HPFP Fuel Pump

[WatchMeSpend]

I was looking at my data logs in VCM and noticed that on a few occasions the pressure of the HPFP was at 2900 PSI or at 20 000kpa. This is supposedly the limit of the stock pump. What is the consensus in regards to replacing the unit with a high performance one. Engine is CREC so I know I need a different (and more expensive ) pump if I replace the whole thing. If I should tackle this, does anybody have any preference of stories over changing the internals vs the whole pump? I have seen a few people complaining about APR failures although they are just a modified stock pump. The vendors selling the whole pumps are claiming that since the unit is tested, you won't have to worry about it binding up and wrecking the cam that drives it. Does the fuel pressure attachment on the pump actually read the pressure or is it a value assumed by percentage of requirement? I'm asking because if I change the pump, will I see higher values in the data logs or just have to rely on duty cycle? The factory pump is suspiciously reporting back maximums of 2900 to 2900.2.

Some times when the pump is at 2900 PSI, I am at 2900 RPM and medium acceleration. Is there another parameter I should be looking at?

TIA

[Mark.in.tulsa]

Looking forward to answers on this one. I'm Crec e85 tuned. Curious if there would be any performance improvement with an upgrade.

[WatchMeSpend]

There is definitely supposed to be with E85 because you need more fuel. Look at Vancity Audi and his IE B8.5 and you can see the difference. He says with no E85 the pump won’t do anything extra but why is the stock pump telling me it is maxed out on my 93 tune. Do you have anyway to log data??

[WatchMeSpend]

Just before launch and then at the 1-2 shift

[qcrazy]

If your fuel rail pressure is going high that is an indicator that you do NOT have a HPFP problem. When you have a HPFP problem you will no longer be able to reach desired pressure.

Logs look fine. If you are really worried about it you should graph the HP fuel pressure. But it is completely normal for fuel rail pressure to spike on a shift. Lambda can also spike as well.

[WatchMeSpend]

Thanks! Am I am also trying to read the IAT, but the parameter listed (not visible in the pics) seems to be affected by how hot it is under the hood and if I move a little air it drops. When I floor it, the only thing that climbs rapidly and returns to normal is the "charge air cooler temp" Is this an accurate way of detecting the IAT?? Initially it drops a bit then increases rapidly and then cools off fairly quick. It's cool outside and I have an APR HX.

[sepheroth86]

Charge Air Cooler is what Audi uses to describe IAT2 or post compressor air temp.

[JWebb_C7_Comp]

If your fuel rail pressure is going high that is an indicator that you do NOT have a HPFP problem. When you have a HPFP problem you will no longer be able to reach desired pressure.

Logs look fine. If you are really worried about it you should graph the HP fuel pressure. But it is completely normal for fuel rail pressure to spike on a shift. Lambda can also spike as well.

You may also want to check for lean AFRs and confirm you’re not seeing misfire or substantial timing being pulled for peace of mind.


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[WatchMeSpend]

I have to see what the parameters are called and where the parameters are to add them. Slowly turning things on bit by bit. Some decent HP tuner vids out there. A lot of the parameters don’t seem to apply to my car.

[Audibellybutton]

I have hptuners if you need help. intake air temp is definitely one of the parameters on there. I can send you a standard layout for datalogging that you can just open and have all the useful parameters

[2k16A6]

I have to see what the parameters are called and where the parameters are to add them. Slowly turning things on bit by bit. Some decent HP tuner vids out there. A lot of the parameters don’t seem to apply to my car.

Its been a while since I tried logging with my HP Tuners, but I know the parameters that apply to the C7 are not the same as for C7.5 being a different ecu. I wonder if they've continued to develop the parameters for simos 16

[WatchMeSpend]

I have hptuners if you need help. intake air temp is definitely one of the parameters on there. I can send you a standard layout for datalogging that you can just open and have all the useful parameters

Thanks. I would appreciate that. I monitored that parameter, but it didn't seem to rise much once I was moving. It went from 93.2 degrees parked/idling in 39 degree weather to around 62 degrees within 4 minutes of driving. I don't have a larger pump or the control wire cut. It seems that when I go above 2700 RPM, the IAT drops. So if I did some spirited 3300 RPM shifts, the IAT parameter drops to around 60 degrees. The IAT parameter was showing 70 degrees until I launched it and that number plummeted to 51 degrees at the top of 2nd. The charge air cooler temps were 91 before launch and they peaked at 105 at the top of second and quickly recovered to about 80 degrees and slowly rose back up to around 93.

[Dasquade]

Thanks. I would appreciate that. I monitored that parameter, but it didn't seem to rise much once I was moving. It went from 93.2 degrees parked/idling in 39 degree weather to around 62 degrees within 4 minutes of driving. I don't have a larger pump or the control wire cut. It seems that when I go above 2700 RPM, the IAT drops. So if I did some spirited 3300 RPM shifts, the IAT parameter drops to around 60 degrees. The IAT parameter was showing 70 degrees until I launched it and that number plummeted to 51 degrees at the top of 2nd. The charge air cooler temps were 91 before launch and they peaked at 105 at the top of second and quickly recovered to about 80 degrees and slowly rose back up to around 93.

A drop in IAT once you start pushing it is normal as under idle/cruising there isn't much airflow in the intake manifold, especially on the end where the sensor is located (it picks up heatsoak there). Once pushing decent airflow (cooled air) meets the sensor...after the initial hit is where a good cooling setup come in play and will show if it is able to keep temps stable.

[WatchMeSpend]

A drop in IAT once you start pushing it is normal as under idle/cruising there isn't much airflow in the intake manifold, especially on the end where the sensor is located (it picks up heatsoak there). Once pushing decent airflow (cooled air) meets the sensor...after the initial hit is where a good cooling setup come in play and will show if it is able to keep temps stable.

