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charleshecht

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    1990 DeVille

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  1. Its sounding like a classic ECM/PCM problem to me. Did your new ignition module come with heat sink paste?, if it did make sure you transferred it to the new distributor. It might just have had a heat transfer strip on it.. Yes, it came with the silicone grease, I thoroughly cleaned the surface on the distributor base before applying the new grease, and I put an even, liberal amount when installing the new one. I hastened to even replace it because I have always found that when they are good, the car runs- if they are no good, the car will not run! Why does this have to be a "classic" ECM/PCM problem? Aren't there any regular problems anymore? Any way to have the ECM/PCM tested before I buy a new one? (other than the dianogstic test onboard). Thank you for your imput! checht I say classic because you are pulling your hair out, have replaced everything but the CAR, and have threatened to shoot it with your 45. In addition, you have having a classic symptom whereas your problem begins when the system warms up, that is a symptom of a bad electronic part. If I were you, I would go back to the scrap yard where you bought the distributor and see if they have an ECM laying around that you can swap in and eliminate this possibility. Have you tried the tap test? Do you know that TV repairmen used to carry a COLD spray that they used for diagnosis, they sprayed a component to cool it and if the problem disappeared they knew they found the problem.. (man am I OLD, now we just throw them out ) But as KHE said, check your wiring I have of course checked the connections in the harness that leads out of the distributor, 'cause I got it with the junkyard dist. I can not see another connection in the engine compartment, I guess it runs directly to the "classic" PCM/ECM? These connectors are all pretty weatherproof and resistant to just comming apart, they have a latch and lock on them. Next step is the PCM/ECM, I will try to locate it and "tap test" it. This reminds me of the old transmission repair commerical- they had a group of chimpanzees banging on a transmission with baseball bats in the back room. I still chuckle everytime I think of that commerical! I'll be back...checht
  2. He swapped in a distributor from the scrap yard however and it did not solve his problem.. My thoughts exactly..........what are the odds?!
  3. Its sounding like a classic ECM/PCM problem to me. Did your new ignition module come with heat sink paste?, if it did make sure you transferred it to the new distributor. It might just have had a heat transfer strip on it.. Yes, it came with the silicone grease, I thoroughly cleaned the surface on the distributor base before applying the new grease, and I put an even, liberal amount when installing the new one. I hastened to even replace it because I have always found that when they are good, the car runs- if they are no good, the car will not run! Why does this have to be a "classic" ECM/PCM problem? Aren't there any regular problems anymore? Any way to have the ECM/PCM tested before I buy a new one? (other than the dianogstic test onboard). Thank you for your imput! checht
  4. the engine only does this at operating temperature, I can make it a bout a mile down the road before it acts up. checht
  5. 1990 Cadillac DeVille 4.5 litre port fuel injection with 194,000 miles. The car was running smoothly until one day while driving it, it started to miss (or stumble) at a level speed. When I came to a stop, or let off the gas it stalled. It would start right up again and run fine during acceleration. Again it would have the same symptoms. I have checked the fuel pressure, changed the ingnition module, cap, coil, rotor, checked and cleaned all ground connections, and added a ground wire from body to engine. HELP! checht
  6. I bought a used distributor from the junkyard (with low miles on the car I took it from- it was wrecked in the rear). The distributor has no measuralbe play (except up & down motion, which is normal). I have replaced the cap, rotor, coil & ignition module. What are the odds that both distributors would have the same problem???? Again, I want to emphazise that the car drives smoothly until it reaches operating temperature! Thinking that there may be a short in the ingnition wire leading to the coil, I jumped it from the battery.....same results! The fuel data center will read 0mpg (as it should)15mpg, all the way up to 70mpg while the car is standing still (foot on brake trans in drive). I am stumped! checht
  7. I also removed the ground wire from the battery to the engine just above the starter and wire brushed it, there were no star lock washers present, so I added a stainless steel star washer and used silicone grease when reinsatlling the bolt. I ran a 10 guage ground wire from the body stud by the battery to the engine (where the dip stick attaches). I also removed and cleaned all the ground wire terminals I could find and reset them with silicone grease. checht.
