Vanagon Syndrome -- Air Flow Meter fix

Transferred from archives

6/9/98 (4:22 PM)

[Note: This fix only applies to the digital FI systems called Digifant on the 2.1 liter engines. Do NOT post questions on pre-Digifat (Digijet or AFC) FI -- use the appropriate symptom topic.]

A number of driveability complaints on water-cooled Vanagons may be addressed by VW technical bulletin, No. 24-92-02, issued April 30, 1992.

Quote:

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"Condition: After driving for an extended period of time at a constant speed, the vehicle may, on occasion, experience a deterioration of performance which may be accompanied by hesitation or surging. In many cases, after turning off the engine and subsequent re-start without having taken any action, the symptoms disappear. These symptoms may not recur for several weeks or months."

"Service: To resolve this condition, wire harness Part No. 025 906 302, should be installed. This harness provides improved signal voltage stability."

Remove electrical connector from air flow sensor. Install wire harness, Part No. 025 906 302, between main harness connector and air flow sensor connector.

Part numbers are for reference only. Always check with dealer for latest parts information. As of 6/1/98, it was still a good number with list price of $138. VW calls it a "transformer" and the technical bulletin does indicate there are "active components" in the harness, so the old manual's trouble shooting resistance of the circuit are no longer valid. They are given in the bulletin.

To test the new harness, continuity between ends readings should be: #1, 0 ohms; #2 greater than 1 megaohms; #3, 4 & 5, 0 ohms.

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We have heard of this update also fixing other symptoms not included in the technical bulletin, such as stalling, missing, hard starting, and loss of power. To see if your Vanagon has the update, remove luggage pad or mattress and open the top of the engine compartment. Attached to the air filter housing is an air flow meter, which then ducts the intake air to the FI distribution box in the center of the engine. On the rear of this air flow meter is an electrical harness that runs back to the brain box, disappearing in the right rear area (facing engine). If the fix has been installed, an approximately 9" long harness will have been inserted at the air flow meter. The original harness then plugs into the fix harness.

[Moderator Note: Original start of post lost during transition to new edition of Infopop. Basically, poster was complaining about cost of harness that had apparently gone up since he had first priced one and was blaming that on the fact the new part was a 'revision' number, which he accused VW of doing only to change prices.]

cost. I then told them about the $138.00 quote for the original in June 98 and that it was unethical to Rev a part with only a cost, not a technical change. I guess this is how they keep ahead of competition in the parts market, but it looks like a consumer rip off to me. The parts man cut my cost on the Rev A transformer/harness to $145.00 plus tax when I bought the part. NOTE: Barter appears to be in, since the retail price quote was negotible, so arm yourself with information before purchasing! Thanks again Capt. Mike! Installation was very easy and straightforward.

Moderator Note: Daniel, if they just wanted to change prices, they DON'T need to change parts numbers. They changes prices every day -- just plug the new number into the computer. And you've surely asked the wrong person -- how many parts counter guys do you know that have the electronic expertise AND opportunity to investigate the contents of a micro-processor? The change may be very subtle -- a material change in the harness wrap, a changed value in a computer board component, or even adding an inch of length for more working room. I don't like VW's pricing policies any more than the next guy, but lets have some hard evidence before you call them thieves. By the way, the prices have come DOWN!

Keith (kaf@canada.com)

10/24/99 (8:28 PM)

I have experienced this problem heavily over the last 12 months. The symptoms were experienced alongside of a more serious problem which required replacment of the motor to deal with corrosion of the cylinder stud threads in the engine block.

Appearing both before and after engine replacement, the symptoms largely disappeared when the catalytic converter oxygen sensor was replaced. There has been one instance of at-highway-speed hesitation since, in about six trips of two hours or more. After the engine replacement but before the new oxy-sensor, the problem was encountered on every trip lasting over two hours.

I just checked -- the "signal voltage stability wiring harness" has not been installed on my vehicle.

7/7/99 (10:04 PM)

Nothing is forever. Including 'fixes.'

