88 SE

this is in no way a complete guide to idle problems, but just how to fix certain problems based on what I have done to my car to get it running perfect at idle. Here goes:

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Looping idle
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99% of the time "looping idle" , or jumping idle is caused by the following:

Vacuum leaks. This is number 1! These cars are very old and prone to developoing leaks. Check check and check again for leaks. Check Intake manifold, intake piping, and the EGR

The other cause is the TPS sensor. Set it using the lights method as the ohms method isnt very effective all the time. Be sure to set the TPS when the car is at full operating temperature.

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Bad idle speed
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If you idle speed is incorrect IE too low or too high, you should try to adjust it. Heres how:

First, Warm the car up, check your TPS sensor adjustment.

Next, Jumper the initial set connector (green socket on drivers side fender near ignition coil with 2 connetors)

Start car up. If the idle is smooth with jumper in. pat yourself on the back. thats an easy fix. If it does NOT smooth out, proceed to check for vacuum leaks.

While the initial set jumper is in, set your timing to spec. Adjust your idle speed to 700-800 rpm.

Adjust your variable resitor (miture settings) until the engine is idling as smooth as it can. Re-adjust idle speed back to 750-800 rpm.

Now is a good time to check your timing. Check and adjust your timing, then repeat the above steps to get idle speed back to 750-800 rpm.

Remove initial set jumper. You're done.

Do all this first to verify your idle setting are correct.

If after you pull the initial set jumper the car begins to have a surging idle again, the culprit is probably a clogged/bad BAC. remove your BAC, clean it well with carb cleaner. Reinstall the BAC and try again.


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Idle speed wont hold after adjusting idle speed
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Try resetting the idle again, but set it with engine on full load. adjust the BAC and idle mixture with all your lights on and the AC on, it helped alot with mine.

If i tried to set mine with no load it would do a fine 750 idle with the initial set jumper in, but when i pulled it, it would creep back up to 1200-1300 rpm with no load.

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Idle rough at load/ with AC on
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Same as above. Set idle with engine at full load with initial set coupler in. You might need to adjust your idle mixture by using the solenoid resistor which is on the passenger side right by the pressure sensor. You will have to remove the factory plastic covering the screw before you can adjust it.

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Car will not idle under 1500 rpm
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Vacuum leak vacuum leak vacuum leak. You have a vacuum leak. Check EVERYTHING. Start with the Intake manifold joints, intake piping, and the EGR which is prone to leaking.

SonicRaT

iTrader: (6)

I must agree, vacuum leaks are the #1 cause of idle issues! I don't know how long I've spent searching and trying to narrow them down, and once I did, jeez what a difference!