Hello all,

I have a 2002 WRX 4EAT with these parts:
STI Hood scoop
UTEC Stage 1 chip.
Greddy Evo Catback
Up-pipe
Unifilter ram pod intake
GFB Blow off Valve
EGT, A\F gauges and factory Boost Gauge.

The car drives fine and pulls strong. The only wierd thing driving is: If I'm going about 90 miles an hour on the highway and hit the gas hard the boost goes quite high on my gauge...above .11 MPa, which really doesn't give me a warm fuzzy feeling. Now If I were to accelerate from 40mph to 90mph this wouldn't happen. I tried adjusting the ABC that comes with the UTEC a bit, but it didn't seem to help. Is it something with the rampod intake and the highspeeds? Any help would be greatly appreciated. Thanks.

 

I have had the same thing happen to me. If I'm hard on it once it goes to shift into OD it wants to overboost. Check engine light comes on. Mine spikes to 1.22 khPa

 

That happens because of the increased load on the engine caused by the tall overdrive gear AND the huge wind resistance ecountered at those speeds... For the turbo to spool, it needs a load to be placed on the engine, and thus the turbo, but when in overdrive, and travelling at high speed, the loads are much much higher, which basically causes the turbo to make more boost than in the lower gears where the load is not as great. Since the wastegate cannot react quickly enough to bleed off the excess boost not being made, you end up with more boost... This is partly why getting maximum performance out of the car in the lower gears comes at the expense of not going WOT in the OD gear since it will cause you to overboost. If your setup is mapped to accomodate the extra boost, then all is good, but if not, then you could be running lean when the boost climbs too high...

This isn't so much of a problem on cars that have an ECU reflash (AccessECU, ECUtek) becuase the ECU doles out the boost based on throttle position (as a result, you only get full boost when you go WOT), so you will find it rather difficult to overboost in your OD gear based on the way the ECU controls boost...

With regard to UTEC, I may be wrong, but I believe that it controls boost in a similar manner to an MBC/EBC in that it suddenly gives you full boost at a certain point in your powerband. In town, it is nice since you get the full boost quickly, but If on the highway in OD, this will make you overboost unless you turn down the boost. But then, turning the boost down dor highway duty also means that you will have less boost when running around town....

 

Thanks, that sounds like a good explanation. Now I don't have a Lap top hooked up to my UTEC, but I guess with that I could fix this problem? Like you said its a trade off. Today coming home I hit .11 again. This is going like 95 miles an hour so I mean unless I was racing the thing on a track, I think I'll go with the faster 0-80 speeds. I think I'm going to turn the boost down a bit with the ABC though...its getting cool. Might as well as my P1's and Toyo Proxes are already in my parent's basement! Winter sucks...I still might get my windows tinted before the winter. Oh and I checked my A\F gauge during the over boosting..it was still reading pretty rich. I'll keep an eye on it though. Thanks again!

 

Opening the throttle more slowly will go a long way toward helping stop boost spikes in top gear on the highway.
If you stop driving the car in a manner to MAKE it overboost, it won't.
Don't stomp it to WOT, ease it to WOT.