My 91 244 has an EGR system. The pipe that runs from the exhaust manifold around the back of the head and into the EGR valve broke (thankfully, right near the exhaust manifold). Rather than trying to patch the pipe or replace it, I just crimped the pipe closed to alleviate the leak/noise. Of course, the check engine light is on with a 2-4-1 diagnostic code. My former mechanic said a non-functioning EGR won't hurt anything, and I live in a state without strict emissions testing. Am I potentially doing any harm?

Also, I've seen some conflicting information online about AMM compatibility with the EGR system. My AMM is an original Bosch unit (0 280 212 016) that FCP says will fit any 89-93 with LH 2.4 injection, with or without EGR. Other online sources suggest an 016 Bosch AMM will only fit an EGR-equipped vehicle. Is there a difference?

Finally, the ECU part number is (0 280 000 556), a specific model for an EGR-equipped vehicle, again according to FCP. Will a 933 ECU interchange and what is the difference? What about a 951 ECU used on non-EGR cars?

I'm headed to look at a parts car tomorrow (90 244) and am hoping these important components are interchangeable with my vehicle. Are there any other major mechanical differences between 90 and 91?

Thanks--