Symptoms, work done S3 8L, help please!

Audifast · Dec 2, 2016

Hi,

I'm pretty new to these forums again, good to be back

Anyway, the symptoms are as follows:

- runs rougher when warmed up, about 75 degree C to 90 (where it stops), runs pretty smooth when cold. Gets a quick "hickup", like a cylinder cuts out randomly.

- needs about 3 cranks to start up smoothly, first two cranks car runs rough/dies (I switch off the ignition quickly to save from rough shaking and vibration). Does this even when not cold weather.

- gets limp mode when driving gently, but NOT WHEN driving more aggressively, when doing this it gets code: P0172 System Too Rich (Bank 1). The common scenario is when driving 90-100km/h down highway, in 5th or sixth gear, (1st to 4th don't seem to do it - again on highway, will limp mode when on streets in lower gear). Lower gear scenario it occurs when driving say in 4th gear up slight incline and car is off boost and put pedal down (bogs abit).

- when pulling up to a service station, it drops in revs and sometimes engine dies (damn no power steerin!!!) It maybe when put in neutral or clutch in) ( I read could be vacuum leak) or dirty throttle body??

Engine work:

new o2 laambda, new n249, new n80 valve, new n75 valve, newish plugs gapped .028, new MAF (chinese, I know a sin lol) aftermarket pod filter, 265hp tune, water methanol, bigger TIP...

So just getting one reoccuring fault code.

Any suggestions?

ps boost guage shows 19 vacuum when warmed up at idle.

Audifast · Dec 2, 2016

Audifast said:
Hi,

I'm pretty new to these forums again, good to be back

Anyway, the symptoms are as follows:

- runs rougher when warmed up, about 75 degree C to 90 (where it stops), runs pretty smooth when cold. Gets a quick "hickup", like a cylinder cuts out randomly.

- needs about 3 cranks to start up smoothly, first two cranks car runs rough/dies (I switch off the ignition quickly to save from rough shaking and vibration). Does this even when not cold weather.

- gets limp mode when driving gently, but NOT WHEN driving more aggressively, when doing this it gets code: P0172 System Too Rich (Bank 1). The common scenario is when driving 90-100km/h down highway, in 5th or sixth gear, (1st to 4th don't seem to do it - again on highway, will limp mode when on streets in lower gear). Lower gear scenario it occurs when driving say in 4th gear up slight incline and car is off boost and put pedal down (bogs abit).

- when pulling up to a service station, it drops in revs and sometimes engine dies (damn no power steerin!!!) It maybe when put in neutral or clutch in) ( I read could be vacuum leak) or dirty throttle body??

Engine work:

new o2 laambda, new n249, new n80 valve, new n75 valve, newish plugs gapped .028, new MAF (chinese, I know a sin lol) aftermarket pod filter, 265hp tune, water methanol, bigger TIP...

So just getting one reoccuring fault code.

Any suggestions?

ps boost guage shows 19 vacuum when warmed up at idle.

Also the boost hesitates when put foot down, like a delay, doesn't seem to be normal spool delay. Sometimes the car will hit boost harder than other times I think, though not certain. Seems to lose power from boost in higher revs.
Thanks

Stuart B · Dec 3, 2016

I'm no expert - but I would start switching off some of the bits to eliminate them, eg

1. what happens if you take away the water methanol? <-- I don't know about this setup but maybe the flow is flooding the engine with essentially water and cannot run at low revs.

2. have you unplugged the N75? <-- just to eliminate its interference

3. you said new N249? <-- why not just remove it?

mine cut out at low revs when I had a vacuum leak near the brake servo, the pipe from the inlet manifold to the brake servo, also this was very sensitive it felt like it was okay sometimes, then over a bump and the engine would stall.

<tuffty/> · Dec 3, 2016

http://wiki.ross-tech.com/wiki/index.php/16556/P0172/000370

The ECU throws this code when it can no longer adapt out what it sees to be too much fuel...

All the issues you describe point at the fuel system running too rich period so typically this could be from excessive fuel pressure from a blocked FPR (rubber fuel lines rot and debris clogs fuel rail and FPR), boost and vacuum pipe leaks and bad MAF sensors...

As you are running a pattern part MAF that would be the first thing I would change... you could also try unplugging it to see if the car runs better or swapping it back with the old MAF (assuming its a genuine one and not faulty)

You need to sort this over fuelling issue out first before you can start looking at any other problems as they are most likely all linked...

Stuart B said:
1. what happens if you take away the water methanol? <-- I don't know about this setup but maybe the flow is flooding the engine with essentially water and cannot run at low revs.

WMI is driven by boost as a rule... assuming the kit thats been fitted is controlled this way then there will be no WMI in play at this point... this is also based on the assumption the WMI is fitted correctly and working as intended

Stuart B said:
2. have you unplugged the N75? <-- just to eliminate its interference

Won't really make any difference to whats going on here...

Stuart B said:
3. you said new N249? <-- why not just remove it?

You still need to leave the N249 electrically connected for ECU adaptions to work

<tuffty/>

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Symptoms, work done S3 8L, help please!

Audifast

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Audifast

Registered User

Stuart B

Registered User

<tuffty/>

Badger 5 Edition...Its all about the flow...

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