Injector/Misfire Problem
02-07-2006, 05:19 PM
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Injector/Misfire Problem Vehicle: 2000 Z28 A4 68,000
Problem injectors: 2/4/5/6
Diag Tools Used: SnapOn MODIS and OTC Genisys
Ok so here it is, I want to know has anyone else experienced the same problem that I currently am. I reciently removed my cats on a basicly stock car. I am now experiencing a misfire conditon on the cylinders listed above. As well on that same bank I am having fuel trim problems. DTC was set for a misfire conditon, I then checked for which cylinders and those above were listed. I checked for a vacumme leak with a SnapOn leak tester smoke machine, found nothing. I then used MODIS to access Datastream and found that bank 2 (B2) had a average 5.42 millisecond injector pulse width where as B1 was a 3.23 milliseconds. Also the long term fuel trim had gone to 15% on B2 and B1 was at 0%. I back-probed injectors 2,4,6, & 8 and verified all had the same pulse width which on the scope appeared to be approx 6 milliseconds, where as B1 was approx 3 milliseconds. The injector drivers all ground at the PCM, and the PCM conections are clean. I then used a SnapOn MotorVac fuel sytem cleaner on the car for one cycle. The misfire has cleared somewhat, but not completely. I rehooked the MODIS and back-probed the injectors again and found the pulse width down to approx 5 milliseconds. I got tired of messing with it so I stopped for the evening. Tomorrow I'm going to verify the O2 voltage which did appear low and had set a code, as well I'm going to do another fuel sys. cleaning and check the plugs if nothing has changed. If this fails I'll have my Father look into it. Have any of you run into this condition before? My buddy has a 02 Z28 and after installing LTs he has developed the same conditon.
Thanks,
Brad
Problem injectors: 2/4/5/6
Diag Tools Used: SnapOn MODIS and OTC Genisys
Ok so here it is, I want to know has anyone else experienced the same problem that I currently am. I reciently removed my cats on a basicly stock car. I am now experiencing a misfire conditon on the cylinders listed above. As well on that same bank I am having fuel trim problems. DTC was set for a misfire conditon, I then checked for which cylinders and those above were listed. I checked for a vacumme leak with a SnapOn leak tester smoke machine, found nothing. I then used MODIS to access Datastream and found that bank 2 (B2) had a average 5.42 millisecond injector pulse width where as B1 was a 3.23 milliseconds. Also the long term fuel trim had gone to 15% on B2 and B1 was at 0%. I back-probed injectors 2,4,6, & 8 and verified all had the same pulse width which on the scope appeared to be approx 6 milliseconds, where as B1 was approx 3 milliseconds. The injector drivers all ground at the PCM, and the PCM conections are clean. I then used a SnapOn MotorVac fuel sytem cleaner on the car for one cycle. The misfire has cleared somewhat, but not completely. I rehooked the MODIS and back-probed the injectors again and found the pulse width down to approx 5 milliseconds. I got tired of messing with it so I stopped for the evening. Tomorrow I'm going to verify the O2 voltage which did appear low and had set a code, as well I'm going to do another fuel sys. cleaning and check the plugs if nothing has changed. If this fails I'll have my Father look into it. Have any of you run into this condition before? My buddy has a 02 Z28 and after installing LTs he has developed the same conditon.
Thanks,
Brad
Last edited by LSWon00; 02-07-2006 at 05:24 PM.
02-07-2006, 11:06 PM
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if it was 2/4/6/8 i woiuld say check your fuel pulse damper. I had a similar problem with mine. Felt like it would studder sometimes and when I gave it gas it would pick up and go.
