2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

hunting idle, help please!

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Old 12-07-02 | 07:15 PM
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kep0ne's Avatar
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From: West Covina, CA
hunting idle, help please!

ok heres the deal.

start the car, idle will hunt right around 1500...(1400-1600)...even witht he car hot, it still does this.

disconnect the bac, still does it, disconnect the TPS still does it. adjusted TPS, still does it.

dont know what the hell is going on...i just removed emissions. before i did that it could hold a idle around 750-800, now it wont. any ideas?
Old 12-07-02 | 08:18 PM
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also, the car is an 88 TII

Last edited by kep0ne; 12-07-02 at 08:21 PM.
Old 12-07-02 | 09:11 PM
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I'd say there is a vacuum line connected where it should not be connected.What vacuum lines did you leave on the engine and where are they going from end to end?
Old 12-07-02 | 09:28 PM
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ok

all the obvious lines (brake booster, omp) are where they should be.

FPR is connected to the nipple between the secondaries.
pressure sensor is going to the bottom nipple on the UIM
BOV is going to the nipple under the BAC.
BAC line is going to the intercooler, and the other nipple next to that (on the intercooler) is going to the top of the UIM, close to the firewall.

could a stuck BAC be the cause of this?
Old 12-07-02 | 09:34 PM
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Bac??? Possible. Might take it off and spray some lubricant in it and flush it out.

There was a nipple b/t the two oil injectors on the intake manifold. Where did you put the hose for that one/????
Old 12-07-02 | 09:47 PM
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doh! i may have left that disconnected. in the heat of connecting and disconnecting and reconnecting...i probably left it hanging. ill try that and see where it goes. let you know if it still hunts.
Old 12-07-02 | 10:00 PM
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Actually, it would not cause the problem if it was left off. It would draw in a little tiny bit of unfiltered air into the rotors, but not cause your problem.

Unless you connected the other end to a source of vacuum. Like the bottom nipple on the throttle body. You know. The three or four nipples that are one above the other. Only the bottom one has a vacuum and it should be going to the water thermo valve. The one we're talking about b/t the oil injectors should go to one of the other nipples above the bottom nipple.

You might try the bac thing, and then if that does not work, try reaching around to the fpr and disconnecting that and plug it with your finger and see if the hunting stops.
Old 12-07-02 | 10:11 PM
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Just so many possibilities here. Say the grommets b/t the fuel injectors and the housing are not seated very good. Causes an air leak. Causes throbbing idle. Should make sure the grommets are resilient(sp) before putting them on. If hardened like a rock they will leak.

I'd invest in a can or two of starter fluid and spray at all possible hose and joints with the engine running and listen for a change in tone from the engines rpm.

What happens if you turn the rich/lean screw on the variable resistor towards the rich side???? You can always turn it back to where you started.

Last edited by HAILERS; 12-07-02 at 10:14 PM.
Old 12-07-02 | 11:46 PM
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ill give that a try tomorrow...maybe i have my vac lines hooked wrong.

ill take another look at the vac diagrams and see if i can fix it up.

would the leak in the injector grommet cause such a rhythmic idle though? its constant.

rich-lean screw has no effect.

well...ill go over the vac again (sigh)...perhaps i should have left all this crap alone...its runs, but not as good as before.
Old 12-08-02 | 02:03 AM
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Just an idea, but you might as well replace the hoses with silicone. This way you KNOW which hoses you have played with, and you will also have no future problems with them (unless of course you decide not to 'leave that crap alone' ).
Old 12-08-02 | 02:34 AM
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thats been done (see emissions removal stated above)
Old 12-08-02 | 03:26 AM
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wardering idle is sually tps in my car,.. and if you disconnected it and it doesnt do anythign it may be bad, my car nearly dies if i dissconnect tps while its runnng,..
Old 12-08-02 | 05:26 AM
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It is likely that something in your throttle it sticking. Try getting the car going and warm and then pop the hood and push on the throttle lever (no in the direction to throttle the motor, but in the opposite direction!). If it drops your motor speed at all, then there's your problem.
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