Hi Everybody:

I have a 93 Auto FD and I'm trying to figure out how to resolve my low idle when in gear issue. Let me note that I have made an attempt to search, and I've read numerous threads, but I have some other questions...so please bear with me. When the car is in Neutral (and the car's all warmed up) The idle sits at 750 with 250-275 mmHg of vaccum, but when I have the car in gear it idles around 550 - 600. My local rotary shop replaced the Air Temp Sensor, but what else should I look at/replace to get it to idle correctly? I had a compression check a couple months back and I had 102 psi on the front and 105 psi in the rear. Boost pattern is .9 kg/cm² for the primary and for the .5 kg/cm² on the secondary. Any suggestions on what to look at? Thanks!

 

750 is normal. try adjusting the TPS if it hasnt been done lately.

 

I know I can always adjust the TPS, but I wanted to know if there is anything else I should check/replace first before resorting to that. Any more suggestions?

 

Get some throttle body cleaner and clean the throttle body first. Then, at normal operating temp set your air screw until you idle sounds normal (located under the throttle body). Lastly, adjust the idle screw to either raise or lower RPM`s.

I keep mine at 900 when in neutral, 750 when in drive.

Good Luck,
Andre

 

Does it idle with the AC on in drive?

I have been wrestling with this same problem for some time...

I have some experience I can share.

 

Well...because the car idles so low in gear, i'm thinking if I turn on the AC, the car will stall out...so I never bothered to turn on the AC. Any other things to look for?

 

Adjust the screw on the fast idle cam on the throttle linkage once the a/c is on.

It`s just that simple.

 

250-275 mmHg is pretty low vacum #

 

I agree... I idle right around -400mmhg.

 

Yeah I'm aware that the vaccum is pretty low...which might explain why i'm getting a .9 on the primary and .5 on the secondary boost. I had a perfect boost pattern after I got the silcone hose job done, but one day it just wasn't boosting right on the secondary and the vaccum was low. Obviously I have a boost/vaccum leak somewhere in the system, but I just want to address one issue at a time. Any suggestions?

 

Cool. So what is the "proper" idle speed with the AC on?

 

900 idle
750 in drive
950 with a/c on and fast idle solenoid engages.

 

Thanks for the info Andre! I'll get some carb cleaner and tackle this project this weekend! Thanks to everyone else for there input!