Continued: stumbling/hunting idle & intermittent loss of spark

[Salinity]

So I'm gathering bits and pieces to start the next stage of troubleshooting and decided to wiggle some wires again. While the engine didn't cut out, it was oscillating after initial startup.

I found that wiggling the left connection from the idle switch seemed to coincide with some initial poor running, and lack of throttle response. However, when I unpluggedthat connection, idle and throttle were ok.

I was slightly wiggling the ignition wire at the coil end and felt spark on may hand/arm twice. nothing big, but perhaps that wire is toast? It's one of those crappy setups with a straght crimp wire bent into a 90* boot. I have some STIs on the way.
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85 1.9L GL Tintop

[Vanagon Nut]

Using the test method shown in Bentley, with meter probes and relevant parts tested then securely connected, as you measure each ignition wire, bend each at-near each each end, push-pull each connector, watch meter for an open circuit or significant resistance change.

Did you try leaving the idle control system disabled?

The Digijet manual has some fairly detailed really useful info on the idle throttle switch.

Neil.
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1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[Salinity]

So the apparent spark loss persists after addressing the Hall Sender pigtail.

V-Nut - I tried running with and without the idle control system engaged - I ran to the store with it hooked up and it ran ok, but idle was still wonky (likely not long enough of a run to make the issue show itself). I disconnected at the store (plugged ends together) and the ride home was a challenge - multiple stalls/spark loss events over 2 miles. I don't think the ICS disengagement caused additional issues (except maybe lower idle?), nor do I think it will solve my riddle. I'm still not clear whether the idle "drop" is related to my acute spark loss or a separate issue. It's definitely hunting after warmup - starts around 1000 rpm steady and slowly comes down to 600ish. Then the tack nearly drops to 0 at times and something kicks in to get it back up, then it oscillates between 6-800 and 100ish. Occasionally it will just stall out.

I really want to change out my ignition wires and coil given what I feel are apparent issues described previously (zaps from the 90* coil end wire connection when gently moving wire around and janky wire connections - I had to re-terminate dist end as the connector broke off in the dist) - I have the wires (STI), but I'm awaiting a new 0061 coil & new dist cap (with pins) from BusDepot so I can upgrade to the pin-style connections. I placed the order 2 weeks ago, as items showed in stock, but I was just informed the coil is NOT in stock. Hopefully I'll get some more info on Monday about supply - otherwise I'll go another route.
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85 1.9L GL Tintop

[steve244]

Doesn't NAPA or other local parts stores have this? Is there something special with busdepot's parts?

[Vanagon Nut]

Other VW's might use the same style wire from coil to distributor. If so, test, install, a known good used coil to distributor wire, see if that changes anything?

e.g. RI CL listing for '91 Cabriolet

https://providence.craigslist.org/pts/d/smithfield-1991-vw-cabriolet/7498746238.html

"thousands" of VW parts:

https://providence.craigslist.org/pts/d/smithfield-vw-parts-thousands-of-new/7485563073.html

Mk2 VW parts:

https://providence.craigslist.org/pts/d/wakefield-parts-for-volkswagen/7491127254.html

Even those Mk2 window cranks might fit a Vanagon? edit: if your Vanagon has a 19 relay for wipers and that seller has a "99" "programable" intermittent wiper relay for a fair price, that part can be swapped into your Vanagon. Very useful.

Measuring resistance of the coil to dizzy wire is likely moot now but testing to confirm it or other wires have a fault would be wise.

A random idle drop and/or engine cut out is likely due to an electrical connection making/breaking contact. A consistent rhythmical pulse up/down might be caused by something else.

As surmised, your engine may have more than one issue causing symptoms you see.

Neil.

[brickster]

Agree with Vanagon Nut: test your wires and coil. Have you already tested the Hall control unit?

[skills@eurocarsplus]

[Salinity]

[Salinity]

[Howesight]

Testing an ignition coil is not a simple matter. You can check the primary side and secondary side for resistance. I don't know the specs.

That said, if the engine will start and run smoothly without ignition-related hiccups, then the coil is good before heat issues are accounted for. In hot ambient temps, with a hot engine compartment, the failure modes can appear. The coil windings, typically, are varnish-coated copper wire. Heat and time can cause the varnish (or other insulator) to fail and short out the windings. The short can be temporary and then disappear when the coil cools off. When a short does occur, then the maximum voltage the coil will put out is diminished. This usually will not affect low-load conditions like idling or low-load driving.

