by "Chairman Kaga" (mike-mckinnon)
Published 02/15/2017 at 11:41
by "Chairman Kaga" (mike-mckinnon)
Published 02/15/2017 at 11:41
No Tags
STARS: 0
Can spark plug wires check out for resistance and conductivity when cold, but begin to fail when hot, then check back out again when you pull them off to test them again? My old GTV6 has a BAD problem of missing, stumbling, and stalling, but only AFTER the car is hot. Runs smooth and clean for 10 minutes then it goes to shit. The symptoms are textbook “bad plug wires, chapter 1.” I’ve repaired and/or replaced literally every other ignition component, checked fuel delivery (OK), etc. The plug wires are damned expensive for this car because they have built-in resistors and each wire is cylinder specific, so I don’t wanna buy a new set unless it’s obvious it’ll solve my problem.
"Junkrat aka Rick Sanchez: Fury Road Edition" (realasabass)
02/15/2017 at 11:51, STARS: 2
Resistance rises along with temp. Dont know much abou GTV6's though.
"My bird IS the word" (mybirdistheword)
02/15/2017 at 11:55, STARS: 0
From experience nothing is a guaranteed fix. Have you cleaned up where the wiring grounds to the body? That is an easy (free!) thing to do that usually clears up alot of electrical issues on older cars. Past that, having replaced all the ignition stuff, fuel boiling would be my only other concern. If the plug wires are old they can do goofy stuff like that.
"SidewaysOnDirt still misses Bowie" (sidewaysondirt)
02/15/2017 at 12:01, STARS: 0
Is it fuel injected? Could be related to an IAT or coolant temperature sensor.
"crowmolly" (crowmolly)
02/15/2017 at 12:05, STARS: 0
OBD II system? Are you getting a code?
"Urambo Tauro" (urambotauro)
02/15/2017 at 12:14, STARS: 0
Technically, there’s always a chance that during the test, they’ve had at least a few seconds to cool off a little, and you might not be flexing them in a way that reveals the problem.
Checking for resistance is still a good practice, but it doesn’t necessarily confirm that they’re 100% good. How old are they?
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 12:14, STARS: 0
I just replaced the coolant temp sensor recently. With this car, if it’s bad the car will just die and not restart until it cools. Ask how I know!
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 12:15, STARS: 0
1982, so no codes. A code in this car is fire.
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 12:17, STARS: 0
Not sure, but pretty old I assume. Given the small amount of time necessary to restart after a stall I assume you’re correct, that by the time I’m able to get a reading they’re back within spec.
"crowmolly" (crowmolly)
02/15/2017 at 12:19, STARS: 1
Hmm.
Maybe try misting them with water in a spray bottle at night to look for arcing?
And above you mentioned old gas. Are you carbureted?
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 12:21, STARS: 0
Yeah, I’ve thoroughly cleaned all of the grounds, coated with dielectric grease, and recheck them pretty religiously.
It’s possible I have bad gas though. It’s winter mix, but it’s possible even with stabilizer there’s been some ethanol separation. I don’t drive enough to burn it fast enough to prevent that. It still had half a tank, which is more than I can store or remove. Maybe I should just got for an extended Italian tuneup when there’s not much traffic and try to get enoughmiut that I can drain and test a few gallons.
"SidewaysOnDirt still misses Bowie" (sidewaysondirt)
02/15/2017 at 12:23, STARS: 0
Have you checked the resistance and continuity of the cables cold and hot? While resistance can change with temperature, it shouldn’t be that dramatic. I’d think different material expansion would be a bigger factor than that. As for the cables having a resistor in-line, you can always make your own cables with a resistor.
"brianbrannon" (brianbrannon)
02/15/2017 at 12:31, STARS: 0
No.
"TorqueToYield" (torquetoyield)
02/15/2017 at 13:44, STARS: 1
Since the ‘wires’ per your description are a lot more than just wire, including connectors, solder connections with resistors, etc, there’s a chance of a wonky connection, solder or otherwise, that faults when hot due to thermal expansion and goes back to OK when cooled. If it was just a simple wire with plugs on the end I would think it unlikely, but what you describe is classic behavior of intermittent solder joint failure. http://analysistech.com/event-detectors/event-tech-solder_joint/
It’s a bear to figure out. Maybe try heating the wires in an oven on low and then trying the continuity test again when you know they’re at operating temp.
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 14:57, STARS: 0
Yeah, I thought about that. Connect the terminals of my multimeter, then pop it into the toaster oven at about 200 degrees, see what happens. Although my wife was none too pleased when she discovered my Bosch auxiliary air valve in the oven last weekend... I’ll need to wait until she’s away.
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 15:23, STARS: 0
I checked with the Alfa guys, and it’s damn near impossible. Each wire has a specific impedence depending on length. Several people over the years have attempted to DIY the cables, but all have failed. Doesn’t seem like it should be that complicated, but there must be more to it.
"Chairman Kaga" (mike-mckinnon)
02/15/2017 at 15:23, STARS: 0
Bosch L-Jet fuel injection.
"crowmolly" (crowmolly)
02/15/2017 at 15:33, STARS: 0
Hmm. I guess it’s easy enough to get some fresh high octane gas in there. I was just wondering if there were rubber components that may have fallen victim to ethanol.