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01 2.5 4cyl twin plug ford ranger/ignition primar/secondary noise on 5vref

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8 years 2 weeks ago #16178 by ifixcars702
I posted earlier about a high idle lean condition on this truck, after repairing a few vacuum leaks and resetting the minimum idle I got the truck idling normal until I snap throttle. After the throttle is snapped it seems like the truck loses control of the iac for a few minutes. After some scope work because i didn't trust all of the scan data values this what I found. yellow is 5vref at pcm harness, blue is my primary current ramp, purple is cylinder 4 secondary, and green is my maf ground. So internally damaged pcm, possible shorted injector, maybe shorted ignition control, bad ground. still trying to find the answer. Fuel trims are still a lil lean. Any thoughts on how all those ignition patterns are showing up everywhere else. The truck seems to run fine until throttle is snapped and everything gets pulled further to ground.
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8 years 2 weeks ago #16189 by Andy.MacFadyen
I think you are perhaps seeing a scope artifact --- you are picking up ignition interference in the leads. Try rerouting your scope leads

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



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8 years 2 weeks ago #16194 by ifixcars702
I believed that initially, but the jumps in the scan data, the loss of the control of certain circuits. That's the also the latest version of shots I've taken. You can see that pattern everywhere, it's the only reason I can find that is causing loss of control. I've routed the leads in all sorts of different ways. I will post all of the shots I have. I have no explanation other than that interference to cause problems in other circuits. It's like all the critical sensors are reset when I snap the throttle.

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8 years 2 weeks ago #16195 by ifixcars702
These are the only ones on my phone

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7 years 11 months ago #17456 by ifixcars702
It's fixed! I kept the truck until today, my job picked up after the holidays so I had to leave the truck alone for a while, since it couldn't pass smog or be registered the owner had no problem leaving it here until I resolved the issue. New o2s, a repair on the alt wiring and a few more vacuum leak repairs were the ticket. I hadn't checked the o2s because the owner told me Ford said they were fine, I know, I know. The alt feed and indicator circuits were intermittently shorting, and the "s" terminal connector was heavily corroded creating resistance and strange symptoms because at times the alt didn't know it was charging. The last of the vacuum leaks took a while for the smoke to get to so I guess I just missed them. I found the intake gasket leak with propane, couldn't find it with smoke, the oil separator was leaking from the bottom mating surface and I was only able to see that one with all the lights off and a really white flashlight. After all this I was finally able to set the minimum idle at around 550 with the tps vat .81. Thanks to anyone who listened, I will post new scope shots when I am done with the job.

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