TheSamba.com :: View topic

Tue Feb 05, 2019 9:25 am

The saga continues.

I checked circuit 15 at the neutral switch and didn't have any issues there.

Then, I checked the big black connector in the engine bay. With the engine running, while messing with it, the engine nearly stalled. Or at least I thought it did. So I cleaned all of the contacts thinking I had found the issue.

Went for a test drive, and it was just as bad as ever.

EDIT: I messed with all of the engine side connectors with the engine running, literally all of them, and nothing caused a hiccup or stall (aside from the big black connector mentioned above).

I tested the fuel pump by jumping the wiring, bypassing the relay. I can't help but wonder if I have a faulty relay, or two. Fuel Pump relay and/or main power relay?

VWHammer - I paid a guy named Dave to do the wiring harness. It was plug and play. He has a good reputation, and has been helping me diagnose this, a bit.

Tue Feb 05, 2019 9:39 am

Was it Dave of TDC shop fame?
He did my harness and has a pretty good set up for making sure it all works.
He even replaced a couple of lengths of cruddy wire on my harness because they were only working intermittently

Tue Feb 05, 2019 9:49 am

vwhammer wrote: Was it Dave of TDC shop fame?
He did my harness and has a pretty good set up for making sure it all works.
He even replaced a couple of lengths of cruddy wire on my harness because they were only working intermittently

Yeah, that's the guy. He has a really good reputation, so I'm not doubting his craftsmanship.

I keep coming back to the fact that...

A) It ran perfectly for upwards of 3k miles before my trans swap.
B) It ran perfectly for upwards of 200 - 300 miles AFTER my trans swap.

This makes it feel like it's more a part failure issue.

From my understanding, the following parts are more of a "pass/fail" type part. i.e. they either work, or they don't. So, should I rule them out?

- Fuel Pump
- Coil
- MAF

Parts that could intermittently fail:

- ICV ? - would only apply to stalls at idling speed, right?
- TPS - I still need to run the TPS tests.
- Crank positions sensor - need to test this still.

Tue Feb 05, 2019 12:09 pm

h00drat wrote:

I keep coming back to the fact that...

A) It ran perfectly for upwards of 3k miles before my trans swap.
B) It ran perfectly for upwards of 200 - 300 miles AFTER my trans swap.

This makes it feel like it's more a part failure issue.

From my understanding, the following parts are more of a "pass/fail" type part. i.e. they either work, or they don't. So, should I rule them out?

- Fuel Pump
- Coil
- MAF

Parts that could intermittently fail:

- ICV ? - would only apply to stalls at idling speed, right?
- TPS - I still need to run the TPS tests.
- Crank positions sensor - need to test this still.

It sounds like a wire(s) or connection(s) is causing this issue.

I don't think the fault is at the fuel pump itself or even due to a fuel delivery issue.

Relevant sections in 24a of Bentley have great useful info.

In my limited experience and re reading Bentley 24a, fuel pump aside in terms of just the part itself:

the coil could fail intermittently or outright.

MAF typically gets dirty and less efficient (easy to clean) but could fail outright.

ISV typically gets dirty thus less efficient or stuck but can fail outright.

Failure of ISV or MAF causes the engine to go into "limp mode" but it should remain "drivable", not stall. Failure of both parts at same time, not sure what engine would do.

If the G28 RPM (crank) sensor fails the engine won't run. Wiring to it could become intermittent or fail but I'd consider the part itself to be a "pass/fail".

Dirty or corroded G40 hall sensor contacts can cause an engine stall but the part itself is most likely a "pass/fail" thing.

While tooling around AZ, I had a poor G40 connection cause engine cut out "blips" at highway speed then an outright stall during a left turn in city traffic. Good times. [edited] At the local AutoZone parking lot I used fine emery to "mash unit" clean the hall contacts then used contact cleaner, Q tips to flush, clean that part out then contact cleaner on the female connector pins. Doing this solved the issue and it has not reappeared.