That's why I said the parameter doesn't look that valuable. I was thinking the charge air cooler looks more important because it was the only thing to increase as I stayed on the throttle. Now I have the catalyst temp on the graph, which is another parameter that goes up when opening the throttle. I'm still poking around looking for parameters I can log that are valuable. I'm getting there...

Getting there.jpg

[qcrazy]

On your data, the IAT is the intake temperature pre-SC. So it will heat soak and cool with air flow. But boost won't affect it, that will just increase air flow and likely cause it to cool a bit more

The charge cooler temps are your intake temps post-SC. When not in boost these temps should be "similar" to the IAT. But once in boost, the charge cooler will rise. The worse your cooling, the more it will rise.

[WatchMeSpend]

Right, so when I see IATs on something like a P3 display, it must be showing post compression because they rise so fast. The IATs related to under the hood doesn’t stay high for very long. Mine is open at the top a bit so I would expect it might be sipping some warm air from underneath the hood. Looks like the next thing is a pump. Driving the car like I do in the summer or winter seems fine since the HX install. Before it got flabby in the hot weather.

Pump would be more for the track unless I see other data when the weather warms up. I think because it’s easy to do, it’ll get done no matter what.

[qcrazy]

Yeah, most people monitor post-SC/IC temps. The pre-temps are not overly useful, unless using for a specific purpose (e.g. check the IC efficiency).

[Botbasher]

Yeah, most people monitor post-SC/IC temps. The pre-temps are not overly useful, unless using for a specific purpose (e.g. check the IC efficiency).

Curious... How many locations would you like to get data from if you had no limit? I have a pair of 8ch high speed DAQs (even have access to a 60ch DAQ too!), a thermocouple welder and 30ga thermocouple wire that I can slip into just about any location without issue.

I'm bone stock currently and going to start the upgrading process so if you want some exact data from difficult locations and specific upgrades, I can certainly help!!

Cheers,

KS

[qcrazy]

In and out on any HX is helpful.

Pre-IC and post-IC is great. On the 4.0T this is provided by Audi. I don't think the 3.0 has this information. This is on the air side.

Similarly, in and out on the IC water lines is also useful. This gives you some great data on the coolant temps that can be used to refine an approach.

Finally, the water temp information (in and out) can also be useful at the main HX, but this is less important. This info can "typically" be inferred from the data above, and the data above is much more useful.

[JWebb_C7_Comp]

In and out on any HX is helpful.

Pre-IC and post-IC is great. On the 4.0T this is provided by Audi. I don't think the 3.0 has this information. This is on the air side.

Similarly, in and out on the IC water lines is also useful. This gives you some great data on the coolant temps that can be used to refine an approach.

Finally, the water temp information (in and out) can also be useful at the main HX, but this is less important. This info can "typically" be inferred from the data above, and the data above is much more useful.

Hate to beat a a dead horse, but, is the car pulling massive timing, misfiring or lean????? If not, maybe don’t freak out….


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[kissdaring]

hey guys, its been a minute. hoping someone on here can help me out. long story shorty,
the HPFP screw bracket on the pump itself broke. i dint know and there were no symptoms at the time however while driving on the hwy the low oil pull over light came on the dash, i found a safe spot to stop "about a mile or driving" and inspected the car and found that this had happened. (Pics of what it looked like on) Had the car towed home and took out the pump. (Pics show findings) Bottom bolt was missing "guess it came loose and fell on the belly pan as the top was broken off or maybe it wasn't there all together no way to be sure as i just picked up the car." I will be getting a replacement HPFP but i wanted to grab a opinion on the body that the pump goes into as its a bit shaved from the pump rubbing. (will this cause any issues??) also do you think the Cam follower needs changing? (Few scratches as shown) i really hope there isn't any internal damage as it would be devastating.

thanks guys,

happy to be back in a Audi and spend my life savaging on her. :)

[kissdaring]

Bump

[HolyHell]

I would replace the pump and follower together then re-check

[WatchMeSpend]

Hate to beat a a dead horse, but, is the car pulling massive timing, misfiring or lean????? If not, maybe don’t freak out….


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For me, I don't want to blow anything up and I want to make sure the cars giving me it's all when I go to the track. I used to have a minor problem where if I let go the throttle on the 2-3 during hard acceleration it would go into limp mode sometimes. I dropped the hammer on the highway once and since there was a car near me, I saw white crap from my exhaust in his headlamps. And of course sometimes the car feels faster and sometimes it feels slower. I'm worried about lean. New coils, plugs and maybe the TCU tune seem to have eliminated the 2-3 limp mode problem. The only engine I ever had fail was during a top speed run and I knew I was lean. I floated a head gasket and fogged the highway.

Now after being curious to see what's available out there for a replacement, it looks like, I can't even find a car as new as mine. Not even if I go to an A8 or S8, the used market is horrible. So I want to make sure I can keep the car for a bit longer.

[kissdaring]

Recheck what exactly?

[f4m0u5]

Recheck what exactly?

probably a oil leak from the damage to the head where the hpfp seals to it, or low oil pressure from metal shavings ect

[kissdaring]

probably a oil leak from the damage to the head where the hpfp seals to it, or low oil pressure from metal shavings ect

im thinking casue the pump want not seated properly a mix of oil and fuel was uzzing out there there. i will get the new pump in and see if there are any other issues. do you guys suggest doing a oil and filter change or just topping up for the purpose of testing things out?

[ActiveMonkey]

Any update?

[Optimus247]

Time to buy an RS 5 ... lighter weight and stiffer suspension ... more of a track car ...

(NOT Meant to hijack - just a bump)