Currently, my car has 2 ECU's, one with a chip and one without one, the one without the chip throws a code P1613, which is something along the lines of bad ecu/tcu connection, everytime the car is coasting the RPM's fluctuate between 450-700 rpm.

That doesnt bother me though, the car drives.

My MAIN gripe is with the new chipped ECU that I got out of a 98 1.8T AEB passat. I had the chip resoldered with stiffer soders becase previously when the ecu was tapped the engine would shut off. But before and after the resodering I had a problem, the car would not start when cold. When I would read codes, there weren't any, but there was a Pending code. P0604 - PCM RANDOM ACCESS MEMORY (RAM) ERROR, when I clear, bam the car starts. No idea what is causing it. While messing about, I cleared the code with the engine on, and now I get an additional code on that ECU -P1545 MANF CNTRL VEH SPD, IDLE SPEED CONTROL AUX INPUTS. I think I basically formatted the throttle body and just need to do an adaptation, if anyone knows or can speculate what is causing the ram error, please post your input.

 

The chip is probably causing the ram error. The vehicle speed limit code is set when max speed is attained. This could also be part of the chp thou. Never heard of that particular idle speed control fault.

 

Ram error is faulty chip or faulty ECU.