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Mon Oct 20, 2008 4:04 pm

Hello to all,
I'll try to explain as best as I can. I have a 1987 2wd Westy.

on a recent 300mi. road trip toward the last hundred miles or so just after pulling up a pass. I gave the vanagon some gas to get it back to 60mph right as we peaked and I felt a little hiccup or hesitation. on the next hill, same situation, the vanagon practicaly jumped as I gave it gas (aka a serious hiccup). it then continued to do this intermitently until we arived at our destination, sometimes the vanagon would shutter violently and acceleration would be very poor. I also noticed it only did this as I tried to accelerate, if my foot was off the gas, no problem, if it was in neutral and I gased it, no problem. there is no loss of electriccal power.

over the next few days on our trip driving it shorter (20mi) distances no problems up and down hills fine, acceleration great.

on the way home there was no problems for the first hour or so then it kicked in and even worse than before. I pulled over let it sit for 20 mins or so, then started off again no problems for about 37mins. this time the hiccuping started and then quit about an hour later then started up again on the final stretches home hiccuping severly in all gears.

this week I have been driving it and it has had a hard time starting well in the morning and has hesitation on acceleration until it is warmed up. although I have not experienced any shutters or hiccups this week even on longer drives just poor starting and hesitation.

Here is what I have checked:
TPS is new and functioning properly
O2 sensor is new and functioning properly
Temp 2 is new and functioning properly
afm seems to pass all test although when I move the wiper blade I recieve an increase in resistance as the wiper blade moves but it is not steady when rests it fluctuates a little i.e. (.407-.416).

Is what I described the vanagon syndrome or something diffrent all together? what else should I check? I have the protraining manuals and ohm meter. any help or advice would be greatly apreciated.

Thanks,
Kyle Hoyer

Mon Oct 20, 2008 4:08 pm

How old is your fuel filter?

Mon Oct 20, 2008 4:10 pm

Easy way to see if it is Vanagon Syndrone is when it starts jumping and hesitating. Push the clutch in an switch off the engine, turn the key until the engine shuts off, not until the steering wheel locks. Leave it off for 10-15 seconds, and then turn it to on and let out the clutch. If it runs normally, after your manual ECU reset, then the syndrome could be the issue. The van goes through a warmup cycle every time it resets, so the true test is after a few minutes.

If it is your problem, you can try the cheap and easy capacitor fix, or search eBay for the harness. Usually goes for $25-80.

Background and fix:
http://www.members.shaw.ca/bilbo/WBafm.html

Mon Oct 20, 2008 4:21 pm

I'm not sure on the fuel filter, I'll check my records.

Thanks for the tip Dogpilot I'll try that if I can get it to do the Symptoms again.

Tue Oct 21, 2008 10:23 am

Khoyer01, thanks for posting this issue...

I am about to post the same but while I am making some searches on the subject, you jumped on... If you don't mind I will add my problem here so it will be easier for others to help us.

I have exactly the same problem as you described above plus this: hard start in the morning, engine die, very rough idle.

the van: 1989 Carat, engine rebuilt w. about 40 K miles, new ECU, new MAF, good compression, use no oil between oil change, never overheat.

the hiccup problem time line:

#1. OCT 2007: put new fuel pump + fuel filter. Trip from Orange County, California to Mammoth Lake, CA (about 400 miles). Hiccup problem came and went at about 8000 feet, ambient temp about 60°F. When back home, mechanic changed spark plugs, spark plug wires, changed temp2 sensor, cleaned dist. cap and rotor. Problem didn't occur again because I didn't use the car on long trip after that. (about 3000 total miles that year)

#2 SEPT 2008: Trip from Orange County, CA to Mammoth Lake, CA (about 400 miles), Hiccup problem comes and go but more severe/often at about 8000 feet, ambient temp about 60°F. When back home, talked to mechanic. He check compression, check fuel pressure regulator (good), cleaned dist. cap and rotor, change spark plugs (again). He says may be valve problem (leak) + injectors problem (original injectors 180K miles), Oxygen sensor problem. He suggests work on valves, change injectors, change Oxygen sensor (none was done before the next trip).

#3 OCT 2008: Trip from Orange County, CA to Mammoth Lake, CA about 400 miles), Hiccup problem comes and go but EVEN more severe/often at about 8000 feet, ambient temp about 50°F. In the morning temp about 30°F very rough idle, engine stalled, I have to hold the gas pedal to keep it running. The van ran for about 10 miles on 3 cylinders, hiccuped severely. I let it sit for 2 hours doing photography and then hit home. Surpise ! ! it ran beautifully, has all the power, hiccuped lightly one or twice, no more.

Note: This problem never occurred in mild/warm ambient temp. and low altitude of Southern California. This problem always occurred at cold ambient temp and high altitude, is there a link to it? Could it be the problem is there and the low ambient temp and the high altitude are the triggers?

