I'm still at a loss.
My truck:
2001 LB7 w/ AFE Intake, 4" Intermediate dumped, and Edge Juice w Attitude on there for about 8 months now. 63k miles

My story:
While driving down the freeway at approx. 75-80 mph, it suddenly cuts power and starts to slow, but motor is still running.
After about 10 seconds or so, it kicks back in.
At first it was one time that day then it becomes more frequent, finally not being able to run more than 2000 rpm and no more than 65 mph.
At first the boost readings on the Edge seemd weird but would at least rise progressively.
Now it just reads 25.6 if I give it gas at idle.

What I have done so far:

I scanned it and it was throwing a P0234 code for overboost which I believed to be a bad MAP sensor.
I swapped that out last night.
Still the same problem.

I then search on here for related issues and everyone seems to think that cleaning the MAF will work.
So I grab some Methanol out of one of the cars here and mist the MAF a few times and light air dry it.
Sensors are all intact on it and look good.
Reintsalled, it still has same issue.

I then call Edge, and they say that I should've disconnected Edge first, but to try that and see if the same thing occurs.
I just did that, reset all codes, and fired it up and it still does the same thing only now it throws the p 0238 code for high voltage, but it is NOT throwing the overboost code 0234.

The search for this code is very limited, but I was thinking my only other possible cause would be the baro sensor.
And if I had to guess this would be the one on the Dr. side that is in a bracket that looks like it just hangs out there with nothing plugged into it underneath.

Any ideas appreciated, anything I missed on here, please show me.
I have the software from GM in our computer for all tech instructions like I've seen printed in a few threads, but what I don't have is a Tech II and I have no way of reading that Baro sensor.
Right now I feel my next step is the dealer.

Thanks in advance.

Dave

PS One more conspiracy theory, this all started after I took it in for a TSB on the Fuel filters.

Search "P0234" on this site. Lots of reading.

Some aftermarket air filter/air boxes sets this codes. I believe this is due to relocating the MAF Sensor, or an smaller aftermarket tube between air box and turbo, which causes higher air velocity, which causes inaccurate MAF indications.

As far as cut-out at 75MPH or RPM limit @ 2000 RPM, I'm not sure. Others have this problem. Many blame this on dirty fuel filter, but that doesn't make sense to me that a dirty filter would always seem to limit RPM around 2000 RPM.
Search this site for this problem. Sorry I'm not any real help.

Drop the filter and put a different one in. You could be sucking air in. At about 2,000 RPM it might be the lucky amount of fuel/air mix that the engine is starving.

It is possible for a dirty filter to restrict fuel to the point the engine will only obtain certain RPMS.

Filter was just changed when I was doing the MAP sensor change.
The condition was there before the swap which made me think my old filter was the cause.
It has a new AFE on it now.

The fuel filter was just changed at the dealer with the mailer deal.

I just checked kPA in the manifold and at idle it's 255.
In the service manual, it says that if it's more than 254 for 2 secs it will throw this code(238).
I also swapped Baro sensors with my friends Duramax, just now, same part number and voltage, no difference.

I think it's going to the dealer in the morn.

The only other two culprits I can think of would be the wastegate malfunctioning or the wiring... and a real stretch, the ecm.

The wiring looks fine and has no visual signs of damage or burns.
I'm not throwing any other codes whatsoever, so I'm not liking the ecm for this.

Thanks for the responses though.

If taking to the dealer, dont forget to remove any performance mods (especially the edge)

If taking to the dealer, dont forget to remove any performance mods (especially the edge)

Oh yeah, it will be off first thing Andrew, plus I have a hookup that can help me out down there.
Anyone with anything else in mind please post up.

My LB7 used to do it. Exactly as you decribe. Defueling is what we call it. I got two codes.. overboost and MAP. I could make it happen at will by laying on the power in 5th gear around 70 mph.

After I installed the 90hp Juice (no attitude) it stopped happening. Before Juice nothing I did would help.

The funny thing is when the truck was just about new and stock, I pulled a 6000 lb load up a hill and it fell on it's face. I though there was something wrong with the tranny. Back then there were very few Dmax's in service so getting it fixed was not a high probablility.

Propane simply helped bring it on. It had the problem from stock. No flashes helped. I was at a loss until the Juice. Someone said the Juice has overboost ingnorance. Maybe someone could elaborate.

I don't know why it doesn't work for you.

After running both propane and the Juice I was so happy.... until she started puking coolant.


No problems like this at all with my Cummins.

My LB7 used to do it. Exactly as you decribe. Defueling is what we call it. I got two codes.. overboost and MAP. I could make it happen at will by laying on the power in 5th gear around 70 mph.

After I installed the 90hp Juice (no attitude) it stopped happening. Before Juice nothing I did would help.

The funny thing is when the truck was just about new and stock, I pulled a 6000 lb load up a hill and it fell on it's face. I though there was something wrong with the tranny. Back then there were very few Dmax's in service so getting it fixed was not a high probablility.

Propane simply helped bring it on. It had the problem from stock. No flashes helped. I was at a loss until the Juice. Someone said the Juice has overboost ingnorance. Maybe someone could elaborate.

I don't know why it doesn't work for you.

After running both propane and the Juice I was so happy.... until she started puking coolant.


No problems like this at all with my Cummins.



No problems like this at all with my Cummins



:rolleyes: Unbelievable

:rolleyes: Unbelievable

Good morning Mac. I see you are right on time.


Yea I should have left out the Cummins comment. That really changes everything :rolleyes:


Unbelievable is the 2wd "nice Kodiak" :muahaha:

I've seen alot of posts on here about towing bringing on these codes and issues.
I've towed quite a bit with it in the time I've owned it and it never had one issue.
All I can figure is there is a short I can't see, or that wastegate is screwed.

Donīt know if this is any help. I had a 238 code for some time and it was traced to the black/orange wire going from the boost sensor into the ecm terminal #34 blue.(I think that was the #) It just wasnīt seated properly.
I too changed filter, sensors etc.
Hope this helps.

Donīt know if this is any help. I had a 238 code for some time and it was traced to the black/orange wire going from the boost sensor into the ecm terminal #34 blue.(I think that was the #) It just wasnīt seated properly.
I too changed filter, sensors etc.
Hope this helps.

Seated properly on the ecm?

I got to thinking about corrosion and the elements, but in the desert here, there's not alot of elemental damage.
But it did rain more than usual, 6 inches instead of 2.
I'll check it out, thanks.

There is a clip that keeps the pins firmly in and mine was caught under this and not seating all the time. wd40 everything I say.........

Where is the boost sensor located on the LB7?

Mike

I can't believe you said that either Hoot. Did you forget where you were? Later! Frank