My sons car is a 1991 Z28, 5.7 Auto, engine is stock, has edelbrock headers and flowmaster catback 3" exhaust system we just installed.

I've had a few issues with it after installing the headers. I've had idle problems, to high @ 1200 rpm. I adjusted the IAC yesterday and it was a little better and ran ok.

Today, we took it down the road and no third gear,, 1st and 2nd good, into 3rd gear, just revs and doesn't engage. Is it something I did with the IAC? Is there an adjustment that I can look at? I've researched some things but haven't had luck with any information. Any ideas or suggestions on what to check or adjust?

 

The IAC has nothing to do with the tranny. If it's neutralizing in third gear, it's probably time to rip the tranny out and have it looked at.

My IROC started doing that shortly after I hollowed out the cat, and I had to have it rebuilt.

 

The transmission was shifting perfect,,,. What a let down. I was hoping there was an adjustment that became loose. Damn

I did buy a T5 5 to 6 weeks ago to put into it down the road but it needs to be gone through. Any trustworthy shops for the rebuild on the T5 or the 700R4 in Southern California? Thank you.

 

if it went from shifting perfect to no third gear id say its a valve body problem.may need repair instead of rebuilding.

 

This is what your third gear clutches will look like.
That requires a rebuild.

 

If you're going to stick with the automatic, Pro-Built is in Calimesa. I'd check their web site and give them a call.

http://www.700r4l60e.com/

When my '03 4L60E (essentially an electronic controlled 700R4) in my M-Body van lost the 3-4 clutches, Dana recommended his 4L60E heavy duty kit.

When the 3-4 clutches went, it did so pretty quick without much warning. The only thing I started noticing was that the 2-3 shift became really soft and then it felt like neutral after a few more shifts.

 

Thank you guys for the info. I'm not keeping the automatic and that's why I don't want to spend a lot of money on a complete rebuild. However, I would like to see if I can't fix it to where it will last me a bit longer.

I need to have the T5 gone thru to make sure it won't grind and will function right. I have to weigh this out, one or the other. I wanted to fix the other things, injectors, sensors etc on this car first.

Too many things going on and very little time to do it right now, but I don't want to disappoint the kid, he loves this car.

Thanks again for your input.