After 124K miles, my Vanagon 4x4, with the Vanagon Syndrome upgrade, began to hesitate, surge & quit idling. It didn't start until the vehicle was fully hot -- usually about 15-20 minutes. A shutdown of the ignition and immediate restart would restore idle until further down the road. With the hesitation & surge, came thick puffs of black smoke. It would run fine at full throttle, but nothing in between.

I had gotten the original harness upgrade back when it was first announced under VW's free campaign. Apparently my 'fix' died. I did do all of the electrical testing and troubleshooting of the FI per the Bentley. The good news was being able to confirm the air flow meter was operating smoothly and with proper readings over it's entire range, so, following the old axiom of "replace the cheapest part first" -- I put in the new, revised harness, P/N 025-906-302A. Immediate cure and it's done fine for years now under all conditions, including extreme heat over 100F.

I have to admit, my original fix adapter was showing it's age. One boot had split and I noticed the in-line transformer would move within the harness. Although I found some aftermarket sources, I went back to my dealer for the real thing and paid US$130, about the same as mail-order with shipping. I think list is near $150; my dealer stocks them.

The part is officially called a transformer, and contains voltage stabilization circuitry. It also reroutes some of the signals through different pins. Despite previous comments on this thread alleging "rip-off", for a fix that is a 2-minute plug in, I can't imagine many electronic experts willing to design and supply the part for much less. I had a solid-state circuitry expert open it up and it showed definate signs of overheating and meltdown of the circuit board.

So if you are experiencing the running problems of Vanagon Syndrome, don't overlook the transormer just because you have one installed. Nothing is forever.

From above and some old posts in archives, a number of people have complained that the Vanagon Syndrome Fix, P/N 025 906 302A is some sort of VW rip-off. One even went so far as to say it couldn't be anything more than a diode or capacitor.

On my Pic post site, linked from home page in the Tech diagrams folder is a photo of the inside of the harness module.

When mine burned out (note the hot spot where board coating melted) I took it to an expert in microprocessor design and manufacture. It contains what they call a "potted" microprocessor chip. Potted means it's encased when molded -- the components are not externally accessible. Now while it's theoretically possible that the chip could be good and one of the smaller components repairable, repairs are not economically feasible -- if one could get the board out!

I don't know what the manufacturing cost is with overhead allocated among the quantity sold, but this is not just some $10 capacitor spliced into a wire. Think again about some homemade substitute.

Hey Captain Mike-

1986 Vanagon GL Westy

I read your post on having to replace the air flow sensor harness -#025 906 302, (I guess it has an A at the end now) and think I may have the same trouble. I saw your picture on your site and was curious if you were able to find the burn on the chip without destroying the part?

I am having vanagon syndrome symptoms and am also getting the black smoke like you mentioned above.
I am trying to get a dealer to let me install a new one and see if it rectifies my trouble on the condition I'll buy it if it does but I can't get a response- don't think they like this very much. But, another dealer told me it would be $100 for the labor to replace so, about $250 total. It took me 5 minutes to remove/replace and I am lousy with auto engines.

Also, when I mentioned the symptoms to another dealer who had the part in-stock, he mentioned it could be the vacuum lines are off going to the fuel pressure regulator or the temp sensor may be corroded (he said look for green corrosion). But this guy also talked how you needed to ground the air sensor replacement harness to the van??? He was nice to provide other thoughts but obviously confused, as there is no external ground on mine.
Any of this make sense to you or any others with Vanagon Syndrome symptoms that wasn't related to the harness? Thanks in advance!
Brian

There's an old joke about $5 to kick the car to get it to start, but $100 to know where to kick it. That doesn't apply to the harness exchange. If it took more than 3 minutes I'd have to question the competency of the shop. I'm guessing somebody didn't want to do it because if it didn't work, then he couldn't charge you for the part. Sort of his insurance for having a part left over he didn't want to stock. This is unethical and I'd consider them such.

There are always a number of things that can give black smoke, but consider the other symptoms -- works fine at full throttle; starts fine after stopping; buck at mid-throttle.

