turbo and smoke issue yet again - Page 2

mikes2 · 12-05-09, 05:59 PM

A G28 error can send it in to limp mode.

Was this with the engine running that you got this code or with the engine off?

It's it's an intermittent type error, it can still cause limp mode without triggering a code

20vcqdriver · 12-05-09, 06:30 PM

Quote:

Originally Posted by mikes2

A G28 error can send it in to limp mode.

Was this with the engine running that you got this code or with the engine off?

It's it's an intermittent type error, it can still cause limp mode without triggering a code

Had a spare one of these sensors so have changed it but to no effect. WHen the codes were cleared with engine running and then went out to put it into limp mode on returning I had no codes...
Now figuring out what to say to turbo repair company....

amanda · 12-05-09, 07:01 PM

[quote=20vcqdriver;54427]Had a spare one of these sensors so have changed it but to no effect. /QUOTE]

Hmmm are you sure your spare is good ?

BW2309 · 12-05-09, 07:49 PM

An intermittant fault with G28 can occur with no actual fault. You should only ever read the codes on a 3B/ABY etc with engine running. Just checking with the engine not running will give a G28 fault. If the G28 crank sendor had failed it would either stop or not start.
Is the throttle body boot OK? ALso, check where things have been adapted for your conversion, i.e, there may be an issue with boost leaking through the system for the carbon canister (that I assume you are no longer using) or possibly with the brakes. 3B should have hydraulic assited brakes, is your now vacuum assited??? Sounds very much like boost leak from here but hard to judge wothout seeing.

BW2309 · 12-05-09, 08:01 PM

Just to add - check also boost pressure hose to ECU, if the ECU sint getting boost to read it can't control it. Also, if there's smoke check fuel pressure/supply.

I shall be quiet now.... Sorry for going on!

20vcqdriver · 16-05-09, 05:50 PM

Quote:

Originally Posted by BW2309

Just to add - check also boost pressure hose to ECU, if the ECU sint getting boost to read it can't control it. Also, if there's smoke check fuel pressure/supply.

I shall be quiet now.... Sorry for going on!

Well! I stripped all the hoses off the back of the manifold and tested each one and found the one to the ECU and pressure reg had a split in it. Not very big but trimmed it back re-fitted and thought that had fixed the limp mode, but er NO. Still the same,

Going for a proper boost leak test next week and managed to locate a working K24 that has no smoke and has previously run on a re-chip without issues. But if non of these 2 issues can sort it, its into the garage and close the door until next year when hopefully I have saved up enough to carry on finding the issue.
One thing that is odd and that Tim is baffled about is why it takes so long to spool up. A K24 should jump to max boost from 2000rpm very quickly but mine takes around 2+ seconds...

20vcqdriver · 18-05-09, 09:36 AM

Quote:

Originally Posted by Gaz

when u say standard or chipped. have you just swapped the chips over? or tried a complete change of ECU ?

Also, could it just be a sensor?

2 different ECU's.
VAGcom has a sensor page that displays the actual readings from the 10 sensors (VDMS page I think) and Tim compared the readings with the manual for the 3B and all 10 were text book correct sitting in the middle of the ranges allowed. The fact that no fault shows up..

20vcqdriver · 19-05-09, 08:05 AM

Found the old N80 carbon canister valve last night and connected it up. Also going to reinstate the breather system as factory with the addition of a oil catch tank between the crankcase and Inlet hose to stop oil getting through. Not sure it will make much difference to limp mode but got to try something...

Woodsman · 20-05-09, 11:03 PM

20vcqdriver
Did you manage to drive the car with vagcom connected?
Does the live data page show knock signal? or ignition advance values?

IMHO you should be looking towards the Injectors, I just saw you mentioned old fuel in a previous thread,totally different system I know but this wreaked havoc inside my fuel distributor

If an injector was partially clogged, it would not show a fault code unless the injector was electrically faulty and would cause a lean mix and detonation, the ecu tries to counteract this by reducing advance and boost, if it can't it goes into limp mode.

would expect to see a knock control fault logged though

suppose they could be tested on the rail, but I didn't recomend that

Professional cleaning and testing is safer.

