So a strange thing started happening today all of a sudden. While driving the car WOT as soon as the boost reaches its set point (10 psi) it starts to sporadically fluctuate between 9 and 12 psi. The car runs great and boosts great, however as soon as it hits its set point of 10 psi it starts fluctuating. There were no changes made to the car since the last time it was boosted hard. The only thing different was that the air temps were a little hot today.

Quick background on the car: It is an S5 TII with a Haltech E6X, full fuel system, straight exhaust, greddy FMIC, intake, etc. Boost is controlled by a Greddy Profec B Spec II.

I checked for vacuum leaks and could not find any obvious ones. I also checked all the boost controller lines to make sure the were all ok and they were.

I can think of two possible scenarios:

1) There is something wrong with the boost controller. However it has never been touched since it was set.

2) The Haltech currently only has a moderate tune for the break in period from when the motor was originally built and has not been retuned since. However that tune has been working great and there has never been a problem with it yet. But maybe with the high temps today it hit a rough spot on the map.

Anyone have any other ideas? Has anyone ever experienced something similar to this before?

 

Disconnect the boost controller and see if the problem continues.

 

Thanks Aaron. I turned off the boost controller and did a couple of runs and it holds boost fine now.

I believe there is an electrical issue with the car that I am going to need to hunt down. However I don't think I will need to look far because I believe it is the taurus e-fan. I have noticed that after the install of the Taurus e-fan my clock and stereo head unit have intermittently been shutting down and coming back on moments later.

The taurus fan is wired up correctly and wired to run only on the low setting. I originally tried using two different GM 6 cylinder fans as recommended by your site. But with each of those fans I tried the car would run hot on the highway (Greddy FMIC). Since they were not cooling adequately on the highway I decided to go with the Taurus fan.

 

wait, what? what does the electric fan have to do with the boost controller? You have a Profec B spec II. Turn down the gain and/or crack pressure.

 

All I am saying is ever since I put on the Taurus E-Fan alot of strange electrical issues have started happening. The boost controller issue may, or may not be related to this. But the fact that I have not touched the boost controller since it has been set leads me to believe they may be related.