The easiest confirmation would be to borrow one from another Digifant Westy owner. Chances of damaging his in a few minutes test-run are slim, presuming you've done the volt-ohmeter tests already to be sure there's not some live voltage leaking in there.

No, there is no external ground -- all circuits are 'resistance' circuits that feed back to the CPU.

Desperate need of HELP! First: I have an 87 Vanagon Westy with 170k, M/Trans. Heads were reworked last spring before I bought it.

My van died Christmas Eve and would not restart. I had been experiencing sporatic hard starting with the turn of the cold weather. Well, after it died, it did not restart. Towed it to the VW garage in town...it was freezing cold and I don't have a heated garage it will fit in. Well, he quickly found the OX sensor was bad and the plugs had fouled. Replaced both and readjusted the idle. It was idling at about 2k when cold! Now it idles at 1k cold. Also it starts right up in the cold now.

Well, he told me that after he got it started, it was running VERY rich. 5% CO. He checked many systems, including timing, fuel filter, fuel pressure, tryed a new airbox, checked the computer (may have even tryed a new computer). Well, he took out the wire harness that had been installed before I bought it and did some other things to get CO to 1.1% I got the car back and immediately realized that the engine cuts out upon full throttle, I reinstalled the old wire harness (pre-rev A). I drove her to Chicago and was not able to accelerate past 55. When I shifted to 4th I had no accelleration past 1/2 throttle. I also noted that I am now getting only 10mpg on the highway. Well, I took out the wire harness at a gas station, and suddenly I was able to accelerate to 70. However, the engine still cuts out at full throttle.

I ordered a new harness (rev A), installed it yesterday, and it made no difference compared to having no harness at all. It definately performed better than the old harness. Something else to note is that it also backfires now when I step on the gas in neutral. So it is in the garage again, and I believe he replaced an air temp sensor.

Any suggestions. I am getting frustrated with the situation. Again the car worked fine before I brought it into the garage (other than the plugs had fouled). And the new harness IS installed. Sorry for the long post. My email address is TrekMTB@aol.com

The fact that you have no difference between having no Vanagon Syndrome harness fix and the new one indicates your problem is NOT Vanagon Syndrome.

There are many possibilities for your symptoms (per other topics). The bad O² sensor was probably not one of them. O² sensors rarely have an effect on starting -- their purpose is to adjust CO while running.

Read the other topics, paying note to the posts on the throttle valve switch -- a common cause of acceleration stumbles or blocks -- and other sensor failures.

I venture your mechanic has introduced a "wrong" idle & CO setting to correct another "wrong". Unfortunately, in cars, 2 wrongs don't make a right, either.

Does this sound like Vanagon Syndrome? I have an '87 Westy that drives like a champ around town. When I try to take her up over the Continental Divde she bucks and surges and feels like she's about to keel. I pull over, wait for about 25 minutes and she makes it back down to Denver as if nothing ever happened. It only seems to happen while under a sustained load. Any suggestions?

I seem to be having some of the symptoms mentioned in other messages here regarding Vanagon Syndrome. The only thing is that the symptoms (cut-out or bucking that is relieved upon letting up the accelerator) only seem to show up in my van when it is below 40 degrees F and they get worse the colder it is. At first, it really was acting like a clogged fuel filter, so I replaced that, no change. As the van warms or has time to warm the engine area the symptoms start to abate. I do not experience any symptoms when ambient is over 50F. Has anyone had this experience or should I start looking in another direction? Thanks for your time.

In 1996 I taveled from the East coast of Canada and across the USA and back covering about 16000 miles.When I entered New Mexico I travelled from Silver City on Highway 180 and then on to Highway 180/190 into Arizona.During this leg of our trip the van(1988)started to hesitate and lose power.Not knowing the high altitude we at,we continued on to Prescott New Mexico for an oil and filter change.I mentioned this to the mechanic and he asked me which route I was on.His theory was that it was the altitude we were at.He suggested that if I was not going to be at those altitudes again he would not recommend any adjustments to the injection system,which he mentioned could be done.To this day and many miles later never again at those altitudes I have never encountered this problem.I wonder if this could be the problem with some of these people operating at these high altitudes.Ke

