With the optical sensor unplugged the engine would not start. It yielded codes P0251 and P0370. When I plugged it back in the engine started and ran rough, as before.

With the engine running at idle, 740 rpm, I unplugged the IAT sensor. The rpm increased to 840, but no codes. When I tried to increase the rpm it was very rough, as usual at around 1500.

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Correction. It was the coolant temp sensor (the one on top of the engine) that I uplugged, which resulted in the 100 idle-rpm increase, not the IAT sensor as I wrote above.

 

I'm beginning to think its the IP but not ready to say for sure yet.

Have you checked the electrical grounds on the passenger rear of the intake yet?

Long shot, but it costs nothing more than about 5-10 mins to check.....


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When I replaced the fuel injectors I "discovered" that the #8 fuel injector was "stuck" to the fuel line, so I was compelled to pull the intake manifold so as to be able to replace the #8 fuel line [after I cut the line to get the injector out]. So I made sure to securely reattach all the grounds that were connected to the intake manifold.

I too am getting that feeling that the IP needs replacement, though I am surprised that it's not throwing a code. If I do replace the IP I will replace the timing chain and gears as well.

Thanks for your input. I appreciate your help.

 

An ip can go south and not set a dtc if it's a mechanical failure/deficiency......


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I too am having similar issues? Figure anything out?

 

Where is the IP/PMD harness ground located?

Is there a lot of vacuum when you remove the fuel cap?

What you did for a blowby test is really more of a CDR test,with the CDR disabled is there much blowby from the oil fill cap?

 

CDR?

 

CDR-Crankcase Depression Regulator,some parts stores call it a PCV.

It is used to maintain a negative pressure when possible on the crankcase to prevent oil leaks,looks like a tuna can on top of the passenger side valve cover and connects to the air intake.

 

What was the fix?

Did a new injection pump solve it?

I'm having the same problem and I'm still testing stuff. My problems get worse as the outside temp decreases. 20f or below gets real bad, below zero it's pretty much un-drivable as I cannot get it to rev over about 1800 rpm. That makes for a very slow ride 12 miles to/from work.

 

Sounds more like you may have a lift pump problem combined with fuel that is gelling-you run any antigell conditioner in the fuel?