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Old May 28th, 2012, 02:40 PM   #30
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Originally Posted by ThinICE View Post
A few issues I noticed with this conversation, and your quote hit it spot on, the EBP sensor on this truck is only used to modulate the EBV. It does not control boost or fuel mapping so a bad EBP sensor only affected the butterfly. This is all controlled by your MAP sensor. (There will be critics of this statement, but it's true). The 7.3L ran like a true diesel, unlike the 6.0 and 6.4 which don't really use the MAP for true boost.

In cases of low boost and slow to build RPM on this truck, I wouldn't be looking to the boost system itself considering you've eliminated an exhaust restriction, intake/exhaust leak and damaged turbo. As long as the MAP's functioning correctly, I would look towards the high pressure oil system. A lack of fuel injected into your cylinder results in less exhaust flow which means less turbo spin equalling low boost. A weak high pressure oil pump can occur with your type of mileage (unless I missed somewhere were you replaced it??) resulting in weak performance but not necessarily low RPMs. Verify the ICP sensor is not contaminated with oil due to an internal leak. The key on engine off ICP voltage should be .18-.24v. No issues there then try and get a scanner to monitor the ICP pressure at start up and under WOT. Please forgive me, I don't remember the exact pressure readings to monitor. I also lean this way because your fuel pressure looks good... 45 PSI or higher under all driving conditions was our rule of thumb. Compression... sure, but later.

The P1298 DTC, if I recall correctly, means there is a DTC in your IDM but it cannot be transmitted to the PCM. This happens because there are 4 communication lines between the modules. Two for IDM-PCM SYNC and two for back-and-forth communication. I've seen this DTC caused by an aftermarket module installed between the IDM-PCM or damaged wires. It is possible there is an IDM fault that's plauging you or it is a complete Bull-Crap code.
ICP voltage about 1 cruising and 3.0 WOT
Inj control pressure approx 2500 at wot

All the diag/symptom charts seem to start with a no start with the code I am getting from the IDM, but I have never had a no start condition or even a hard start.

I don't have access to a scanner today. But like I thought the ebv tube is not restricted nor damaged. The last week or so I have been able to get 10 psi of boost, but today its back to only reaching 5psi. I went out and unplugged the map and drove it with no difference other then the shift points seemed firmer. I then changed out the cam sensor with a new one I have kept in the glove box since I purchased the truck and it had no change either.

I can't say for sure as I don't drive the truck often and rarely ever through the winter, but if I had to say I think the idle is ever so slightly rougher. I honestly cant tell but it just 'feels" off from what I thought it had been and almost to me sounds just a hair different at idle as well. I can't say for sure but its just this slight observation. It might not be at all different then its ever been but just a feeling.
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