Crank but no start!
Thread Starter
TECH Regular
Joined: Jan 2004
Posts: 426
Likes: 4
From: Austin, TX
Crank but no start! Tried to start up the Chevelle for the first time tonight and no spark or injector pulse. The engine is a L76 that has had DOD removed. The harness and program is a Speartech. There is 12 VDC at all injectors and coils both in the run position and the crank position on the ignition switch. I presume that this means that there is something wrong in the crank sensor or cam sensor circuit since it does not pulse the injectors or coils. TAC operates fine. I have pulled the crank sensor (no small feat with the headers in place) as well as the cam sensor and need to know if there is a simple troubleshooting process to verify if the sensor is bad. All the wires check back correct to the ECM.
Anything that I have missed?
Thanks, John McGraw
Anything that I have missed?
Thanks, John McGraw
Thread Starter
TECH Regular
Joined: Jan 2004
Posts: 426
Likes: 4
From: Austin, TX
Never mind, I found the problem! It was a case of optical rectumitis. This occurs when one has their head so far up their butt, that they can't see.
While I had ohmed all the wires by color code back to the ECM for the proper value, I failed to realize that I had swapped the B and C pin on the cam sensor so the sense and the ground connection were transposed! DOH!!!!
Moved the pins, put the sensors back in, put the starter back on and replaced the passenger side header. I still have to put the plugs back in the passenger side head and tighten the headers, but I cranked it enough to see the noids flashing on the injectors, so I know it is fixed. Chased my tail all night for such a simple problem! If I could just learn to read a schematic completely.
Too late tonight to start it up, but it will be running tomorrow night as soon as I get home from work.
Regards, John McGraw
While I had ohmed all the wires by color code back to the ECM for the proper value, I failed to realize that I had swapped the B and C pin on the cam sensor so the sense and the ground connection were transposed! DOH!!!!
Moved the pins, put the sensors back in, put the starter back on and replaced the passenger side header. I still have to put the plugs back in the passenger side head and tighten the headers, but I cranked it enough to see the noids flashing on the injectors, so I know it is fixed. Chased my tail all night for such a simple problem! If I could just learn to read a schematic completely.
Too late tonight to start it up, but it will be running tomorrow night as soon as I get home from work.
Regards, John McGraw
Thread Starter
TECH Regular
Joined: Jan 2004
Posts: 426
Likes: 4
From: Austin, TX
Glenn,
Yea, I had already thrown in the towel for the night and was sitting in the recliner in front of the TV watching the news. The more I got to thinking about it, the more I just had to go back out to the shop and check the schematic again. Almost as soon as I started ohming out the wires again, I noticed the swapped pins! I had removed the pins from the connector body so I could slip some of the DEI heat sleeve over the wire several months ago, and just screwed up when I inserted the pins back into the plug body.
I really wanted to run it last night, but I figured my neighbors would not appreciate it!
Regards, John McGraw
Yea, I had already thrown in the towel for the night and was sitting in the recliner in front of the TV watching the news. The more I got to thinking about it, the more I just had to go back out to the shop and check the schematic again. Almost as soon as I started ohming out the wires again, I noticed the swapped pins! I had removed the pins from the connector body so I could slip some of the DEI heat sleeve over the wire several months ago, and just screwed up when I inserted the pins back into the plug body.
I really wanted to run it last night, but I figured my neighbors would not appreciate it!
Regards, John McGraw
