[mgmshar]

I posted this on another Buick board, and got no response. Maybe somebody here can help me out...

Ever since I got my new turbo (TA-49) and Terry Houston DP, I've had a problem that I can't seem to lick. I imagine that somebody on this board has seen this before...

Whenever I run the car under high-boost conditions (i.e. 20+psi with the dump off the DP), the computer will shut-off the signal to the wastegate solenoid for a split-second at the top end of second gear or the bottom end of third gear. I know this is happening, because I can see it in the DirectScan data. At 5000+ rpm in second gear, the computer will drop the boost PW to zero, and then slowly bring it back up to the normal value. The result is that my boost drops from 20+ psi to about 15, and then slowly builds back up as I go into third gear. What's weird is that this happens every time with the dump off and high boost, but never happens when I run with the dump on and lower (i.e. 17psi) boost. On some occasions, I can see that the LV8 value and injector PW value also go to near zero at the same time as the boost PW. However, that doesn't always happen, unless the DirectScan isn't catching it.

I've tried several different chips of my own, and I've tried a Red Armstrong chip, and none of them seem to fix the problem. I've also tried several other things:

1. Replaced the MAF sensor.
2. Tightened the four grounds on the rear of the engine.
3. Checked both battery cables.
4. Jiggled/tightened the connectors to the ECU.
5. Put a Q-tip in the DirectScan cable connector to keep it from sliding too far onto the ECU board.

The problem seems to be in the ECU, because DirectScan is telling me that the ECU is dropping the boost solenoid PW to zero. The drop doesn't correlate with a knock event, a third gear transmission event, or anything else that I can see. Has anybody seen this before? Why would this only happen under high boost conditions, and always at the top end of second gear? Does this have something to do with the MAF reset problem that I've read about?

Any help would be GREATLY appreciated!

Amazingly, even with this problem, I managed to run my very first 11-second time this past weekend, on 100-octane gas. I'm still giddy about that one. It's amazing what 40 degree air will do for these cars!

Thanks,

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