Running Lean Or Am I? Ross-Tech VAG-COM VCDS

[gregski 0]

Hello,

 

I live in California the dark place where vehicle emission controls come from. When I had my VR6 SMOGed the tech told me I am running lean. So I bought Ross-Tech's VCDS-Lite and started looking, but honestly I don't know what "Group" or "Measuring Block" I should be looking at.

 

Just so you know in order to pass my SMOG inspection I had to take the intake manifold off and separate the throttle body and clear out that pesky EGR port, I say this because I put the parts back on reusing the old gaskets, the one between the throttle body and the intake and the one between the upper and lower intake. Was this a bonehead move and is this the cause of my lean condition. (I tried to find the leak by spraying carb cleaner all around the intake boot and intake manifold as well as all the vacuum hoses but the car would not stumble)

 

Also I have a brand new Lambda Sensor (oxygen sensor) since the car threw the code to replace it so I did.

 

The O2 Active seams to be around 1.000 plus or minus .100

 

Today I replaced my MAF with a used one and readings stayed the same, but I only drove it with the newer MAF for 30 minutes or so.

 

I have no idea what ISV Adaptation means and it is at .984

 

ISV Duty Cycle % is between 49-59%

 

Idle Adapted Value - 1.967 ( lean ? )

 

Part Throttle Adapted Value - 1.975 ( lean ? )

 

Full Throttle Adapted Value 0.797

 

- - - thank you for reading this lengthy post, I figure the more you know the better you can help me - - -

[Kevin Bacon 5]

How lean is it running? Did the guy give you any indication of Air fuel ratio or CO? Is it just at idle it's running too lean?

 

Running lean in California is good though :D Did it actually pass the smog test and the lean running was just an advisory from the tester?

 

It should hold 14.7 Air fuel ratio and the lambda takes care of that at idle and during part throttle cruising. Past 4000rpm and 80% throttle, the lambda is ignored and runs one of a few base fuelling maps depending on throttle position and engine load (MAF).

 

I would ignore the lambda monitoring in VCDS, it's too slow to keep up but if the number is moving, it's generally a good sign. A more accurate test is to hook up a high impeadance Auto test meter across chassis ground and the lambda signal wire. The voltage should rapidly fluctuate from 0.1 to 0.9 V after approx 2 minutes.

 

The lambda then actively controls the fuelling when the coolant temp has exceeded 70 deg C.

 

ISV adaptation simply means the adjustments it's making in order to maintain the idle speed. Looking at the ISV duty cycle, it seems to me it's opening the valve a fair amount. 59% open with an ISV that large will give a very high idle speed, so something isn't quite right there.

 

It might be worth disconnecting the battery to reset the ECU since you've fitted a new MAF and Lambda. Sometimes this can help.

[gregski 0]

I'm getting a lot of great advice here so I will break it up into section as to not miss anything:

 

How lean is it running?

- Honestly, don't know.

 

Did the guy give you any indication of Air fuel ratio or CO?

- No, technically they are a "Test Only" outfit which prevents them from troubleshooting, he just blurred it out under his breath sort of speak, and inquired if I get good gas mileage. (I believe he was giving me a bit more credit than I deserved, and was assuming I knew what I was doing, and did it on purpose).

 

Is it just at idle it's running too lean?

- I don't know, I don't know how to check idle vs running, can Ross-Tech tell me that?

 

Running lean in California is good though :D Did it actually pass the smog test and the lean running was just an advisory from the tester?

- Yes, that's the kicker the car was running fantastic, no CEL error codes either. Also the SMOG check is two parts, emissions and EVAP. In my case the car passed the emissions part flying colors, but failed the evaporation part. So techs at both shops were baffled. Turns out the dealership put the rubber O-ring fuel pump gasket in wrong in the fuel tank when my brother took it in a few years back, half of it was dangling down inside the tank. (We dropped the tank, pressurized it a little bit with a bicycle pump with a mickey mouse nozzle adapter, and get this, sprayed Windex window cleaner soap like solution all over the tank, and bubbles started forming around the jar like lid which encloses the fuel pump inside the tank) So I unscrewed it with my hands properly fitted the rubber gasket, screwed the top back on, mounted the tank, drove back in for a FREE retest, and whalla it passed !

