racin951

Let me start from the beginning. I installed a 993 Varioram in my 72 911 Coupe recently. Along the way I had the computer reprogrammed by GIAC. I also removed the power steering pump. With the pump removed, I fabricated the necessary items to reinstall an oil cooler on the block. This meant machining the the camshaft stub on the rear off. I reset the cam timing according to what the driver's side was at. I'm not sure if the 0.95 mm is correct or not. I also installed headers and some nice stainless mufflers with small 4" cats inside the muffler. All 4 Oxygen sensors are installed.

Since I started it up the check engine light comes on and stays on. When I disconnect the battery, it takes a little driving before it comes on. The engine has a little popping or backfiring sound coming out of the passenger side exhaust. GIAC says I needed cats and their computer programming wouldn't cause the light to come on. So I added cats with no change.

One more note to all this. I noticed when I bought the engine that it came out of a car that was hit on the passenger side. The reason I know this is the sheetmetal still had stickers from the dealer and the fuel rail has a small dent in it.

I've driven the car maybe a couple hundred miles. It has tons of power but I'm not sure if that's because the car is light. It revs up to 7000 quick with no hesitation.

Any help in what direction I should begin would be greatly appreciated. I just don't know where to start.

Kevin

One quick note, how do you have the DME wired? You need to have constant power to it when you turn the ignition off. Also, your cats need to be close to the headers for them to lite off. You might have a damaged plug wire from the accident.

racin951

The cats are close to the headers. I will check the plug wires and the wiring for constant voltage at the DME. Thanks for you help and I'll post what happens.

NRK

I have a '95 993 and added an RS varioram. Similar symptoms -- a minor pop or two on rapid drop throttle. No big deal, and my chip (an FVD unit) is probably responsible. Nice power boost, BTW, though my fuel mileage dropped considerably.

R SQUADRON 911

Had the same problem with my car, but after I changed the O2 sensors the problem was solved.

Might not be a problem, but it's worth a look. I'm also gusessing that your car is now OBDII? Get a scan tool onto it and see if you come up with any engine misfires.

hope this helps