Car: 1985 GSL-SE, 74,xxx miles, great general condition.



Situation: Out of nowhere the car will start to erratically idle at approximately 2,000 RPM with the clutch pushed in and rev itself, automatically, between approximately 1,500 RPM and 2,000 RPM with the clutch let out. On and off throttle response is exagerated. For example, slightly pressing the gas pedal makes the car lurch forward while in gear instead of a smooth transition like it should be.



Comments: The car has done this on several other occasions but the symptoms went away almost immediately. When I parked the car it was still revving itself from 1,500 RPM to 2,000 RPM. I left it running and popped the hood. I squeezed the short rubber hose that goes from an elbow off of the intake tube to a metal connection point on the intake manifold or throttle body. Squeezing this hose shut (to cut off the air transfer) seemed to alleviate the problem and as soon as I let pressure off of the hose the car went back to it's said state.



I cut the car off and restarted it only to have the car go to approximately 3,000 RPM and stay there.



Any ideas on what this could be?

 

Check you vaccum lines.One might have popped off.It should idle at around 850 rpm not 1500 unless you have a serious port job done.

 

Vacuum lines, TPS adjustment, TB has to be clean and not sticking. Etc. There has been much discussion on this tread, but If you need help PM me.

 

It's probably the vacuum line that your squeezing (on the intake) my SE did that and I just put a little gasket sealer on both ends of that hose and it idles smooth again

 

My cars been doing almost the same thing...



It warms up fine, then drives fine....but after driving for about 10-20 minutes it will start idleing jumping from 1K-1.5K. If I ignore it, it will go away...and come back.....then go away....then come back. It also is jumpy when you just press the gas lightly like you described.



I have no idea what to do either Its damn annoying.



BTW I have a 85 GSL-SE too...tell me if ya figure out whats wrong...

 

While looking around, it appears that the two solenoids that control the BAC (idle control system of which I still am not sure the full name) on the motor are failure prone. I literally tapped lightly on these two solenoids as well as the BAC and my problem has at least been delayed, as the problem has not occured in over a week.



Check the Frequently Asked Questions portion, as well as my almost identical post on RX-7 Club. There are a couple links at these locations that describe our exact problem.

 

This might help..



If you remove the throttle plate assembly, (remove the 'air horn' and cables, coolant lines, vacuum lines. I soaked the whole thing in parts cleaner, then blew all the little metering passages out with compressed air. then wd40 the springs and throttle plates. Next replace all the vacuum lines. Reassemble it. Disconnect the BAC solonoid, (all the little electric connections at the rats nest). Set the idle with the screw on top of the air horn assembly (the little one that set in the cast throttle section). If that doesnt get u an idle at 700rpms look for the small straight bladed screw / set screw in the throttle assembly, it has a lock screw. I had removed my air pump and blocked off some vaccum lines going to the air pump etc, and so my car idled way too low. This caused my BAC to go crazy, by raising my idle by opening the throttle stop a little (about 1 turn) this allowed me to back off the other idle adjustment (the screw in the top of the throttle assembly) . ONce I hooked the bac assembly back up everything worked fine. U might want to spray some carb cleaner in your solonoids and in the BAC (Thing on the drivers side of the intake that the little air hoses are connect to)l. I will take some pics at home if it helps, but basically once u disconnect all the solonoids, it acts like a normal intake . U should get a stead idle (and also adjust the rich-lean so your idle is nice and smooth) and set the TPS before hooking all the BAC stuff back up.



I know its a bit vague, but hope it helps.