Fuel Issues- Trim Variances, Rail Pressure

[frontside0815]

Hey Guys,

maybe you have some more ideas, cause i dont really know what else i could do:

In December i installed my Stage 2 Turbos (TTE) in my car- since then we are tuning it. First Map was a pleasure, car pulled like a train- but after logging we saw that the rail pressure is diving hard.
I thought okay HPFP is still the first one and boost is a little bit too much for the stock fuel system.

I changed the HPFP to a new one and logged again last week (after we made some progress with boost curve etc). But again: Rail is dropping, especially in the lower gears. And the Trims are so far away from each other...

Also i see my LPFP dropping in lower gears to under 60, sometimes under 50.. I have a Walbro 450 installed in stock bucket from a guy who does it very often here in germany. I will have a look if all hoses in the bucket are ok, but i think so.

I know that pressure on the lpfp is not everything, but the target is like 72PSI so i think the HPFP needs the fuel pressurized to 72PSI to work on spot?

After looking at my Walbro again my next idea would be changing the injectors.

Logs:
http://datazap.me/u/raffi/v8-0?log=1&data=3-24-25-26

See the big difference in trims + dropping of HPFP in higher RPM. With more boost the AFR already began to raise over target.


Any idea is appreciated!

[frontside0815]

No one?

[Milan]

Who is doing your tune? Your LPFP is dropping and the HPFP seems to be dropping proportionally. Why are you commanding such rich AFR? Makes me think your tuner has no clue what he is doing or has no experience with direct injection engines (probably both).

Also your timing is pretty inconsistent but I don't really see any corrections, what shape are your valves in? Throw another Walbro 450 in there or check to make sure the lines aren't kinked or anything

[frontside0815]

Tuner is fine, as is AFR. The car needs to be fine on WOT Pulls for 10min (german highway) So we need richer AFR values here in Germany, nothing wrong with that.

I did not really see that much problems concerning timing? Valves were cleaned 1.000 miles ago.

I will check my Walbro to see if there is anything kinked, thats what i was thinking also..

[Milan]

Well if you would command a leaner AFR you would 1) make more power 2) put less stress on your fuel system

You aren't gaining anything @ 11.0:1 AFR on a direct injection engine. Also you are getting timing drops (not just during shifts). Your log is kind of $#@!ty but it looks like you are commanding 6* timing across the board (during your pull)?

[frontside0815]

Concerning AFR Values i know that the american guys are a mapping a little leaner... but i rather be safe than sorry.

i see one timing drop in your screenshot- timing is not finished, we still trying to solve the fuel issues and want to get a good boost line first. then we will get to timing...

[Milan]

Concerning AFR Values i know that the american guys are a mapping a little leaner... but i rather be safe than sorry.

i see one timing drop in your screenshot- timing is not finished, we still trying to solve the fuel issues and want to get a good boost line first. then we will get to timing...

You aren't being safe though. You are not gaining anything by running that rich on pump gas.

[Milan]

Here maybe you and your tuner will learn something:

http://www.innovatemotorsports.com/resources/rich.php

Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13. Let's assume the optimum is in the middle at 12.5. This means that for every kg of air, 0.08 kg of fuel is mixed in and vaporized. The vaporization of the fuel extracts 28 kJ of energy from the air charge. If the mixture has an air-fuel-ratio of 11 instead, the vaporization extracts 31.8 kJ instead. A difference of 3.8 kJ. Because air has a specific heat of about 1 kJ/kg*deg K, the air charge is only 3.8 C (or K) degrees cooler for the rich mixture compared to the optimum power mixture. This small difference has very little effect on knock or power output.

[frontside0815]

please just lets not talk about AFR values...I appreciate that you are trying to help but i saw soo much logs an i know that most of the "good" Tuners Keep it rather fat than lean... For 102 Octane Pump Gas it is ok.

And the drop in Rail and LPFP + Odd trims are not a result from the AFR values?

