Overboost more and more frequently. High boost readings.

Cantbuytime · Dec 29, 2015

So I posted a while back about over boost. I was getting while towing only 3000lbs with performance tune. Went back to tow tune then no overboost. Had dp tuner write me a custom race tune. And I ran it a while then it gave me over boost, called jody and he rewrote the tune eliminating my over boost but the truck easily pegs boost gauge at part throttle. I do not tow with this tune.

Then I started getting over boost in tow tune while towing same weight. And every canned tune is over boosting and throwing the code. They are all boosting around 25 psi while cruising and pegging the boost gauge when the cruise accelerates up a small hill. This is not towing either. On flat ground it's below 10 lbs of boost but just a bit on the throttle and boost is pegged.

I'm using an sct 3015r egr turned off, 4" diamond eye from downpipe back, no muffleror anything and an sb cai. And honestly the over boost didn't get more frequent till the sb cai. Talked to a performance shop and they said absolutely do not run the canned tunes. Only custom tunes. I do not like that cause the canned race tune is giving me a real 20.9 mpg and the custom tune is a real 19.3 mpg. Lower then what the lie o meter says.

I don't know what to do here with no other codes thrown.

sootie · Dec 29, 2015

Replace your back pressure sensor and tube. Then get good tunes. Gear head would be the favourite.

drunk on diesel · Dec 29, 2015

I wouldn't worry about it.

footlong70 · Dec 29, 2015

What do you consider overboosting? Sounds like a frozen ebp tube issue. These threads pop up every winter. Did you ****** the egr coolers? When they get removed, there isn't enough heat around the ebp sensor or tube to stop it from freezing off due to condensation. With no pressure getting to the sensor, the ecm has no idea what to do with the vgt which sky rockets your boost and back pressure to ridiculous amounts. I remember mine hitting as high as 67psi pulling a hill, empty on stock fuel and turbos one winter. If its not frozen then I would suspect a bad ebp sensor or plugged off tube to the sensor. Lastly though i'd suspect a stuck vgt.

taterthedog · Dec 29, 2015

Just changed my EBP sensor today. Was freezing up. Didn't change the tube. Made sure tube was not restricted. With the sensor freezing up, my boost was all over the place. Do you have anyway to monitor EBP? It should respond really quickly with the throttle. I noticed mine was acting up before it even threw a code. Changed a sensor 2 years ago for the same issue.

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taterthedog · Dec 29, 2015

Also, I would think any tuned 6.4 will easily peg the factory gauge. Are you getting a code for it as well?

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Cantbuytime · Dec 29, 2015

P0234 for overboost and p1000 for the stored code.

All factory egr stuff is on the truck still. Just turned off with tuner. I drove it a bit today after reinstalling the custom tune. The boost seems normal. Not really getting above 35ish psi even at hard throttle while engine is Starting to warm up. Once the motor gets completely warmed up then the stock boost gauge starts maxing out at even a little throttle