Booty · 20-05-09, 11:31 PM

That's thinking outside the box for you Dave. Got to be worth a shot I.M.H.O.

12-05-09, 05:59 PM	#11
mikes2 4 ring whore! Classic Audi Club Member Join Date: Nov 2007 Location: Polmont Posts: 2,617	A G28 error can send it in to limp mode. Was this with the engine running that you got this code or with the engine off? It's it's an intermittent type error, it can still cause limp mode without triggering a code __________________ 1991 90 quattro 20v sport 1991 90 quattro

12-05-09, 07:01 PM	#13
amanda quattro hussie!! Classic Audi Club Member Join Date: Jul 2007 Location: doin' it on all fours!! Posts: 5,993	[quote=20vcqdriver;54427]Had a spare one of these sensors so have changed it but to no effect. /QUOTE] Hmmm are you sure your spare is good ? __________________ Mystic blue m3 ghay hairdresser mobile 4 sheds 1 shopping trolley Gti RS6 ...my baby

19-05-09, 08:05 AM	#18
20vcqdriver 4 ring whore! Classic Audi Club Member Join Date: Dec 2007 Location: Wirral Posts: 3,910	Found the old N80 carbon canister valve last night and connected it up. Also going to reinstate the breather system as factory with the addition of a oil catch tank between the crankcase and Inlet hose to stop oil getting through. Not sure it will make much difference to limp mode but got to try something... __________________ Coupe quattro 1986:-~450bhp + loooong list of mods! Audi A7 Bi-TDI SLine Black edition 2015 mapped to produce 600lb/ft torque! Audi S4 4.2 V8 cabriolet 2004:-

20-05-09, 11:31 PM	#20
Booty Moderator Classic Audi Club Member Join Date: Sep 2007 Location: Deepest darkest Shropshire Posts: 5,077	That's thinking outside the box for you Dave. Got to be worth a shot I.M.H.O. __________________ 1987 Audi Coupe quattro - Clarion Tribute Car 2012 Audi A6 Allroad 2004 Mercedes SLK 350 2017 Mercedes GLA 220

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12-05-09, 07:49 PM	#14
BW2309 Banned Join Date: Sep 2008 Location: Derby Posts: 1,245	An intermittant fault with G28 can occur with no actual fault. You should only ever read the codes on a 3B/ABY etc with engine running. Just checking with the engine not running will give a G28 fault. If the G28 crank sendor had failed it would either stop or not start. Is the throttle body boot OK? ALso, check where things have been adapted for your conversion, i.e, there may be an issue with boost leaking through the system for the carbon canister (that I assume you are no longer using) or possibly with the brakes. 3B should have hydraulic assited brakes, is your now vacuum assited??? Sounds very much like boost leak from here but hard to judge wothout seeing.

12-05-09, 08:01 PM	#15
BW2309 Banned Join Date: Sep 2008 Location: Derby Posts: 1,245	Just to add - check also boost pressure hose to ECU, if the ECU sint getting boost to read it can't control it. Also, if there's smoke check fuel pressure/supply. I shall be quiet now.... Sorry for going on!

20-05-09, 11:03 PM	#19
Woodsman Grown up member Join Date: Apr 2009 Posts: 92	20vcqdriver Did you manage to drive the car with vagcom connected? Does the live data page show knock signal? or ignition advance values? IMHO you should be looking towards the Injectors, I just saw you mentioned old fuel in a previous thread,totally different system I know but this wreaked havoc inside my fuel distributor If an injector was partially clogged, it would not show a fault code unless the injector was electrically faulty and would cause a lean mix and detonation, the ecu tries to counteract this by reducing advance and boost, if it can't it goes into limp mode. would expect to see a knock control fault logged though suppose they could be tested on the rail, but I didn't recomend that Professional cleaning and testing is safer.