A few months ago I acquired a 1983 242ti Flathood Turbo. The only perceivable problem with the car was a rough idle while the car was warming up. It was a minor annoyance only. Then last month, the head gasket failed. I took it to a repair shop that specializes in all european cars. When they sent the head off to the machine shop, the machine shop said: "hey, this head has been ported and polished." After the head came back to the shop, they reassembled the car and tried to tune it. A timing light revealed the timing at 23 degrees advance. The car idled very roughly. They wondered aloud "say, do you think this car has some hot rod cam?" They fiddled with the car for a while, then the shop owner test drove the car. I was the passenger. The car seemed to pull well, but the shop owner kept on and on about how the car had that "hot rod cam" in it and it would never run right. It was late, well passed closing time and I had no other way to get home, so I took the car.

It had absolutely NO power below 2500 rpm - and then above 2800 it would knock, but had power. What instantly stuck me was, I wonder if they got the timing belt off by one tooth. Isn't 1 tooth equal to 12 degrees?

I brought the car back and they kept it for a couple days. I suggested that the belt was off by one mark. The said "impossible... well, possible, but not likely..." They called me and told me that all it needed was a new cap and rotor.

I picked up the car and drove it for a few days. It has a growl upon acceleration that was not there pre-head gasket. It has power across the spectrum and accelerates nicley. But the car idles VERY roughly and it would exhibit a strange behavior: When cruising at 2600 rpm or less, when the throttle is just barely depressed and the Turbo gauge is showing near zero total manifold pressure (not vacuum, but when the needle is in the 9 o'clock position), the car hesitates ever so slightly. It acts like it doesn't want to run at all. But then if you open the throttle up, the car zooms forward.

Fast forward a couple days:

This past saturday, I started the car and it idled (while cold) at about 2400rpm. After the car reached full operating temperature, the car decided not to idle at all!

so now I am a bit perplexed.

Several questions and comments...

1) If the cam is a "hot rod cam" (presumably one of the ipd/iskiderian cams, what are the distiquishing markings?

2) Does one of these cams require special valve clearance settings?

3) My money is still on the timing belt being off - I think they rotated the distributer and fiddled with the mixture to get the car closer to normal settings.

4) Any ideas about the bizarre idling troubles?

thanks in advance!