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Big D · 07-20-2015

Ok, the saga continues. First, I believe I have found the problem but ran out of time last night to fully verify. Looks like I have a bad connection at the ECM connector, probably a pushed back socket at A8 or I oversized it so that the pin doesn't make good contact. Now the story. First I disconnected the electrical connectors from all of the injectors. Then, using a 9 volt battery, I checked the # 6 injector and the # 2 injector as a knew the # 2 was good. I jumpered from the injector to the battery negative side and then touched the positive side and got a good click each time. Did the same to # 2 for comparison and it acted the same, so I ruled out a faulty injector (which I basically had already). Next I pressurized the fuel rail and did the battery check again. Looking down the injector port you can see the injector spray end and tapping the positive produced a nice spray out of the #6 injector, same with # 2, again verifying the good injector. Then I re-connected the plenum electricals for my next test. With the ignition module now connected I reconnected the #2 and #6 injectors electrical connectors. I had my assistant (daughter) turn the car over while I looked down the injector port. # 2 sprayed very nicely but #6 did not. So, back to shooting wires. Checked wire from injector to ECM, no problem. Looked into the ECM at pin 8, .7 K ohms. Re-connected the yellow ECM connector. Then I did voltage and ohm checks of each injector connector pins. With the key in the run position, "B" side should read around 12 volts (from the ignition) and the "A" side is looking for a ground into the ECM. I'm assuming here from data I have generated that the "A" side should read about .7 - .8 mega-ohms in this setup. (all "A" side resistance was around this number except for # 6). # 6 showed an open circuit on the "A" side but 12v on the "B" side. Ok, so the "A" side is not getting the signal from the ECM. Removed the yellow ECM connector and re-verified continuity between it and the #6 injector and it was good. Verified .7 k ohms into the ECM at pin 8 and it was good. Checked other injector pins into the ECM and got the same results. Next I jumpered from pin 8 of the ECM to socket 8 on the connector. Went to the injector connector and ohmed out pin "A". It read .7 k ohms. Then I was out of time. I will try and "fix" the socket to get a better connection with the pin and then do the injector test like before. I feel pretty confident right now that the plug is the problem. I'm thinking I might have used a test pin into the connector that was too large when I was first doing my injector tests when this problem first surfaced and the larger pin opened up the socket too much. Will get back at this next weekend, hopefully with good results.

07-20-2015	#27
Big D Join Date: Jun 2014 Location: Washington State Posts: 17	Re: LT5 miss at all speeds Ok, the saga continues. First, I believe I have found the problem but ran out of time last night to fully verify. Looks like I have a bad connection at the ECM connector, probably a pushed back socket at A8 or I oversized it so that the pin doesn't make good contact. Now the story. First I disconnected the electrical connectors from all of the injectors. Then, using a 9 volt battery, I checked the # 6 injector and the # 2 injector as a knew the # 2 was good. I jumpered from the injector to the battery negative side and then touched the positive side and got a good click each time. Did the same to # 2 for comparison and it acted the same, so I ruled out a faulty injector (which I basically had already). Next I pressurized the fuel rail and did the battery check again. Looking down the injector port you can see the injector spray end and tapping the positive produced a nice spray out of the #6 injector, same with # 2, again verifying the good injector. Then I re-connected the plenum electricals for my next test. With the ignition module now connected I reconnected the #2 and #6 injectors electrical connectors. I had my assistant (daughter) turn the car over while I looked down the injector port. # 2 sprayed very nicely but #6 did not. So, back to shooting wires. Checked wire from injector to ECM, no problem. Looked into the ECM at pin 8, .7 K ohms. Re-connected the yellow ECM connector. Then I did voltage and ohm checks of each injector connector pins. With the key in the run position, "B" side should read around 12 volts (from the ignition) and the "A" side is looking for a ground into the ECM. I'm assuming here from data I have generated that the "A" side should read about .7 - .8 mega-ohms in this setup. (all "A" side resistance was around this number except for # 6). # 6 showed an open circuit on the "A" side but 12v on the "B" side. Ok, so the "A" side is not getting the signal from the ECM. Removed the yellow ECM connector and re-verified continuity between it and the #6 injector and it was good. Verified .7 k ohms into the ECM at pin 8 and it was good. Checked other injector pins into the ECM and got the same results. Next I jumpered from pin 8 of the ECM to socket 8 on the connector. Went to the injector connector and ohmed out pin "A". It read .7 k ohms. Then I was out of time. I will try and "fix" the socket to get a better connection with the pin and then do the injector test like before. I feel pretty confident right now that the plug is the problem. I'm thinking I might have used a test pin into the connector that was too large when I was first doing my injector tests when this problem first surfaced and the larger pin opened up the socket too much. Will get back at this next weekend, hopefully with good results.