MASSIVE timing pull

[kb03gt]

B6 A4 1.8T

New: Fuel pump, Fuel filter, MAF, Upstream O2, DV

Problem: No powwa, timing pulled 12%, injector duty cycle 90%

[IMG][/IMG]


[IMG][/IMG]

https://docs.google.com/spreadsheets...it?usp=sharing


Any insight would very much be appreciated.

Thanks!
Josh

[kb03gt]

Also, Car is completely stock with a K03 turbo minus a forge DV

[blitz2190]

seems you guys are having the same issues
http://www.audizine.com/forum/showth...tor-duty-cycle

[Seerlah]

Looks like you hit full 11psi boost (I think this is requested, looking at it again), go into limp mode or boost cut, and your loss of power comes in. If you look at your lambda, you run lean most times.

For reference... 1=14.7 for 91 octane in atmospheric pressure...1=14.3 for 93 octane in atmospheric pressure. Multiply your lambda by 14.x to get your AFR depending what fuel you are running. Makes it easier. You run lean, ECU dumps fuel, and your car runs like poop. Find out why you are running lean, because your 120g/s is correct for a stock turbo air intake. I would start with checking fuel pressure at the rail.

http://wiki.ross-tech.com/wiki/index.php/Fuel_Trim_Info

Also, when did issues start happening (ie before or after parts replacements)? And you used an OEM o2 sensor with quality fuel pump?

*no expert by a long shot, but where I would start

[Seerlah]

Another thought, since fuel pump was just changed, is fuel pressure drop at the rail. Your fuel feed system is a loop system, though not rising rate. This means you have static pressure at the fuel rail vs having it raise 1psi per boost pressure on the charge pipe. With a rising rate system, say you have a 4 bar (58psi) at the fuel rail. With each psi of boost positive pressure, the fuel pressure will increase 1psi. For example, if you are running 11psi (stock) then you should be running 69psi at 11 psi (58+11=69) on a "rising rate" fuel system. But the B6 AMB stock is static at the rail...and should be a constant 58psi at 4 bar. The fpr (fuel pressure regulator) for the AMB is in the fuel filter. So from the fuel filter to the fuel rail, the fpr is trying to keep the fuel pressure at 58psi in the feed line.

But where does it gets this pressure from?

It builds pressure from the fuel pump that moves at a constant speed, depending on voltage and age (condition of pump). Meaning, it pumps a certain liters per hour at such and such voltage. That is how they are rated, meaning in an hour this pump can move this amount of fuel at this amount of voltage (so you can understand graphs). The lower the voltage, the slower the pump will work. This pump that is constantly pumping is not just moving fuel but building pressure for your fuel feed system, preferably at the rail.

But if you loose pressure before the FPR, you won't have adequate fuel pressure to keep the rail static (58psi) when the fuel injectors spray. Your return fuel line is at the fpr and dumps off the extra fuel back into the tank, versus building extra pressure in the line between pump and FPR. Figure...lines bursting from too much pressure or premature wear of the fuel pump constantly fighting the pressure.

Back on topic with losing pressure before the FPR, the opposite effect can happen to what I just stated about too much pressure...with NOT having enough pressure to keep static pressure in the fuel feed line. So if there is a leak in the fuel line anywhere between the fuel pump and the FPR, the pump will still flow the same. But...it won't have enough to build adequate on the spot pressure that the rail needs.

Not saying that this also is the case, but avenue you may want to look into since you stated fuel pump and filter replacement. Quite possibly you sprung a leak.

[kb03gt]

Right now:

Fuel pressure at idle: 56 PSI
Part throttle vac: 52 PSI
Boost: drops to 50

Would a 6psi loss constitute this much timing pull etc?

(Fuel pressure taken at rail)

[kb03gt]

I bought the car with the problem. I didnt have Ross-Tech so I was kind of playing the guessing game until now.

[blitz2190]

or the wiring has become corroded somehow and not providing enough amps to keep up with the current draw.

