low boost pressure? found problem... help!

david burton · Post by **david burton** » Sun Oct 21, 2007 2:10 pm

aaaargh.

I've noticed my car seems to be struggling up to 2500rpm. It still revs hard up to the red line but getting there from low down is an issue.

a couple of weeks ago there was no boost at all. I left the car but when I came back it was fine. I read somewhere on the forum that if you disconnect the MAF sensor and it works OK then it's the MAF sensor that's the problem.

However, when I tried that today the bloody exhaust emissions light came on, and now won't turn off!

not happy.

so at the moment the battery is disconnected, hoping that the exhaust emissions light was just because I took the sensor off, and it will be reset.

... and also hoping the radio code will be sorted out by the ECU.

anyone else experience a lack of boost at low revs?

Cheers

Dave

Post by **alexperkins** » Sun Oct 21, 2007 4:54 pm

Whats happening with the radio code!?

david burton · Post by **david burton** » Sun Oct 21, 2007 5:13 pm

i thought it'd be lost and be in "safe" mode, but it wasn't on reconnection... ecu is supposed to automatically enter it

Post by **alexperkins** » Sun Oct 21, 2007 5:14 pm

Indeed it is - when ignition is on, after radio is on it learns

meeker855 · Post by **meeker855** » Sun Oct 21, 2007 6:49 pm

I had the same problem (no boost), the other day.

Turned the engine off and back on again and all appered normal, after a few more miles it happened again so I disconnected the MAF sensor, It made no difference.
At the moment it's working fine, but I know its not gone away!!

Will be interested to see what your fault is.

david burton · Post by **david burton** » Sun Oct 21, 2007 7:05 pm

So I take it your exhaust gas emissions light didn't come on then? I'm concerned the remap might be turning the exhaust gas emissions on, but this is only a stab in the dark. will get it looked at as soon as I can.

chris4500uk · Post by **chris4500uk** » Sun Oct 21, 2007 7:06 pm

Maybe check the air filter and fueling?

Get a vag-com on it as well

david burton · Post by **david burton** » Sun Oct 21, 2007 7:08 pm

yeah I'm planning on a DIY service next weekend, might opt for a green air filter.

AKs_SlickPolo · Post by **AKs_SlickPolo** » Sun Oct 21, 2007 7:57 pm

Maybe worthwhile cleaning out the EGR valve. I did mine on my petrol recently and low down acceleration has improved as it was slightly clogged with carbon.

Mine did not trigger the emissions lamp as it weren't too bad, but a fault code was registered. I know on a friend's Diesel the same thing happened but it showed a emissions lamp on the dash.

Fairly easy to do - only parts required was a new gasket.

david burton · Post by **david burton** » Sun Oct 21, 2007 8:14 pm

could you let me know how to do the EGR valve if it comes down to this being the problem? cheers.

david burton · Post by **david burton** » Mon Oct 22, 2007 10:11 am

well the emissions light has gone off, but I'm still low on boost up to about 2500rpm......

perhaps the simplest thing (air filter) is where to start!

dino · Post by **dino** » Mon Oct 22, 2007 4:26 pm

David - i'd drop Richard a line as he may have some knowledge on this. I had an issue with my boost after the remap but he sorted it out straight way!

david burton · Post by **david burton** » Mon Oct 22, 2007 6:14 pm

already done that, going to fit new air filter later in the week and see if it helps at all. he thinks I need to check the MAF.

AKs_SlickPolo · Post by **AKs_SlickPolo** » Tue Oct 23, 2007 10:26 am

david burton wrote:could you let me know how to do the EGR valve if it comes down to this being the problem? cheers.

The EGR is on the right hand side (from the front) and you simply have to unplug the connector and it unbolts off. To clean it out I just used carb cleaner to get it nice and shiny and also had to use a plastic scraper gently at times - took about 30 mins to do!

Though if your emissions light is gone it may not be this at all (but it never triggered a light on my petrol then again

)

Best thing is to get Vag-com on it before shelling out on any new parts though!

david burton · Post by **david burton** » Sat Oct 27, 2007 7:16 pm

Took it to be vag-com-ed today, there was a Mass Air Flow Sensor error (open short to ground G70) however I have heard that when I tried to disconnect the sensor and run the car then this would also produce the same error code.

Stupidly I didn't get the guy to reset the codes.

So, I cleaned the MAF sensor this evening and it hasn't helped.

I've got a clearer picture of the symptoms though - it's under full throttle that it decides to give less boost. If I accelerate under 50% throttle it's actually faster than full throttle.