S3 MAF sales will be stopped until the "lean" codes are defined/resolved
03-22-2004, 03:54 AM
#1
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S3 MAF sales will be stopped until the "lean" codes are defined/resolved
I switched may car back to stock injectors yesterday and disabled the ARC-2. Which puts me on the same level playing field as most who are reporting the lean codes. Tho I did run this setup for months before installing them with no problems or codes of any kind.
I'm working on a prototype sensor inlet orifice that will get the g/s velocities into the sensor wires back up to where it was before. This should also cure the long term fuel trim issue if one exists. The problem I'm running into is that inlet tube is very very sensitive to I.D. and length. Differences of a thousandth or two in it's inside diameter or it's lenght cause friggin HUGE differences in the volume/velocity of air moving past the sensor wires. I may end up making several dozen of these trying to get back to stock readings. Once I finalize a specification that works I'll make them available to everyone with an S3 MAF at no charge. And it will be a simple press-on interference-fit that slips over the existing sensor stem inside the MAF with no adhesives.
The biggest problem I'm running into with early version is too much fuel trim. They make the car too fat (rich).
The other thing some are going to have to face is that it may not be their S3 MAF causing their lean condition. Or, it may be only aggrivating a pre-existing condition. And I've got a pretty strong hunch in some cases it's going to come down to old O2 sensors and in some cases even new generic sensors. The feedback I'm getting from the local non-Audi repair shops is they've had to stop using them altogether. Too many weird/strange occurences associated with their use. I found this out on my UrS4 years ago as well and have documented those findings here nigh on a year ago. They are cheap but they're not perfect.
Another thing when reading/chasing codes is the arbitrary selectiveness of what you want to believe or not. If you pull DTC's and there listed as:
1. Air leak or faulty O2 sensor
2. R. Bank too lean
3. L. Bank too lean
You cant just ignore or say "I dont believe the first one" but I'd like to know what's causing 2 & 3. Ya damn well better believe the first one as it may be causing #2 & 3. And just because you installed new generic sensors last summer or put some RJ11 cable around your TB/plenum gasket is no hedge against the codes credibility or validity. You just can't "pick-n-choose" the codes you "want" it to be. And the ECU doesn't make these codes up to suit. If the ECU says it's there you can damn well bet "IT'S THERE!!
Other people with 120k miles on stock O2 sensors should just assume it's time for new ones. You've actually gone double the recommended life of the pre-cat ones. Anyone with 60k miles on the pre-cat sensors could benefit from new ones.
I'll get your fuel trims back up. Piece of cake! But I've got a strong gut hunch thats not going to put a lot of CEL's out. And the large percentage of those it does put out still have other issues pending under the hood that need be addressed. Due to the sheer volume of S3 MAF's out there and the relative low numbers of lean-related CEL's just leads me to believe the MAF is more likely aggrivating a pre-existing condition than "causing" one.
Give me thru next weekend to dial in the sensor-inlet orifices. And I'll let everyone know when I find the "Eureka" specification.
I'm working on a prototype sensor inlet orifice that will get the g/s velocities into the sensor wires back up to where it was before. This should also cure the long term fuel trim issue if one exists. The problem I'm running into is that inlet tube is very very sensitive to I.D. and length. Differences of a thousandth or two in it's inside diameter or it's lenght cause friggin HUGE differences in the volume/velocity of air moving past the sensor wires. I may end up making several dozen of these trying to get back to stock readings. Once I finalize a specification that works I'll make them available to everyone with an S3 MAF at no charge. And it will be a simple press-on interference-fit that slips over the existing sensor stem inside the MAF with no adhesives.
The biggest problem I'm running into with early version is too much fuel trim. They make the car too fat (rich).
The other thing some are going to have to face is that it may not be their S3 MAF causing their lean condition. Or, it may be only aggrivating a pre-existing condition. And I've got a pretty strong hunch in some cases it's going to come down to old O2 sensors and in some cases even new generic sensors. The feedback I'm getting from the local non-Audi repair shops is they've had to stop using them altogether. Too many weird/strange occurences associated with their use. I found this out on my UrS4 years ago as well and have documented those findings here nigh on a year ago. They are cheap but they're not perfect.
Another thing when reading/chasing codes is the arbitrary selectiveness of what you want to believe or not. If you pull DTC's and there listed as:
1. Air leak or faulty O2 sensor
2. R. Bank too lean
3. L. Bank too lean
You cant just ignore or say "I dont believe the first one" but I'd like to know what's causing 2 & 3. Ya damn well better believe the first one as it may be causing #2 & 3. And just because you installed new generic sensors last summer or put some RJ11 cable around your TB/plenum gasket is no hedge against the codes credibility or validity. You just can't "pick-n-choose" the codes you "want" it to be. And the ECU doesn't make these codes up to suit. If the ECU says it's there you can damn well bet "IT'S THERE!!
Other people with 120k miles on stock O2 sensors should just assume it's time for new ones. You've actually gone double the recommended life of the pre-cat ones. Anyone with 60k miles on the pre-cat sensors could benefit from new ones.
