Firstly, I'm new to the Forum...so hello to all!!!
Secondly, before I get going, what's CEL I read a few threads about DVs and people kept mentioning this.
Right, I have a Mk4 Golf GTi Turbo - Engine code: AGU. When I bought it, it had a Baileys dump valve, it had been Superchipped, and it was 170bhp running approx 16psi. More to the point...it used to hold boost and would pull well throughout the rev range.
I decided I wanted 200bhp, and so went for a remap. Chris Wells at CC Tuning (http://www.cctuning.co.uk) did it for me. He said his remap alone would achieve 195bhp. He'd then fit the N75J (Boost Control Solenoid) from the TT which would make it hold boost longer, adding about 10bhp and making it 205bhp running approx 20psi.
When I got it done, it did feel quicker....but not 200bhp quick. I took it for a Rolling Road, and it was 170bhp running approx 14psi. Strangely, boost get's to about 12/13psi when you boot it...but then as of 3500rpm...boost just drops off...as does torque.
So...I took it back to the remap guy. He was (obviously) confident in his software, and says he's done 100s of 1.8 20v T engines with this same remap and they're all fine. He's a nice guy though and so he started to help me try amd diagnose the fault.
He had a Mass Air Flow (MAF) in stock, so we changed that (as it's normally everyones first suggestion)...and it made no difference.
We then took the throttle body off and gave it a good clean...but still no difference.
We checked the air filter, and it looks almost new, so no problem there.
We then noticed that the Baileys DV was open on half throttle. It only closed on full throttle. So he suggested a Forge 007 (yellow spring) Re-circ DV as he new these were tested against several levels of boost. He also noticed though his laptop that coolant temp was lower than expected.
So...I coughed up for a new Forge DV and also got a replacement Coolant Temp Sensor from VW. STILL no difference.
All the above failed...we assumed there must be an air leak somewhere, losing boost. Took it to ADC diagnostics in Bulwell. To be fair, he did only have the morning on it...but much to my disappointment...he called back a few hours later saying he couldn't spot any obvious boost leaks anywhere.
SO....PLEASE can you help me!!!
I've done EVERYTHING i can to try and rectify this problem myself. I've also spent a fair amount attempting to get a garages to try and diagnose this fault...but as of yet, i've had no luck.
No fault codes come up on the VAG-COM to indicate anything suspicious. I'm basially stuck. And i'm a week away (got it in somewhere else on satuday) from saying to Chris to put my original software back on it and to have my money back. I'd really prefer not to have to do this, because the reason I spent the money in the first place was to have my golf at 200bhp....but if the problem can't be solved....i'll av my £300 back thank u very much.
Any advice you can offer is GREATLY appreciated.