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checking senors for idle on 2000 3.8

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pbob42

New member
Got a 2000 3.8 with 131k on it. Was gettting fast idle error code and intermittant stalling. Pulled of the throttle body and cleaned it up. Also cleaned the IAC. Ran better but still idling about 1000 rpm when warm and still stalls.

Stalls when idling or decelerating. Was sitting at a light and the rpm started hunting, wavering between 600 and 1200. Started smelling some pretty strong exhaust, pumped up the gas and it cleared up. When it stalls it starts right back up.

Now I realize I can start working through the MAF sensor, MAP, IAC and several other senors. How many of these can I test with a meter or by other means? Like everyone I am wrenching because I can't affort to pay someone else to do it. I would rather not just start buying sensors until I hit the right one.

No error codes. Track off is lit.

thanks for any input or wisdom.
 


you could have a cracked vac line, or even a clogged cat, or maybe even a bad crank sensor. ( the tach ever drop to zero, then stall?)

the original code never came back? what was it for the hell of it?
 
The original code was P0507 - unexpected high idle. Think I cleared that up with by cleaning the throttle body. It was coated with grime.

The clogged cat in interesting. I really noticed a ton of exhaust smell in the car when the idle was wavering. How would I check that?
 
Sprayed starter fluid around and didn't see any leaks. Have not seen the tach drop to zero before it dies. It does drop to zero when it dies :).
 
Another common issue to cause high idle is the looping of the cables on the strut tower. Ensure they aren't causing an issue. Maf is about the easiest to check. Simply unplug it. Try driving a bit that way (Don't go into boost if you have it.) if the car runs better, typically it's a maf
 


sticky cables. inside the throttle cable is like a bike brake line, cable in the metal flex tube, as we all learned as kids the brake cables frays up and get sticky, then breaks.

same for the throttle cable. make sure its free feeling and not holding the TB open.
 
of maf test, unplug it when the cars off, then start it up, if it runs better, the maf is bad.

clogged cat, does it feel gutless when you floor it? sound like a vacuum under the hood? the cel ever flash when floored?

you can also drive it spirited for a bit pull over look to see if the cat is glowing red, you need to do this at night.

or hit the cat with your hand, ( when cold) and listen for it to rattle inside it. if you hear nothing it should be ok.
 
Your cables do a 360 degree loop on the strut tower. If oen is out of place or got pulled oddly it might be pulling on your throttle, which causes a high throttle issue.

Try closing the throttle plate by hand. If you can feel that it isn't closed, unhook one cable at a time. The one that allow the throttle to close fully is the one causing the issue. Typically adjusting or slightly moving it on the tower will fix the issue.
 


ok - swapped the MAF - ran fanstastic for 15 minutes then strted doing the same thing again. I am leaning to clogged cat. Drove it around the other night - got very hot but was not glowing. Usually starts after 15 minutes of driving. Car will stall at idle and restart rather easy. Has acted up when cold but only one time. Any more thoughts?
 
OK - I can make it happen. It happens when it is tacking 2,000 rpm or higher and I let off the gas. Sometimes the rpms will drop to about 600 and pop back up to 1,000. Sometimes it doesn't stop and just dies. It seems that the idle circuit is not catching up quick enough.
 
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