I'll get your fuel trims back up. Piece of cake! But I've got a strong gut hunch thats not going to put a lot of CEL's out. And the large percentage of those it does put out still have other issues pending under the hood that need be addressed. Due to the sheer volume of S3 MAF's out there and the relative low numbers of lean-related CEL's just leads me to believe the MAF is more likely aggrivating a pre-existing condition than "causing" one.
Give me thru next weekend to dial in the sensor-inlet orifices. And I'll let everyone know when I find the "Eureka" specification.
03-22-2004, 06:10 AM
#2
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For what worth you find in my experiences . . .
My lean CEL's came from installing modded TB and intake manifolds without resetting the ECU. This accounted for post-mod lean codes, but not the rest of them.
For those, I bought an adjustible fuel pressure regulator [FPR]. If you read the Bentley Manual, you will find that there exist a whole host of fuel trim related error codes that at faulty FPR may cause. Not knowing that I could have one made cheaply, I spent a chunk of money on an ECS adjustable FPR, because I read pages and pages of stuff that read something like this:
if error code xxx is read, replace fuel pressure regulator;
if error code xxy is read, replace fuel pressure regulator;
if error code xxz is read, replace fuel pressure regulator;
if error code xyx is read, replace fuel pressure regulator;
if error code xyy is read, replace fuel pressure regulator;
if error code xyz is read, replace fuel pressure regulator;
if error code xzx is read, replace fuel pressure regulator;
if error code xzy is read, replace fuel pressure regulator;
if error code xzz is read, replace fuel pressure regulator.
Get the picture?!
I never got a single lean code from installing UrS4's S3 MAF; however, I had my adjustible FPR in the car prior to UrS4's 12v hardware coming on-line. So, for those of you who have problems, perhaps you should replace your FPRs, as the S3 MAF in combination with an old FPR may have caused your lean codes.
My $0.02!
For those, I bought an adjustible fuel pressure regulator [FPR]. If you read the Bentley Manual, you will find that there exist a whole host of fuel trim related error codes that at faulty FPR may cause. Not knowing that I could have one made cheaply, I spent a chunk of money on an ECS adjustable FPR, because I read pages and pages of stuff that read something like this:
if error code xxx is read, replace fuel pressure regulator;
if error code xxy is read, replace fuel pressure regulator;
if error code xxz is read, replace fuel pressure regulator;
if error code xyx is read, replace fuel pressure regulator;
if error code xyy is read, replace fuel pressure regulator;
if error code xyz is read, replace fuel pressure regulator;
if error code xzx is read, replace fuel pressure regulator;
if error code xzy is read, replace fuel pressure regulator;
if error code xzz is read, replace fuel pressure regulator.
Get the picture?!
I never got a single lean code from installing UrS4's S3 MAF; however, I had my adjustible FPR in the car prior to UrS4's 12v hardware coming on-line. So, for those of you who have problems, perhaps you should replace your FPRs, as the S3 MAF in combination with an old FPR may have caused your lean codes.
My $0.02!
03-22-2004, 06:42 AM
#3
AudiWorld Super User
Thread Starter
Good info and it bears mentioning that the FPR's vacuum line can cause most of those FPR-related...
codes as well as the FPR itself. If there's a loose-fiting, cracked, broken or leaking vac line anywhere on that vac circuit you can get lean codes.
I've also used the adjustable FPR as well. I mean I make them so might as well use them. But I haven't for about 6 months because I wanted to get the ARC-2 balanced to "0" with stock fuel pressure as that would most closely represent a stock car without an ARC-2 installed. When the ARC-2 is dialed to all zero's there's no adjustment dialed in whatsoever. Tho I am running a new FPR since I buy them 12 at a time to convert to the adjustable units so I have them lying around.
Another reason our Long Term Fuel Trim doesn't move much is related to the 471A MAF sensor itself. It already has an encapsulated 10mm orifice cast in. Unlike the 471 MAF which DOES affect LTFT dramatically more than the 471A. When I have tried the S3 MAF using a 471 MAF the LTFT's fuel trims have gone to hell in a banana boat. The 471A does NOT go lean enough to warrant ANY concern whatsoever. Trust me I have dozens and have tested frequently. Anyone who tells you otherwise doesn't even have one to test and is speculating. But none-the-less I'm going to eliminate the possibility even if it causes the cars to be slower, mileage to diminish back to stock levels and CEL's to go out... and it will do ALL those things! But while I can lead a horse to diminished orifices I can't "make" him use them.
And when I have this item available it's going to cause some CEL's to go out. Not because you were too lean but because you're back within the threshholds of a faulty pre-existing condition. When you get around to fixing that feel free to remove the orifice I send you. Because then, and only then is your car really "fixed." What I'm doing is providing you with a means to lie to your ECU until you come up with the time/funds to fix the REAL problem.
Gotta love the mass-hysteria created by the few. Now everyone with a lean code and an S3 MAF automatically presumes the MAF. While the people with stock MAF's set about finding/fixing the problem. I'm tired of being the "lean-code scapegoat"... and I'm about to force many of you to start looking for the real problem. It aint the MAF, it aint the velocity stack, it aint the screen removal. It's YOUR car!!