Having said that, it remains possible that an internal short or break in internal wiring is causing intermittent coil output problems. However, the probability that your wandering idle has anything to do with the coil is exceedingly low, in my opinion. I would suggest focussing on other areas.

The Digijet idle control system depends on a proper base idle adjustment and uses variations in spark timing to smooth out idle speed. Its effectiveness is, therefore, very much dependant on having the base idle speed adjusted as close as possible to the specification.

I am not commenting here on the cutting out and stalling problems, just the wandering idle. However, a higher base idle speed might indirectly help with the stalling issue.

Generally, there will be no impact of a
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'86 Syncro Westy SVX

[brickster]

[Salinity]

[brickster]

NP! Hoping that a new set of wires is a game-changer for you. While you wait for parts, clean up all coil connections.

On my coil, the female connector for the cap wire was filthy and oxidized heavily. Not surprising given the engine compartment's exposure. When you reassemble your new ignition wires, use some dielectric grease on the rubber boots (not on the electrodes) to seal out moisture and grit.

[Salinity]

Right on - definitely plenty to address while I wait, but I really want this issue sorted so I can enjoy the van locally between projects. To that end I send BD a cancel my order email and placed an order with rock auto for an aftermarket coil & Bosch dizzy cap (to convert mine to pin style m4(?) connectors).
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85 1.9L GL Tintop

[Salinity]

Happy July 4th weekend all.

So my first report from the parts cannon fizzled like so many defective bottlerockets. I installed a new coil, pin-style dizzy cap and STI wires all around. The first startup after this installation gave me hope - things sounded GOOD and smooth. nice steady idle and just sounded good - for about 30 seconds. Then the stumbling/hunting began. After 2-3 rounds of stalling and restarts things actually got worse - it wouldn't stay running for more than 5 seconds and would pretty much stall out immediately. Further, when trying to overcome stalling with some throttle there was little to no response and almost sounded like it was missing.

The cap didn't come with a new rotor, and I didn't do any sort of adjusting there - perhaps I should have? The cap is a BOSCH, as is the dizzy, so I figured plug and play, but maybe not. I'll go back and do some reading.

I went ahead and removed the new stuff and put the old wires and dizzy cap back on with the new coil and it started and idled as before - wandering after the initial 5-10 seconds and trying to overcome itself. But it didn't immediately stall out as with the new cap and wires. I swapped in the old coil just for fun and there was no change. Unfortunately, in my haste and frustration, I parted the new STI coil-dizzy wire at the boot. Pretty bummed, as those wires don't seem to be user-terminat-able.

So I suppose this means it's not my coil or wires that are the issue, though the dist and/or hall sender could still be a culprit (next up in the parts cannon?).

Just for fun I tried the 180* ECU trick. That didn't yield any changes.

I haven't swapped in a new ignition switch yet - I can't imagine that's causing the issue (I wiggle the key at idle and nothing really changes), but would that be worth trying? Any other suggestions (other than going back through setting the idle control per the manual again)?
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85 1.9L GL Tintop

[DanHoug]

i'm not going over 7 pages of posts to see what's been done but given your current conditions, there's 3 basic questions i would want resolved:

- is this fuel delivery related?

- is the fuel mixture related?

- is this spark related?

Fuel delivery: put a pressure gauge on the tap and a noid light on the injector harness. you want the BOSCH2 noids, a couple are handy to test one side at once. you need to observe all 4.

Mixture: remove the AFM cap and when the missing starts, push the vane around both directions from where it is setting/twitching. does it run smoother in one direction or another?

Spark: put a timing light on the coil wire, observe the flashes when running smooth and then observe when roughness starts.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Salinity]

[crazyvwvanman]

Have you tried a different ignition module?

https://www.ebay.com/itm/184237224180?hash=item2ae564f0f4:g:40gAAOSw-B9ehjmy

Mark

[Ahwahnee]

[skills@eurocarsplus]

i'd also be looking for vacuum leaks.

like i said, i have a complete engine/harness etc if you're interested. i think i have some idle stabilizer relays as well

it refusing to take fuel could also be a worn AFM track. the pic you posted seems to be pretty worn. i just tossed a low mileage one about a month ago as no one wanted to pony up 50 bux for it.

fuel pressure is important, but so is volume. don't get fooled that the pressure is ok, make sure you check how much is flowing
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