no closed loop
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Joined: Jan 2002
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From: ny
no closed loop
I am having a problem with the vette.I used the Diacom and get a code 13 and 36.The O2 sensor is steady at 425mv and won't go into closed loop.The O2 sensor is 1 year old.I always get a code 13 when driving on the highway for a few minutes.Has anyone had a similar problem?Thanks for any info
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Joined: Sep 2001
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From: Athens AL
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Re: no closed loop (Pete89)
Replace both MAF relays behind the battery on the firewall. Clear the codes and see what comes back.
Usually if you fix the code nearest to the front of the car, the one downstream will disappear.
Usually if you fix the code nearest to the front of the car, the one downstream will disappear.
Team Owner
Joined: Sep 2001
Posts: 62,160
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: no closed loop (Pete89)
A bad ECM is a last resort fix, only when you eliminate everything else should you consider it the problem.
But these symptoms can be explained by having a bad one, its just that the MAF-related stuff is much more likely to fail.
But these symptoms can be explained by having a bad one, its just that the MAF-related stuff is much more likely to fail.
Le Mans Master
Joined: Feb 2000
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From: Kempner Texas
Re: no closed loop (Pete89)
What are the symptoms of a bad ECM?
This was my first forray into the TPI world, so I had a steep learning curve to deal with.
I borrowed a friend's ECM, swapped PROMs and the timing problem went away. I knew then it was the ECM, so I bought a remanufactured one from O'Reilly's and 3 years later it's still going strong. $100.00
I've had my share of MAF problems too. Drivability was awful but the car would start and run. I borrowed a MAF from a buddy's 85, plugged it in and she was back to normal. Bought a MAF off a wrecked Vette from a salvage yard; that was two years ago.
Hope this helps.
Jake
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Joined: Dec 2000
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From: SE NY
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Re: no closed loop (Pete89)
Indeed get rid of the MAF problem before attacking the other. If the relays don't fix the issue, try to borrow a MAF for test purposes (the MAF from a 3rd Gen. F-body will fit).
If it was running fine for a while after you installed the headers, replace the O2 sensor. If the problem just started after doing the headers, install a heated O2 sensor.
If it was running fine for a while after you installed the headers, replace the O2 sensor. If the problem just started after doing the headers, install a heated O2 sensor.