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View Full Version : Engine Underboost DTC?



LBZoom
July 10th, 2008, 04:35 PM
Hey guys,

I've got a 2006 LBZ engine, and lately I've had a DTC come up for an engine underboost code, and I'm thinking there's no way it can be underboosted....I've turned the turbo up a pretty fair amount and i'm not even cranking enough fuel to blow smoke when it kicks down yet :confused:

Also, looking at the tables for desired boost w/EGR off, at 800 RPM's the desired boost levels range from about 14-17 lbs of boost in my particular tune depending on altitude, and according to my log file the truck idles (700RPM) at about 15lbs of boost....my gauge shows the truck idling between 2-4lbs of boost...which one is right? What kind of boost pressures are some of you guys reading on your gauges at idle?

Here is my log file...starts with idle, then a couple revs, and then take-off

Sparky8370
July 11th, 2008, 07:28 AM
You have to deduct baro pressure to get boost pressure. At sea level it's 14.7 lbs, so if you were reading 20lbs at sea level, it's actually like 5.3 lbs of boost.

LBZoom
July 11th, 2008, 07:46 AM
Ohhh...okay now I understand haha. Thanks man!

killerbee
July 12th, 2008, 11:55 PM
its a misnomer code. You get it when vane position is maxed out, and you still cannot attain desired boost. It typically codes when doing what you are doing.

ratlover
July 13th, 2008, 05:57 AM
if your target vane position isnt close to what it should be for your desired boost it can throw it. also if you arnt making what you call for it can too. I swing no boost at an idel.

LBZoom
July 15th, 2008, 04:41 AM
Awesome thanks for your help guys!