My g/f's Z28 is a 98 auto roughly 48K miles. Whenever she is at a red light(or just stopped in drive) the car idles slightly low(or so it seems) and the car vibrates alot. The worst part is under the hood it sounds like a diesel engine chattering!! I popped the hood and it sounds like a rediculously loud knock right under the manifold...or so it seems.

Also as soon as you put it in neutral the noise immediately stops as if nothing was wrong. The noise is pretty much there either if the engine is hot or cold. The only other symptom is then it seems to have trouble downshifting. At one point i had my foot mashing the pedal and it never went. It finally went after a few mashes... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

The only things i can think of are clutch packs in tranny are worn(causing the srewed up shifting) But as for the loud knock could that be a busted Torque converter?! Once again i am guessing...

Well thanx for the help.

FYI- i am an avid poster here but usually for my '00 T/A M6. I have no clue about autos so i need your help! ASAP! <img border="0" title="" alt="[Embarrassed]" src="gr_emb.gif" />

 

Is the car all stock? Does the problem only happen in Gear (any gear)?

Sean(Pig)

 

Sounds like an issue with the trans / converter / lock-up.

Mike

 

Mikey is right on I think. Same thing happened on my wifes Grand Am, it was the converter lockup solenoid/switch. The converter is attempting to lock when it should not.

 

BTW-there are no codes being thrown whatsoever. The car is bone stock. The only mod was a tire replacement when the GS-C's went bald. <img border="0" title="" alt="[Razz]" src="gr_tounge.gif" />

thanx for the info keep em coming. I do like that converter lock up solenoid idea. Any idea how to check that? Or what to do to make sure that is it?

 

except for the rougher idle, i would say cracked flexplate

 

TTT

 

Eddie it sounds like when you drive the car your extra weight taxes the drivetrain and the car just cant take anymore.. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

I believe the TC lock up solenoid is the thing to look at.

 

There is a section under transmissions in the Helms manual about vibrations and such to help troubleshoot whether the problem is engine/trans related. Could be helpful?

 

Does the problem remind you of what happens if you let out on the clutch of a manual trans car without giving it any throttle? This would be akin to the torque converter trying to lock while you are sitting still at a light.

 

If you can get your hands on a Tech 2 you can manually activate the TCC solenoid and shift gears manually.

Sean(Pig)

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by XtraCajunSS:
<strong>Does the problem remind you of what happens if you let out on the clutch of a manual trans car without giving it any throttle? This would be akin to the torque converter trying to lock while you are sitting still at a light.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">In a sense yes.

Well we are going to check it out wed or thurs. We will replace the solenoid first. If that is not it then tranny is coming off next. <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />