1995 Jimmy rough shifts and idle, not the trans

[wingzfan99]

I have a 1995 Jimmy SLT 4x4 (4.6L Vortec V6) with approximately 131,000mi on it (and still more to come!) but since I bought it a couple of years ago, I've had some issues with how it shifts and idles. For context, though, I had to have the Trans rebuilt in September 2010 because I had no-go in all gears (but lots of revving). The rebuild got it moving again, but I still have the same issues:

1) Between 1 and 2 (in D or OD), it hits about 2600 or 2700rpm and holds there, and won't shift unless I back off slightly or put it on the floor. A similar issue occurs between 2 and 3, but not as severe.

2) At a stop, the RPM's are so erratic that it is actually revving itself... goes from about 600 to 1200 and back down again... it doesn't happen regularly, though.

I suspect that the two issues are separate, and I've been considering swapping both the EGR valve and the TPS for some time, but I don't want to go ahead and do it unless I know that's whats wrong. I'm assuming (or hoping) that with the recent trans rebuild, these aren't transmission-related at all... (if it helps, I also have very rough starts... takes about 5-10 seconds of starter before it finally grabs on).

Any ideas?

 

[barks507]

Start with something simple like cleaning the throttle body, IAC valve and check MAF sensor for cleanliness.

Worth a shot for the price of some cleaner.

 

[Molson02536]

I have a 1995 Jimmy SLT 4x4 (4.6L Vortec V6) with approximately 131,000mi on it (and still more to come!) but since I bought it a couple of years ago, I've had some issues with how it shifts and idles. For context, though, I had to have the Trans rebuilt in September 2010 because I had no-go in all gears (but lots of revving). The rebuild got it moving again, but I still have the same issues:

1) Between 1 and 2 (in D or OD), it hits about 2600 or 2700rpm and holds there, and won't shift unless I back off slightly or put it on the floor. A similar issue occurs between 2 and 3, but not as severe.

2) At a stop, the RPM's are so erratic that it is actually revving itself... goes from about 600 to 1200 and back down again... it doesn't happen regularly, though.

I suspect that the two issues are separate, and I've been considering swapping both the EGR valve and the TPS for some time, but I don't want to go ahead and do it unless I know that's whats wrong. I'm assuming (or hoping) that with the recent trans rebuild, these aren't transmission-related at all... (if it helps, I also have very rough starts... takes about 5-10 seconds of starter before it finally grabs on).

Any ideas?

Start with cleaning the EGR valve if not replacing it will address the idling issue, and also cleaning the IAC in the thorrle bosy which is common for the 95 vortec's.

Replacing the TPS will address the shifting issue to your transmission. Keep us posted and stay safe.

 

[wolf87ca]

Hi there, i had this same issue, for me it was a leaking fuel pressure regulator, which was spilling enough fuel into the upper plenum to cause it to flow over into the cylinders every few seconds, causing it to rev, if i was idle at a red light and didn't have my foot on the brake it would actually lurch forward in some cases, after replacing the part (about $65) I found that my fuel economy went up, the idle is *perfect* e.g. i can idle with no brake and it will not move an inch, and my shifting is a lot smoother.
i posted a link on the forums here where i found the info on what to look for, just hope its your Regulator and not the CPI itself.

EDIT:, heres the link by the way http://www.automotiveforums.com/vbulletin/showthread.php?t=503238