If the engine consistently stalls when moving the big round black plug, closely inspect engine harness wires where they exit the plug. A magnifying glass and good light will help, especially since grease and mung gather at that point. Do consider what wires get moved or stressed when moving that plug and or disconnecting-reconnecting it.

Neil.

Tue Feb 05, 2019 6:24 pm

On a business trip, so I’ll have a few nights off from the van. Which gives me more time to think? Anyway...

One thing that happened during the trans swap is that the battery died. Like dead dead. I thought I had brought it back, and I installed a volt gauge to keep an eye on it. I wonder if maybe, just maybe, the battery is failing?

I checked my voltage today after it sat overnight in the cold and it was In the low 12’s. Like 12.3 ish. After driving it last night it was closer to 12.9. 12.3 sounds quite low. It takes longer to start than it use to, but I still don’t see how this could necessarily be a likely culprit. Thought it worth mentioning.

Sorry for typos. This site sucks on mobile.

Wed Feb 06, 2019 1:03 pm

IMO, I don't think a low starter battery by itself is causing the engine to cut out or stall. Especially if you had a manual tranny, van was in gear and engine RPM was above idle when cut out or stall happened. But.....

since your van has the auto transmission.....

in gear at a stop, engine at idle RPM or if coasting in gear foot off the gas did same, if lots of electrical accessories were on at that time and the battery was really low, dead or dying (was creating a big load on charge system), maybe at that point, the alternator isn't able to keep up with those electrical demands and the ignition and/or engine management isn't seeing enough voltage/Amps to operate correctly and a stall or cutout might happen. IF so, if you have house batteries, if they were quite low or in poor condition, that might exacerbate things. And, a poorly operating alternator might do same.

Try operating all your electrical loads, maybe with your house batteries drawn down, then coast in gear or put van in neutral. See what happens. Measure alternator voltage. Clean all your battery connections.

edit: I've run my 15º ABA with an old borderline starter battery and both house batteries run down somewhat low, headlights on and maybe even heat fan on and never had the engine cut out at idle. IIRC, though a rough measurement, the engine management including the ignition coil only drew 4-5 Amps at idle.

Neil.

Thu Feb 07, 2019 5:43 pm

I don't have any house batteries. Just the one starter battery.

Based on your response, it sounds unlikely that this is the culprit, especially since my volt gauge is showing good numbers when running (14's). Engine has only died once or twice when idling, typically dies while running / driving.

Business trip was busy, so I didn't have much time to ponder all of this stuff. I heard it's pretty cold back home, but I'll probably still try to get back to it this weekend. I need to spend some time reading your posts, Neil, and try to figure out what my next step is.

I'd LOVE to trouble shoot / rule out ONE thing at a time.

Thu Feb 07, 2019 10:47 pm

You say the rpm's drop when this hiccup occurs. I may have missed your explanation in a previous page, but can you elaborate a bit for me?

Is this a sharp cutout or a surge? A sharp cutout is likely an ignition issue where a 'slow' RPM drop usually points to a fuel issue. You'll see the tach fall off suddenly if it's ignition related while it slowly fades out when you have intermittent fuel delivery.

Have you checked your plugs, wires, and cap? Don't forget to check the simple things :) I've had an instance where my cap wasn't clipped on perfectly after a fresh tune-up and the rotor wore the center contact irregularly. It worked great the first few hundred miles, but eventually broke contact and sputtered out. Brilliant!
How do the plugs look? Even burn?
How about the hall sender? Is yours still firmly attached to the dizzy? Give it a wiggle while its idling and see if it cuts out.
These are simple tests that can rule out important variables.

Also, ABA coils are known to shit the the bed...it's their Achilles heel for some reason or another. Buy a new one for a spare, but also plug it in and see if it solves your issue.

Intermittent cutouts are the hardest to troubleshoot...but you'll get there. It's usually something simple.

