Need help with my LT1
10-21-2018, 03:43 PM
#16
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Re: Need help with my LT1
Clear the codes. Pull the “PCM BAT” fuse in the box under the hood for 30 seconds. Then crank the engine (fully charged battery) for an extended period. Then check for codes. DTC 16 will set under those conditions. And, while cranking the engine, watch the tach to see if it jumps up a couple hundred RPM. In the data log, there was an RPM reading when you first started cranking the engine, but as I recall (I am not in a location where I can access your file) the RPM reading disappears. I'll check that tomorrow morning.
10-22-2018, 10:13 PM
#17
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Re: Need help with my LT1
Okay, I pulled the fuse for a few minutes and put my charger on the battery so it wouldn't die for extended cranking. I did not see the RPM jump, in fact I didn't see it move at all. Looking at the scanner the RPMs were between high 150s and low 170s but mostly in the 160s. The scanner does not show any DTC codesi.I attached the file from the scan. Thanks again for the help. It will be nice to figure out what the problem is eventually.
After you cleared the codes, DTC 16 would have come back while (extended) cranking. DTC 42 will also set while cranking. DTC 64 will not reset, if active, until the vehicle is fully warmed up. Question is why did 16, 36, and 42 set previously and remain as stored codes? Something happened to the Opti.
I went back and looked at a few data logs that actually show cranking. All of them started very rapidly, but in the 2 or 3 lines of data, the high MAP, “0” MAF, and long injector pulse widths were similar to yours.
Next checks:
- do you have spark at all the plugs?
- what is the fuel pressure with the engine cranking (but not running)?
- can you check for injector pulse, with a ‘noid light or a stethoscope?
10-25-2018, 10:04 PM
#18
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Re: Need help with my LT1
The RPM is in the log, so the Opti is working. In the brief first log, it appeared the RPM disappeared, but apparently you just stopped cranking the engine.
After you cleared the codes, DTC 16 would have come back while (extended) cranking. DTC 42 will also set while cranking. DTC 64 will not reset, if active, until the vehicle is fully warmed up. Question is why did 16, 36, and 42 set previously and remain as stored codes? Something happened to the Opti.
I went back and looked at a few data logs that actually show cranking. All of them started very rapidly, but in the 2 or 3 lines of data, the high MAP, “0” MAF, and long injector pulse widths were similar to yours.
Next checks:
- do you have spark at all the plugs?
- what is the fuel pressure with the engine cranking (but not running)?
- can you check for injector pulse, with a ‘noid light or a stethoscope?
10-27-2018, 11:54 AM
#19
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Re: Need help with my LT1
I put a noid on all of the injectors and it flahed. I checked one spark plug wire for spark and got nothing so I checked for spark at the coil and got nothing. Bad coil?
I have to get a fuel pressure tester to check it. That'll probably be Monday.
If the coil was the issue the whole time, would it have acted like it did (bogging) before it got to this point of not running?
I have to get a fuel pressure tester to check it. That'll probably be Monday.
If the coil was the issue the whole time, would it have acted like it did (bogging) before it got to this point of not running?
10-27-2018, 03:25 PM
#20
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Re: Need help with my LT1
Hi Sacto,
Just a thought (while waiting for the Injuneer) but what coil do you have? Earlier you said that the old opti was MSD, is the coil also MSD? I had serious trouble with a MSD coil not making good connection with the stock GM coil wiring plug (it fit a little loose and the pins didn't always connect causing an intermittent problem). I changed back to a Delco coil and have had no problems since.
Just a thought (while waiting for the Injuneer) but what coil do you have? Earlier you said that the old opti was MSD, is the coil also MSD? I had serious trouble with a MSD coil not making good connection with the stock GM coil wiring plug (it fit a little loose and the pins didn't always connect causing an intermittent problem). I changed back to a Delco coil and have had no problems since.
10-27-2018, 03:44 PM
#21
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Re: Need help with my LT1
Hi Sacto,
Just a thought (while waiting for the Injuneer) but what coil do you have? Earlier you said that the old opti was MSD, is the coil also MSD? I had serious trouble with a MSD coil not making good connection with the stock GM coil wiring plug (it fit a little loose and the pins didn't always connect causing an intermittent problem). I changed back to a Delco coil and have had no problems since.
Just a thought (while waiting for the Injuneer) but what coil do you have? Earlier you said that the old opti was MSD, is the coil also MSD? I had serious trouble with a MSD coil not making good connection with the stock GM coil wiring plug (it fit a little loose and the pins didn't always connect causing an intermittent problem). I changed back to a Delco coil and have had no problems since.
10-29-2018, 12:45 PM
#23
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Re: Need help with my LT1
No and not at the coil. I slapped a new coil in and still nadda.
Thanks again for the help.
10-29-2018, 02:34 PM
#25
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Re: Need help with my LT1
OP, do this. Also use a heat gun on it if you can to bring it up to engine temp artificially.....ICM's can test "good" when room temp...its when they heat up that issues happen with them.
If it tests good cold...try heating it up and then re-testing
If you wind up replacing it, get a AC Delco. More $ than off brand ones but worth it IMHO
If it tests good cold...try heating it up and then re-testing
If you wind up replacing it, get a AC Delco. More $ than off brand ones but worth it IMHO
10-29-2018, 04:42 PM
#26
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Re: Need help with my LT1
ICM tested bad. I bought a new one and it's running again. Thank you! However it seems to be running the same (bogging) as it did before it quit running. I'll hook up the laptop, record it driving, and post it.
10-29-2018, 11:07 PM
#27
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Location: Hell was full so they sent me to NJ
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Re: Need help with my LT1
OP, do this. Also use a heat gun on it if you can to bring it up to engine temp artificially.....ICM's can test "good" when room temp...its when they heat up that issues happen with them.
If it tests good cold...try heating it up and then re-testing
If you wind up replacing it, get a AC Delco. More $ than off brand ones but worth it IMHO
If it tests good cold...try heating it up and then re-testing
If you wind up replacing it, get a AC Delco. More $ than off brand ones but worth it IMHO
10-30-2018, 01:59 PM
#28
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Posts: 1,083
Re: Need help with my LT1
My comment, after you recommending OP test his ICM, was "if" it did test good "cold" than heat it up to test it ideally under use temperature.
But yeah Fred since it tested bad cold...it was dead. Good recommendation to the OP to test it
But yeah Fred since it tested bad cold...it was dead. Good recommendation to the OP to test it
11-01-2018, 12:57 AM
#29
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Re: Need help with my LT1
I pulled the fuse to the PCM and let it sit for about 8 minutes, re-installed it, and drove it home from work recording the drive home on the laptop. The noticable hickups happen during the 60 seconds of 22:22 hours, 22:24 hours, and 22:28 hours. I wish I could have gotten more acurate within the 60 seconds of those minutes but I was doing this by myself while driving. It did throw the DTC 36 and 41 codes. 41 was immediate, 36 came in during the first hickup at 22:22 if I saw it correctly. The actual "bogging" on light accel seems to mostly gone away or feels a lost less present. I've very excited that it is at least running again, I can't say thanks enough Injuneer!
Last edited by sactodreamer; 11-01-2018 at 01:01 AM.