Hey all,

I've finally put the car back on the road after 18 months on SORN. Passed MOT first time

However, the turbo is not kicking it AT ALL. There's literally nothing there was I put my foot down, severe lag.

The EGR is blanked off from the last time this happen and it was fine before it went off the road. What other things would cause this? I disconnected the MAF and went for a drive and this didn't help all it did was throw black smoke out the exhaust.

If you could let me know a few things to check that would be great.

anyone? I need to get this sorted ASAP. cc

heyup, glad to read your car is back on the road.

ok, as for boost, check the boost control valve, its either near thebattery if its been re sited, or down below the air box near the front - see the guide section. I suspect this is the culprit, as your MAF appears to be functioning (if it was, unplugging it would result in poor performance up to a certain point in the rev range, lots of black smoke as the engine struggles to breathe)

Double check your I/C pipes, passenger side remove the inner arch and inspect the pipe for splits etc..

good luck!

Unplugging the MAF gave me worse power and loads of black smoke even resting on the accelerator. Going uphill at the moment is a real struggle.

Would the MAP cause any power issues? There's one of EuroCarParts for £14. Worth replacing?

Any tips for checking the boost solenoid?

Hey guys. Just plugged in the car to check some error messages. 3 cleared one remains as the AC has no gas in it.

However, I checked the BOOST VALVE with the car running and under FULL load it drops to 36.16%. I'll be honest and admit that I have no idea what this means - but maybe someone else could shed some light?

Image and graph export attached.

** EGR is blanked off so I assume this is why it's at 1% **

if unplugging the MAF gives you worse power then the MAF is probably ok. The MAP sensor can be cleaned, but if its never been changed then go for it if you want for the sake of £14, potentially it might make a difference.

As for the Boost Solenoid issue, im no expert so I cant really comment, but if its dropping then that may be a sign its sticking - again im not 100% on that. Try this guide with regards re siting it, because then you can have a look at the general condition-its a common fault on these cars due to the position and they get wet, the moisture stays inside and cant dry out and so they die slowly.

if like the later 16v jtd, the boost solenoid should probably be around 75% at idle which is max spool position then say when full boost the % would reduce down to reduce boost pressure as fueling increases 20% being the min amount(trying to reduce boost )
there is an open loop and a closed loop control for vnt% , to a certain fuel mg value it just reads off vnt map value and sets vnt to value, above this set point it moves into closed loop and then uses boost pressure as a feed back value to control vnt%.
in that shot above boost is not ticked?
try a log when driving 3rd or 4th gear, get to 2000 revs and floor throttle and log as high as it goes or 4000 if you can.
you may see vnt% increasing but boost not increasing= problem
log boost and maf airflow if maf shoots up but boost doesnt probably a boost leak somewhere.
then post log here and ill try to find a vnt control map tonight to see how it compares.
log revs , desired boost, actual boost and vnt%
have you had a quick look for split boost hoses etc
also as you have fes you can log fuel total injected quantity and maf airflow to see if its bogging due to lack of air seen by maf and hence cutting fuel.
side note some of the vw cars vnt control switched from 80%=max spool to 20%=max spool so at idle should be max spool and read what vnt% is.
if you can get someone else to stop and start the car you can visually see the turbo actuator pull the vnt to the max stop screw and then when stopped see it return to fully open min spool position, if not as mentioned above check boost solenoid and or vac from vac pump to boost solenoid.

ok I think I found a vnt map off a 115

give you an idea of what vnt% you should be seeing at revs left axis and total fuel on top axis
and heres your boost map

Thank you.

I'll plug back in this evening and post results.