Fri Feb 08, 2019 5:02 am

Does the tach get signal from the hall sensor in the distributor? I’ve had a ball sensor fail in a 93 5cyl engine before. I was also going to suggest the plugs wires cap rotor thing. The plugs on my vr6 were bad and any pedal over half way made that thing fall on its face, hiccups and bucking.... your problem is intermittent though, mine was constantly. Good luck man. Don’t give up!

Fri Feb 08, 2019 9:24 am

uberaudi wrote: You say the rpm's drop when this hiccup occurs. I may have missed your explanation in a previous page, but can you elaborate a bit for me?

Is this a sharp cutout or a surge? A sharp cutout is likely an ignition issue where a 'slow' RPM drop usually points to a fuel issue. You'll see the tach fall off suddenly if it's ignition related while it slowly fades out when you have intermittent fuel delivery.

Have you checked your plugs, wires, and cap? Don't forget to check the simple things :) I've had an instance where my cap wasn't clipped on perfectly after a fresh tune-up and the rotor wore the center contact irregularly. It worked great the first few hundred miles, but eventually broke contact and sputtered out. Brilliant!
How do the plugs look? Even burn?
How about the hall sender? Is yours still firmly attached to the dizzy? Give it a wiggle while its idling and see if it cuts out.
These are simple tests that can rule out important variables.

Also, ABA coils are known to shit the the bed...it's their Achilles heel for some reason or another. Buy a new one for a spare, but also plug it in and see if it solves your issue.

Intermittent cutouts are the hardest to troubleshoot...but you'll get there. It's usually something simple.

Hey! Thanks for chiming in.

The tach drop is, in fact, instantaneous. Not a slow drop. I'm glad for your input as it helps me focus on the electrical system, which fortunately is where I have been spending most of my time.

I was suspicious of the coil from early on, so I ordered a new one. It should arrive today. I figured if I was going to start ordering parts blindly, it should at least be cheap ones, and also ones that I already wanted to replace. If nothing else, I'll know that I have new coil :)

I'll check the dizzy, plugs and wires again, but last I checked, there were no issues there.

Fri Feb 08, 2019 3:18 pm

dhesq wrote: Does the tach get signal from the hall sensor in the distributor? I’ve had a ball sensor fail in a 93 5cyl engine before. I was also going to suggest the plugs wires cap rotor thing. The plugs on my vr6 were bad and any pedal over half way made that thing fall on its face, hiccups and bucking.... your problem is intermittent though, mine was constantly. Good luck man. Don’t give up!

AFAIK no, the tach gets it's signal straight from the negative terminal on the coil. If that wire were to come off, the tach would drop, but I don't believe that would actually cause the motor to stop running. Of course, I haven't tried that (maybe I should?).

The quickly dropped tach keeps pointing me back to the coil, or power to the ECU. I feel that if either of those were to fail, the tach would lose signal at the same time as the engine cutting out. Not to say those are the ONLY two logical variables left, but definitely high on my suspect list.

Fri Feb 08, 2019 5:22 pm

I have been trying not to comment on this as my conversion is different wiring than yours. So compared to Neil my knowledge is low on this system. If you tac drops to 0 like when you shut it off that means you are losing spark a electrically problem. So on my van power to the coil and distributor comes from the fuel pump relay or the ecu relay I don’t remember. In my van they are under the rear seat. I would hook up a volt meter to where the power comes out of each of those relays and see if the voltage drops when the van stops running that will tell you if you are losing power to the hole system or part of it and work from there. Happy hunting. John

Sat Feb 09, 2019 12:03 pm

h00drat wrote:

AFAIK no, the tach gets it's signal straight from the negative terminal on the coil. If that wire were to come off, the tach would drop, but I don't believe that would actually cause the motor to stop running. Of course, I haven't tried that (maybe I should?).

Since you installed a wire to connect the Vanagon tach to the Jetta coil "1", .....

Temporarily disconnect that added tach wire?

Longshot theory;

if that wire were shorting out to metal coil housing, i.e. to vehicle frame, would that cause the ignition to cut out?

Neil.

