Originally Posted by jage
I saw MAP of 34s and 54s at various times, but I can't tell you when in the trip as it wasn't something I was watching closely.
If I take it out just to test, how long do I need to drive and what conditions should I be noting the MAP under?
And I am hoping it mouse related, not poop, but some chew on one of the sensors.
MAP is horrible to follow on the scanguage, it's so inaccurate and slow to read, plus it will jump out of range at the top levels that it's not great diagnostic to use. But if it's all you have it will work.
First you are trying to work out your Boost in PSI as that's what baseline is. Max boost is not hit until in 3rd gear, and in the van should be around 22~25psi. So get on an onram and floor it, you should see around 25psi in 3rd gear or above.
MAP reading is Boost just not in PSI. You can follow the scanguage instructions to get a Boost PSI reading from MAP, or simply subtract atmospheric pressure from MAP reading.
Atmospheric pressure is ~14.7 at sea level and 11.8 at 6k ft, so depending on your elevation, you will need to subtract something between 12 & 15 from MAP reading to get PSI reading.
When MAP get's to it's top reading point (around 32~35 on the van), it will jump very high, ignore those readings.
As long as it can regularly hit 22~25psi when you floor the van, and your getting valid fluctuation while driving (not just 0 or 100%), I think
that's the only real testing you need to do.
Due to different driving styles it's hard to say what you should see driving normally. Obviously it fluctuates as the RPM & load does. I think when I'm at 70mph on cruse control, my boost is constantly fluctuating between 5 and 10psi as the cruse control is making small changes, that may be a good test as well.
So your readings listed look perfectly normal to me. MAP at 34 is normal, 54 is just erroneous scanguage reading that all have.
P0299 is underboost, so that means the ECU is asking for X psi and not reading X on the MAP censor.
So other things to check would be leaks in the turbo piping (common in the van) / inter cooler cracked (more common in the truck).
Going back to the turbo, (which is most lightly your problem on a 6.0 with this code) you can also monitor Variable Geometry Turbo Charger Duty Cycle %
with the scanguage, so program that one in as well, and your best off searching the forums for an explanation of expected readings on that.
I believe things like the Exhaust Backpressure Sensor is also used in Boost management, so you may want to monitor that from the scanguage, but I don't think that would make the underboost code come up.