Thanks for the help several weeks ago, I have fixxed a good portion of the problem, but not all. Motor is an '89 L98 LPE 383 with the Big mouth style plenum and throttle body. Originally the car would not idle after it was warmed up. I pulled the throttle body and removed and cleaned the IAC module and the orfice where it resides. Now the car holds an idle of about 900 rpm(is that too high?) when sitting. When you drive it, it runs well but as your slowing down or in between gears the idle will not drop below about 2100 rpm's. If you blip the throttle, it will drop to 900 rpm 90% of the time.
It otherwise will stall. Sometimes it will act like it is hunting for an idle speed. So I was just out driving it and when the car exhibited the 2100 rpms I pulled off the road,popped the hood and looked at the throttle position. Itwas open a tad causing the motor to race. I pushed it back until it rested on the idle screw and it idles at 900 rpm. In the process of troubleshooting this I have monkeyed with the TPS sensor location and tweaked the idle screw.
My questions are these:
Did I just not clean the IAC well enough?
Did I screw up the TPS?
Could the spring be bad on the throttle?
I also sense the car is not completely in tune, what tools(scanners) do I need to do a complete tune on the car? I assume I need to check and tune the IAC, TPS, the MAP, idle, fuel mixture, fuel pressure. Is there anything else?
Spring is comong and I feel th need for speed. Thanks in advance for any help you can give. :confused:

John


[Modified by mac383, 2:57 PM 3/9/2002]

 

With the engine off I would move the throttle body blades by hand to see if they stick when you let them close. If you can get the throttle body to stick, I would then remove the cables from the throttle body and see of it does it then. If it does, then there is a sticking point in the throttle body, perhaps some judicious lubrication, or some very gentle polishing, might free it up when you figure out where in the TB it is sticking.

If the TB won't stick without cables, then one of your cables has a bind. I would repeat the above with just the accelerator cable attached. If it sticks, then you have a bind in the cable, or perhaps your pedal is hitting something or needs some lube. If the accelerator cables doesn't stick, remove it and attach your TV cable (if you have an auto), and repeat the above...etc, etc. this shuold help you pinpoint the sticking point. Good luck.

 

I have the same problem on occasion..... part of it is a careful blend of the right TPS voltage setting and idle screw adjustment. There is not 100% correct way to set it, you simply have to experiment.

Do you have the LPE billet 58 mm tb or somebody elses throttle body.

Part of the problem, especially with your idle staying up at 2000 rpm is the freakn throttle body when heated up is contracting around the blades, and also the shaft.... that coupled with the bigger 58 mm blades the vacuum can create havoc..... at least the above is the problem I have with my BBK 58 mm throttle body. I was hoping a switch to a higher quality billet throttle body would fix this problem.

As a note, I'll bet a nickel if you switch to a 52 mm throttle body, 80% of your problems will disappear, or at least they did with me.

Let me know what you discover, it should apply to me as well.

Beach Bum