I have a 91' 3000 GT SL with 51,800 miles. Have had problems for a long time with engine intermittently missing.....drives ok for a while then takes a nose dive and looses power and wants to stall....kinda feels like the engine is running on less than 6 cylinders (as if someone pulled a couple plug wires while running).....if I play with throttle, the engine will sometimes come back....other times not. The tach wildly jumps between 0 and 7000 RPM while it misfires. I replaced the PTU and all three coils with NOS parts as I was getting error codes of 52 and 53....trhat made sense to me because the PTU feeds the tach. Ran ok for a while than did the same thing again. Took the coils and PTU out again and bench tested to be sure they were OK....then put back in the car. Each time I did this, I took the neg battery cable off to be sure I didn't short anything. The second replacement I did I noticed a "click" when I put the neg cable back on....sounded like a relay switching or a fuse link or fuse blowing. This time the engine turned over but wouldn't start. I checked all the fuses under the hood and dash and all fuses look good. I'm not a total gear head but I can follow directions and can figure things out. Can anyone give me some help with this???
thats a toughie, i would look for vacuum leaks to start with.
Have you checked your ignition relay? Mounted under carpet passenger side of center console. Have you checked for fuel pressure?
Also check your negative battery connections on the frame and motor. These cars are known to do all sorts of weird things when grounds are not perfect.
I did check grounds on transmission and the two on the firewall (first one to the ground side of battery and second one from firewall to motor) they were OK. When I heard the click is sounded like it came from the top or rear of the engine and the more I think about it I think it sounded like a relay or spark jump. I will pull the ignition relay.....is there a bench test to check for defects???
yes, go to you tube and type in "how to test automotive relays". also, ericthecarguy.com has a vid or 2 on this subject.
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