  8. Yes, that is what a few have done on the 4.9, run a new ground from the starter area to the frame, but anywhere you can run a ground from the engine to the frame will be good. Check your grounds behind the battery also, sometimes acid eats them up. By the way, have you had your battery load tested? Try running with a fuel pressure gage connected so that you can see it (with a long hose and tape it to the windshield) so you can see if you are losing fuel pressure when this happens Well, I have checked all my battery and ground connections (unless there are some I don't know about). I found that the positive terminal was a bit corroded, so I cleaned it and put a new bolt in also. I am still having the same problems. I guess the next step is the PCM. Does anyone know if the PCM off a later year (1991 thru 1993 or later) will work with the 4.5L engine? Local junkyards seem to be out of 1990 Caddys!.... JUST A THOUGHT...I would like to eliminate all this computer stuff and convert the engine to a carbureted engine with a HEI distributor, how dependable and simple my mid 70's GM engines were! This car was my brother's car when new, he gave me a manilla envelope with all the work he had done on the car when I bought it from him, it was extensive! This car was never butchered or torn apart, all the work was done by certified mechanics, I just can not afford them. The age of the car does not warrant spending megabucks either! I have the shop manual for this car, the "computer system diagnosis section" seems to be written in a foreign language! Thanks to anyone and everyone out there for help and advice! Any additional info that may be helpful is appreciated! checht Come on.... your car is reliable - it made it 17 years and 190,000 miles before this problem... Check for codes - and post back. You may get lucky and a code might be stored that will lead you to the trouble. If no relevant codes are stored, I would use Mike's suggestion and duct tape a fuel pressure gage to the windshield and watch the fuel pressure when it starts to act up. It is time for some troubleshooting vs. throwing parts at the problem. I am going to follow everyones suggestions, first with the ground wire above the starter, then with the fuel pressure guage taped to the windshield as I attempt to drive it down the road....With the economy as poor as it is, I can not afford a new car at this time! Thanks to everyone participating in my discussion! I will post back when results are available. I will attempt the code thingy too! checht Cool, you will get it, have patience. I have tried the fuel pressure guage taped to the windshield, the results were; a steady fuel pressure of about 40 lbs even when the car stalled. Following suggestions from this discussion board I turned the key on, pressed the 2 proper buttons for a dianostics check (warmer & off). The results were shown as follows; codes E52, E53, and E75 showed up on the fuel data center then a 7.0 followed and stayed on the screen. I went to the website that was given and it says that E52 is PCM memory reset, E53 is distributor signal interrupt, and E75 is intermittent VSS signal. Can someone tell me what all this means please! Thanks, checht.