[Seerlah]

Right now:

Fuel pressure at idle: 56 PSI
Part throttle vac: 52 PSI
Boost: drops to 50

Would a 6psi loss constitute this much timing pull etc?

(Fuel pressure taken at rail)

Not fluent on the B6 like that, but I would conjecture the fuel pressure to not drop off like that except when in boost. I would wait for another to chime in to correct or confirm my speculation. No expert and I am a driveway mechanic. This is just my hobby.

[rocket1420]

I would hook a fuel pressure gauge to the rail and verify you are getting 58 psi (4 bar). Rev it a little, and the needle shouldn't move.

[kb03gt]

I did take it from the rail.

idle: 58
part throttle: 52
Boost: 50

Frustration is in full force.

[Seerlah]

OP, you do this work or a garage? I would def investigate where you are losing pressure. It could also be something simple like a kink in the line in the tank.

[kb03gt]

I have done some of the work but the pump and filter was done at a garage. They said it was falling drastically once boost hit. Right now the car is at a local tuners as we were thinking the turbo was at play. He has done good work so far tracking this down but right now we are at a standstill. I guess at this point I need to open the tank and look to see if they messed anything up.

[Seerlah]

It's not the turbo. Look into your fuel pressure. The turbo only has to do with your air intake, and you are hitting 120g/s like you should. Your lambda logs clearly shows you running lean. And this fuel pressure situation is your best lead. If electrical, start with the fuel pump relay. With more electrical items being used, your voltage drops. Couple that with extra resistance and your pump is now inefficient.

Blitz2190 has a good point. If the voltage drop is too much, that can also cause fuel pressure drop with the pump not pumping how it should.

Partially correct, partially incorrect. Correction below: Use a different garage. It is supposed to drop once boost hits. 1 psi fuel pressure drop for every 1psi of boost. So at 5psi boost, you are supposed to be 53psi fuel pressure at the rail...if it isn't supposed to drop at all during regular vacuum operation. This is due to the offset of the intake manifold pressure in positive pressure (this is what your MAP sensor is used for in regards to the ECM, and how you can views boost actual/requested logs). It also has pressure against the fuel injectors, trying to push the fuel back. Hence, the pressure drop. Normal operation!

[kb03gt]

I will dive deeper into the pump etc. The turbo was a problem before this, just the problem just ended up being unrelated to the timing pull (mostly hunting loss of power). That problem has been corrected prior to the log being recorded. Thank you guys so much, lighting the car on fire and rolling it over a cliff started to becoming a viable solution.

[Seerlah]

OHM out the coil on your fuel pump relay and test for any voltage drop on the contacts (use a little 12v dc battery...or "safely" use the car battery...which I do).

Better yet, hold the contact closed on the relay with something non-conductive like a plastic pen (what I do), give the throttle some gas, and see if the pressure drops. This can all be done by taking the cover off the relay, while it is still in the slot.

I don't have much confidence in that shop, and they do get paid by the hour (or full book quote).

[vtraudt]

Can someone confirm what the stock fuel pressure should be under part throttle and WOT?
In other words: should pressure be steady at 58 psi?
Looking for facts, not opinions.

Is the drop from 58 psi idle (4 bar, as per spec) to 52 (driving, WOT) indicative of a problem?
With:
a) pump?
b) filter?

[Seerlah]

Been waiting for that answer for a while. Help the man get his car running.

[naysay15]

Where's OG????

[Seerlah]

Texted a B6 forum member and got the info. Def a fuel pressure issue.

With correction for the misinformation above...it is supposed to be 58psi ALWAYS. That means in and out of boost. And...I just learned something new.

Info credited to Andrew aka Wet0willy01

Always 58 psi no matter vacuum or boost. Pressure drop in boost means the pump can't sustain the flow needed to maintain 58 psi due to high flow rate/duty cycyle of the injectors.

Now with that information, you can see in your logs that you run 8 lambda at points. That is super rich and when the ECM dumps fuel...because of the inadequate fuel pressure. Your duty cycle reaches 90% when it dumps fuel (assumption). Your fuel pressure issue is your problem. Get it looked into.

