I recently purchased a '90 GTU, and now it is giving a CEL, Code 27. I know that this is the MOP (Metering Oil Pump). We check the connections and pulled and cleaned the entire unit. Reset the ecu (disconnected battery) and recheck to make sure the code was cleared.

The unit looks good with oil flow through the tubes and no leaks.

After 10 miles of driving the code pops up. When I restart the car the check engine light goes off until I drive another 10 miles.

Besides replacing the entire MOP unit, are there any other fixes that we should try?

-T

 

Pretty much going with a standalone engine management system and using premix is your only other option. That costs $ though. Getting a used MOP is a cheaper alternative, but you still run into the problem of it crapping out again. The S5 MOPs are flaky.

I believe several people are working on a way to fool the car's ECU into believing there is a functional MOP there and just using premix instead. This would bring it out of limp mode and you would have the premix for the seals. However, I have not heard too much as of late on that project.

Best thing to do right now is drive the car as little as possible and if you have to drive it, throw some premix into the gas tank to make sure you get those seals lubricated. Good luck.