Behaviour when coming on boost

[Rusty]

Not had the boost cut since fitting a spare, unmolested WG cap but still got slightly odd behaviour coming on boost. On occasion, when going full throttle from low revs, the boost ramps up as expected and then goes to 1.7 bar, drops back to 1.6 bar briefly before it then ramps up to 1.8 bar. I can feel and hear this happening,. Tried a spare MAF and boost tested it to 1.5 bar with no change. Need to try stock chips to see if the same happens. Just want to get it running as best I can before fitting the new engine, when it's ready. Might be nothing but it's different to how it's been on previous setups.

[macspring]

Is both your N75 and bypass valve brand new, if not, it may be worth incurring the expense of replacing them so that they cannot be at fault, given what you're up to.

What coil arrangement are you using ?

Interested to see what it turns out to be.

Regards.

[Rusty]

DV was serviced recently but the N75 isn't new.

[macspring]

Ok, so worth a try. Helped when I changed mine recently.

[newsh]

Measured boost is more than requested, ECU backs it off.

Are the chips correct for the spec? Turbo, manifolds etc?

[Rusty]

Yes, chips are correct. Gauge sees what the ECU does.

[newsh]

You could try washing the N75 out with GT85 or WD40.

[SteveH]

Knock detection dialing the ignition back?

[newsh]

Knock detection dialing the ignition back?

Unlikely boost would drop back.

[Rusty]

Yes, I think I'll clean the N75 as I did the ISV the other day and need to lubricate it now as it's stalled a couple of times since.

[220bhp]

What chips are you using.

[Rusty]

N75 cleaned and DV checked. Just going to check the knock sensor bolt torque next and clean the IAT sensor up, in case it's a bit gunked.

[andyg plym]

Have you retried the ts chips? Still the same?

[Rusty]

I'm going to try some stock RS2 chips. The TS chips are consistent but have some of the safety net items disabled, so aren't any use for troubleshooting.

The car drives well and a run to a local shopping centre confirmed that Just when it comes on boost that there was some funnies but didn't get chance to check that earlier.