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View Full Version : 35 PSI and Still Getting Boost Codes


Danfunk
07-13-2011, 11:23 PM
Hello everybody. I need help troubleshooting a continual Limp Home Mode situation that I have been dealing with for some time. Last year my turbo broke and I replaced it with one from Turbo Charger Pros. They sold me on a brand new "generic" model that was identical to the Garrett. I couldn't drive the van for more than ten miles without it going into LHM and having a Charge pressure Control code stored on the ECM. I went through the entire system looking for boost/exhaust leaks that could cause low boost. I purchased a DAD and according to my DAD the turbo was putting out 29 PSI wide open which at the time I thought was plenty. After being left with no other option I called them and had the turbo replaced under warranty. There was vast improvement with the new turbo. The van was much more responsive and under heavy load wide open I was getting 35 PSI from the turbo. That seems congruent with what I have found on this forum. For a time the LHM issue was fixed. I took the van on a couple of 1,000 mile trips and it every now and again would go into LHM. No huge deal, I thought. It's now going into it again much more frequently. Again, the only code being stored by the ECM is the Charge Pressure Control code. The van runs perfectly and is putting out great boost but for some reason keeps going into LHM. Are there any other factors that I don't know about that could be causing this? Could it be the MAF sensor or the throttle positioning sensor? The other day I did a little 200 mile round trip to Austin and on the way there I went into LHM several times. On the way back I went into LHM right away, then restarted and set the cruise to 65 MPH and didn't touch it the 90 miles back to my house and had no issues. Even going up big hills I just let it downshift and ring its neck until we were over it and nothing happened (my LHM issues are usually under high load).
I don't know what I'm missing here to make the van run right again.
Thanks everybody
p.s. the van is a 2004 158"WB High top passenger with 192,000 miles on it

WAYNERODD
07-15-2011, 01:30 AM
My 2005 used to give me the same issue.

The problem was that my EGR valve would sometimes stick open & allow my boost pressure to be dumped into the exhaust during hi demand.

DAD does have a EGR test that my help you find your problem.

Another option may be to remove your valve and clean it.

A good valve will always spring return to the closed position on the 2004-2006 engine.

Danfunk
12-10-2011, 10:00 PM
Thanks WAYNERODD for the advice. I apologize for updating this thread so late. I put a new EGR in the van not too long ago and have tested the one I am using now and it has no issue.

Just last week the van finally threw a code other than just the charge pressure code P2359. I had logged several P2088 codes corresponding to the ambient air temperature sensor on the intake manifold and a P2068 code corresponding with the MAF sensor. I called Doktor A and he advised me to start with the Air Intake Temp Sensor before replacing anything else. It was cheap and only took a minute to install. He also explained that the oxygen sensor on the exhaust are notorious for failing as well.

I've put about 300 fully loaded highway miles on the van since yesterday and all seems well. The throttle response even feels better than it did before. I might be imagining that though. The frustrating thing is how long it took the van to give me an indication of a very regular sensor failure. After meticulously going through the all of the mechanics of the boost system and finding no fault I have suspected sensor issues but I have never had the money to throw at random solutions.
From here on out I will seek the wisdom of the gurus much sooner.

Thanks everybody!

surlyoldbill
12-11-2011, 01:48 AM
Does anyone know if the OM612 motor has a similar fail rate with the intake temp sensor? I believe it's that same part # as the OM647 motor.

And for Dr. A, would you suggest a routine schedule for sensor replacement, for example: O2 every X miles, MAF every X miles, Intake temp every X miles, etc.?

talkinghorse43
12-11-2011, 01:54 AM
Does anyone know if the OM612 motor has a similar fail rate with the intake temp sensor? I believe it's that same part # as the OM647 motor.

And for Dr. A, would you suggest a routine schedule for sensor replacement, for example: O2 every X miles, MAF every X miles, Intake temp every X miles, etc.?

My IAT sensor hasn't failed yet. No O2 sensor for the 612, EGR is controlled by ECM calcs based on IAT, rpm, MAP and MAF

surlyoldbill
12-11-2011, 02:48 AM
My IAT sensor hasn't failed yet. No O2 sensor for the 612, EGR is controlled by ECM calcs based on IAT, rpm, MAP and MAF

I think it's funny how I can find O2 sensors for sale online for 02-03 Sprinters; I didn't know they did not have them!