Defi gauge showing 28-29 boost spike

cnj4ever · Oct 24, 2009, 10:10 AM

Ok so I installed a Defi Cr white racer boost gauge, and when I floor it, the gauge shows a spike of 28-29ish then settles around 23. Is this normal or is this bad. All my mods are in my Sig except i took off the MBC. Thanks

wongck · Oct 24, 2009, 10:15 AM

it looks a bit high. Are you getting any error codes? It seems like with winter rolling around, a lot of people are running into problems of overboosting

jd888jd · Oct 24, 2009, 10:16 AM

It might just be off....get ur car in a dyno and get an accurate reading. happened to me to.

WaitForIt · Oct 24, 2009, 07:36 PM

Mine does the exact same thing. It seems to be maybe 1-2psi off at most when I datalogged. I would still be seeing mid to upper 27's peak boost. Stock except for a once piece UIP. Couldnt find any definite reason as to why and was told it was more or less normal as I wasn't throwing overboosting codes or anything. This was also in the summer with 70-80 degree days.

LVSBB6 · Oct 25, 2009, 11:04 AM

I'm in the same situation. Seems to me the boost pressure is very sensitive to weather change.

My car was dyno-tuned via ECUflash to 26.5psi just a two weeks ago. Nothing has been altered since, except our weather changed a bit and became colder since. I was triggering ASC light at peak boost and my mode23 datalogs showed I was boosting at 31psi!? In other words, I was overboosting.

I brought it back to the tuner to check for possible vaccum leak, he checked every vacuum hoses and confimed everything were intact. I have been running the JUN wga and he wondered whether if it was set too tight for the cooler weather, so he disconnected the stock boost solenoid vacuum hose, boosting solely using the JUN wga. I did several pulls to see whether I would still trigger the ASC light. Datalog shows 19psi at peak with this test, with no overboosting issue.

He said that it is not unusual for the boost to increase due to colder weather, especially when using stock boost solenoid. He recommends getting aftermarket boost controller to avoid this from happening. Do you guys agree with his comment?

Our temperature is now 10 degress celcius, compared to two weeks ago about 20 degrees celcius. But I'm still surprised by how much boost I am seeing now compared to two weeks ago due to this change (31psi vs 26.6psi!).

sne2040 · Oct 25, 2009, 04:22 PM

do you get the overboost when you're in lets say 3rd gear at 3500 rpm and you go WOT? that's actually quite common because your load (i believe it goes past 240% load) just flies through the roof and it spikes for that second or so. If you notice, it actually drops down to normal afterwards (ex. 25 psi) and gradually decreases while you climb up the RPM value. From my understanding, a 3-port ebcs can cure that issue.

LVSBB6 · Oct 26, 2009, 05:46 PM

^yes it would happen in any gear other than 1st. My load hit as high as 300% at 4000 rpm.
I retuned my boost map and fixed the issue.

Clipse3GT · Oct 26, 2009, 11:04 PM

I had this same issue. My problem was fixed replacing the stock BOV. Yes, I poped in a GFB and the boost went back to normal. That is just my finding. I don't know if this is the case here as well.

MR. Tim · Oct 27, 2009, 09:38 AM

To the OP - you should log the car with evoscan. See what the ecu is seeing, not what an aftermarket gauge is telling you.