 

I will address the other points in a separate post, and thank you very, very much for the additional follow up questions and advice. I am learning here, I am fairly new to automobile repair.

[Kevin Bacon 5]

Yes, that's the kicker the car was running fantastic, no CEL error codes either.

 

And when the CEL lights up, it runs poorly?

 

Next time the CEL comes on, load up VCDS and have a look in the Engine's fault code section and see if anything is listed in there.

 

I would perhaps not read too much into the 'running lean' comment from your tester.

Maybe he's more used to thumping great V8s than small, quirky little Euro engines? :D

[gregski 0]

 

And when the CEL lights up, it runs poorly?

 

 

Nope, runs fine.

 

 

I would perhaps not read too much into the 'running lean' comment from your tester.

Maybe he's more used to thumping great V8s than small, quirky little Euro engines? :D

 

 

Touche!

 

 

Next time the CEL comes on, load up VCDS and have a look in the Engine's fault code section and see if anything is listed in there.

 

 

00537 - Lambda (Oxygen Sensor) Regulation

..........08-10 - Control Limit Surpassed - Intermittent

 

00561 - Mixture Adaptation

..........14-10 - Adaptation Limit (Add) Exceeded

[Kevin Bacon 5]

00537 - Lambda (Oxygen Sensor) Regulation

..........08-10 - Control Limit Surpassed - Intermittent

 

00561 - Mixture Adaptation

..........14-10 - Adaptation Limit (Add) Exceeded

 

Yeah that's quite a common one that. People commonly mistake that as a faulty lambda sensor, but what it actually means is the Lambda controller was unable to bring the fuelling right within it's range of adjustment, which is only +/- 15% on OBD1 SLCs. OBD2 had this adjustment range extended to +/- 25%.

 

I suspect the MAF sensor you fitted could be faulty. The bulk of the fuelling adjustment is covered by the MAF sensor. The lambda just trims it to maintain 14.7 Air/fuel ratio at idle and part throttle (less than 80% throttle and / or 4000rpm).

 

So if the MAF is not functioning correctly, the lambda is having to do more work than usual and it just runs out of options.... then it throws that error message.

 

Mixture adaptaton - ditto the above! It couldn't ADD enough fuel to bring the mixture right, which is quite telling. Definitely a duff MAF sensor I would say.

[corrado9a 0]

It could also be something as simple as a bad plug wire, old distribuitor or faulty coilpack, if you get a radom missfire, then the unburned fuel would be noticed by the lambda sensor.

[Kevin Bacon 5]

Yep, could also be that. The OP didn't mention misfiring so skipped past that.

 

Did the Califorian spec SLCs got misfire detection? I know some of their Golf VR6s did.

[gregski 0]

Thank you all for taking the time to help out.

 

 

It could also be something as simple as a bad plug wire, old distribuitor or faulty coilpack, if you get a radom missfire, then the unburned fuel would be noticed by the lambda sensor.

 

 

How can I check if the vehicle is misfiring? Also it is the older model so I don't have a coilpack. The dizzy had a broken hall sensor plug on it, so I doctored it up a bit, I wonder if that is the problem. I do own a second dizzy which I bought used, I was planning on replacing mine with it, but I held off thinking why fix it if it aint broken, but now I think it may be.

 

Plan so far.

 

1. Replace the distributor. Drive and test the car with Ross-Tech.

 

2. Remove and inspect the black rubber intake boot for cracks/holes. Drive and test the car with Ross-Tech.

 

3. Install brand new intake manifold gaskets between the throttle body and the second one between the upper and lower intake. Drive and test the car with Ross-Tech.

 

wish me luck, lol

[Kevin Bacon 5]

You can usually feel a misfire on the VR6. Feels and sounds like it's running on 5 or 4 cylinders.

