bronze93 Posted September 13, 2010 Report Share Posted September 13, 2010 I've searched and searched and tired of reading. My problem is now that it is getting colder the idle has really deteriorated. When I start the car the idle jumps up to 3000 rpm, then drops to 500, then jumps up again, and so on. I've done the idle relearn. I'm not sure where to start. I've thought about IAC, IAT, vacuum lines, etc. This only happens when the temperature drops to around 60. Any help is greatly appreciated. Quote Link to comment Share on other sites More sharing options...
WhatTheFehl Posted September 13, 2010 Report Share Posted September 13, 2010 IAC or Throttle Position Sensor... or you have a vacuum leak somewhere. Quote Link to comment Share on other sites More sharing options...
jeremy Posted September 13, 2010 Report Share Posted September 13, 2010 I'm gonna say LIM gaskets Quote Link to comment Share on other sites More sharing options...
birdman Posted September 13, 2010 Report Share Posted September 13, 2010 I second the gaskets, they will shrink in the colder weather. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted September 13, 2010 Author Report Share Posted September 13, 2010 I looked at the lower intake gaskets and they appear to have already been replaced. I don't know for sure but they look new. I just bought the car in June so I really don't know. Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted September 14, 2010 Report Share Posted September 14, 2010 Unplug the IAC while the idle is acting up, and see if it continues. If it stops, id say the IAC is lazy and might need replacing / cleaning. If it continues, I'd guess vacuum leak. Â Basically what Mike already said... Quote Link to comment Share on other sites More sharing options...
slick Posted September 14, 2010 Report Share Posted September 14, 2010 The intake gaskets on the 3.4 are only like a 1 hour job, and are dirt cheap. Â Just start the engine, spray some carb cleaner around the gasket mating surfaces, and see if it makes the idle jump. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 5, 2010 Author Report Share Posted October 5, 2010 Alright I've finally had a chance to work on the car cold. I unplugged the IAC and it stayed run with a high idle of about 3k. So I'm guessing the IAC is bad? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted October 5, 2010 Report Share Posted October 5, 2010 I just went through this with my 3.4...scan tool finally found the problem, the throttle position sensor was sometimes not returning to closed, the scantool would show the car thought the throttle was between 2 and 5% open when it was actually closed. Â I think a new TPS cost me maybe $25.00. Worst part was getting a torx bit down into that little space to replace the sensor. I took my IAC out just to make life a little easier, the whole thing probably took 30 minutes to replace. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 5, 2010 Author Report Share Posted October 5, 2010 I changed the IAC today we'll see how that works. What type of scan tool do you have? I have a actron cp9145. I have looked at the information on it but don't know what most of it is. What am I looking for on it? Quote Link to comment Share on other sites More sharing options...
AL Posted October 6, 2010 Report Share Posted October 6, 2010 Tps voltage or percentage... 0 volts or .5 volts is ok I think but if its percentage then it should be 0 or .3 when your not touching that pedal... Let us know what you find Quote Link to comment Share on other sites More sharing options...
Night Fury Posted October 6, 2010 Report Share Posted October 6, 2010 I agree with Jeremy and... uhh...... whoever else said LIM gaskets Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 6, 2010 Author Report Share Posted October 6, 2010 Well I went out and started it up this morning and it idled smooth and sounded great. But I'm going to be a pessimist on this one and give it a couple of days before I think its fixed. Also I checked the scanner and it read Throttle 0%. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 7, 2010 Author Report Share Posted October 7, 2010 Ok I started it up this morning and the strange idle is back. The only thing I did to the car last night was put the 3.4l dohc plastic cover back on. My guess is possibly a vacuum line under there is bad. I'll take the cover off tonight and see if that makes any difference tomorrow morning. If it is a bad vacuum line can I spray the carb cleaner on them when it is warm and get the same results as when it is cold? Quote Link to comment Share on other sites More sharing options...
spiderw31 Posted October 7, 2010 Report Share Posted October 7, 2010 If it is a bad vacuum line can I spray the carb cleaner on them when it is warm and get the same results as when it is cold? Â It should, assuming that the expansion of the lines due to heat doesn't seal the leak. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 8, 2010 Author Report Share Posted October 8, 2010 Tried spraying the hoses and lim gaskets with carb cleaner after work with no good results. I took the cover back off and left it off to see what the results are tomorrow morning. I won't be able to spray it cold until Saturday morning. Hopefully the removal of the cover will make some difference. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 8, 2010 Author Report Share Posted October 8, 2010 It idled little better but still oscillates up and down just from 2k down and then back up. I put the code reader on this morning while waiting to get gas and apparently threw a code yesterday while spraying carb cleaner. The code was p0131 Bank #1 HO2S lean. Quote Link to comment Share on other sites More sharing options...
bronze93 Posted October 13, 2010 Author Report Share Posted October 13, 2010 Alright, I replaced the UIM, LIM, and the oil gasket underneath. This morning was the first real test with cold weather and it seems to be working great. I found all kinds of crap under the LIM. Looked like a mouse nest. I've got it back on the road but noticed the temp gauge was reading kinda abnormal like temp jumped almost to 260 so opened the bleeders and let the air out. Temp was still running funny this morning but never got over 210 while parked. I'm going to open the bleeders again to see if I have more air in there. Thanks to all that helped. Also, If you can change the LIM in an hour your a GOD. It took me most of the day Monday (5.5 - 6 hrs). I guess the more you do the quicker it is. Thanks again. Quote Link to comment Share on other sites More sharing options...
slick Posted October 13, 2010 Report Share Posted October 13, 2010 210*F while sitting and idling is normal. Quote Link to comment Share on other sites More sharing options...
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