1989 Pontiac Bonneville LE V6 3.8L AT

I got some screwed up problems with a car again, I'm starting to hate Pontiac. When shifting between drive and reverse, or netural to reverse, the engine kicks like someone slams into the car. Every single motor/transmission mount had to be replaced because they all broke at once, and it'* not long till it happens again. Also the electronic ildler control valve had been replaced. From what I can make out of it is that it seems like the car is to rev'ed up and that'* why it kicks when shifting. The engine even sounds a lot louder like someone has their foot on the gas. Is there anyway to adjust anything, the cable for the gas or an adjustment on the ildler?

Thanks for any help.

I took it to the shop to get the mounts replaced, I was planning on doing it myself but it took a little over one hour to get one nut unloosen and then it was hitting the compressor so I coun't even get it off all the way, gave up and threw it in the shop and they replaced them all for a little over $400. From the looks of it.. all the motor mounts are brand new and it was all installed fine.

Your first best bet really is to get the car scanned with a full readout, then make sure you get a copy and tell us what it says or scan the sheet and post that. It will certainly help us to help you if we know what the ECM is seeing.

As far as your hate for Pontiac right now, I understand that you are frustrated right now. We all get that way at some point if there is a particularly annoying/difficult analysis or problem that is giving us headaches. It'* even more annoying when there is more than one thing wrong at one time. But do remember that your car is 17 years old.

Any car that old will develop issues that are larger than the standard maintenance items you would see on a younger car. Things wear out and need to be replaced eventually.

You have certainly come to the right place to seek diagnostic help. The folks here are pretty experienced with this car and likely can help you resolve your issues if you work with them and give them enough information to go on.

EDIT: Oh yeah. And it'* important to realize that when the shop replaced the motor mounts, if the car was reving too high at the time (as it sounds like it was), all they did was fix a result of your real problem. They did not fix the root cause of your problem.

I understand, and thanks for any help. Sounds like an ECM scan is the best idea than to jump off spending money and just guessing at it. I'll see what I can do about getting a test ran on it.

A malajusted Throttle Position Sensor (reading over .42v at idle) can cause an abnormally high idle (should be 625-725 rpm when warmed up and not over 1500 rpm cold) a high idle will cause a jump when shifting into gear.

Adjusting just is a matter of loosening two screws on the throttle body and rotating the TPS.

Also a coolant temperature sensor reading abnormally low can cause this but generally will not run well.

thanks, I'll take another look at it. Last night it looks as if the TPS was rotated as far as it could go and was already hitting, but I'll have to take another look at it.

Just to clear things up a bit..
(random img.)


I'm pretty sure the TPS has been replaced before but im not sure when, but when the throttle lever is pulled back (being pushed in pic) the engine quiets down and is not idled as high. So it seems the only adjustment that needs to be done is to the throttle lever or the throttle cable.

yea i just about to state that the IAC/EGR has been changed and I was told it didn't need to be cleaned on the flange and that another gasket wasn't needed. I'm starting to think that might be where my problem is.

It'* and older IAC that came off a Buick and the flange wasn't cleaned and theres no gasket.
Could that be what'* causing the engine to kick around and a high idle?