No start, help needed--Sorta resolved

[DuncanS]

On the morning of Saturday, November the 12, I loaded the '91 2WD GL with boat models and other paraphenalia and got in to to pick up a fellow member of our club and head to the meeting. The car had been running flawlessly and would typically start in under 1 ½ seconds of cranking. It drove into the garage where it had been kept for the fall...not stored, just returned there after use. I was running late and needed to get going. Turned the key and run,ruh,ruh,ruh...... Nothing. Not a cough, nada. Crap, what to do? Ripped off the engine cover, and did a visual. OK...hoses and stuff looked fine. Why would it run well when pulling into the garage and then nothing? Mice? Had a previous brush with death when the buggers turned my fuel hose over the tranny into a New York fire boat welcoming the QE 2 into the harbor. Maybe a loose wire. Ran my hands, palm down, quickly over the engine touching all the wires on the top surface. Back in the seat and Whoom, off I go with the typical 1 second start.

A warning to clean up a bunch of the 31 year old wires and get a new harness and restore it to newness. A rebuilt went in 3 years ago with a Matt Steedle tranny shortly afterwards. New exhaust, clutch, AFM and some other goodies too. I'll get to it says I, but like the leaking roof........... Four days ago, went to take a trip into town and Ruh, ruh, ruh again. Magor wiggling of the wires have done nothing to improve the situation. Back in August, I had the coil out and cleaned all the grounds in the vicinity and the terminals and connectors for the coil.

Tomorrow I'll slap on Mark's wire for a test and see what happens. https://www.thesamba.com/vw/forum/viewtopic.php?t=349429

Not my engine bay, just copied from Mark's topic.

Let's assume I still have nothing. What do you suggest should be the targets and in what order do they get tackled?

Duncan

[Wildthings]

You have to have air, fuel, and spark for the engine to run. Very seldom is air going to be the problem so that leaves fuel and spark.

[Captain Pike]

Using your remote start harness(make one). You will test for spark at the engine bay, pin test the injectors...........
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LEARN TO SELF RESCUE
59 Panel bus, 1966 Single cab. 73' 181. 73 Westy. 91' H6 Vanagon 3.3L.
.....................All Current.......................

[DuncanS]

Already have the test harness.

The harness will tell me if I have a coil connection, fuel pump and ECU power, but not a whole lot else.

Fuel is easy and spark too. Assuming they are OK, then I guess the hall sensor? And what after that? It has to be an intermittent connection or failing wire internally somewhere.

Duncan

[Wildthings]

There is a complete FI electrical and fuel system diagnostic given in the Bentley, takes about 1/2 hour to do the complete set of tests.

[DuncanS]

Thnx guys. Will give updates as I proceed. No work today as the stuff-of-life cropped up.

Duncan

[Captain Pike]

Nope, the 1 connected to the starter(that you made). Then you can diagn.................
_________________
LEARN TO SELF RESCUE
59 Panel bus, 1966 Single cab. 73' 181. 73 Westy. 91' H6 Vanagon 3.3L.
.....................All Current.......................

[DuncanS]

Very good point about being able to start the engine from the bay. since I already have a hard start relay, that is a breeze.

Duncan

[DuncanS]

Wow, two weeks since the last post. Well, Santa's elves, power outage 'n other stuff of life. Excuses, excuses, but with 15º in the unheated garage and 18" of super wet heavy snow, I just didn't feel like it and didn't need the car.

Now I do.

First took Mark, crazyvwvanman's emergency diagnostic harness I had made a couple of years ago and slapped it on. Nada.

A reminder, engine cranks well, but no spark.

In a discussion with Dave K, I told him I had fuel as the smell is prevalent, or was in the beginning, but now I don't crank enough to flood the engine during tests, so no smell. 12 volts at the coil and the green tach wire is not shorted to ground. Open circuit when I test its continuity to ground. The next step is to follow the ProTraining manual and Bentley. PT is clearer.

