Hi, I have a late series 3 4.2 which has a problem with the idle speed dropping when it is fully warmed (more than 30 minute drive). Gradually drops to around 600rpm or less in drive and then will stall if changed into reverse. It will start okay but will keep stalling when a gear is selected. After a few minutes it works again.
I had adjusted the idle speed using the usual allen key adjustment below the AFM to the max, but it was still not enough.
A local Jaguar /MG specialist has attempted to fix it but has not succeeded. The mechanic has suggested there is a problem with the torque converter locking up, and suggested pulling it apart to check. I have had no trouble with the transmission in any other respect. My gut feeling it is the too low idle speed causing the problem.
The mechanic has checked timing, cleaned the throttle body and made various adjustments. He did remark that the inlet manifold vacuum was slightly low at 16 hg? when it should be 19.
After their second attempt to fix it, I requested they drive the car to my house which was a 40 min drive.
When the driver attempted to reverse, the car stalled. He did manage to reverse it into my garage, presumably by keeping his foot on the throttle.
Any ideas what would cause the hot idle speed to keep dropping? or could it be a torque converter issue?
Any help appreciated.
Philip, 1986 Sov. S3, Auckland, N.Z.