PeachParts Mercedes-Benz Forum - View Single Post - bweger- My 72 280 sel 4.5 hardly runs!

Tomguy · #2 07-23-2006, 01:35 PM

Assuming your wiring harness isn't bad, your D-Jet computer may have some loose solder joints in it (or be on its way out) resulting in this. Many mechanics that work on these have spare 4.5 ECUs lying around. It wouldn't hurt to try a new ECU out on it for a few days and see if that resolves your issue. If your mechanic doesn't have a spare ECU, see if you can pick one up on eBay usually for $20. A 3.5 ECU, although not a perfect match, will allow your 4.5 to run fine if this is the problem. It won't have the 10% full-throttle enrichment and will probably have a different fuel curve, but it will run a lot better than what you're describing. Check your wiring harness's ground wires, which I believe are behind the battery. Make sure they aren't loose or rusted - it will result in injector banks not firing (4 at a time). The 4.5 will run on 4 cylinders, but will have no power and be very rough.

As for engine harm, it depends on how hot your engine gets while making this trip. There is a good chance it might overheat. Keep an eye on the temp gauge. Better yet, stop by and see if he has a spare ECU you can borrow, and put that on yourself.