View Full Version : Tranny problems?

11-24-07, 05:11 PM
Any known problems for with the Northstar tranny? I have 1994 Seville SLS and car is bucking like a bronco (shaking and shuddering) after it warms up and under load. Very apparent in 4th gear (OD) and cruising on highway. Just nudge the gas to get a little acceleration and the whole car shakes. Two PCM codes come up PO39 and PO60. But I know the PO60 is because i often shift into neutral with the cruise engaged because i live in an area that is hilly, and i often can coast for some long stretches. So I dismissed both as having to do with the same issue.

I've had stumbling problems before about 4 years ago, and i ended up changing coils, ignition wires and spark plugs without relief. Than I found a leak in the catalytic converter, and when i replaced with new and sealed up the exhause system, it was back to working good as new.

This time around, I started with same suspects but found nothing wrong with exhaust. Found a vacuum hose had come loose after a month of trying the other things. When i reconnected the hose the stumbling got better especially when engine is cold. I also notices that if i really put my foot into the gas, the shuddering seems to stop temporarily. All this was leading me to think my mixture was running lean. But I dont know where to go from here

The engine idles fine, and in neutral or in park, it revs cleanly to the readline and i can use the gas pedal to steady state rev at all RPM's without stumble. All this leads me back to the PO39 code. Could the tranny be the cause of the shudder? the tranny filters were cleaned and 100% of the tranny fluid changed out 4 years ago at 123K miles, with no evidence of metal grindings. The car only has 159K miles on it now.

11-24-07, 06:07 PM
Based on that DTC it sounds like a TCC problem. Did you use A/C Delco wires & plugs?

11-24-07, 06:18 PM
Yes AC Delco wires and plugs. But wasnt the issue 4 years ago, and doesnt appear to be the problem this time. I'm stumped.

The biggest improvement came when i found the disconnected hose and reconnected it. but it still shakes badly when load is but on it. Doesnt stumble at idle or at high revs in park or neutral, and not really in first gear until speed gets above 10-20 MPH

11-24-07, 08:28 PM
Being OBDI, you can go into the diagnostics and see if the TCC is working (I think). You can probably override it as well to check it. You'll need a FSM to get the procedure though.

Tommy Deville
11-26-07, 04:47 PM
I had the same exact prolbem in my 95 Auora, I had Oldsmobile change all the plugs & wires, checked for Vaccum leaks, it never stopped, no explanation, evantually the Motor failed

11-27-07, 08:50 AM
Had a CrownVic & VW that did this. I would clean the the wires in the Airflow sensor very gently and it cleaned it up.

I notice that a lot of folks overlook cleaning the MAF every now and then. They get dirty, but do not throw a code.
Had a VW TDI that ate MAF's until I put a MBenz sensor in it.