Sat Feb 09, 2019 1:10 pm

Lower fuse panel and inspect for any burned or faulty looking connections or contacts. IIRC theres a pin or other contact to panel that can get heat damaged and in part, possibly cause the ignition system to fail.

Closely inspect coil contacts, connector to coil and wires to that connector.

Can't recall if you checked already but check main ground connections at metal ground buss at engine block.

Bentley 28a-4 outlines testing power to coil and coil itself. As long as your test connections are reliable and don't cause a false reading at VOM, you could move the coil connector around to flex the wires to it and see if a fault appears (loss of switched positive or constant ground. Of note, that ground comes from engine block through big round connector then to coil).

IMO, the older Telefunken coil with green label will stand a chance of lasting longer than the Beru or other aftermarket coil. If you suspect a fault at coil, try spraying water on it or carefully heat it with a heat gun. See if you can cause it to fail.

For your Motronic 2.9 OBD1 interfaced to the Vanagon wiring:

The black 15 ignition coil wire from the ignition switch connects to a junction in the Motronic harness which supplies switched positive via Motronic black wires to:

- Jetta coil 15

- ECU 38

(- and via a black/white wire to VSS but I'm assuming that wire was capped and bundled in the Motronic harness)

A2 Resource describes the switched positive to ECU as:

Ignition Switch Start/Run Power

It appears to me that it powers up the ECU which then turns on the "power supply" relay so it can supply positive to various loads like fuel injectors.

There's a black/red wire between coil and ECU 8. A2 Resource describes that wire as being:

Coil Pack Pin 2 (VR6 Coilpack), Coil Signal (ABA, VR6 Dist.)

Reading 28a-4, it seems the ECU supplies a pulsed negative via that black/red wire to the coil. Regardless a fault in that wire path would cause the engine to cut out or stall.

Inside the Motronic harness, I doubt there's an issue between the black wire to ECU 38 or black/red wire to ECU 8 but if connections to coil were dirty or poor, that could cause the engine to cut out.

Neil.

Tue Feb 12, 2019 10:21 am

Hey guys! I meant to post this sooner, but I've been digging myself out of 2 feet of snow the last few days.

Anyway, new coil arrived on Saturday. Installed it, and have gone for two cross town adventures with NO STALLING. None at all. Given the snow, and driving with chains, I haven't hit highway speeds yet...but the last time I drove it before the new coil it stalled 3 or 4 times before I even got to the freeway.

At any rate, it feels like I found the source of the issue.

Thanks again for all of the insight and help trouble shooting.

A picture of it in the wild, with my 4.5 year old co-pilot.

Tue Feb 12, 2019 10:27 am

Woohoo! That's great man, hopefully that's the end of that nonsense. Let it snow!!!

Tue Feb 12, 2019 11:48 am

Sweet!

Order up another coil and toss in the glovebox, the ABA coils seem to die prematurely for whatever reason...

Tue Feb 12, 2019 11:52 am

tristessa wrote: Sweet!

Order up another coil and toss in the glovebox, the ABA coils seem to die prematurely for whatever reason...

For sure! Definitely an affordable backup part to keep handy.

Wed Feb 13, 2019 12:27 pm

Easy fix!

Nice!

LMK if you want these pics removed. :)

Images of a failing then failed coil from a 5 cylinder Eurovan. It's basically the same as the ABA coil. While on a summer road trip, I swapped one of my spare green Telefunken ABA coils into a stranded EV. It fired right up. I took their coil home so I could take it apart.

I'd guess the failure in the coil is typically at coil windings but have no real idea.

Neil.

EV Beru coil

Inside the coil. Part that's separated from the PCB (it has two legs; it's a type of rectifier??), *may* have been fault cause. Theory: heat is causing the fault.

Part shown sits against this part. Heat mark shown?

MOS

Tue Mar 26, 2019 9:26 pm

Hello,

I also have an ABA swapped (50 degree) Westy. I'm currently experiencing an issue with a surging idle, have you experienced this at all? It's fine until the engine warms up, then the idle surges up and down. Other than that the engine drives pretty perfectly.

Thanks very much,

Nick