Could this really have been the problem
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
Could this really have been the problem
Almost afraid to post this since it does not make sense to me, but here goes.
Monday, A/C went out. Nothing but warm air all of a sudden. Had been putting out really cold air. Took it in for service and turns out the low pressure switch needed replacing and wiring harness for it was right near the header. Replaced switch and wiring harness and evacuated system and recharged. Not following problems are all gone:
1. Never could get the timing set right. Set it by hand. Have it advanced and, if pings under WOT, back off a bit until pinging stops. Then, sometimes pinging returns on the new timing for a bit. Had been writing this off to different gas from different stations.
2. Runs very slightly (emphasis on slightly) rough. Nice sound from Borlas but still just a bit rough.
3. Shifting a bit sluggish.
Now runs great. Smooth with just nice mellow sound from Borlas. Shifting nice and smooth - with 3.55 rear end over stock, firm shift, but otherwise nice transition between gears.
Could a short of something with the wiring harness and low pressure switch have caused my problems - slight, but problems.
Monday, A/C went out. Nothing but warm air all of a sudden. Had been putting out really cold air. Took it in for service and turns out the low pressure switch needed replacing and wiring harness for it was right near the header. Replaced switch and wiring harness and evacuated system and recharged. Not following problems are all gone:
1. Never could get the timing set right. Set it by hand. Have it advanced and, if pings under WOT, back off a bit until pinging stops. Then, sometimes pinging returns on the new timing for a bit. Had been writing this off to different gas from different stations.
2. Runs very slightly (emphasis on slightly) rough. Nice sound from Borlas but still just a bit rough.
3. Shifting a bit sluggish.
Now runs great. Smooth with just nice mellow sound from Borlas. Shifting nice and smooth - with 3.55 rear end over stock, firm shift, but otherwise nice transition between gears.
Could a short of something with the wiring harness and low pressure switch have caused my problems - slight, but problems.
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
Assuming you have an 82 with the stock tbi and distributor both of which are controlled by the ECM. Did the shop fix any wires not related to the low pressure sensor?
Last edited by MelWff; May 2, 2018 at 04:04 PM.
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
I do understand the ecm controls the distributor and carbs. Any mods to tbi's and replacement parts to distributor and ecm were done years and years ago. Just don't understand why running so well now after the described a/c repairs/service.
Last edited by Wrecked82; May 2, 2018 at 01:48 PM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
With an ECM, you never know. They are very sensitive to grounding problems and/or 'spurious' pulse signals in the power/signal lines. Intermittent shorting of that switch wire might give the ECM problems, as 12vdc power signal is fed through that switch. Hope it keeps working well.
Last edited by 7T1vette; May 3, 2018 at 12:04 AM.
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
Years ago, replaced ECM when it finally died. At same time, replaced all the electronic innards of the distributor.
Car ran "perfectly" before the a/c repair - except for my observations posted originally.
Thread Starter
Le Mans Master
Joined: May 1999
Posts: 6,692
Likes: 29
From: Texas
With an ECM, you never know. They are very sensitive to grounding problems and/or 'spurious' pulse signals in the power/signal lines. Intermittent shorting of that switch wire might give the ECM problems, as 12vdc power signal is fed through that switch. How it keeps working well.
