2000 A6 4.2 - Project Mayhem

[beemercer]

Couple of questions to start:
-What gear did they do the runs in?
-Would the shop be able to provide a run from some other stock car? It could be a low reading dyno, so if they have a stock car (any car) to compare against that could give you some insight. For example when I dyno'd my S4, a stock S4 did 264whp/247wtq so my car did 65whp/43wtq over a stock car.
-RE: the AFR, was that measured with a tailpipe sniffer? Do you have any cats? I would log the requested and actual lambda fields to ensure the measurement is accurate.

Comments:
-Something definitely seems amiss with the intake manifold, you should see a single torque spike, not the double (or the negative spike). To confirm you could have someone sit in the car and rev the car in neutral and watch the actuators. They should move once the car is started changing it over to the long runner, then change back at around 4.5k to 5k rpm. I suspect you'll see a change at ~3k and ~5k rpm similar to how the tri-runner manifold works. I never found a measuring block that recorded the voltage to the vacuum solenoid, but you could log that manually if you have the equipment.. the stationary test should be sufficient though.
-Its too late now to test on the dyno, but one trick is to pull the vacuum line off of the manifold switch over solenoid and cap it. This will lock the car into the short runner, redyno and overlay the charts. Your low end should be worse, but the top end of the curves should more or less overlap after the switchover point (+ some rpm due to the disturbance of moving the flap), if they don't there is an issue. You could test this in your logs as well, do one with the line connected and one with it pulled/capped, look at the MAF g/s curves as a function of rpm (unfortunately vcds does not line up each measuring block, so to do it dead on you have to extrapolate rpm from the time stamps).
-The 93 tune will be much stronger, there isn't as much room in the 91 tune.
-For the logs, your timing retard looks very low which often indicates a free flowing exhaust (removing cats helps reduce retard quite a bit).
-Could you repeat the log in a 3rd gear pull, from 1800-7200 rpm, and with turbo mode enabled if it wasn't (higher sampling rate)? The longer pull will give more even data for better conclusions. The 100mph top end can be hairy with law enforcement so do a few dry passes to make sure no one is watching. All my logs are in 3rd gear so I can compare more directly with a 3rd gear log.
-One thing I noticed is in 2nd gear the dip in MAF g/s at 5000k prm, likely due to the change in runners. My logs typically plateaued there, not dipped (dMAF/dt=0 not <0). That could be an indication of an issue with the intake manifold runners switching.
-If you can get a 003/020/021 3rd gear log to start, then I can look up other blocks to log to check the injectors/AFR.

[v8a6]

Thanks for all the tips.

Gear was either 3rd, or 4th, or both (maybe third on first run and fourth on next). Will confirm with the Neetronics. Ill also ask them about a stock car run. Axel's JHM supercharged S4 just put down 421 to the wheels on the same dyno.

I run Magnaflow highflow cats. No precats. And I believe the AFR was recorded with an AEM tailpipe sniffer. I will try and log some lambda with Vag on one of the upcoming sessions.

Good tips on testing the intake. Ill try it out.

Good info on the timing retard and free flowing exhaust. At least that is looking good :)

Ill see what I can do about the 3rd gear pull. Comparing to yours would definitely be helpful.

Agreed on the MAF g/s at 5000.

Thanks again for the help!!!!

[v8a6]

For Beemercer

[v8a6]

The intake actuator pods were not working in unison. Not sure if there is a problem with one of the pods, or with the tune. Anyway, I disconnected both to leave the intake in short runner mode.



If MAF g/s is .8 crank HP, then it looks like I gained over 20hp at high RPM making the change. However, it still looks like there is a problem. The MAF g/s drops after 5700rpm on the second run.

I tracked the two o2 sensors on 31, and they are way off. One is newer than the other, so maybe one is bad.

[v8a6]

I also swapped in the S8 throttle body with the manifold. Is it possible it works differently than the A6 4.2 one?

[v8a6]

From what I read, the ECU acts in Open Loop at WOT. I wonder if a dirty or bad MAF is causing a problem. Im going to clean the MAF tomorrow, and replace the air filter.