  9. Yes, that is what a few have done on the 4.9, run a new ground from the starter area to the frame, but anywhere you can run a ground from the engine to the frame will be good. Check your grounds behind the battery also, sometimes acid eats them up. By the way, have you had your battery load tested? Try running with a fuel pressure gage connected so that you can see it (with a long hose and tape it to the windshield) so you can see if you are losing fuel pressure when this happens Well, I have checked all my battery and ground connections (unless there are some I don't know about). I found that the positive terminal was a bit corroded, so I cleaned it and put a new bolt in also. I am still having the same problems. I guess the next step is the PCM. Does anyone know if the PCM off a later year (1991 thru 1993 or later) will work with the 4.5L engine? Local junkyards seem to be out of 1990 Caddys!.... JUST A THOUGHT...I would like to eliminate all this computer stuff and convert the engine to a carbureted engine with a HEI distributor, how dependable and simple my mid 70's GM engines were! This car was my brother's car when new, he gave me a manilla envelope with all the work he had done on the car when I bought it from him, it was extensive! This car was never butchered or torn apart, all the work was done by certified mechanics, I just can not afford them. The age of the car does not warrant spending megabucks either! I have the shop manual for this car, the "computer system diagnosis section" seems to be written in a foreign language! Thanks to anyone and everyone out there for help and advice! Any additional info that may be helpful is appreciated! checht Come on.... your car is reliable - it made it 17 years and 190,000 miles before this problem... Check for codes - and post back. You may get lucky and a code might be stored that will lead you to the trouble. If no relevant codes are stored, I would use Mike's suggestion and duct tape a fuel pressure gage to the windshield and watch the fuel pressure when it starts to act up. It is time for some troubleshooting vs. throwing parts at the problem. I am going to follow everyones suggestions, first with the ground wire above the starter, then with the fuel pressure guage taped to the windshield as I attempt to drive it down the road....With the economy as poor as it is, I can not afford a new car at this time! Thanks to everyone participating in my discussion! I will post back when results are available. I will attempt the code thingy too! checht
  10. Yes, that is what a few have done on the 4.9, run a new ground from the starter area to the frame, but anywhere you can run a ground from the engine to the frame will be good. Check your grounds behind the battery also, sometimes acid eats them up. By the way, have you had your battery load tested? Try running with a fuel pressure gage connected so that you can see it (with a long hose and tape it to the windshield) so you can see if you are losing fuel pressure when this happens Well, I have checked all my battery and ground connections (unless there are some I don't know about). I found that the positive terminal was a bit corroded, so I cleaned it and put a new bolt in also. I am still having the same problems. I guess the next step is the PCM. Does anyone know if the PCM off a later year (1991 thru 1993 or later) will work with the 4.5L engine? Local junkyards seem to be out of 1990 Caddys!.... JUST A THOUGHT...I would like to eliminate all this computer stuff and convert the engine to a carbureted engine with a HEI distributor, how dependable and simple my mid 70's GM engines were! This car was my brother's car when new, he gave me a manilla envelope with all the work he had done on the car when I bought it from him, it was extensive! This car was never butchered or torn apart, all the work was done by certified mechanics, I just can not afford them. The age of the car does not warrant spending megabucks either! I have the shop manual for this car, the "computer system diagnosis section" seems to be written in a foreign language! Thanks to anyone and everyone out there for help and advice! Any additional info that may be helpful is appreciated! checht
  11. In adding a redundant ground should it be from the chassis to the engine? Thanks, checht
  12. Hi, I have a 1990 deville with 4.5 litre port fuel injection. This car has 190,000 miles and has always run like a top. Maintained properly etc... I recently was driving the car when it suddenly started to studder (misfire) at a level speed. When I put my foot into it it still accelerated very strongly, however, when I came to a stop it stalled. It would restart immeadately and continue to run on acceleration, but misfire or stall when I leveled out the speed. The next day, I checked the fuel pressure suspecting a bad fuel pump or clogged screen. The pressure checked out OK, so I continued on with other basic suspected parts. I added gas dryer to the tank just incase of bad fuel. Then I replaced the distributor cap, rotor (they really needed replacing!) and ignition module. Still having the same problem, I replaced the ignition coil, no luck there either. About a year ago, I replaced the plugs and plug wires, I do not suspect them as I have looked under the hood at night with the engine running for shorts in the wires - none. I have noticed that it seems to make it about 1 1/2 miles down the road before it acts-up, so I am guessing what happens has something to do with the engine being at operating temperature? Yesterday, I thought about the pick-up coil in the distributor, went to a junkyard and found a low mile -wrecked in the rear- 93 deville, pulled the distributor out and replaced mine with it. Still the same problem. I have noticed that the milage sentry goes a little crazy when the car starts acting up, and today noticed the fuel guage first read 9 gallons, then went to low in a flash. Any ideas what this problem could be? Thanks for any input from experienced Caddilac owners or mechanics! checht
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