Cleaned TB now a very high idle

[techno1154]

Since pushing down on the trottle body tend to reduce the RPM's, I would concentrate on the trottle body.

Disconnect the trottle cable, TV cable and cruise control cable. Maybe one of them is sticking.

Check the TPS to see if that is holding the trottle open.

If that do not solve the problem, lube the trottle body shaft inside the throat as well as outside while opening and closing the trottle engine off course.

Lastly, there is an allen screw under the plate that is used to adjust the closing of the trottle plate. The trottle body have to be removed to access the screw. I have never heard of anyone who had to adjust this.

On my XJ, the butterfly closes completely. There is no light visible between the plate and the body. It seem something is holding the one on your XJ open.

 

[winterbeater]

Exactly! The fact that when you push it closed more, it slows down, shows that it is not closing enough. You can' push it past the throttle stop. It should close down to the stop without you pushing on it.

 

[joe_peters]

The gap was only around 1/16" at the largest spot. Is that enough to make it idle so high?

Go to page one of this thread.

Read my post on adjusting the "base idle screw".

 

[MudfrogK5]

Go to page one of this thread.

Read my post on adjusting the "base idle screw".

I did, I saw where the screw is but did not see how to access the screw as it appears there is a metal plate in front of it?

 

[MudfrogK5]

Exactly! The fact that when you push it closed more, it slows down, shows that it is not closing enough. You can' push it past the throttle stop. It should close down to the stop without you pushing on it.

It still idled high when pushing it down just not quite as high. Also I had to push really hard, didn't think it would take that much force to close it.

 

[NorCalChris]

Lastly, there is an allen screw under the plate that is used to adjust the closing of the trottle plate. The trottle body have to be removed to access the screw. I have never heard of anyone who had to adjust this.

did you remove the tb?

 

[MudfrogK5]

Not this time around. I'll try this at work today.

 

[MudfrogK5]

Tinkering with the screw seemed to have fixed my idle issue.

 

[gradon]

ta-da!

 

[techno1154]

Tinkering with the screw seemed to have fixed my idle issue.

Isin't it nice when one finally have the problem beat. :yelclap:

 

[MudfrogK5]

Yes it is, now I just need to make sure the rpm's aren't to low. Seems ok so far though.

 

[westvirginia24976]

Just in time for the next batch of snow! party1:

 

[MudfrogK5]

Quick question. This morning with the engine cold it would not idle at all, would this mean I have turned the screw too far? I thought I did it until I saw a little bit of movement from the plate but I was looking for the smallest bit of movement.

 

[xjbubba]

You've probably screwed up the factory established relationship between "minimum air" and the TPS setting. That screw you played with, has to be correctly adjusted so that the ECM can correctly assume the TPS voltage it's seeing represents "0" throttle angle.

 

[MudfrogK5]

You've probably screwed up the factory established relationship between "minimum air" and the TPS setting. That screw you played with, has to be correctly adjusted so that the ECM can correctly assume the TPS voltage it's seeing represents "0" throttle angle.

So I would need to recaliberate the TPS, correct?

 

[xjbubba]

So I would need to recaliberate the TPS, correct?

You may need to determine the correct factory procedure to re-set the "minimum air" adjustment first.
Generally, (I say generally because I have not researched minimum air set-up for the 4.oL) minimum air is set with the Idle Air Control solenoid totally extended, then electrical disconnected; this insures the ECM doesn't interfere with the idle while you're trying to make the adjustment. You need to know what the base engine RPM is supposed to be--such as 450RPM---then set it, following the factory procedure. After min-air is adjusted, then adjust the TPS for whatever the factory recommends; the '88 4.oL would be set to .8v between terminals A and C.
This all assumes the engine is running properly. So whatever issue you had going on before screwing with the "idle adjustment screw" needs to be corrected first.

 

[joe_peters]

I give up.

NO "BASE IDLE SCREW" EXISTS.

Fix the IAC/TPS/ECU/other sensors so the IAC can do what the ECU tells it to do.

AND STOP FRIGGIN' AROUND WITH THE "KEEPS THE HARD STEEL THROTTLE PLATE FROM SLAMMING FULLY CLOSED AND DAMAGING THE SOFT ALLOY THROTTLE BODY" SCREW.

Once it has been set as I described on page one of this thread, leave it alone. The only reason you had to reset it is because some moron screwed with it sometime in the past.