for the weekend. What kind of data is interesting? Water temp, Air temp, Air flow? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 25, 2012 Report Share Posted September 25, 2012 A test I do is to leave the car shut down overnight, then hook up the scantool before having started the car. Check live data, and see what the coolant temp being reported to the ECM. It should be very close to ambient air temp. If not, replace the coolant temp sensor. When I replaced the brake booster, I took the plenum off because it was easiest to get it out. The gaskets were replaced then. I also replaced some of the vacuum tubes because they were broken. There certainly could be more broken ones as well as I just goofed putting it back together. I ordered the scan tool yesterday and it hopefully will be here for the weekend. What kind of data is interesting? Water temp, Air temp, Air flow? Quote Link to comment Share on other sites More sharing options...
Tabiji Posted September 28, 2012 Author Report Share Posted September 28, 2012 I got the scan tool today. I have not idea what program to use or what I am looking for. One kind of worked. I got the USB version from OBD Diagnostics (http://www.aldlcable.com). Some of the programs ask what "car" to use, non match. One displayed what appeared to be correct voltage, but nothing else. Defiantly don't see the cool stuff that is in the TunerPro link above. Kind of stumped now. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted September 28, 2012 Report Share Posted September 28, 2012 download tunerpro and i have a decent walkthrough posted for using it. the 91-93 LQ1 is a common application. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted September 28, 2012 Report Share Posted September 28, 2012 Sounds like classic lower intake manifold gaskets. You mentioned replacing the plenum gasket, but you didn't replace the LIM gaskets, right? That'd be the ones between cylinder heads and lower intake manifold. If it's a bad enough leak, spraying carb cleaner around the gasket area may result in a detectable change in engine sound or RPM. That's one way to confirm LIM is leaking (but lack of RPM change doesn't necessarily mean LIM gasket is good). Quote Link to comment Share on other sites More sharing options...
Tabiji Posted October 8, 2012 Author Report Share Posted October 8, 2012 Woot! It is running correctly again. I replaced the LIM gasket, Plenum gasket, fuel injector o-rings, 1 vacuum fitting (loose, but did not seem to leak), and thermostat over the weekend. It started great yesterday, but it was warm. This morning at 34 degrees, it also started normally. On a side note, I still don't have that ODB-I reader working as expected. I'll save that for another time. Oh, I also picked up a 97 Grand Prix with a 3.8. Amazing how much technology changed in 5 years (the eninge looks mostly the same though). Thanks all for your help again. Quote Link to comment Share on other sites More sharing options...
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