 

Whilst you've got the tools out, take the sparkplugs out and check for oil fouling and excessive wear (huge gap between electrode and ground strap). Oil fouling of plugs 1 and 6 is a common cause for misfiring when everything else is good.

[gregski 0]

Well before making any further changes, I decided to reset the computer (ECU). So I unplugged the battery for a couple hours and then plugged it back in. Here are the before and after Group 006 Fuel Trim results.

 

Initial Group 006 Fuel Trim (02 Sensor)

 

 

After Resetting the ECU Group 006 Fuel Trim (02 Sensor)

 

 

Notice how the after results; Part Throttle Adapted Value and the Full Throttle Adapted Value are at 1.000, that can't be right. How long does it take for those fields to update after an ECU reset?

[dr_mat 0]

They will adapt quickly given the right type of driving, but the values you had pre-reset are bonkers..! I assume you ran through the full reset sequence with the high-rev acceleration/deceleration cycle?

[gregski 0]

 

I assume you ran through the full reset sequence with the high-rev acceleration/deceleration cycle?

 

 

No Sir Dr. Please do not give me that much credit, lol. What full reset sequence do you speak of, I will search the forum for it now, by the way is it in the Bentley manual for I have one of those.

[RW1 0]

Notice how the after results; Part Throttle Adapted Value and the Full Throttle Adapted Value are at 1.000, that can't be right. How long does it take for those fields to update after an ECU reset?

 

Yes the results are OK, but depending on time elapsed since the battery was connected and how much time you've been driving.

 

Idle appears almost immediately.

Part throttle after about 15 minutes of driving.

Full throttle after about 30 to 40 minutes of driving.

 

They all don't really settle down until after about 4 hours driving, despite the times above when values first appear. And once settled, there will still be minor adjustments going on for such things as quality of fuel, ie different brands, different fuel batches of fuel from a gas company. The "tweeking" by the ECU is normal.

 

You can do the "Basic Settings" part of the procedure as many times as you like without any adverse effect. So one after a 30 mins drive after initial drive sequence, then another a week later will be fine. After that, once every 6 months but certainly at every service.

 

The full VR6 ECU Reset is in the Wiki. Do it all as it asks. Just driving the initial few "speed sequence runs" is a waste of time as it states in the procedure. NB. Never reconnect the battery and allow the engine to idle continuously during the first 10 minutes. Plan to start the Corrado and drive away immediately so the ECU sees an engine under driven loadings. So the engine needs to be pre-warmed up before disconnecting the battery. ;)

 

Its not in the VW's manuals or the Bentley in one spot. I wrote the ECU set up procedure to pull it all together and the VCDS Corrado VR6 label file as all the other Corrado VCDS label files that download from Ross-Tech in the program "exe" file.

 

Also try exercising your ISV as it looks sluggish in the other topic by using "Output Tests" - See here. Let it click away for about 3 minutes and see how that goes.

 

If you disconnect the battery again in the future, you start all over again with the ECU procedure.

 

.

[gregski 0]

well while checking for vacuum leaks the Idle Air Control Valve Noise Damper crumbled in my hands, it must have been broken already because I am always careful. Also I could not find a missing piece of the lid for it so I assume there was a hole in it already. I have seen posts of guys deleting this pest, so I will bypass it for now, and order a new one from German Auto Parts in New York.

 

[RW1 0]

Ahhh, that explains the higher stored lambda values above 1.00 in Measuring Block 006 fields for idle and part-throttle.

 

Also an idle less than perfect as well.

 

.

[gregski 0]

The intake was greasy at the heater tube location, that's the Positive Crankcase Ventilation PCV valve area. You can see that in the first pic when I flip it upside down to show you it's belly.

 

 

So I decided to take the opportunity to completely take apart and clean all the greasy intake components, on the kitchen table [ahem] indoor workbench and kitchen sink ie parts washer. I was amazed how well an old girlfriends toothbrush worked with some good ol' dish soap.

 

All squeaky clean with the brand new Idle Control Valve noise damper installed and ready to go back on the car.

 

New Fuel Trim numbers coming soon...