[vtraudt]

AFR not reached, fuel trims at 10+, injector duty cycle at 90+%, pressure drop to 52 psi (confirmed now to be 58 constant): no enough fuel.
a) filter (ordered)
b) pump (trying to find swap pump quickly

Note: both "new" by previous shop.

[Seerlah]

Oh, you are the shop?!?! You are credible though (from my section), and have a few builds under your belt. Feel bad bashing you now. My apologies!

And texting with him now, trying to understand the B6 static fuel pressure better. The car's fuel pressure regulator works just like any other pressure regulator. So, it tries to maintain whatever pressure rating it is designed for (ie spring and diaphragm relief) just like any other pressure regulator. Nothing special.

Pressure does not drop, due to the FPR trying to maintain that 58psi (my misinformation above again,now corrected). But...you still have that manifold pressure to combat when manifold pressure is positive. This makes the injector duty cycle duration longer, higher the manifold pressure increases to reach the same flow rate of the injectors original design (ie 630cc rated @3bar). Hence...why the static system is limiting for the B6 guys (I don't own a B6 A4). IDC (injector duty cycle) gets maxed and no more fuel. Cure...bigger injectors with the static system or simply convert to the rising rate system.

[Detroiter]

Just shooting in the dark but could there be a small leak in the fuel system allowing there to be pressure but not able reach/hold the desired 58 psi? Possibly the seals for injectors into fuel rail or the connections on the filter done by the previous shop. I'm sure you'd be able to smell it if that was the case but worth a check I guess.

[Seerlah]

More like shop changed nothing or something. Never know!

[Seerlah]

New idea. Check for kinks on the line underside of the vehicle. Or kinks in general. It will create a decent pressure drop before the rail.

[Wet0willy01]

Texted a B6 forum member and got the info. Def a fuel pressure issue.

With correction for the misinformation above...it is supposed to be 58psi ALWAYS. That means in and out of boost. And...I just learned something new.

Info credited to Andrew aka Wet0willy01



Now with that information, you can see in your logs that you run 8 lambda at points. That is super rich and when the ECM dumps fuel...because of the inadequate fuel pressure. Your duty cycle reaches 90% when it dumps fuel (assumption). Your fuel pressure issue is your problem. Get it looked into.

Or in this case a possible restriction like a fuel filter or weak pump will increase IDC. My quote above is referring to the downside to static fueling when trying to run high boost/big turbo.

[Seerlah]

If people understood the content of this thread, they should have been able to decipher that . And thanks for the help, Andrew.

OP said both pump and filter were replaced. But it is clearly a pressure drop somewhere. Hoping it is something like a huge kink underside of car they can cut out.

[Wet0willy01]

Can someone confirm what the stock fuel pressure should be under part throttle and WOT?
In other words: should pressure be steady at 58 psi?
Looking for facts, not opinions.

Is the drop from 58 psi idle (4 bar, as per spec) to 52 (driving, WOT) indicative of a problem?
With:
a) pump?
b) filter?

58 at all times. Static.

- - - Updated - - -

If people understood the content of this thread, they should have been able to decipher that

OP said both pump and filter were replaced. But it is clearly a pressure drop somewhere. Hoping it is something like a huge kink underside of car they can cut out.

OEM or aftermarket filter? The FPR is located in the filter in the b6s

[Seerlah]

Not sure. And honestly...who is to say what the shop did or did not do. I don't trust shops. Shop tried to rob my mother of $1,300 for a rack on MY Maxima couple months back, stating rack leak. It was f*cking residue because zip tie broke. Tried to take advantage of my mother. All from a warranty on a muffler leak she said she will take care of for me. Thieves!!! She called me right up, was right there to inspect, and we have to play the dummy role in front of each others (manager and I) to not cause a scene in a place of business. But I was quite perturbed. So...just one example of why I don't trust shops.