1980 Vanagon: Engine speed not decreasing when decelerating

[cegammel]

Hi all,

I have yet another issue: My van runs great, thanks to you guys, but maybe a little too well. When I push in the clutch and take my foot off the accelerator, the engine speed maintains at whatever it was running before decelerating. If I can get the van stopped, put it in first and then ease out the clutch, the engine speed drops under the lug of the van's weight, and then stays at a normal low idle. It's smooth at both low and high engine speeds, and everywhere in the middle; it just doesn't know when to stop. I've tried adjusting the throttle speed switch, with no change.

Any help is appreciated!

[Amskeptic]

If I ease out the clutch, the engine speed drops then stays at a normal low idle.

Sticky distributor advance . . . slightly fast idle speed.

Adjust idle to 950 rpm.
Check timing here.
Rev engine.
Idle now fast?
Check timing here.
Let us know.
Colin

[cegammel]

I assume there's no way to do this one without a tachometer?

[ruckman101]

Tach/dwell meter, yep. Otherwise, just an ear.

neal

[SlowLane]

Mine has done this at various times in the past as well, usually when it's gotten good and warm.

Aside from a sticky distributor advance mechanism (which is a very good thing to take care of in any event), It could possibly be a mis-adjusted (ie. too tight) throttle cable. Could be that it's just got enough tension on it with throttle closed to sometimes keep the throttle plate open just a hair. May also be a sticky throttle plate. The quality of the fit of the VW throttle bodies leaves much to be desired.

To test: With it idling fast after releasing the throttle in the drivers seat, get to the back of the van and manually put pressure on the throttle mechanism to force it closed (well, don't reef on it with all your might). If the engine speed drops to normal idle, try repositioning the throttle cable clamp to provide for a little more slack in the cable.

[Amskeptic]

Mine has done this at various times in the past as well, usually when it's gotten good and warm.

Aside from a sticky distributor advance mechanism (which is a very good thing to take care of in any event), It could possibly be a mis-adjusted (ie. too tight) throttle cable. Could be that it's just got enough tension on it with throttle closed to sometimes keep the throttle plate open just a hair. May also be a sticky throttle plate. The quality of the fit of the VW throttle bodies leaves much to be desired.

To test: With it idling fast after releasing the throttle in the drivers seat, get to the back of the van and manually put pressure on the throttle mechanism to force it closed (well, don't reef on it with all your might). If the engine speed drops to normal idle, try repositioning the throttle cable clamp to provide for a little more slack in the cable.

Another very good point.
Colin

[cegammel]

It'll be a week or two before I can get a tachometer and get on this. I'm sort of leaning toward sticky pedal...Is there a way to de-sticky the vacuum advance? I haven't checked the book on the distributor at all, so I'm woefully uneducated on this one.

[Westy78]

I'll add one more scenario that I've experienced that caused a hanging high idle when coming to a stop. At one point I had the fuel mixture adjusted to rich. Adjusting it back to where it should have been corrected the lazy idle drop.

[cegammel]

It looks like I'll be working the next several weekends, so this job may have to be added to the Colin list. Is there any truth to the 'remove the access on the distributor and spray WD-40 inside' trick? That seems a little fishy to me...

[SlowLane]

It looks like I'll be working the next several weekends, so this job may have to be added to the Colin list. Is there any truth to the 'remove the access on the distributor and spray WD-40 inside' trick? That seems a little fishy to me...

That would probably work in the short-term, and would be a good diagnostic step to see if the advance mechanism is indeed the sticky culprit. But you would want to follow it up in fairly short order with a disassembly and re-lube.

It isn't all that difficult, but you need to have a clean area and a calm mind for it. If you can source a junk distributor from a wrecker to fiddle with and learn on first, that can make the job less stressful.

[cegammel]

If I ease out the clutch, the engine speed drops then stays at a normal low idle.

Sticky distributor advance . . . slightly fast idle speed.

Adjust idle to 950 rpm.
Check timing here.
Rev engine.
Idle now fast?
Check timing here.
Let us know.
Colin

Ok, i checked the idle speed, and it is right on. I forgot about the accelerator cable tug, that will be tomorrows job .

[Amskeptic]

Ok, i checked the idle speed, and it is right on. I forgot about the accelerator cable tug, that will be tomorrows job .

My test was not a test of the idle speed, per se.
It was a test of initial timing at idle speed vs timing at hung up fast idle vs timing at re-established idle speed. That is how I distinguish between things like "hung accelerator cables and hung distributor advance weights.

per the lubrication angle, you also have two shafts in the distributor, a lower shaft and the upper shaft which has the breaker cam lobes. The felt wick under the rotor is to allow you to apply a drop of oil or two and let it slowly work down between the shafts. The weights should not get a generalized WD-40 spray with distributors that have breaker points. They should be carefully spot-lubricated with engine oil. Pertronix? Not so sensitive to oil vapors.
Colin

[cegammel]

Oops...I'll try again. I don't think my distributor is Pertronix. I'll try spot oiling this weekend as well. The van's a California model with electronic ignition...I don't know enough about the distributors to know if that matters as far as this conversation is concerned. I'll hold off on the WD-40 spray...

[Amskeptic]

Oops...I'll try again. I don't think my distributor is Pertronix. I'll try spot oiling this weekend as well. The van's a California model with electronic ignition...I don't know enough about the distributors to know if that matters as far as this conversation is concerned. I'll hold off on the WD-40 spray...

Any electronic distributor should not have generalized spray of lubricant.
Good call . . .

[cegammel]

Ok...this is getting annoying...the van only does this racing engine thing when very warm (more than 30 minutes of straight driving). Dripping oil around the dist. shaft doesn't seem to help, and when I was in the yard and able to get to the engine bay to pull the cable, I couldn't get it to race...

I guess I can stick the wife in the back to wiggle my throttle while I drive...