The idle speed on my TPI 305 has gotten out of hand. Until its completely warmed up, it idles about 2600 then finally, after it COMPLETELY warms up, the idle goes down to about 2000, or 1500, or 1800, or 1000 or whatever speed it decides on at the moment. Everytime I let off the gas the idle is in a different place. It's smooth and constant, just changes all the time and always TOO FAST. So far I've:

Changed injectors
Reset IAC and adjusted minimum idle about 100 times
checked and set TPS voltage a bunch of times
fixed a couple of minor vacuum leaks
Changed O2 sensor
Cleaned the air filters

With the IAC closed and disconnected, I can get the idle down to a tick. Plug the IAC back in and it goes to 1000. Drive it around a bit and its all over the place again.

Anybody has any ideas, I'm all ears.

 

How old is the IAC? It could be sticking, which would explain the random idle speeds.

 

Its new and I cleaned the TB real good before installing.

It is, however, an autozone special.

 

Have ya tried the method of setting the IAc and TPS at the same time.That usually cures a "hunting" idle in most cases.This is assuming you dont have any vacuum leaks,timing is set right,good fuel pressure,good injectors,cts sensors are working properly and dont think the car is -40* lol etc.Do you have a check engine light on aswell?

 

Nope no light. When I jump A & B I get code 12, which is all OK. I set the TPS voltage and minimum idle within 15 minutes of each other last night with the engine completely warmed up. New (FIC reman) injectors (Bosch IIIs) were fired last night for the first time. New runner, plenum, and TB gaskets went in yesterday. Fuel pressure is 42# + or -. Vacuum leaks are always possible, but when setting minimum idle (w/IAC unplugged) it ticked over slow and smooth. Timing haven't checked. Dont have a light, but havent touched the dist. since it idled normally some months ago. Don't have a light, but guess I could borrow one from the zone or O'reilys

I suspect the MAF might be crap. I'll get one of those first chance I get. Pretty sure the one on it is original....twenty years old. Don't know if the MAF would cause this problem though.

 

I don't think it is the MAF you would have a code. When the pickup coil in the dizzy fails or is going south it will cause that problem.

 

I've been looking for an excuse to get one of those MSD 8366 ready to run pro billet distributors. Took my dist cap off a couple of years ago and it was full of fluffy white corrosion. I cleaned it up and it seemed ok. You just cant beat the quality of the MSD stuff, though.

 

Disconnect it, and start the engine....

 

The car will not start with the MAF disconnected.

 

I have the MSD 8366, when my pickup coil went, I just replaced the dist. with the MSD 8366. Its awesome unit, roller bearings, billet alum. The quality compared to a stock one is unmatched. My car also starts alot faster with it.

 

Yeah I have a pro billet in my 69 camaro. That and the 6AL box improved drivabilility of that car 100%. With a .510 lift cam in a 350, the car goes through school zones in fourth gear smooth as silk. I've never had any complaint with MSD. It's top notch stuff.