Compression Ignition Addict
Join Date: May 2010
Location: Raleigh, NC
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Idles fine, misses under throttle
First off, a couple weeks ago the truck initially dropped a cylinder or 2 or however many for a few seconds. truck was warm but had been sitting for maybe 30min so not hot. This happened about 1/4mi up the road and seemed like it was when I let off the go pedal. let it idle for a few seconds and it straightened itself out. Got another 1/4 mile or so and same exact thing. turned around and headed home. During each of these the CEL came on and went off as soon as it cleared up
I later did some testing to see what did what. I replaced the CPS, no change. Unplugging either of the passenger side UVCH plugs reproduces the symptoms but without the CEL and when I rev it to reproduce, the symptoms don't get any worse. The driver side plugs do the same thing but when I rev it to reproduce the symptoms, it fires on even fewer cylinders and eventually dies.
I can reliably reproduce symptoms by revving it to a bit over 1000 RPM and letting off. Haven't tried any higher. If I don't rev it quite as high it will do it but won't do it as long it seems like. It varies in how long it continues running rough. IT will idle all day long no problem.
I replaced the passenger side valve cover gasket and the two harnesses under the VC and symptoms persist.
Last week I bought AE to figure this out and here are my results.
Ok so ae is hooked up. Initial codes were as follows:
P1280 icp sensor circuit low
P0113 intake air temp circuit high input
P0470 exhaust pressure sensor
P0476 exhaust pressure control valve range/performance
CCT produced no codes until i started unplugging uvch connectors.
With the cyl 1&3 connector unplugged i got:
P0263 cyl1 contribution/balance fault
With the 5&7 connector unplugged:
With 2&4 unplugged the truck shut off during the test.
With 6&8 unplugged, no codes for some reason. Wanted to shut off it seemed like.
It doesn't seem like it's storing the code that triggers the CEL when symptoms are present unless I'm just not doing something right.
I'm at a loss here guys, any help is very much appreciated!
1996 F350 4x4 CCLB-- I'll miss her
1996 F350 4X4 RCLB zf5 213K
Mud Country 315/75/16
There u go Tom. John may not be sexy, but he can tutor you, lol.