Idle problem NO ONE can diagnose.
#1
07-03-2018, 03:08 PM
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Idle problem NO ONE can diagnose.
1997 b250 3.9. Van has been running for multiple years with an idling problem. For 2-3 key cycles it will run fine, then the next it will start up and run at 2000rpm. shut off vehicle, turn key to on and wait for all lights to come off then start and it may run perfect again or it may idle super high again. Sometimes it runs great then idles up while driving putting load on back tires which is very inconvenient in the wintertime. No vacuum leaks as its sporatic and sometimes runs fine sometimes doesn't. Replaced every sensor TWICE. Literally every sensor. Alternator and battery is fine, no ac ripple in alternator. Tried stock PCM, Cardone reman, and junk yard pull off from another 97 and all three acted exactly the same. The only common thing is that if its idling high and you turn it off then back on and wait for all the lights on dash to turn off then fire it up it will USUALLY fire up fine. Every morning it starts up fine but on way to work it idles up. if I shut if off and do the little light sequence it will run fine from then on till I shut it off again and restart it for lunch. Any help PLEASE
#2
07-03-2018, 07:21 PM
You mentioned changing sensors (I assume iac, tps possibly map...) but no mention of removing and cleaning the throttle body, especially the orifice where the IAC is mounted as well as around and under the throttle plates at the top that they are free of crud to open/close. If you have never done or had it done this is a fairly easy job and may help your problem. other question is what brand sensors and which are the ones you replaced? Because of failures in the aftermarket sensors, many guys are promoting buying OEM/ mopar sensors as they tend to be more reliable, also a tad bit more expensive.
another thing I had always neglected in previous years was replacing the gasket that sits top of the TB and the aircleaner hat, I think it makes a difference having a good seal there.
another thing I had always neglected in previous years was replacing the gasket that sits top of the TB and the aircleaner hat, I think it makes a difference having a good seal there.
#3
07-03-2018, 11:03 PM
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First time I replaced everything which I believe I replaced an air sensor, Idle Air Control Motor , throttle position, for some reason I even remember changing coolant temp sensor but I don’t remember and that sounds silly. Either way first time I replaced it all I took the throttle body off and used carb cleaner and a tooth brush and air and cleaned the entire thing spotless looked like new , used a new mounting gasket also . After nothing changed I drove it for awhile and then later on that summer replaced idle air and throttle position again a second time but each time was with Borg Warner from oriellys . Little nervous to buy another idle air motor at the price but maybe Mopar part will fix the problem . I even calibrated it as the manual says to . Pretty stumped
#4
07-04-2018, 03:24 PM
I figured you did... The gasket I was speaking of is for under the air cleaner housing to top of throttle body to prevent outside air being drawn in other than through the breaher /housing tube
read your other forum thread and if permitted to borrow that other van's IAC for test purposes it might be worth a shot trying it out. I don't think the part numbers changed between engine size or newer model years according to what I gathered from rockauto.com, but bring yours with you, or a close up photo to compare the harness plug to be sure it matches.
If testing works and resolves the revving issue rockauto has both Mopar and Delphi IAC available in the 2000 to 2004 sections. If plugs don't match you can likely order Delphi through Napa for your 97,
Call to be sure
4-5 years ago I had the opposite problem with the IAC, where the engine die coming to stops unless I had a foot on the brake and one on the gas till it got rolling again. That's when I cleaned the TB and the IAC. cured the problem and really made a good difference in overall performance. I had bought a standard motors IAC to swap in if necessary too. Once running well again for a couple days I decided to save my original OE for a known good spare and swapped in the new standard brand, it ran well for about 3 days then back to stalling again. Pulled it out and the pintle sleeve had broken apart. Put the cleaned up original back in and has been going ever since.
read your other forum thread and if permitted to borrow that other van's IAC for test purposes it might be worth a shot trying it out. I don't think the part numbers changed between engine size or newer model years according to what I gathered from rockauto.com, but bring yours with you, or a close up photo to compare the harness plug to be sure it matches.
If testing works and resolves the revving issue rockauto has both Mopar and Delphi IAC available in the 2000 to 2004 sections. If plugs don't match you can likely order Delphi through Napa for your 97,
Call to be sure
4-5 years ago I had the opposite problem with the IAC, where the engine die coming to stops unless I had a foot on the brake and one on the gas till it got rolling again. That's when I cleaned the TB and the IAC. cured the problem and really made a good difference in overall performance. I had bought a standard motors IAC to swap in if necessary too. Once running well again for a couple days I decided to save my original OE for a known good spare and swapped in the new standard brand, it ran well for about 3 days then back to stalling again. Pulled it out and the pintle sleeve had broken apart. Put the cleaned up original back in and has been going ever since.