Itinerant Air-Cooled

Mountainhide wrote:Yes it does. I hooked up a vacuum guage today and I'm running 9". I got some carb cleaner and sprayed it down everywhere needed and the vacuum never changed. Going to the shop tomorrow.

9" sounds really low ..... IIRC think you need to be around 18" at idle?? Can someone more knowledgeable than me support this? Also, I'm not sure if carb cleaner is volatile enough to give you a change in idle - needs to be starting fluid...and a fresh can at that. Did you ever replace/inspect the TSII?

My two pennies - unless it is your DD, or have some epic trip coming up, I would take the time to trouble shoot yourself....about the only thing I will take my bus in to a mechanic (I'm excluding itinerant visits) is for front end alignments. Search this site - I had the EXACT same problem...haunted me for a couple of years.

Federal : 15-17" inHg at idle, 7.5 BTDC, 800-950 RPM, CO% 1.0 +/- 0.5 (14.28 AFR - 13.94 AFR)

On a California emissions vehicle times at 5 degrees ATDC, with both hoses on, idle vacuum will be in the 12" Hg range at the prescribed idle speed of 850-950 RPM, so 9" isn't too far off, but a bit on the low side.

Thanks SlowLane, I forgot he has a California model.

luftvagon wrote:Thanks SlowLane, I forgot he has a California model.

I had to scroll back to the first posts to refresh my memory.
The California deceleration valve also opens at a lower vacuum than the Federal one. Like at about 15-17" Hg. Probably not related to the issue here, but worth keeping in mind.

Well here I am. Actually I do have 15" of vacuum at idle. Still experiencing the same problem. Unfortunately I am involved in a major remodel on our property that is consuming all my time right now. I actually have the van at a shop. Once we find something out I will let everyone know. Thanks for all the advice. All of it I put to practice and still have the problem. Here it is . It is very drivable as long as you don't hard excelerate. I can rev it up in my shop to the point that it starts surging and it spews black smoke and is about 8% rich. No where close to reaching the wot switch. Exchanged out with a known ECU board and had the same problem. Checked out temp sensor, rebuilt air flow meter, timed, tuned checked dwell at 1600 and 3200 rpms,fuel press,new filter. And the list goes on.

Let you know when we find something

Mountainhide, they dont rebuild AFM.. at best they moved, and re-positioned wiper or potentiometer board, and reset the spring to factory tension...

That's a new clue you gave us... starts surging, and black smoke comes out -- so we know fuel is not cutting out, and fueling is related to pulses from coil, and or ignition control unit on California model.... divided, and then padded by TSII, TSI and AFM voltage, so...

... you either have a very bad vacuum leak, and AFM was set to compensate for such.
... your AFM is broken or configured incorrectly. spring too loose, or wiper moved to the left too much.
... ignition control unit is broken, and is pushing more pulses to the ECU at higher RPM.
... TSII not grounding right, wiring broken, bad TSII
... cold start valve opening on its own -- highly unlikely -- but plausible. ..

..and if I was a betting man.. I would say ignition control unit or AFM or vacuum leak with rest of the system configured to compensate, or TSII in no particular order. AFM is very easy to test for defectiveness using analog V meter. TSII does go bad, and they will check out good on bench, so I wouldn't rule that out too.

Happy hunting!

oh, and one more thing i thought off...i'd try disconnecting one injector at a time, and trying to rev up past 3000.. just for sheets and giggles. sticky injector unlikely, but plausible.

Actually they did rebuild the AFM and calibrated. New potentiometer board, spring and all related parts. Rebuild done by Richard at FIC in Tracy. No vacuum leaks already tested for them.nCompletely went through the wiring harness, which all my troubleshooting for the past twenty years has been done with my SIMPSON 260 analog. All readings according to my Bentley manual are with in specs. I will do the injector test for fun you just never know.

There were no new AFM boards made that I know of, unless Richard had someone else make a new board or stocked up on these boards... I called BOSCH, Sfernice and Bourns two years ago to confirm. Part has been discontinued for a long while. Can you please take a picture of the AFM potentiometer board with any identifying marks. It would be interesting to see if there are wear marks and where your pointer is at.

There are no wear marks. The old one had wear marks big time. This particular company is an old school fuel injection shop that makes repairs and rebuilds on all related parts. You can google them to see their site. Fuel Injection Corporation, Tracy Ca.

Please take a picture of the AFM potentiometer board as well.

updates?

Well I got it out of the shop and they unplugged the alternator, which is new the problem was resolved. They re- wired the alternator from the starter to the battery. Still confused as to why. Still having issues at full throttle. They said after the cat I have 6 to 7 pounds of back pressure and it is only suppose to be around 1 to 2 pounds. The vanagon is in my shop on the back burner until I get caught up with building projects. Thoughts?

Sorry Mountainhide, I know nothing about mechanics of exhaust back-pressure and catalytic converters. Logically speaking, the higher the back-pressure, the less power engine will produce. Theoretically, this could be preventing you from making power, and making your van buck. You could always take off your catalytic converter, and run the engine to test this theory. Keep us posted. Still wanting to see those pictures - engine bay, AFM board, etc.

Sounds like you are very close in getting this thing identified.