Engine run on....and on
06-20-2016, 06:47 PM
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Engine run on....and on So I have completed my swap using a 2004 4.8L and I am having a couple of issues.
1) Engine run on. When I shut it off it keeps running for a second or so after the key is turned off
2) CEL light is on for P0101 MAF sensor. But I replaced it and it still happens
3) P0135 and P0155 keep coming on. Always both. But I can drive it for days then without it popping up this code. But it always returns. Never have these codes and P0101 at the same time but all three codes return at some point.
Any body out there have any ideas? The oxygen sensors I have verified have 12V power and ground and the sensors have a good resistance at about 6 ohms.
1) Engine run on. When I shut it off it keeps running for a second or so after the key is turned off
2) CEL light is on for P0101 MAF sensor. But I replaced it and it still happens
3) P0135 and P0155 keep coming on. Always both. But I can drive it for days then without it popping up this code. But it always returns. Never have these codes and P0101 at the same time but all three codes return at some point.
Any body out there have any ideas? The oxygen sensors I have verified have 12V power and ground and the sensors have a good resistance at about 6 ohms.
Last edited by Safariwagon; 06-20-2016 at 07:17 PM. Reason: typo
06-23-2016, 11:38 PM
#2
the run on is from voltage back feeding into the PCM from something with an electric motor; fuel pump, electric fans, etc.
I had an old Chevy truck in the shop about a month ago that did this. Whoever wired up the Holley ECU apparently didn't understand how relays and power feeds work.
The truck would only run on if the cooling fans were running when you shut it off. The fans created enough voltage to keep the ECU alive until the fans stopped.
I had an old Chevy truck in the shop about a month ago that did this. Whoever wired up the Holley ECU apparently didn't understand how relays and power feeds work.
The truck would only run on if the cooling fans were running when you shut it off. The fans created enough voltage to keep the ECU alive until the fans stopped.
06-24-2016, 05:06 AM
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I connected power up to the under hood fuse box where the power comes into it. Put me down as one of those who don't understand how this should work. What's the fix? A diode or something?
