Had my car (04 Astra GSi - Z20LET) on a rolling road today at V Sport near Durham, and it only made 185.3 bhp. In March this year at Well Lane it made 215bhp. It certainly doesn't feel like its lost any power, and I changed the boost control solenoid after Well Lane to try and cure a big flat spot between 3500 and 5500rpm.
I paid an extra fiver today to have the boost and emmissions checked on the rolling road, as the flat spot still seems to be there a bit. He said that it wasn't holding boost and that it was running lean, so he pretty much aborted the run.
However on the road the boost gauge shows that the boost never drops and is held constantly fine!?
I'm wondering if he left the traction control switched on??? But surely it wouldn't drive up to 6000rpm with it on would it??????
I switched the traction control off as I drove onto the rollers, and left the engine running. He then switched the engine off to connect the boost measuring pipe for the dyno, then started the car up. If he didn't press the traction control button again, it would have been on again.
So my question is: Would it still drive up on the rollers with traction control on,or would it kick straight in and be obvious???
Also: If I had a boost leak, wouldn't my boost gauge show this????????
Any ideas and help appreciated, as the car drives as strong as ever on the road!