turboAWDfanatic
20+ Year Contributor
- 347
- 35
- Aug 22, 2005
-
Colorado Springs,
Colorado
Been a long time since I've posted here, but this one has me stumped. I have a Tial MV-S on a recirculated MAPerformance O2 housing bolted to an HX35 on a BEP DSM turbine housing. 3" exhaust, no cat.
The problem is, I have the springs set to open at 18psi but it will overboost to 30psi the first few times I do a pull (even after warming up the car thoroughly). Over the course of the next 10 minutes or so, the max boost will back down little by little every couple of pulls, 28psi, 25, 22, 20, then finally settle at 18psi where it should be. For the rest of the drive it will stay rock solid at 18psi. This is with the boost source routed directly from the compressor housing to the side port of the Tial with the top port left open. I have tried changing the boost source to the BOV line with no changes.
I have an alternate high boost setting that I trigger with a flip of a switch to run in conjunction with water/meth, but I have eliminated this completely until I figure the overboost situation out. For now we're dealing with just a straight connection from the compressor housing to the side port of the MV-S.
It's as though the MV-S valve is seizing shut, but opens up once enough heat is flowing through the entire O2 housing/wastegate. Warming the car up via regular driving has absolutely no effect on this. I've driven at freeway speeds for over 20 minutes and it will still overboost on the first several pulls but then settles to 18psi as mentioned before. It only seems to right itself after I have gone WOT a fair amount of times. Has anyone encountered an issue like this before?
The problem is, I have the springs set to open at 18psi but it will overboost to 30psi the first few times I do a pull (even after warming up the car thoroughly). Over the course of the next 10 minutes or so, the max boost will back down little by little every couple of pulls, 28psi, 25, 22, 20, then finally settle at 18psi where it should be. For the rest of the drive it will stay rock solid at 18psi. This is with the boost source routed directly from the compressor housing to the side port of the Tial with the top port left open. I have tried changing the boost source to the BOV line with no changes.
I have an alternate high boost setting that I trigger with a flip of a switch to run in conjunction with water/meth, but I have eliminated this completely until I figure the overboost situation out. For now we're dealing with just a straight connection from the compressor housing to the side port of the MV-S.
It's as though the MV-S valve is seizing shut, but opens up once enough heat is flowing through the entire O2 housing/wastegate. Warming the car up via regular driving has absolutely no effect on this. I've driven at freeway speeds for over 20 minutes and it will still overboost on the first several pulls but then settles to 18psi as mentioned before. It only seems to right itself after I have gone WOT a fair amount of times. Has anyone encountered an issue like this before?
