I was driving home today, and when I got on the gas on the entrance ramp to the highway, my boost gauge shot up to 30+ PSI!!! YIKES!!!

I checked the MBC and all the hoses and they look fine...the MBC appears to still be on the same setting it always has been...21 PSI. Now, I know that 30+ PSI is not possible on the stock turbo, plus I would have hit fuel cut or blown the engine and I didn't, so there must be something wrong with the way the gauge is reading the pressure. Has anyone experienced anything like this with the Defi D-Gauge???

I pretty darn sure I'm still at 21 PSI, but this is bugging me...can anyone help???

 

Might be a slight short in the electrical line. Then it reset thereby sending a full signal to the guage. Don't worry too much.

 

Yeah, except mine is a D-gauge...a mechanical gauge, not an electronic one.

 

Since your dynoflashed you no longer have fuel cut. A 30 psi spike is definitely feasible with the stock turbo. My bet is your MBC got stuck and you hit 30 psi.

 

+1 ive heard about this happeneing to a few people with metal check ***** in the MBCs

 

i think the most logical question is, did it feel like it? there is a big difference between 21psi and 30psi, you should notice some difference if it really hit that much boost...

 

There are many people that have problems with the D-gauge. Mine messed up only a month after I bought it. It started off just 5psi high before long it was reading 15psi higher then it should.

 

the DEFI-D boost gauge is a really good gauge. to test it, just get an air pump w/ a gauge and test the DEFI-D gauge for accuracy. my guess is like everyone else's that your MBC somehow got stock allowing higher boost.

 

I too have a DEFI D-Gauge.

The only thing i've ever experienced was one day I started it up and the boost gauge stayed at 0, even though the car was idling. I'd hit the gas, and it would stay at 0. IF i FLOORED it, then it would go upto like 5psi, but come right back to 0 (while idling and driving).

Even though the car drove and felt normal.. and after like 5 mins of driving the gauge just went back to normal.

Really strange..

 

My Defi D reads 7 psi high now. It use to be only 3 psi.

 

Frankly, I don't think 30+ PSI is possible with the stock turbo. It was just a brief spike. I hope I didn't damage my engine....I still think it's the gauge.

If the ball in the MBC is sticking, can I just turn it out a few turns, then back in to loosen it? I thought I had the Pro with the ceramic ball...guess I better check it again.

 

I thought fuel cut was just raised a bit, not removed entirely. I'll have to check with Al on this.

 

Really??? That would explain it, then. I'm gonna take it easy on the gas until I can take another look at the MBC, though.

 

the Pro RX has the ceramic ball, the Pro is SS. I believe Hallman advised 03BREvo8 to oil the ball ocassionally to prevent the sticking, maybe you can try PMing him. He's one owner that I know experienced a 30 psi spike at around this time last year.

 

Yeah...mine does that too sometimes...it's something to do with where you connect the hose for the pressure reading...when the engine is hot, it can take a few minutes for the gauge to read properly.