Another overboost thread (different from the other one)

Pocket · #1 Mon, August 8th, 2011, 11:26 AM

Ok, I can't figure this out.

I can run up to 30 psi of boost, and have no overboost code. Yet yesterday I was hitting at least 35 psi of boost at the track (might have been more, my gauge only goes up to 35 psi) and it set the overboost code every time.

I don't get it. First, I thought the MAP sensor was already well out of it's range before 30 psi, so why would it trigger at over 30 psi, but not at or just under? Second, where is the switch to just completely disable any ability for it to register a trouble code for overboosting? I thought I took care of that already, but apparently not.

GTS · #2 Mon, August 15th, 2011, 05:43 AM

What year truck? The '94-'97 trucks won't set the code or defuel until the 35+psi range.

Pocket · #3 Mon, August 15th, 2011, 10:57 PM

Quote:

Originally Posted by GTS

What year truck? The '94-'97 trucks won't set the code or defuel until the 35+psi range.

Mine is a 2002

Shaw · #4 Wed, August 17th, 2011, 11:50 AM

I remember reading a while ago about the issue you are talking about pocket. I think it was TDS or maybe PSN. I think it was the thread that Matt came up with a different Map sensor that gos to 3 bar instead of the 2.5 bar or something like that?

***cleatus12r*** · #5 Wed, August 17th, 2011, 12:34 PM

There are a few things to look at and from what I have seen and had to deal with over the past, you may or may not be able to "fix" this. Here are some hints anyway:

Turn off the MAP enable switch. This will cause your boost/fueling to follow the inferred boost map.

Change the MAP operating range high to "1023". To go with this, you can change the MAP transfer function as well.

Heck, if you get so inclined, there are quite a few MAP and EBP maximum pressures and time parameters you can raise as well.

Pocket · #6 Wed, August 17th, 2011, 08:53 PM

Quote:

Originally Posted by cleatus12r

Turn off the MAP enable switch. This will cause your boost/fueling to follow the inferred boost map.

This I have not tried. Reason is I wondered how it would affect high altitude driving. But..... I see a test in my future.

Quote:

Originally Posted by cleatus12r

Change the MAP operating range high to "1023". To go with this, you can change the MAP transfer function as well.

This was the next thing I was going to try. I already changed it in my tuning, just haven't punched it yet to see if it works.

Quote:

Originally Posted by cleatus12r

Heck, if you get so inclined, there are quite a few MAP and EBP maximum pressures and time parameters you can raise as well.

Those I have messed with. In fact, I have no EBP codes that pop up.... ever. It's just weird how there's more functions to control the EBP error codes than there are for the MAP sensor overboost. It was easy for me to kill off the EBP sensor, and I thought it was just as easy for the MAP. Guess not. Oh well.

Thanks for the info. I'll report back on what changes work when I get a chance to test them.