[v8a6]

Cleaned the MAF, and it looks like the air flow numbers are now a constant climb on the latest 2nd gear run. Can anybody tell me why LOAD% barely goes above 80% in measuring block 002-2 at WOT?

[v8a6]

Im really starting to think that the MAF is reading low. This would explain the weird readings MAF readings, and also the possibly lean condition at WOT. I wonder if somehow the ported heads are throwing it off. Maybe, they are pulling in more air, but at a lower speed than stock. I feel like replacing the MAF as a troubleshooting step, but if the ported heads are throwing it off, then the new one may read the same. I have read of people installing a CAI, and it throwing off the MAF readings, so it doesnt sound ridiculous that the heads could do the same.

I ordered a wideband o2 sensor. So, I think I will wait until it is installed to see what the AFR is. If the tune is providing the amount of fuel at WOT based on the MAF, and the car is running lean, then that will point towards a low reading MAF.

What do you guys think?

[v8a6]

In order to eliminate the possibility of a malfunctioning MAF, Im going to swap it with a new one.

Also, did a second smoke test at the shop to eliminate the possibility of any vacuum leaks.

Innovate LM2 on the way :)

[v8a6]

Swapped the MAF, but the numbers didnt seem to change much.

[v8a6]

Did another 2nd gear run. The injectors seem to be adding more fuel on this one, although both o2 sensors are still reading pretty lean



At 6720 rpm, the injectors are running at close to 90% duty cycle, and the engine still looks like it is running lean. Once I can confirm the AFR with the wideband, Ill have to see if the injectors need an upgrade. I found a set of 36# Bosch for a couple hundred bucks, that should do the trick. I think the stock ones are only 18 or 24#.

I am not exactly sure how LOAD is calculated, but it is higher on this run. I am guessing it factors in fuel and air intake.

[v8a6]

I threw the stock (backup) ECU back in and did a quick 2nd gear run. What is interesting, is that the stock ECU seems to be pushing the injectors even harder. They are at 90% by 6320 (lower redline). MAF readings look the same. There is a drop from about 4500 to 5000, that still doesnt make any sense to me. I have the runners locked in short mode. They would normally flip about 5000 rpm.

[v8a6]

a HA!!!!! Found a big part of the problem!!!!!




I was looking at a video I made of the intake manifold arms, and noticed that under hard acceleration the nut and threaded rod on the end of one of the levers was moving. It didnt make sense to me unless something was broken inside, since that rod connects to a part that is tied into the intake flaps. If the rod was moving, then the flaps were 'flapping'. I pulled the levers off and found the plastic was broken. So, this makes sense why the air was fluctuating, and up and down on one side. The flaps were moving around as the air pressure would push them one way or the other. They were likely never all the way closed in either direction, on the one bank. The pods themselves are still actuating at the wrong rpm, but that should be able to be fixed with an update to the tune.

There is a writeup on another forum where I guy fixed his by machining a new part. However, I am looking for an easier fix. Do you guys think crazy glue, or some type of epoxy will work to put the piece back together? Any other options?

Here is a pic of the machined one

[v8a6]

Going to try and JB Weld it up.

[v8a6]

Found an S6 intake at a wreckers, so I ordered it. This is my THIRD one! First one, I ordered from Germany a few years ago, and it came incomplete. This second one, is obviously broken with a part that is not separately replaceable. Hopefully three times is a charm :)

[khalimadeath]

Man I always check that on 4.2's. Both mine had broken ones.

There can only be one fix for that http://gruvenparts.com/website/cart/...category_id=60


Edit: O I see its the actual part that pivots. how do you keep breaking that??

[v8a6]

O I see its the actual part that pivots. how do you keep breaking that??

Yeah, bad luck I guess. It was likely broken when I got it, since I have only had it on the car just over a week. Unfortunately, there is no easy fix. The JB Weld thing wasnt even close to working. Cheapest option is to try another one.

[Scotty@Advanced]

I also swapped in the S8 throttle body with the manifold. Is it possible it works differently than the A6 4.2 one?

