Strange running problem - no codes?

[Christian1402]

Having some strange running issues with the ed30 at the moment and I can't seem to get to the bottom of it.

It idles really rough, hunts quite a bit, doesn't boost and has cut out a couple of times. Still starts no problem.

I put a new PCV valve on it and its made no difference, also took the diverter valve out, checked and rebuilt it with no change. The bit thats really baffeling me now is the fact I had it scanned yesterday and its not thrown any fault codes up at all, even when I dissconnected the maf sensor while the car was running the day before it was scanned?!

Has anyone got a diagram of the whole PCV system? Am I right in thinking the pipe from the crankcase to the PCV valve has a non return valve in it? and if so, would that cause these sort of issues? As I changed the valve assembily itself but not the long plastic pipe to the block.

I was thinking of changing the fuel filter too just to make sure that isn't causing the problem, but then a blocked fuel filter wouldnt cause it to hunt surely?


Any help would be much appriciated.
A really confused GTI owner 

[karl210]

did you scan it with vcds or a cheapo obd code reader?

[Christian1402]

I'll admit it was scanned with a copy of vagcom. However I'm planning on limping it to a friend's accross town tonight so I can use his genuine copy.

[karl210]

if its a copy im guessing it will be vcds lite which i think doesnt do the canbus systems like the mk5 so your best bet is to get it scanned with a genuine canbus version. If your mate doesnt have the newer can version then there will be someone on here willing to help.

[doylebros]

Have a read this it may help you?

http://www.mk5golfgti.co.uk/forum/index.php/topic,44709.0.html

[Christian1402]

if its a copy im guessing it will be vcds lite which i think doesnt do the canbus systems like the mk5 so your best bet is to get it scanned with a genuine canbus version. If your mate doesnt have the newer can version then there will be someone on here willing to help.

Oh I see, that's probably why it never picked up on the Maf sensor too, it never got scanned last night with the proper vag com, hopefully that will happen today. Thanks for the info though, I've used his copy before on my old r32 so just presumed it would work on a mk5 too

[Christian1402]

Have a read this it may help you?

http://www.mk5golfgti.co.uk/forum/index.php/topic,44709.0.html

I've had a read of that mate, just put a brand new pcv valve on it. Also rebuilt the diverter valve and checked for rips etc.
Does the pipe from the oil cooler to the pcv have a non return valve in it? That could have gone maybe?

[Christian1402]

Bit of an update, found loads of codes, cleared them and sorted something I found but one code still remains. 004243 bank 1 sensor 2. Anyone know what this is?

Te car now boosts and doesn't miss fire however when first started the revs climb up to 3k rpm, I hit the accelerator pedal and they drop back down, then rise up again. It will do this 3 times before the revs finally settle on idle at about 1250rpm. It then hunts up and down quite quickly to 1500rpm.

Anyone have any ideas? Had a look at the fuel pressures on measuring blocks 108, 140, and 230 from memory. All fuel pressures look fine.

No other fault codes apart from the one mentioned above

[Christian1402]

Another update, after pulling the dip stick out while the car was hunting it made no difference what so ever. It's pointed me in the direction of the pcv again. Having just out a brand new one on, I swapped it back to the old one, out of curiosity, and well well well, the car now runs fine! No hunting, no random revs on start up. So, a bad pcv valve so it seems, even though its brand new!

[bacillus]

Assuming the error was actually "004243 - Bank 1; Fuel Measuring System 2: Malfunction" then you need to have a read here.
http://wiki.ross-tech.com/wiki/index.php/17501/P1093/004243

I would live log your fuel rail pressure as my gut feeling is your Low fuel pressure sensor has problems.

[karl210]

Id check for a Vacuum leak. Copied this off another forum:

Easiest way is to check block 032.

There are two fields in the block, and both belong to fuel trims.

Left hand one is short term adaption, right hand one is long term adaption. Left hand one is the one to look at in this instance.

Make a note of these two figures. Reset the fault codes (even if there are none), as this will clear the fuel trim data back to 0% for both blocks.

Then start the motor and log block 032. If the value in the left hand block steadily climbs to or past the 3-4% area, it's normally a good indication of a leak.

The lower the % the better, ideally 0% or 1%

[Christian1402]

Thanks a lot for the replies regarding the fault code. I will have to get it back on the computer and check that out. The car is running fine now though, doesn't seem to be holding back so I'm presuming the engine is getting enough fuel.
I'll defiantly look into it though, thanks.

[M7AXB]

Try this for logs http://www.goapr.co.uk/support/datalogging.php

[Christian1402]

I'll have a look now, thanks