Yesterday I was doing a track day on Portland International Raceway. For those of you not familiar with my setup I will give a brief overview:

Turbonetics ST (watercooled version, updated piping)
Built block
Utec running built in boost controller, set at 8psi (7psi wastegate spring installed)

The car has been tuned and running for about two months now, and has been holding boost beautifully with no issues. I have had it at two autocrosses and it has about 1400 miles on the new engine so far.

Anyway, my first 20 minute session on the track went great beside when I blew a coupler off the throttle body. Easy fix.

I go out for my second session and the car hits overboost fuel cut immediatly on the front straight. I continued on for a few more laps but it kept happening. I notice my boost gauge was showing over 10psi when this happened. So I pull off the track, get out my laptop and check out the utec to see what psi the overboost fuel cut was set at... 12psi.

The only thing different about my setup and the conditions that day was that it was close to 100 degrees outside temp. My car has never seen over about 70 degrees since the turbo install.

I checked all the vacuum lines, they seem fine so far. I am going to do a closer inspection to make sure there are no pinholes, etc. The problem does not seem to be the utec's BCS because I turned all that off and went to spring pressure and it still overboosted. The problem is also not with the map sensor because its showing proper PSI in comparison to my boost gauge.

Beside an issue with the wastegate itself, do you guys have any ideas why I would be overboosting so bad? I want to narrow down the things I have to check to get this resolved. I think I will pull the wastegate today and check it.

Thanks

 

Defenatly not the heat, heat would usually bring the boost down. Cold however will mess with boost pressure. If you have never had the problem before, and all vac lines check out good. Sounds like a wastegate issue, either not getting a great vac singnal or being stuck or not opening all the way.

 

Yeah.... it has to be the wastegate. Swap it out for another.

 

Thanks for the input guys. I am thinking the wastegate might be stuck shut for whatever reason. That, or one of my vacuum lines run to it got crimped or melted.

 

Well I checked the vacuum lines again and they seem fine. I am thinking I may change to braided vacuum lines regardless though, because I notice those that are near high heat areas have gotten a little "mushy".

Now if my problem turns out to be the wastegate itself, should I replace it with another evolution, upgrade to a racegate, or use an adapter plate to switch to a v-band style wastegate like the tial's? I am pretty sure I will be going with an open dump as well.

 

personaly, i like tial gates. But i know the hks makes good units as well. It comes down to what size you need and space allowed. Some get rather large.

 

I had the exact same problem and it turned out to be the wastegate vacuum line that melted because it sat too close to the wastegate overboost pipe...I simply cut it shorter and re-attached and everything was fine.
A SS vacuum line would be added security. Cool. Didn't think the wastegate would just fail like that though. Have you opened it up yet to see if anything internal crapped out?

 

Not yet, I haven't had time to pull it off and open it up. I am hoping it can be saved, and that its just stuck shut or something. But my kit was used, minus the turbo, so who knows how much use its seen. It might just be spent.

 

yea, if its the evolution wg, toss it. and go with tial.

 

Well I finally found my issue today, turns out it was the bottom port vacuum line after all. It had burned thru just a bit where it contacted the uppipe/wastegate flange.

While I was fixing it, and wrapping the hell out of that line so it wont happen again, I also converted to an open dump using a Treadstone dump pipe. It looks ****, a 45 degree bend off the wastegate and dumps thru my ARC undertray.

I would have taken pics but my girlfriend left me and took the camera. LOL