A6/S6/S8/A8 throttle bodies are pretty much all the same. What MAF and tune are you using? The S6 MAF is different from A6 4.2

[v8a6]

A6/S6/S8/A8 throttle bodies are pretty much all the same. What MAF and tune are you using? The S6 MAF is different from A6 4.2

Good info on the TBs. The tune I am using is from JHM, so I am not sure if it is based on the S6 tune. I asked them this last week to verify that the tune was setup for the MAF I am running, 0280218015 / 077133471G. Ill see what they come back with.

[v8a6]

Picked up a set of reconditioned injectors, since it looks like mine are well above 80% duty alot of the time. Bosch 36lb. Anybody know if I will need spacers, washers, or anything special to install them? I realize I will also need the tune modified.

[alterdcreations]

Honestly, can you bolt on the oem manifold and t/b......just to make sure you atleast regain the lost power?

[v8a6]

Honestly, can you bolt on the oem manifold and t/b......just to make sure you atleast regain the lost power?

I dont really want to do that. I would rather just try the new S6 one that I should have in a couple weeks.

Power still feel pretty strong. I am wondering now if the MAF is reading low in VAGCOM, but not internally. I only guess this because when I swapped in the stock ECU (albeit one from a US A6 4.2, not the actual orginal), the readings were pretty much the same. Yet, the MAF readings at 4600rpm in all of my runs do not line up with the HP that the dyno shows at that RPM. I am pretty confident that a tune that flips the flaps at the proper RPM, and a functional S6/S8 intake will sort out a lot of the issues. Plus, I think the injector upgrade (and a 93 tune, if it ever becomes available) will sort out the rest.

[alterdcreations]

best of luck, as long as everything is mechanically sound then you'll be good. Also ever think of a phaeton manifold? I have one Sitting in my garage waiting to go on and looking at it I noticed They replaced the plastic flaps with individual fingers. Its should be worth 35hp over the stocker....might even be better than the s6 manifold and more reliable.

[v8a6]

best of luck, as long as everything is mechanically sound then you'll be good. Also ever think of a phaeton manifold? I have one Sitting in my garage waiting to go on and looking at it I noticed They replaced the plastic flaps with individual fingers. Its should be worth 35hp over the stocker....might even be better than the s6 manifold and more reliable.

Yeah, thanks. Actually, I think your Phaeton manifold may be the same as the S6/S8 one. Ill shoot some pics of the spare S6 one I have a bit later, for comparison.

BTW, I think I know why the plastic broke in the one I have. It was sitting for at least a year, after I bought it. And was probably very stiff to flip the flaps before that. Both of the small actuator arms were broken when I got it, so I replaced them with the billet Gruvenparts ones. Well, it makes sense that with the new billet arms, something else had to break, because it wasnt going to be them. That is probably why the plastic part broke. On the next one I get, I am going to make sure it operates smoothly before putting it on the car. Ill take it apart if I have to. There is a writeup on another forum on fixing the stiff flaps.

[v8a6]

[alterdcreations]

yup same internals. mine has the short linkage arms. Thanks for loving your car enough to help pioneer the way for some of the rest of us!!! hope the tuning and manifold situation goes well

[v8a6]

yup same internals. mine has the short linkage arms. Thanks for loving your car enough to help pioneer the way for some of the rest of us!!! hope the tuning and manifold situation goes well

LOL. It was not by choice :) I honestly thought I would just bolt on the parts and it would be good to go :) Hahaha... Oh well. It will be all the better once it is done.

[v8a6]

Im one step closer to meeting my power goals :) fixed another problem today.

The air intake snorkel seems to have bent and warped over time. It also wasnt attached correctly, pulling in warm air from behind the rad, instead of from the front of the hood. I pulled the airbox and did a quick Darintake. Even with the broken intake manifold, the g/s jumped up about 10% from my previous highest logs. At around 5500-6000rpm, the engine pulled back dramatically. I checked the codes, and there was nothing. Not sure if the throttle plate was pulled back or not. Have to do some more logging and get the wideband installed.

