embalmer41 Posted January 28, 2006 Report Posted January 28, 2006 I have a 1989 Oldsmobile Cutlass Supreme, 2.8l with an unusual problem. We got the engine instaleed and it fired up with no problem at all. Ran perfectly for about a week. After installation i only put 80 miles on the engine so far. Got ready to go home from work , the engine cranked fine and as soon as i was backing out of the parking lot, the engine died. Tried to crank it, no start. Got it home and checked for spark, and fuel and they are both ok. Now the engine tries to start but it does a kickback like it wants to turn over in the opposite direction. It's almost like a backfire. Everything on the engine is brand new, i didn't use any of the old parts from the original engine. Tried cranking it again today, it cranked but ran really rough, but when i switched it off and tried to crank it again, same problem but this time i got a backfire followed by a flash of light called fire. I have a new cat installed so exhaust being clogged is not the problem. Someone suggested the knock sensor might be bad, because that's what the ECM uses to control engine timing. Any help would be greatly appreciated. Quote
Supreme Cutlass Posted January 28, 2006 Report Posted January 28, 2006 is the ECM working properly? I assume that by saying "everything on the engine is brand new" you mean sensors, too? Quote
sdwhite Posted January 28, 2006 Report Posted January 28, 2006 If the knock sensor is activated it will retard the timing and set a code in the computer and turn the check engine light on. This sounds more serious than that. Actually, it sounds a lot like a spark coil dying. Quote
embalmer41 Posted January 28, 2006 Author Report Posted January 28, 2006 Everything is brand new. Computer, sensors, new injectors, new ignition module, new coil packs. Everthing is new out of the box. The car ran fine for a whole week without any problems, and no codes in the computer. I remember putting in the new crankshaft position sensor and noticed that it was longer than the original one in the old engine. Hmmmm. I may be on to something here. Quote
SUPERDUTYD Posted January 29, 2006 Report Posted January 29, 2006 check for wiring melted against exhaust or engine parts. Quote
GutlessSupreme Posted January 29, 2006 Report Posted January 29, 2006 check for wiring melted against exhaust or engine parts. Â x2 friend had that happen to his O2 sensor on his caravan after we swapped the motor. wire was hanging on the downpipe. Quote
Rocketman Posted January 29, 2006 Report Posted January 29, 2006 check for wiring melted against exhaust or engine parts. Â x2 friend had that happen to his O2 sensor on his caravan after we swapped the motor. wire was hanging on the downpipe. Â x3 i had my Crank sensor too close to the x-over and it started to melt it. Quote
GP1138 Posted January 29, 2006 Report Posted January 29, 2006 check for wiring melted against exhaust or engine parts. Â x2 friend had that happen to his O2 sensor on his caravan after we swapped the motor. wire was hanging on the downpipe. Â x3 i had my Crank sensor too close to the x-over and it started to melt it. Â x4 Did the exact same thing with the crank sensor wire. It actually had me chasing my tail for months, as it was routed around the o2 sensor and it took months for the wiring to melt and the wires to short. The car would alternately run fine and then just miss and die. Quote
embalmer41 Posted January 29, 2006 Author Report Posted January 29, 2006 The crankshaft position sensor is to close to the crankshaft and it needs to be shimed. The sensor is reading 4000 rpm while cranking, thus dumping the fuel to it and causing the kickback and also affected the timing beacuse pcm sees high RPM. So i'll just use a shim to back it off a little and see what happens. Quote
R Dubya Posted January 29, 2006 Report Posted January 29, 2006 shouldnt have to shim it, those are precision parts meant to be installed one way and one way only. I wouldnt rig it, I would take it back to where you got it and exchange it for the correct one. Quote
embalmer41 Posted January 29, 2006 Author Report Posted January 29, 2006 Did that already. Did the same thing. I just finshed working on the car. I shimed the sensor anyway and the engine fired right up. Runs like a top. I compared my old sensor to the new sensor and the new sensor is almost 3/8 inches longer than the oem part. I told the parts guy the sensor looked longer than the original one and he said it was the right one. And i went to Autozone and they they had the same sizes as Advance Auto Parts and it was also 3/8 longer than the oem part. Go figure. Drove around for about thirty mins and no problems or anything. Looks like they are not that precise huh. Quote
R Dubya Posted January 29, 2006 Report Posted January 29, 2006 I personally wouldn't take a gamble on it. If it's not the same as the OEM part, then it's not the right part. But hey, to each his own, good that it runs, hopefully you don't see any negative effects. Quote
Canada Posted January 30, 2006 Report Posted January 30, 2006 What was your fuel pressure? It usually takes at least 25 psi to start an engine......40-45 psi is a lot better. Quote
embalmer41 Posted January 30, 2006 Author Report Posted January 30, 2006 Fuel pressure was 42 psi. Quote
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