I have an 86 Wolfsburg Westfalia, auto transmission, with 154,000 miles. It runs great!
I do not have any of the power loss symptoms I have been reading about here, however, after driving for a while, whether on the freeway or on city streets, it will sometimes suge at ide. It doesn't die, it just acts like I'm stepping on the gas slightly and letting off continuously. If I let it idle for a long time it will sometimes smooth out; but for most stop lights it does it continuously. I usually just put it in neuteral.
Is this part of the "Vanagon Syndrom" Do I need to install the upgrade harness?
Thanks...Frank

This is not Vanagon Syndrome but all vehicles, whether having problems or not, should install the upgrade harness so as not to disguise other component symptoms.

Suggest you check the O² sensor, sensor caused idle and misses/surges topics in this forum.

Thanks Capt. Mike,
I will install the upgrade, then look at the O2 sensor.
Frank

Since my 87 GL Syncro doesn't have the Vanagon Syndrome fix, I figured why not buy one. Only problem is my local dealer could not find it (in the Parts Dept.) and upon talking to a mechanic (the service guys had to call him in for me) he stated that they only ever installed the air box harness fix upon replacing the entire air box because he claimed the bad wiring causes the box to malfunction.

He kept insisting they DO NOT sell the harness fix alone. Even after mention of a local German Expert shop suggesting to get the harness only.

I will test my luck at another nearby dealership, but from my experience with my first choice dealership I'm willing to bet the other guys aren't any better.

What's the point? I really hate buying parts from the dealership, I wish there was a better way. They certainly couldn't care less about Vanagons, Syncro or not.

I'm sorry you have a horses' ass dealer that can't read their own part fiche and service bulletins. The part number is given in this post and a parts guy that can't look up the part number is pretty sorry. You have my permission to tell him so. The tech bulletin number is also given (and quoted) in this topic. Ditto for the service guy. I'd complain to VW headquarters & your local CoC or AG that you have found a dealer that is trying to pyramid parts sales, which is unethical. Each part can be tested separately and there is no reason to replace one that is working perfectly.

The harness fix is available from a number of aftermarket vendors. See the PARTS forum; several sell the same OEM harness fix. Van-Again is one such.

I boughta used 1987 Westy with 2.1L motor. Ran fine on test ride. Replace muffler and added KN aircleaner. Ran fine then sorta died at 60mph on freeway,dropped to 30 mph.made a quick exit.Idle great but would not take gas underload.Then Voila- all ok. I replaced the fuel filter and now have symptom of loss of power. All plugs burning lite toast color. Replaced vacuum hose to fuel regulator- bad looking.Reinforced crankcase breather hose internallly- thought it may be collapsing- very soft. STill no good. Does not seem to respond to gas pedal correctly. Will rev at idle ok but under load has reduced power.
Is this they symptom for the AFM fix or??
Sid Vicious in New Orleans

Per the tech bullitin posted above, these are not typical "Vanagon Syndrome" symptoms; probably sensor, throttle switch, aux. air regulator or a vacuum leak.

From Gary:

VW AFM Harness

Thanks; great pictures.

After the fuel line ruptured and a near death experience our 1980 vanagon shortlythereafter started to do the lurch and choke. We could not get it above 80 on a straightaway and maybe 40 uphill. It was like the gas was being pumped intermittantly with the brakes. After spending over 1000 at 3 different mechanics (one being a volks dealer) no one could tell us what it was. We eventually bought a used motor and had a mechanic put in the carbs from it hoping that the problem would be solved. We are not actually sure if that is what they did but it works better but still is sluggish as hell. Could this be the syndrom? It was a very frustrating 6 months. Sometimes it is still doing the lurch uphill but of course not nearly as bad. http://www.westfalia.org/infopop/emoticons/icon_eek.gif

Read above -- 1st post in this topic answers your question.

