2000 4.2

On cold start the idle bounces 2-4 times from 600-1400 rpm then levels off at 1200 or so for warm-up and kick down when warm fine. After that there's no trouble and it starts fine when warm no bounce. Only in cold start.

I replaced the MAF, Temp sensor, and all Vacuum lines. The vac system is holding vacuum. Lambda is 0.0% on all four after warm-up.

I have these two codes - but no CEL

P1564 Throttle actuator(J338) under voltage during basic setting - intermittent

P1141 Load Calculation cross check - implausible

any suggestions?

 

Throttle Body most likely.. have you re-adapted?

Also, apparently you can pull it apart and hit with contact cleaner:
http://tech.bentleypublishers.com/th...41526&tstart=0

 

Agreed, do a throttle body adaption.

 

That was the first thing I tried, no success.

So going of the "under voltage" DTC I pulled the terminal off and cleaned it, Nothing. Then I pulled the side cover off
took a nail file to the top two terminals ans sprayed the rest with MAF cleaner and just tweaked the four lower terminals.

For those that need pictures (midniteoyl) Please scroll down.

I did mine with the TB on the manifold. I don't know if you can do them all that way. Stuff shop rags around it before popping the clips or you'll be sorry!

One of the clips


The upper terminals I cleaned with a nail file. Blow out the filings with air!


The lower ones I sprayed and bent them out very slightly so they make good contact.


The cover I sprayed


The cold start idle bounce and the surge while driving is gone. Acceleration from a stop is much smoother.

 

COOL!

Whats wrong with wanting pics?

 

Thank You Jackem Up...I did what you posted and the pics along with your tips helped me do the job and IT WORKED..NO MORE BOUNCY IDLE!! Getting the clips off and back on is the trickiest part of the job...one thing I did was to put strips of blue painters tape on them which allowed me to retain them once I popped them off the sensor and also helped me reposition them when putting everything back together..duct tape might be better. Anyway thank you so much for posting what you did..it solved my problem!!!

 

I just saw that.

Great !

That should cancel one of those bad things I've done somewhere

Lord knows I been paying homage to the GM Mechanic gods lately.