My thinking: May be something to do with all wiring and electrical contacts (loose or dirty). May be the TPS (throttle position sensor) is bad or out of adjustment, or coil, or it needs new dist cap and new rotor.

At one point during the OCT 2008 trip I was so distressed that I was thinking of getting rid of that WBX and get a Subie engine.

Let's hope that someone can help us in here...

Good luck to you .... and to me too... :-)

Edit: I find this link --> http://www.vanagain.com/bucking1.htm

Tue Oct 21, 2008 10:30 pm

I started experiencing what I think was vanagon syndrome with my rebuilt 2.1 WBX a couple months ago. When I bought the van, the WBX had the VW issued pigtail harness fix already installed (in my mind showing that this had been a problem in the past).

The hiccups started happening on the return home of a trip, and then showed up on the next few outings...to the point of getting pretty bad sometimes. One time I pulled over, turned the motor off, and then restarted it about 15 minutes later...and the problem was gone (ECU reset?).

The next day it starting happening again.

A friend suggested adding a ground to the ECU under the rear seat. I got a piece of 8 gauge wire, crimped a ring connector on, and found a good spot to hold it down on the ECU (one of the screws). Attached it to the body of the van to ground it.

Problem has not shown itself since.

At this point I have to believe that this has made the difference. At first I was skeptical to say so, but it's now been a month and about 600 miles of hiccup-free driving.

It's a simple thing to do, and definitely worth a try!

best of luck.

Wed Oct 22, 2008 11:08 am

thanks Jamos,

I am making a complete list on what to check and what to change and give it to my mechanic.

Wed Oct 22, 2008 2:56 pm

This is an interesting thread for me. It seems like the vans with issues seem to be the newer (digifant) types, does the same thing happen with the 1.9 digijet or a 2.1 running on digijet injector system? :?: If tencent is out there, have you noticed any difference in the two fuel systems and this issue?

Wed Oct 22, 2008 7:13 pm

well Ccisco...

I can't answer your question but I have had a 1985 Wolsburg weekender from 1994 to 2006, I and my family went camping from Alaska to Cabo San Lucas (the tip of Baja peninsula) and many many time in Yosemite, it's was not as good shape as my actual van...

but...

in 12 years....there was NO hiccup .. NONE... ZERO....

and I still don't know why... :shock:

Sat Oct 25, 2008 12:14 pm

I checked my fuel filter it is also new. have we come to any conclusions as to weather our symptoms are indeed vanagon syndrome? I have not experienced any more hiccups or shutters, furthest I've driven is 150mi., just poor starting in the morning and when it has been sitting for a while. it also feels slugish until it is warmed up. very slow steady reaction from when i put my foot into it, to actual acceleration.

I hate to throw parts at a problem but I'm about to with, two expensive parts. AFM and ECU :(

Kyle

Sat Oct 25, 2008 12:25 pm

I just come back from the mechanic shop. I let the van there for couple days. I told them to do the following:

- check and clean all electrical contacts.

- check and clean all ground contacts.

- replace the battery ground cable (they found it has too much resistance)

- replace the MAF (they found a flat spot). Will replace with a new or a rebuilt.

- replace the oxygen sensor.

I will keep you informed.

Sat Oct 25, 2008 12:45 pm

Before I would shell out the money for the new AFM, have them show you this flat spot. Personally I would like to know bout this phenomenon. Mechanics have been replacing this waaaay too much lately with little or no improvement for the consumer. They like the big markup on this part, when the problem is usually quite simple, giving little opportunity for markup.

I loaned my spare to Depravation, but he didn't have any improvement either. It is a part we look to as a failure source, but it usually isn't it. It does have moving parts, so the opportunity for failure is there, but it is a little overblown.

Sat Oct 25, 2008 5:23 pm

Dogpilot, thanks for the suggestion..

I was there for 3 hours, I even guide/help them to troubleshoot. We took the TPS out and test it it was good. We measure the resistance from the engine to the ground post of the batttery. On the ground bolt the resistance is about .5 or 1 ohm. On the battery post the resistance is about 20 ohms. We took the AFM out and measure it full closed = about 50 ohm and full open is 400 ohm. We move slowly the butterfly and and it went from about 50 (closed) to 400 (open) but not smoothly, somewhere along the way at about 180 or 200 the resistance dropped to 70 and then to 50 and and up again and back to 50 again...
We did this many many times and it gave us the same scenario. I told the them to do the same test with the new one if they ever find one..

thanks again

Sat Oct 25, 2008 6:01 pm

Although I could be totally off base (I am not a mechanic), consider the catalytic converter.