Does this sound like the dreaded problem to you:
Van runs fine when cold. After running for about 10 min.to 20 min. at highway speeds the engine bogs severely. It sputters at low rpm <4K. When you press the gas normally it almost does nothing. However, when you floor it and kick it into over drive (I have autmoatic) (ie when rpm are 4 or above and accelerating) the engine seems to engage fully and accelerate properly. When it drops below 4K rpm, it really sputters. It almost seems like half the engine is running constantly. It will only perform when floored and over 4K rpm and of course you cant run it like that. SOMETIMES, after turning it off, it runs fine for a while then does the same thing...eventually.
What has been done: The fuel pump and filter have been changed with the same negative results.

What year? (Guideline #3!) Vanagon syndrome is only applicable to Digifant systems per above posted tech bulliten. The symptoms you describe are similar if in a Digifant model as described above in the 5 Aug 2000 post.

One question,, does it clear itself by "resetting" by qucikly turning the key off and on while running? If so look at the threads regarding the O2 sensor. Sounds a bit like a problem I had and then cured with a new O2 sensor.

Icarus

Transferred from chat room due to response.

werner-max Junior Member Posted January 05, 2006 06:54 AM

HI, I m a new member and had a technical question posted earlier and can't find it anymore or any responses. Please help me re-direct my inquiry: [Moderator note: email blocked, unable to send courtesy message.]

I have an '87 Westfalia with now 127,000km and live in Calgary. The car runs great - except when hitting higher altitudes. Driving from here to Banff the car seems to get the hick-ups. Sometimes so bad I have to stop and watched the tach needle moving wildly until it seems to go down to normal idle speed. After a small rest stop the car drives OK again, but as long as I'm in the mountains the hick-ups coming back.

Some people recommended a new air-flow meter, a new oxygen sensor or a new fuel pump. Surely it must have something to do with hitting thinner air or the engine needing to work harder.
My mechanic cleaned the ECU grounds and adjusted the coast idle switch and now recommends replacing the wiring harness [parts#025-906-302-A]

Whenever I see a fellow Westy I talk to the driver, but so far my problem seems unique. Any suggestions - please...thank you ..Werner in

icarus Super Member Posted January 05, 2006 08:32 AM

Werner,

Your post answers are in: electrical-vanagon syndrome.

If you do not have the updated wiring harness patch cord installed, I suggest that you install one. It would be rare not to have one at this late date. If you have one, trade it for a known good one.

While your altitude assumption has some merit, Banff is not very high as places go. Many places in Colo. are better than 8-10,000 ft. I suspect is is conincidental. Vanagan syndrome usualy happens after periods of extended running. The trip from Calgary to Banff for example might be long enough to induce the problem. The quick cure is to momentarily turn the key off and on again while the engine is running. This "resets" the computer. The other thing to look at it the O2 sensor. Read the posts there. I had similar problems that were cured by replacing the O2 sensor.

Read all the posts carefully, and remember that there are threads within threads, so the information that you are looking for may be hidden within the major catagories. Capt. Mike tries hard to keep the site clean and easy to navigate. If your post was cut, you should have recieved a e-mail telling you why.

Good luck and keep us informed.

Icarus

Thanks Icarus for your help, Yes it sure sounds like the Vanagon-Syndrome. I ordered the new wiring harness and the O2 sensor too! Seems like a very common problem and I find it odd that some of the mechanics I talked too didn't know about it...thanks again...werner

Werner,

Read the posts about the O2 sensor wiring harness problems. Often times, a short will develope in the harness where it plugs into the main harness. You can unplug the O2 sensor and run without it connected. The car will run in a default mode. If this cures the problem it tells you that the either the sensor or the sensor wiring harness is bad.

