S6 timing

[HMS-S6]

Dave. This is why I wanted to see a real world photo of the inside of a tank mate? To make sure that someone hasn't assembled something incorrectly in mine or something!

[HMS-S6]

The pump is a new Audi item so I don't think the pump itself is the issue. However it has to be something in there. I was thinking maybe an issue with the basket? Although it looked clean on the filter maybe I thought with the tank over 2/3 full it'd be spilling over the top of the basket OR a split return or something introducing air into it? I need a proper look in the tank rather than just looking at the filter. Or maybe a situation where the filter was a bit blocked even though it looked ok?

[UrS4boy]

BUT , , , , I've discovered a definite link AND the reason I thought it was fixed. Wait for it , , , , on a full tank it pulled like a train with perfect AFR, let it run to around 2/3 and it starts to lean off. I'm going to let it go low/lean off once more then fill it up and make double sure it richened back up then take the tank top out again and have a better look!

Previously, I suggested

...Might be related to how high the fuel level is in your tank. When it high, i.e. filled to the second click, fuel is in the No.2 pipe above the fuel tank. Therefore, there could be a leak at the connection between Item 5 Hose and items 1 (tank) and 2 (filler pipe).

When the fuel level in the tank is high, the pressure head on the fuel pump inlet is higher, making it easier for the pump to increase the pressure to that required at the fuel rail (4Bar plus boost pressure). When the fuel level is lower, there is less pressure head on the fuel pump inlet, making it more difficult for the pump to increase the pressure to the required levels. As a result, it is possible that your lack of fuel is the result of a weak pump that is aided by higher fuel levels and hindered by lower fuel levels.

Bottomline: I would change the fuel pump using the DIY that I have posted at least once in this saga, er, thread.

[UrS6 - IamS6]

Hope you're getting close.

[HMS-S6]

Fuel pressure gauge turned up yesterday so obviously not had time to fit it up BUT , , , , I've discovered a definite link AND the reason I thought it was fixed. Wait for it , , , , on a full tank it pulled like a train with perfect AFR, let it run to around 2/3 and it starts to lean off. I'm going to let it go low/lean off once more then fill it up and make double sure it richened back up then take the tank top out again and have a better look!

[A1QSHIP]

This may be a stupid idiotic question but I dong suppose the destroyed flywheel and gearbox could cause any running issues with maybe ignition timing or making noise for the knock sensors to pick up by ANY chance? Just a thought!

On my 7a Coupe I had a broken inner exhaust valve spring cause the knock sensor to pull timing. The engine would not reach redline & felt as if was being held back. Initially it sounded like a knackered distributor drive gear.
Mechanical noises in the engine or flywheel could cause the knock sensors interpret this as a combustion knock. One way of testing knock sensors is to monitor the knock sensor values with a scan tool & use something like a wrench or hammer to tap on the block near the knock sensor location.
HTH, Chris

[driftin jo]

Shouldn't make it lean though. Pretty sure Prj has said in the past too that motronic richens up the mixture when knock is detected for safety.

Hence the reason I said “I don't think in this case that's what is going on”

[Kieron20V]

Shouldn't make it lean though. Pretty sure Prj has said in the past too that motronic richens up the mixture when knock is detected for safety.

[driftin jo]

This may be a stupid idiotic question but I dong suppose the destroyed flywheel and gearbox could cause any running issues with maybe ignition timing or making noise for the knock sensors to pick up by ANY chance? Just a thought!

I don't think in this case that's what is going on but, it is possible
for the ECU to pull the timing because it THINKS the engine is knocking.
Mine did this years ago when my alternator came loose, the vibration
at certain rpm would every now and then have me reduced to spring boost as the ECU would turn off boost control.

[HMS-S6]

This may be a stupid idiotic question but I dong suppose the destroyed flywheel and gearbox could cause any running issues with maybe ignition timing or making noise for the knock sensors to pick up by ANY chance? Just a thought!

[HMS-S6]

Even between MAF and turbo?
I thought unmetered air made it lean?
I'm still planning on measuring fuel pressure first I'm just also trying to have a game plan for what next if it is ok.

[prj]

Air leaks in the intake will make it rich under boost, not lean, so don't waste your time.

[HMS-S6]

Pressure gauge hasn't arrived yet plus a very good friend of mine is in intensive care in a serious condition so I've not had time to work on the bus at all recently.
If the pressure is ok I might try putting the MAF on the boost side to rule out completely any air leaks in the intake.

[newsh]

[HMS-S6]

He needs to measure fuel pressure while on a WOT run and see what it is doing.
That will tell whether it's a fuel delivery problem or it isn't.

That said, if load is 140 at WOT, that seems low as well.

Dmitri, would you say only 140 at WOT is enough to take AFR up to 13.7:1?