I had what sounds like the same problem with my 1991 Vanagon Carat. It was fully packed and driving from Delaware to western Pennsylvania on the PA Turnpike. All went well for the first 150 miles or so, but then I began to have problems.

It hesitated, hiccoughed, and refused to "get up and go." Even on level ground. At first I suspected ethanol in the fuel. I filled up and added fuel injector cleaner. I rode on the shoulder with flashers. I stopped frequently.

I went under tow for the last 37 miles...

Once I arrived at my destination, I was fortunate to be given the number of a local independent mechanic. He asked a series of very pointed questions then asked me to take the van out early the following morning, while the air was still cool, and run it up the biggest hill I could find. It ran like it should. However, once it got warm it started to "argue" with me again.

Turns out it was the catalytic converter. He replaced it, and $114 later I had my beloved vehicle again.

Just another possibility for you to consider. Good luck!

Sat Oct 25, 2008 8:14 pm

Something that is really easy to do and solved the same problem for me was to pull all of the grounds from where they connect to both the engine and the engine compartment, spray with engine, or preferably electrical contact cleaner, and wire brush while they are wet, clean them off with a rag. Do the same thing with the bolts/screws that ground the wires. Spray the bolt holes and clean-out with a q-tip. If possible, buy a battery cable of sufficient length and replace the main engine ground on the driver side of the engine with it.

It was like a miracle after that. It took an hour and cost less than 10 bucks.

Sun Oct 26, 2008 8:16 am

Motogiro,

That sounds like a plan for many of us to do to our vans. Thanks for the tip.

Wed Oct 29, 2008 9:22 am

ccisco wrote: This is an interesting thread for me. It seems like the vans with issues seem to be the newer (digifant) types, does the same thing happen with the 1.9 digijet or a 2.1 running on digijet injector system? :?: If tencent is out there, have you noticed any difference in the two fuel systems and this issue?

I really don't have much hands-on with the Digijet, so I couldn't say. Judging from anecdotal accounts here, I would say that Digijet suffers from just about as many electrical gremlins as the later system. I've said it before that most of the problems with all the Vanagon engine management systems can be blamed on the mediocre job they did with wiring, not the design of the FI systems themselves, which are in fact extremely robust by and large.

The one big difference between the two wbx systems is that Digifant integrated ignition control within the ECU, so more problems can arise there if the ECU isn't well-grounded, is getting reduced voltage supply (although it's supposed to be accounting for that), or isn't receiving clean signal from the Temp2, AFM and Hall gen.

But then Digijet has two additional components to handle ignition that Digifant eliminated, the transistor module and Digital Idle Stabilizer, so there are additional opportunities for failure there. The DIS has been shown to fail a lot, and that wouldn't be so annoying if it simply failed outright (plug the connectors together and away you go), but what it tends to do is degrade very gradually. Since all spark signal passes thru it, that can manifest as all kinds of ignition errata, which are hard to tease out from FI errata without the use of test equipment that most of us don't have access to. Luckily, the DIS is so easy to rule out by just bypassing it, since it's basically a superfluous component.

The subject of this thread, though, was Vanagon Syndrome, and so far as I know, it only occurs with Digifant and originates in the AFM signal. Luckily it is pretty easy to identify, because it has a clear symptom set:

Only happens after extended running at steady rpms (if you're having trouble when driving around-town, VS isn't your problem),

Disappears immediately with a key off-key on restart (no waiting time required that I ever saw; my van had it bad when I first got it), and

May not occur again for hours, weeks, months, whatever. If you're on a highway trip, have the classic VS loss of power, and do a quick restart, the symptoms won't return until you've again spent some time running at a steady rpm, so if you do a restart and the loss of power returns after only a couple minutes, you should be suspecting the lambda circuit instead of the AFM signal.

Wed Oct 29, 2008 9:57 am

0to60in6min wrote: Dogpilot, thanks for the suggestion..

I was there for 3 hours, I even guide/help them to troubleshoot. We took the TPS out and test it it was good. We measure the resistance from the engine to the ground post of the batttery. On the ground bolt the resistance is about .5 or 1 ohm. On the battery post the resistance is about 20 ohms. We took the AFM out and measure it full closed = about 50 ohm and full open is 400 ohm. We move slowly the butterfly and and it went from about 50 (closed) to 400 (open) but not smoothly, somewhere along the way at about 180 or 200 the resistance dropped to 70 and then to 50 and and up again and back to 50 again...
We did this many many times and it gave us the same scenario. I told the them to do the same test with the new one if they ever find one..

thanks again

I've been messing with the AFM's a lot in the last couple years, and was long confused by the test directions in Bentley. At this point I think the only useful AFM test in the book is to look at the IAT (Temp1) thermistor resistance-to-temp according to the table (ohms between pins 1 and 4). The other tests are useless, because they separate out two circuits on the wiper board when what you want to know is the net effect of those two circuits. When you look at the net effect, you see that the AFM is just a potentiometer with a directly-linear response to the varying vane position.

