Low Pressure Fuel Pumps & Pressures

[DeckedS3]

I've been out of the game for a while, but the cars been tucked up for the last 2-3 years and recently come out to play.

I suspect I've maxed out the limits of my low pressure fuel pump so curious what uprated fuel pumps are people dropping in these days? There used to be a TTRS pump that people used but it needed modifications to work. Is there anything that's just plug and play?

Also, what pressures should I be seeing from the Low pressure pump?

Thanks

 

[DeckedS3]

I've checked a few things today and was wondering if someone with an S3 & VCDS could do me a favor.

Could you go into the engine module (01), measuring blocks (08) and check group 103 and tell me what the current fuel pressure is. I think this is the low pressure pump value. And also check group 106 and tell me what the fuel rail pressure is. This may rise over time and if you could watch this for a min and let me know what it starts at and builds to on idle that would also be appreciated.

Thanks

 

[nluk100]

103 - low pressure 4.82Bar at idle
106 - rail pressure 49Bar at idle

Stage 3 TTE420

 

[DeckedS3]

Really appreciate you checking this out . There goes my theory....

Just out of curiosity, did the rail pressure creep up or stay at 49?

I've tested an S3 8V and the pressure starts at 45bar+ and goes up the longer the car idles for. The 8P sticks at 49bar.

 

[nluk100]

That was warmed up, didn't start logging until the oil was up to temp. Obviously goes up when you open the throttle.

 

[DeckedS3]

Thanks once again.

I'm going to do a quick video later today and see if anyone recognizes the issue or has any suggestions.

 

[DeckedS3]

See if anyone has any ideas...?

 

[nluk100]

Has it just started doing that as I see you have a HPA intake which I think has the runner flaps removed(?) and needs to be coded into your software.

 

[Daveyonthemove]

What was the last mod that was done to the car before it started running like that?
Undo that last mod and see if it cures it.

 

[DeckedS3]

I should of said. No mods have been done to the car in at least 2-3 years.
It happened while I went out for a spirited drive, I noticed it wasn't responding as usual so decided to turn around and come home. When slowing down for a T junction about half a mile from my house the car cut out. I started it back up and this is when I noticed the car was running rough. I managed to drive it home but since then I haven't been able to get it to run right. It seems to run ok on boost but on idle it's close to stalling (and sometimes does).

 

[Daveyonthemove]

Done the usual checks of coolant, oil etc?
Removed the MAF to see if it changes how it drives/idles?
Had a coilpack/spark plug change recently or done them at service intervals?

 

[DeckedS3]

Done the usual checks of coolant, oil etc?
Removed the MAF to see if it changes how it drives/idles?
Had a coilpack/spark plug change recently or done them at service intervals?

Yeah, MAF has been unplugged and even replaced. I'm puzzled. The engine was stripped down and built about 5k miles ago with enlarged pistons, rod etc and had a checkup after 2k miles, all was good. Coil packs are about 7k miles old but I guess these things do go so I'll grab a set and swap them out. Haven't stuck to regular service intervals as the cars only done limited miles from new and only used for abuse.

 

[DeckedS3]

Small update. After taking things apart, putting them back together and testing everything I could think of, I noticed the car sounded different after swapping the coils and cleaning the spark plugs. Rather embarrassingly I thought I'd test the spark plugs and found one of them wasn't sparking..... I've never had a new-ish spark plug completely fail. So I have a new set coming later today. Hopefully this cures all my problems!

 

[core00]

good to hear that you are almost complete in rectifying the issue. Not sure if it helps, cause I saw that you have a PCV delete kit?, I had the same rough idle came up whilst cruising and upon checking, the front PCV breather pipe came loose. Fitted it back and runs great again.