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Old May 28th, 2012, 01:00 AM   #29
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Originally Posted by CheapThrillB2 View Post
When the tube was plugged and the sensor bad before, I had no noticeable issues outside of the driving when the truck was cold. Still gonna pull it anyways and check it.

But if I have lack of boost, but have no issues with rpms or getting to high rpms quickly, and no restrictions in the inlet/outlet of the system as far as exhaust and air filter. If I can easily get to 3K in rpms shouldn't it still build normal boost pressures regardless of any sensors or similar not working right messing with fuel?

I could see struggling with rpms and not getting boost, but I have no issues getting up to high rpms.
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.

Last edited by ThinICE; May 28th, 2012 at 01:07 AM.
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