So here's what you do:
With the AFM installed as normal, key off, pull back the rubber boot from the harness connector so you can probe the connections from the backside. Alternately, if you have removed the AFM cover you can probe from inside the wiper box. Connect your voltmeter, not ohmmeter, with ground at pin 4 and the other probe at pin 2 (if your VM is digital it won't matter which is which).

Now key on. What you will see is a clean, linear voltage response that starts near zero and increases to almost 5V as you push the vane open. Move the vane slowly up and down its full range of movement, looking for anyplace the voltage signal drops out or jumps. If you don't see any irregularities in the curve, your vane-pot section is OK (the IAT test has to be good for your entire AFM unit to be OK).

If you want to see more, leave the VM connected and start the engine. At idle, the V is around 1 +/- 0.3 or so (these aren't hard numbers, just what I've seen, so please don't come back fretting that your idle wasn't 1V). Rev the engine and you can watch the V increase with the airflow. A quick blip of the throttle in neutral will show V go up, maybe as high as 3 or 4V, and settle right back down aways because there is no load on the engine revving in neutral. If you were to take it out on the road and watch the V you would see V go up when you put the pedal down and decrease gradually as the engine revs catch up to your desired speed.

This is the AFM indicating engine load. The ECU knows how fast the engine is turning, because it receives the rpm signal from the Hall gen. It's the relationship between actual air volume being pulled in and the potential volume that the engine would pump WOT at a given rpm that represents load. When those volumes are equal is when the load is greatest. The ECU needs this signal to lookup the enrichment values and in the case of Digifant the ignition retard to manage detonation.

That's it, no more looking at the silly sawtooth resistance pattern and wondering what it all means. There are two resistance circuits across the printed wiper board, with printed resistor blocks arrayed along the wiper track. The ECU introduces a regulated 5V at pin 3 (also at pin 1 for the IAT, an independent circuit), and current is split between the two resistance circuits, such that as the vane moves the wiper along the track, the voltage that reaches pin 2 is the result of the average resistance between the two possible circuits. It's the voltage returning on pin 2 that the ECU reads to represent airflow volume and engine load. Simple.

Dog already knows this because A.) he's really smart, and B.) he has a Boehlert Digitool which also looks at the V signal coming back to the ECU and dispays that V.

Wed Oct 29, 2008 10:23 am

10¢ is correct about the raw resistance curves. BTW, not smart, obsessive. I hate loose ends, need answers. Part of the reason 10¢ suggestion is so correct in checking voltage, is this is what the ECU actually sees. The theory of the vanagon syndrome is the wiper gets a vibratory resonance. This bouncing of the wiper on the resistance track causes the voltage to go all over the place making the ECU loose track of the actual fuel air ratio it needs along with the incorrect ignition map. So the car is bucking and acting weird. The reset done by restarting, zeros all the registers in the computer and the bad data disappears.

The fixes, such as the capacitor or the VW pigtail just smooth out the signal. The capacitor acting as a high frequency filter, and the pigtail is actually a small circuit that averages the signal and completely isolates the ECU from the real AFM signal. Both work, the pigtail being more effective than the capacitor, but at 100 times the price.

During a period of excess money last year I invested in the Hot Wire AFM. Does it work substantially better than the AFM, well not better enough to warrant the price, but better. The original AFM design is not bad, but again it has moving parts and is out of production. Most folks spend the $250-300 for a replacement and then find, well that wasn't the problem.

Most vans wold benefit better by having Kyle make a replacement harness for the engine compartment. This would be the best money any van owner could spend, along with a new O2 and Temp II. All the corroded connectors, broken wires and bad connections at the multiple crimp locations in the big bundle would go away. Besides it was really crappy wire to begin with.

We all need to flood him with requests for the 2.L engine harness so he will actually make some. I'd make mine, but I am actually a bit short on time lately for feel good projects.

Wed Oct 29, 2008 10:40 am

Yes, indeed, I'm waiting anxiously for when Kyle tackles the 2.1 harness, too. Not that I would buy one immediately, I've worked the gremlins out of my setup for the time being, but having new ones available might be a boon to my engine customers.

There are also certainly opportunities to actually improve on the physical arrangement of the harness, rather than simply duplicating the OEM setup. Moving the ISCU to a short stub-harness right off the ECU, so it could be positioned inside the vehicle where it is safer and drier would be a nice improvement that I reckon would cut down a lot on the raw footage of wire needed, and might save some of those controllers from failure brought on by the tough environment they were mounted in.

Offset the cost savings there (small) with a huge multipin master connector that would enable engine removal with one disconnect (huge), and I would lay out the scratch to get myself a new one!