85 GSL-SE
Good compression, fresh tuneup and fuel filter. OK compression.

I can't get the idle set to 800 rpm. I stepped through the idle setting procedures as per the FSM.
Warm the car up. Set the TPS. Disconnect the vacuum and vent solenoids. Set the idle at 800 rpm using the Air Adjusting Screw. The problem is I can only get the idle up to 300 rpm. Once I plug the vacuum and vent solenoids back in, they will compensate and bring the idle up to 800 rpm.
Any ideas what is causing this? The car will stall when you quickly let off the gas in this current condition.

My understanding is that this engine should run around 800 rpm simply running on the ECU. So what is causing it to idle so low? I have looked for vacuum leaks and come up empty so far.

 

85 GSL-SE????? On the Second Gen Forum?

 

Hailers, thanks for answering. The reason I posted here is because of the second gen efi knowledge. The GSL-SE with the 13B EFI shares more with the second gen than the first. Agreed?
Any ideas why I can't get the idle set up to 800?
You have helped me in the past and I appreciate it.
dave

 

Time to adjust the mechanical throttle stop screw.
Just open the setting enough to where you can use the bleed screw to fine tune it.

Is the dash pot keeping your throttle from banging shut?

 

are you talking about the TPS screw on the throttle linkage?

I would think that if the dashpot were holding the throttle plates open it would idle high not low.

 

hmm,

do you have an adjustement for the fuel mixture like on the second gen ? (variable resistor, it's called, good only for idle)

I see many reasons why it would idle high, but very few why it would idle low.

timing maybe ? too retarded

I think you should be able to reach the 750 rpms even if the nut on top of the intake (the 8mm one) is totally loose and does not make contact.

Maybe the throttle plates are not in spec in the throttle bore when at rest ?

Don't know ...

Hugues -

 

There is a procedure that you are using that is not normal on a second generation.

That talk about solenoids vacuum/vent does not apply to a second generation.

On a second gen you set the timing, then install a thing called a initial set coupler which keeps the bac from reacting to the adjustments you are about to do. Then you adjust the screw on top of the dynamic chamber for idle speed......and if needed, adjust the variable resistor if there needs to be a fuel adjustment for the idle. You aim to get the idle as close to 750 as possible doing that/those things.

Then you remove the initial set coupler where upon the idle might pickup a bit to get you to 750rpm

So .....if you don't have the initial set coupler, don't worry. Just pull the bac plug off and set the idle using the screw on top of the dynamic chamber and variable resistor if you have it installed. THEN put the bac plug back on. It might chugg two or three times but then settle down to approx 750. Make sense??

On the timing. It should be done first. Some install the initial set coupler to do that. I don't along with any number of folk that I trust. As long as the rpms are below 1000rpm the ECU won't advance the rpms on its own. Try to have the idle approx 700 to 800 for best results. And another thing. Make sure the engine is fully warmed up prior to adjusting the timing. I know the timing is retarded when the engine is cold. I've see that with a timing light and I read the fsm which says so. It's possible that if one installed a initial set coupler that the timing might not be retarded when the engine is cold . I've never checked that. I don't believe in messing with cold engines when doing adjustments. It just does not make sense to do so.

 

Hailers agreed on the engine temp. I own two second gens also so I understand what you are talking about. When you disconnect the vacuum and vent solenoids you are taking the BAC out of the equation essentially. There is a variable resistor on the first gen just like the second gen.

I had planned on checking the timing also. This car has been abused. Whoever has messed with it before jury rigged it to make it work. Instead of fixing the idle they just tightened up the cruise control linkage to get the idle up.
So far I have found and fixed the following items:
Bad TPS
One bad injector
Air pump not hooked up
Power steering pump shaft broken off (didn't fix it, don't need it)
Alternator not mounted correctly

So it is entirely possible they screwed with the timing too.