But don't take my word for it. Let me show you. Gimme the week.
I've also used the adjustable FPR as well. I mean I make them so might as well use them. But I haven't for about 6 months because I wanted to get the ARC-2 balanced to "0" with stock fuel pressure as that would most closely represent a stock car without an ARC-2 installed. When the ARC-2 is dialed to all zero's there's no adjustment dialed in whatsoever. Tho I am running a new FPR since I buy them 12 at a time to convert to the adjustable units so I have them lying around.
Another reason our Long Term Fuel Trim doesn't move much is related to the 471A MAF sensor itself. It already has an encapsulated 10mm orifice cast in. Unlike the 471 MAF which DOES affect LTFT dramatically more than the 471A. When I have tried the S3 MAF using a 471 MAF the LTFT's fuel trims have gone to hell in a banana boat. The 471A does NOT go lean enough to warrant ANY concern whatsoever. Trust me I have dozens and have tested frequently. Anyone who tells you otherwise doesn't even have one to test and is speculating. But none-the-less I'm going to eliminate the possibility even if it causes the cars to be slower, mileage to diminish back to stock levels and CEL's to go out... and it will do ALL those things! But while I can lead a horse to diminished orifices I can't "make" him use them.
And when I have this item available it's going to cause some CEL's to go out. Not because you were too lean but because you're back within the threshholds of a faulty pre-existing condition. When you get around to fixing that feel free to remove the orifice I send you. Because then, and only then is your car really "fixed." What I'm doing is providing you with a means to lie to your ECU until you come up with the time/funds to fix the REAL problem.
Gotta love the mass-hysteria created by the few. Now everyone with a lean code and an S3 MAF automatically presumes the MAF. While the people with stock MAF's set about finding/fixing the problem. I'm tired of being the "lean-code scapegoat"... and I'm about to force many of you to start looking for the real problem. It aint the MAF, it aint the velocity stack, it aint the screen removal. It's YOUR car!!
But don't take my word for it. Let me show you. Gimme the week.
03-22-2004, 07:43 AM
#4
I never believed it to be directly related to the S3 MAF especially since I've had the S3 for 9 mos
and just started getting codes in the last 2 months.
I'm gonna see how this new (old) vacuum line I installed works out. So far so good. :-D
I'm gonna see how this new (old) vacuum line I installed works out. So far so good. :-D
03-22-2004, 08:12 AM
#5
AudiWorld Super User
Thread Starter
you've been GREAT! And you and I have worked behind the scenes to try and find the issue...
Gonna be terrific if that vac lines turns out to have been the problem. Falls right into what JWG and I discussed in an earlier post in this thread. How long have you been error-free now vs how long did it take a CEL to occur once you cleared it before??
I know when you tried the new sensor I sent you the CEL was back within minutes and now it's been several days with the vac line replacement and no code, right?
I know when you tried the new sensor I sent you the CEL was back within minutes and now it's been several days with the vac line replacement and no code, right?
03-22-2004, 08:32 AM
#6
The code varies in frequency from a couple days to 2 weeks. It's been averaging about once a week.
I think I got the last code last Thursday morning (4 days ago) and I installed the new (old) vacuum line that night. I'll have to check my VAGCOM laptop when I get home as I save all the codes and dates.
When I installed the new MAF sensor I got the CEL the next day. Speaking of which should I hold onto the sensor for a while longer or send it back to you? Or do you want my old one back? Thanks.
Also, what ID is your Porsche vacuum line?
When I installed the new MAF sensor I got the CEL the next day. Speaking of which should I hold onto the sensor for a while longer or send it back to you? Or do you want my old one back? Thanks.
Also, what ID is your Porsche vacuum line?
03-22-2004, 08:46 AM
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Say, if the lean codes were in any way MAF-related....
wouldn't my home-made MAF (no sampling tube/screen) cause more likely a CEL than your precisely fabricated MAF housing? Sure, your MAF is bored, mine isn't, but keep in mind I'm at sea level.
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03-22-2004, 09:09 AM
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I've said it before, and I'll say it again - I have some of the exact same lean issues and...
I've never installed an AA mod. I'm going to buy the VAG-COM tool today and start pulling my own codes and keeping track of dates.
Mance, you listed a number of items I need to check out to determine if they're culprits. Things like fuel pump, FPR, FPR vac lines, fuel filter, pre-cat O2 sensors, etc. Is there a way to check these items without actually buying replacements? Also, where do you recommend I pick up "reasonably" priced 02 sensors. I'm guessing they've never been done and I'm at 87K miles.
Mance, you listed a number of items I need to check out to determine if they're culprits. Things like fuel pump, FPR, FPR vac lines, fuel filter, pre-cat O2 sensors, etc. Is there a way to check these items without actually buying replacements? Also, where do you recommend I pick up "reasonably" priced 02 sensors. I'm guessing they've never been done and I'm at 87K miles.