Today i had Little misfires (at least it felt like this) and smoke on idling after cold start...I had rough idling and a Little bit stutter all the time when its cold (i thought its from the NGK plugs) but not that harsh... My AFR when idling was not stable and sometimes went down to 10- i think one or two of my injectors is bad, i will Switch the 3 bank 2 injectors on the Weekend.

But i dont see why the rail should drop that much with injector Problems...?

[Milan]

man...some people just can't be helped....good luck with everything

[bradsm87]

You aren't being safe though.

Yes he is. It's a touch richer than I would run but richer definitely keeps in-cylinder temps and EGT down for those long WOT runs.

OP, change your in-tank fuel filter unless you have already.

I have always had a trim variance. Not that much but around 7-8% difference. Both trims follow the same patterns so I don't see an issue and sometimes one bank would max trims and start to go leaner than target sooner than the other like in your logs when my HP fuel pressure got low. Start with replacing the fuel filter for sure.

[Milan]

Yes he is. It's a touch richer than I would run but richer definitely keeps in-cylinder temps and EGT down for those long WOT runs.

OP, change your in-tank fuel filter unless you have already.

I have always had a trim variance. Not that much but around 7-8% difference. Both trims follow the same patterns so I don't see an issue and sometimes one bank would max trims and start to go leaner than target sooner than the other like in your logs when my HP fuel pressure got low. Start with replacing the fuel filter for sure.

No he isn't. Did you read the article I posted or are you purposefully trolling?

Again, the AFR isn't the issue but it will make more power and put less stress on his fuel system so that's two steps in the right direction for sure.

There is absolutely no reason to run these engines as rich as so many people on here do. The rail pressure is (trying) to be fixed, since the HPFP is mechanical. The richer you go the harder it is on your fuel system. Over simplification of course

[frontside0815]

Yes he is. It's a touch richer than I would run but richer definitely keeps in-cylinder temps and EGT down for those long WOT runs.

OP, change your in-tank fuel filter unless you have already.

I will change my injectors, excited to see how my trims are after changing them to index 12.

With fuel filter you mean the filter which connects to the walbro? I think the guy who build my bucket made it new. On the weekend i will pull the bucket to see whats going on.
Just did a log an LPFP dropped to 45... so i think its 90% a problem coming from the lpfp side.

Will keep you informed just for people who maybe will have the same problem finding this thread- i hate it when you find a thread where somebody had the exact same symtoms and then the OP does not say what has helped him in the end

[bradsm87]

With fuel filter you mean the filter which connects to the walbro?

No. The factory fuel filter/FPR unit that has probably never been changed. The one BMW say to always change if replacing the fuel pump.

Number 2 in this diagram:

http://www.realoem.com/bmw/enUS/show...diagId=16_0601

[frontside0815]

So you mean the bucket on the Drivers side?
Hopefully i am able to dismount it, cause i do not have the Special tool for it...

[TwistedTuning]

From the outside looking in it seems like a tuning issue. The trims show adding 5-20% fuel during your WOT pulls. 5% is not bad. But 20% is a bit excessive. and should be rectified as soon as possible.

I saw you mention replacing fuel injectors. Before doing that i would first adjust the tune accordingly. I know you don't wish to go any leaner due to long WOT pulls. But targeting 11.8-12AFR insted of 11-11.5AFR is far better and is still fat enough to give some cylinder cooling. Try resetting all fueling related adaptations and then do a couple pulls and adjust the Fuel scalar to bring trims closer together. and i would target 11.8AFR as the richest fuel point target.

I also noticed a couple areas where timing was pulled without a correction, which makes me think there may be a limiter being hit. Add "Torque Actual" and "Torque Limit Active" to your logging parameters and post a log please. That will tell me more.

[frontside0815]

You wont believe it:

The issue was only injector related! I really have no idea how and why the DME is doing that, but after changing out the Bank 2 injectors to 3 new index 12 ones my rail pressure and LPFP pressure is absolutely stable!

I will change Bank 1 also just for peace of mind...