Will run then stall, does not idle?

Tiny
R6VETTE
  • MEMBER
  • 1992 CHEVROLET CORVETTE
  • 5.7L
  • V8
  • 2WD
  • MANUAL
  • 141,000 MILES
It will run really rough for maybe a minute (if I give it gas, it won't stall), then start to stall out. I've replaced the opti,icm,coil,wires,plugs,injectors,fuel pump, fuel filter,fuel pressure regulator, and water pump. This was a project car that wasn't running until I replaced the injectors. So it sat awhile, and now it's stalling..

I do have 40 PSI at the fuel rail. I have also removed the TB and cleaned it, as well as the IAC, which didn't help. I checked for codes and I’m getting h16, and following the fsm, I went through the code 16 flowchart and measured the voltage on terminal A at the ecm side of the ignition test connection, which is on the passenger side near the fuel rail. I got only 0.04 volts, indicating a faulty ecm, ecm connection, or an open or grounded low resolution from the ecm to the test connector.

Did I do this correctly? Would the car still run with a faulty ecm? Also could fouled spark plugs cause this?

Included video of car below.
https://imgur.com/OR2M9oS
Thursday, September 28th, 2023 AT 3:07 PM

8 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,139 POSTS
Hi,

I watched the video, but for some reason, there was no sound. As far as the issue, yes a faulty ECM can still run an engine. The ECM is responsible for multiple things. It really would matter what has failed internally.

As far as the diagnostics, take a look below and let me know if that is what you did. Keep in mind, if it sat, there could be corrosion at the connectors.

Let me know.

Joe

See pics below.
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Thursday, September 28th, 2023 AT 9:24 PM
Tiny
R6VETTE
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Yes, the 2nd picture is correct. I’ll do another video of the car and follow the flowchart again.
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Friday, September 29th, 2023 AT 12:32 AM
Tiny
R6VETTE
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Flowchart.
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Friday, September 29th, 2023 AT 6:36 AM
Tiny
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2nd part.
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Friday, September 29th, 2023 AT 6:36 AM
Tiny
R6VETTE
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I can rule out a defective connector. When I installed the new opti, I purchased a new one, however using the OEM connector to replace it still causes problems. Are you still interested in seeing it run and stall?
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Friday, September 29th, 2023 AT 6:40 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,139 POSTS
Hi,

Yes, let me see what is happening. If I can't help, we have a guy that certainly can. He's the site owner.

Let me know.

Joe
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Friday, September 29th, 2023 AT 9:59 PM
Tiny
R6VETTE
  • MEMBER
  • 11 POSTS
Well, I already took apart the whole c4 and while doing so I found one of the spark plug wires wasn’t all the way in, so maybe that could’ve been the issue.
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Saturday, September 30th, 2023 AT 5:07 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

That can certainly cause an issue. When you properly installed it, does it run properly or is there still a problem?

Let me know.

Joe
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Saturday, September 30th, 2023 AT 9:50 PM

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