Icarus

PS. I realize this should be posted in the O2 sensor thread, but since you may be chasing either problem,,,,,

Hoping to write in the right place. I have a 1991 Vanagon. We went on a trip and we used 47liters of fuel for 225 km!!! Actually the van will run fine for 10-15km and then loose power, emit black smoke, and no use in dowmnshifting, it will die off. I can restart immediately and every thing will be almost fine for 10-15 km. And again. I can just turn off the ignition and put it back on and the situation will be fine.
I had the car to the garage. They checked the O2 sensor, the harness, the air filter, the catalytic converter; the temperature sender was changed last fall.We then checked for loose grounds. They noticed that the AFM had been tempered with and that it could not be ajusted to specs. So we ended up changing the AFM and the van had never run so smooth...for 17km. Then it lost power, emitted black smoke and died. It restarted easily. I simply don't know were to look for. I would prefer not to be on a trial base all summer.
Thank you
Luc Lachapelle

This is the Vanagon Syndrome topic -- per VW technical bulletin, No. 24-92-02, issued April 30, 1992. Symptom are similar but you didn't even tell us if you have the fix P/N 025 906 302 or attempted to change or test that fix part. This topic doesn't address the AFM but note that the fix makes the AFM work correctly, not the other way around. Missing or defective fix harness will not be corrected by changing the AFM.

Am considering buying the GoWesty engineered conversion of the AFM system to an Air Mass Sensor 'hot-wire' substitute.

http://www.gowesty.com/library_article.php?id=804
http://www.gowesty.com/library_article.php?id=805

Anyone have experience with this modification?

Help me out, here Capt Mike- dunno where to post this-
KennekeComm in Albany , Oregon is a total scam. They sell waterboxer AFM's cleaned up with the tantalum resistor for $139.95.

They sent me one, okay but it was a dud, said to send it back, end of story. Money gone, core gone, no such place as KennekeComm.

Get one from GoWesty- the ONLY reliable place for one I know.

[Moderator Note: Kenneke Communications topic established in PARTS forum. Please post all comments on vendor there. :cool:]

New to the site, but Capt Mike, I think my harness has given up and is now time for a replacement. Who currently stocks the harness and what is now the current price. I orginally bought mine about 9 years ago for about $120.

The site doesn't support "where can I get" type posts (Guideline #5). To the best of my knowledge they are still available from VW (Guideline #8) and several vendors in the PARTS forum.

Sorry, but someone had posted here that VanAgain was a source for these harnesses and I did check there and they don't list them anymore. I did find the harness on a couple of other parts sources, other than VW Canada, and it seems they have increased in price to about $330.

Captain Mike,

I have a 1991 Vanagon GL full camper with AT and about 155,000 miles. I've only had the van a few weeks and it has ran flawlessly - until yesterday. I recently went on a 900 mile road trip and returned home with no problems. When I went to start the van the next day it turned over, started, and idled very roughly and sporatically (400-2000 rpm) then it died. I tried starting it a few times with the same result. Sometimes it would start and sound ok - but then when I put it into gear it would die. I've read the posts on the Vanagon syndrom and I installed the replacement harness, but the same problem still exists. Any suggestions?

Thanks,
Mark

It's NOT Vanagon Syndrome. With Vanagon Syndrome, it ECU will reset, start and run fine for a period. See the factory tech bulletin in the first post in this topic that describes the symptoms. You have other FI problems covered by the other topics in this forum. Have you done any diagnostics per the Bentley or those topics?

Capt Mike, I know about the Vanagon syndrome as my 89 had it. With the advent of the AFM harness, these symptoms went away. Something that has just started is the engine will cut out occassionally, no backfiring, just complete loss of power. This will last a couple of seconds and it will kick back on again, or if I just pulled up to a stop, it will quit. When I restart, it is like nothing happened and it runs again. The harness, as I stated below, was installed about 9 years ago. Is this a resurrection of the Vanagon syndrome or do I have another problem.

Sounds like it. Did you do the tests VW published in the Tech Bulletin (also listed above this topic)? One other test is, when it does this, will it respond to full throttle? Most failures of the harness update will usually idle or run full throttle with nothing in between but smoke & bucking or die. Do this test on a back road w/o traffic! I've got a pic posted page 1 of my failure.

Capt Mike; I see one of the suppliers is advertising a rebuilt AFM with the harness built into it. Are there any reports or feedback on this unit?

Who? Nobody can comment if we don't know who the vendor is! Have you read the post in PARTS on "KennComm . . ."?