Excessive High Idle - TCCoA Forums
 
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post #1 of 12 (permalink) Old 09-18-2006, 10:04 AM Thread Starter
 
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Angry Excessive High Idle

First off,

Hello from a new member.

Here's my problem. I've got a 90 3.8 n/a with high the famous high idle problem.

I just picked up this car and I'm getting it ready for daily use, So I did an oil change, new plugs/wires/cap and rotor, and a new coil.

it was running really rough when I picked it up, that's why i decided to do all the maint. that I've done so far.

I even pulled the EGR and the IAC and cleaned them as well as the upper plenum.

When I finished the upper plenum I painted it and put it back on the car and used new gaskets for everything.

when I started the car, it still idled rough...blew black smoke horrible and fouled my new plugs...multiple cursewords and a beer or two later, my friend comes in and tells me the MAP sensor vacuum line is not connected.

I go and look, sure enough it's not connected, and there's nowhere to connect it.

ARGH!!! Well I go to NAPA and get a "T" and cut the top vacuum line on the intake and fit the "T" in between the cut line and the MAP sensor. I put the cleaned up plugs back in the car, replaced the wires and fired it up.

Much smoother running and no black smoke, it just idles really high. I unplugged the IAC, no change, I unplugged the TPS and it made no difference.

I'm at a lose

Any Ideas guys??

Any help would REALLY be appreciated.

Thanks
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post #2 of 12 (permalink) Old 09-18-2006, 10:06 AM
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IAC! Get a new one.

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post #3 of 12 (permalink) Old 09-18-2006, 02:52 PM Thread Starter
 
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Quote:
Originally Posted by bad93bird
IAC! Get a new one.
Roger that!!

Thanks
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post #4 of 12 (permalink) Old 09-18-2006, 03:39 PM
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yea definitely get a new IAC and try it out, same problem with mine.
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post #5 of 12 (permalink) Old 09-19-2006, 03:54 PM
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Did you read any codes?
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post #6 of 12 (permalink) Old 09-20-2006, 09:30 AM Thread Starter
 
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NOPE on the IAC

Well guys the IAC is NOT the problem.

I replaced the IAC and fired the car up and I have the exact same problem. HIGH IDLE.

I unplugged the IAC while the car was running and it just kept on running so i plugged it back in.

I then unplugged the TPS and still no changes whatsoever. I plugged it back in as well.

I even unplugged the MAP sensor, no help. The only time it will idle down is if I take the vacuum line OFF of the MAP sensor, but then the idle is rough.

Any one have an idea as to what's going on with this car or should i call a priest for an Exorcism??

Truly baffled now
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post #7 of 12 (permalink) Old 09-20-2006, 11:49 AM
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Double check everything for vacuum leaks. Spray WD-40 around all fittings and the intake manifold gasket surfaces just to be sure. If the idle changes in any way, you've got a leak.

I've experienced a faulty TPS that caused a high idle. Usually when you unplug the TPS, the idle shoots up anyway. See if you can find out what the TPS voltage is.

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post #8 of 12 (permalink) Old 09-21-2006, 07:37 PM Thread Starter
 
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Help Me, Help Me Lord

Well Guys,

I've replaced the IAC, the TPS, the MAP sensor and I STILL have the dang problem.

I set the TPS to .998 volts at idle and I even tried to set the timing down, bad move the exhaust manifolds started to glow red.

I removed the upper plenum again and checked ALL of the vacuum hoses for leaks and even replaced a few for good measure, and all new gaskets AGAIN!!!

Has anyone got any idea what in the world is going on with this car???

I'm going nuts here
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post #9 of 12 (permalink) Old 09-24-2006, 01:30 PM
 
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Check your codes like the previous poster said. It'll at least lead you in the right direction.

Make sure you remove the spout connector before changing your timing!!!!
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post #10 of 12 (permalink) Old 10-09-2006, 09:50 AM
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Ok where did you buy all of the sensors? Do you have a MAF or MAS sensor. Try that MAP sensor also. That could also be it. You need to get the codes pulled.

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post #11 of 12 (permalink) Old 10-09-2006, 04:02 PM
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This is all great info, but did YOU READ THE CODES? Go to a parts store and get the codes read!
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post #12 of 12 (permalink) Old 10-16-2006, 11:04 AM
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If they don't go get the codes read, there is really no since geussing. I had the same experience with my 93'. Just going by what I had to replace.
I'm also thinking ECM maybe faulty. Not real sure on that.

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