[Widebody4.2]

You're a pioneer buddy keep the info coming

[v8a6]

You're a pioneer buddy keep the info coming

Hahaha.... thanks. I'm in too deep now to turn back anyway :) Plus, now I have to prove something to all the naysayers out there. I think they're just jealous because they have skinny fenders ;)

[v8a6]

More issues sorted out today. First, I got impatient waiting for the S6 manifold to arrive, and made a trip to a local wreckers. I had found a 2004 Volkswagen Phaeton manifold there. The Phaeton intake manifold is the same (as far as I can tell) as the S6/S8 one. I would have liked to swap the whole thing on my car, just so I could say in my parts list that I am running a VW Phaeton manifold. However, it was much easier just to swap out the arm assemblies which swapped right into the S8 manifold I have on the car.


Big thanks to REDNECK TRUCK, who figured out that I had the vacuum tubes setup wrong for the S8 manifold. He explained that the S6/S8/Phaeton only have one actuator, since both move in unison. Makes perfect sense after someone explains it to you :)

After sorting out a vacuum leack, I did a quick second gear run, and finally, we have some numbers that are starting to make sense


Things to note:


Injectors are getting maxed. By 6240rpm they are already at 86% duty cycle. And after 6800rpm they are 97 to 99% right up until redline.

The load % is much higher, especially at lower rpm. At 3500rpm (should be peak torque) it now up to 96 (previously was in the high 70s, low 80s).

The MAF readings still look low to me. If you use the calculation that the MAF g/s is about 80% crank HP, then it looks like I am making about 330hp at the crank. If that is the case, why would I be maxing out the stock injectors, which are the same ones used on the 2001 Audi S8 that makes 360hp? You would think they would be good up to at very least 400hp, since I doubt Audi would be running them over 60%-70% on the stock tune. I have 36# injectors ready to go in, but I think I should hold off until I get a tune that accounts for them. Would it be OK to put them in now, or would that just mess things up?

Anybody know what the specs are on the stock 2000 A6 4.2 injectors are?

The MAF readings are FINALLY going in one consistent direction! yeah!!! It looks like the flaps are flipping about 5700rpm, as I see a jump in the g/s around that time. I think the S8 flaps are supposed to flip at 5200rpm. Can anyone confirm?


Next steps

Get the wideband installed and check AFR.
Sort out injector issue
Sort out intake manifold flap RPM issue

[v8a6]

Stock injector is Audi part 077133551M, if anyone has the specs

Looks like the Bosch # is 0 280 155 921

[Castor Troy]

do the S6/S8 run higher base fuel pressure? that would explain why they get more power with the same injectors

[v8a6]

Hmmm... good question. I just assumed they would all run at 43.5

[v8a6]

Think I found the stock injector data. Now I just have to figure out how to convert it to CC

[v8a6]

Well, unless I am reading things wrong, it looks like the stock injectors are 195 cc at 300kPa (43.5 psi). That means, at 43.5, they will barely support 260hp, at 80%. This isnt making sense to me.

EDIT: Maybe they are running different pressures on the fuel pumps.

[v8a6]

Found this on another forum

Bentley A6 Service Manual - Fuel pressure specs

2.7L and all V8 idling, gauge connected inline bet. fuel rail and fuel suply line.
-Fuel pressure regulator vacuum line connected = 3.5 bar (51 psi)
-Fuel pressure regulator vacuum line disconnected = 4.0 bar (58 psi)

Residual pressure, leave gauge conencted, shut off engine, wait 10 mins
-Warm engine = 3.0 bar (44 psi)
-Cold engine = 2.5 bar (36 psi)

So, does that mean that they are 3.5 bar or 4.0 bar stock?

[v8a6]

It looks like it uses 4bar. And, it seems the S6/S8 use slightly bigger injectors (214cc instead of 195cc @43.5) =

A6 225cc at 4bar
S6/S8 247cc at 4bar

They still seem undersized to me.

[v8a6]

3rd gear

[alterdcreations]

nice to see everything start to come together. Are the injectors physically the same size as OEM? Swap em out and see how the ecu treats everything.