Hello all,

I've been having ongoing driveability problems with my '89 740 Turbo. It's had an ongoing stumble that could be characterized as a lean/fuel starvation problem. Recently as the weather got drastically colder the car ran more roughly with what appeared to be lowered turbo boost. One day after work it would not get above about 15 or so mph without backfiring and losing enough power that you would have to back off the accelerator in order to keep it creeping along at 10 - 15 mph speeds. I was able to get a long enough run-up to keep it going until it hit the 40+ mph range and was able to get it home. I haven't been able to run it for the past month or so because it's been so cold the car would only run at about 10 mph or so. Today it was running better although I had to jump start it and keep the accelerator floored for what seemed like minutes before it finally caught and was able to start up and run. I was surprised to find that it would run and the turbo boost gauge would climb up to the yellow portion and a little beyond, however the boost seemed to be lacking and when I floored it it would backfire and seem like it was really being held back almost. I got it drove it around for a few minutes then parked it. After popping the hood I saw the exhaust manifold between the manifold and the turbo was red hot. Is this a plugged catalytic converter? Also, I had replaced the knock sensor a while back in case anyone was thinking that might be related. I believe the previous owner had replaced the O2 sensor as well. I read about another brickboarder whose cat was disintegrating inside and pieces would momentarily block the outlet creating a loss of power. I'm wondering if this is what happened to mine and now it's simply had an internal meltdown. Sorry about the length of the post.

Matt Campbell