help?'81 Westy won't idle...

Hi, I have a 1981 Westfalia, had been stored for about a year..It starts fairly easy...idles well when cold, but after a few minutes (warm) won't idle unless I give it throttle.Has fresh gas, can't find any vacuum leak etc. Does anyone have any suggestions? aux air valve? idle stabilizer? temp. sensor? O2 sensor? Has anyone else experienced this? I'm not looking for any guesses, but if you have been thru it, I'd love to hear what you did to rectify the problem. Thanks a lot for any answers.

Reply to
fandalay
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Check your compression... Just went through the same thing. Turned out to be a burnt intake valve and a whole lot of $$$$$

Reply to
westfaliaguy

Compression is good. runs smooth when I give it a bit of throttle, just won't stay running when I take my foot off the gas.

"westfaliaguy" wrote in news: snipped-for-privacy@z14g2000cwz.googlegroups.com:

Reply to
fandalay

Compression may be good..... but what is it????

Check for a hose off or split....... sounds like a vacuum leak.

Reply to
Karl

The most common cause for this is a vacuum leak. It apparently is not a bad leak as the cold start injector provides enough gas to keep it running as long as it is working. Apparently your auxiliary air valve circuit is working properly as well.

What is happening to that vintage of engines is that the original pre-formed hoses throughout the FI system are crumbling away, especially on the bottom sides, closest to the heat-source. Unless you take each one off and inspect it, you'd swear it was as good as new. Take it off and give it a little squeeze and the sucker crumbles to dust!

Most commonly what happens is while driving, a person has a rough railroad track crossing and then the engine dies and won't come back to life. They inspect everything and all the hoses appear to be in place. Because they are pre-formed and have been in that position all these years, they stay in close enough proximity to their attachment that they appear to be snugly attached. Primary suspects are the big hoses that attach to the "S" hose at the throttle body.

Check all the hoses by physically taking hold of each end of each one. Procede with diagnosis by clamping off all the vacuum lines (one at a time if you wish to isolate the cause)

Related items: Fuel pressure regulator possibly gummed up and not offering enough resistance (fuel pressure too low) Clamp the return line partially (if fully clamped off, engine will run way too rich and black smoke will billow - fuel pressure can exceed 100psi when clamped off!)

CHT sensor at (Hmmm - they are at #3 cylinder on '79 and earlier - are they at #1 on Vanagons?) At approximately 68°F they are supposed to have approximately 2400 ohms resistance. As they get warmer, the resistance drops off (leans out mixture) SO- if for some reason that circuit is open, the engine will puff black smoke and probably not run, if closed (shorted to ground) there will not be enough fuel to keep the engine running.

The triggering mechanism for the injectors is the ignition system. Are you certain all is well there? I suspect it is. I also suspect you have plenty of fuel pressure as your cold start injector would place an additional drain on the fuel rail and if there was not sufficient pressure for the 4 main injectors, the 5th injector simply would not help.

Of the "storage" related items: Varmints chewing through rubber hoses... Here's a good one: The vane inside the airflow sensor may be stuck. You can actually reach in with a pencil (eraser end) and push and prod and wiggle it to see if it swings freely. Also related is forgetting to re-plug the airflow sensor wiring harness when servicing the air cleaner.

Please write back what you find / don't find. Was it stored outside? Is there water in the gas (Not likely to cause your symptoms, but there could be a combination) Also - double relay could be screwed up, but if it runs after you release the key from the "start" position, not likely. Hope I've helped. -BaH

Reply to
Busahaulic

I just re-read your symptoms. Does it run well when off-idle? There is a possibility, however remote, that the surfaces of the PC board inside the airflow meter that the points wipe accross could be contaminated or simply worn out. It usually happens to vehicles that have been exposed to great amounts of dust but high moisture could cause corrosion if the points sat in the same position and there was already some contamination. If the big black plastic cap (kida square about 2" x 2.5" as I recall it - and flat) on the top of the airflow meter has been removed ever, there is a high liklihood. If it is still glued on, much less liklihood.

Most commonly, these wear grooves at "normal cruising speed" location and the symptom is this: You drive along on level road with no abnormal resistance (like wind) and you are near your normal cruising speed, holding a steady throttle. You sense that the engine is no longer running and you push harder on the throttle or release slightly on the throttle (either one) and the engine "fires up" again. The cause is a worn spot on the PC board.

I am assuming through all this that you have L-Jetronic FI. It was stock on 1981's... The Oxygen sensor should not be a factor in what you are experiencing. If it runs well above idle, fuel pressure, injector dwell time and head temp semsor should not be factors. I still "lean" toward a vacuum leak of small-to-moderate size. Inspect the hoses carefully. Inspect the big "S" hose as they crack terribly (I hear shoe-goo is the fix!) {About 8-9 years ago I searched through two bins full of "S"hoses

- each bin was about 3ft X 3ft X 3ft heaped full - looking for some that had no cracks. Out of all those - maybe a couple hundred? - I found 3 that had no cracks in them and only one was in excellent shape. I was looking for the next older model from yours, so that excludes all the Vanagon ones in the bins, but the point is, at this age, they are failing} You also have small vacuum lines to your distributor (and a diaphram there), to the fuel pressure regulator, to the air cleaner charcoal cannister valve... and the big line to the brake servo with inline check valve that sometimes does not seal completely. Do you have an EGR circuit on that engine? Mechanical? You can remove the valve, make a new gasket with no hole in the center and bolt it back together to see if there is a vacuum leak there. If so, you can leave the block in place. Decel valve? Put corks in the attachment nipples so there is no vacuum leaking - if it solves the problem, you can also live without the decel valve and will have better throttle response without it, but more rumbling and popping on deceleration and downhills.

Vacuum. I cast my vote for vacuum. (Change your fuel filter, BTW!) -BaH

Reply to
Busahaulic

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