A3 2001 Limp mode and excessive fuel consumption.

[Sniper210010]

Hi all,

I hope you can help

I have just bough a 2001 a3 1.9 TDI, the issue i have is that the car goes into Limp mode at around 3000 RPM reguarly and i cant figure out why? i have also used almost a quater of a tank of fuel and i have only done 40 miles on very sensible driving!

I have previous tickets for work done and the Mass airflow was replaced in 2005 due to "Poor Performance"??

I had a friend look at it and he found some small pipes (part of the Vac in/out) had holes in them and these were replaced but the problem persists :/

When i started the car this morning it really struggled (Its cold and been snowing) and snorted a big puff of white smoke when it did start. i had read somewhere that the turbo may be leaking?

I have a code reader on its way so should be here this week for more info.

Can anyone shed any light on this in the meantime??

 

[Paul_TDi]

Limp mode will usually produce a fault code along the lines of boost deviation which usually means either leaking vac lines (have you replaced them all?) dodgy N75 valve or choked up/dieing turbo.

Boost leaks may be something else to look into before replacing the turbo, as the intercooler pipe work have joints prone to leaking. (assuming to have a PD130)

 

[Sniper210010]

Thanks for the quick response Paul_TDi

Not all of the Vac lines have been replaced yet, i will certainly do that - Oh good please do let it be the turbo :/

Would any of the issues you have listed above contribute to poor fuel economy then?

The car is a 110 SE <---- im not sure if that helps.

If i may ask.....what would you check first as process of elimination and how would i know whats faulty or not?

I have a Diagnostic tool on order so hopefully that will shed some light on this in a couple of days.

Aside from a new turbo are the other parts expensive do you know? fitting is not an issue as i have a mechanic on hand for the labour

Many thanks again!

 

[Sniper210010]

hey guys,

got these codes when running a diag scan....

17965
19561
17664
18062
18058

Any help is much appreciated.

 

[<tuffty/>]

hey guys,

got these codes when running a diag scan....

17965
19561
17664
18062
18058

Any help is much appreciated.

Have a look here and post up the result
Category:Fault Codes - Ross-Tech Wiki

<tuffty/>

 

[Paul_TDi]

Well your first code is what I suspected, unfortunately I don't know what the others mean.

the 110's had a simpler intercooler pipework connectors so less likely to be a boost leak from the joints.

The N75 valve is fairly inexpensive about 30 quid tops from dealers.

Naturally do the cheapest things first basically, vac lines, N75 valve and the N239 valve was mentioned in those codes to.

You could also attempt cleaning the turbo, a lot of people are working the actuator loose with Mr. Muscle oven cleaner, see here

 

[Sniper210010]

So a mechanic friend told be to clear the codes and drive around until it hits limp mode again, then do another check:

Here's what I got....

17965 - Suspect N75 valve, have just been to parts specialist to pick up a new one, its also worth noting that the mass air flow sensor was replaced by Audi in 2005. If the vac lines are the culprit would that explain the 17965 error code? and mean that I might not even need a new N75?

18062 - Please check DTC memory of instrument cluster <---- I don't know what this is?

Is it safe to say that the turbo almost defiantly is NOT at fault??

Again thanks for the great info!

 

[<tuffty/>]

17965/P1557/005463 - Ross-Tech Wiki

17965/P1557/005463 - Charge Pressure Control: Positive Deviation

VNT vanes in the turbo are blocked by the sounds... common problem...

<tuffty/>

 

[Sniper210010]

would that cause the car to use excessive fuel then?

 

[<tuffty/>]

would that cause the car to use excessive fuel then?

From what I understand yes...

<tuffty/>

 

[<tuffty/>]

click here....

<tuffty/>

 

[Sniper210010]

So I have replaced the vac lines and the n75.... Still getting limp mode with the 1 code: 17965 :/

Something else just happened an it's the first time it's done it. Started the car from cold pretty much and had it running while i de-snowed (been snowing here). About a mile down the road it completely lost power after a sudden shudder and was billowing white smoke from the exhaust..... Pulled up and no lights came on, did an immediate code check with the U281 but no codes appeared. Drive the car 10 mins home and limp mode kicked in.... That's when I got the code 1965?

So potential boost leak? Or turbo issue?

Dont even know where to start with what just happened

Again still thankfull of any advice

 

[Cobra88]

About a mile down the road it completely lost power after a sudden shudder and was billowing white smoke from the exhaust

Mine has done this a couple of times and it turned out to be my Glowplugs.
just not heating the charge enough in the cold weather and basically blowing out the source of ignition.

Dont use a lot of throttle when the engine is cold and it should be fine (and get someone to check that all the glowplugs are working and the heaters near the Vac Pump (3 glowplug like items) that heat the water on initial start)

Regards
Rick