Confused here. If voltage was OK.....Diode must flash while testing. But the next section says "If diode flashes, the coil is kaput", while if it doesn't flash, coil is good and go on to checking the Hall sender. Isn't this backwards? I'm assuming the diode is connected positive to terminal 1 of the coil and the other end to ground. If so, this would show the pulsing from the ECU.

So I don't get it. " Diode must flash", so .....? Since I have fuel, doesn't this mean the Hall sender is sending a signal to the injectors to squirt and wouldn't that automatically assume the coil is getting the signal from the ECU, if the green wire from the ECU is OK?

I also assume that any 12v LED will be an equivalent of the VS US 1115 LED tester. Yes/No???

In the meantime, I will swap the ECU for one of my several known good ones.

Plz straighten out my thinking here.

Duncan

[Wildthings]

They are saying that if the diode flashes and you are not getting spark the ignition coil is likely bad.

[DuncanS]

Right, but why is it bad? I would think this only proves the ECU is OK, but have no information about the coil. Where are the LED leads supposed to connect? Positive on the coil, teminal 1, but where does the other go? If it goes to ground, then the LED is bypassing the coil windings and not saying anything about the coil..........unless the checking low voltage winding somehow is part of the LED tester which I don't know about.

Still confused.

Duncan

[hardway]

The later 2.1 Vanagon provides power to terminal 15 at the coil directly from the ignition switch. The earlier 2.1 has power to the coil provided by the Digifant relay. To me they went backwards. I have seen no start issues caused by low voltage to the coil before. Usually the ignition switch.

Either measure the voltage at the coil during cranking or run a jumper to 15 at the coil and recheck. IF you have good power at 15 and the power pulses at #1 and no spark is produced at the coil tower then the coil is defective. The key to definitively proven the coil to be defective would be to prove that the control unit pulls terminal #1 fully to ground. You would need a Digital Storage Oscilloscope to see that. But if a test light at terminal #1 pulses when cranking you have a pretty good idea.

[DuncanS]

[MarkWard]

The Hall effect sender in the distributor sends a signal to the ECU first. Then the ECU fires the coil by removing the ground from the negative side of the coil. The led tester in the picture above is testing the Hall effect and that the hall is getting power.

An LED testlight connected to power and probing the negative side of the coil should flash during cranking. If it does flash, likely the problem of no start is the coil, coil wire to the distributor or the cap and rotor.

I have tested coils that failed, but on the bench pass the Bentley manual ohm tests.
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[DuncanS]

An epiphany. Was looking at drawing of the ECU harness and where all the ends go. Bentley 28.39 One goes to the ground at the hall sender. This could have been wiggled when I brushed my hands.

The first thing today--14º--will few to clean the GRRRRRROUND. How many times do we talk about clean grrrrrrounds? I did the coil, but.....Dumb me.

Will letcha know.

Merry Christmas, Duncan

I'm gonna get a new coil anyway as it's 31, about to be 32, years old.

Duncan

[ALIKA T3]

[Zeitgeist 13]

I've found crank but no-start issues with the WBX to be predominantly a bad coil or failed Hall sender.

On 24V VR6 EVs, the same issue is more than likely caused by a bad CPS.

On an AC Beetle et al, it's mostly a bad condenser, coil or maladjusted points.

YMMV
_________________
Casey--

'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik?

[Wildthings]

[DuncanS]

20º and with difficulty I was able to get the ground bolt out of the engine block between the number 3 and 4 cylinders. A 6th of a turn with an open ended 10m wrench loosened it enough that I was finally able to get a socket on it with a universal joint as the compressor won't allow a straight shot at it. Fastened there are a heavy ground wire whose other end goes to the tin under the coil which I had cleaned about a month ago. Also there is a white wire which disappears into the ECU harness. What? A white wire going to ground? Definitely not a OG Wolfsburg wire as all ground wires are brown or a combo of brown plus black or something. A PO mod which is another reason to put the reclaimed good ECU harness on in the spring.

The ends of the number 2 wire ground are steel and the side towards the engine was quite rusty and corroded as was the terminal for the white wire. It cleaned up easily. The plating got sanded off as I was cleaning it and revealed a brass eye. However the heavy ground wire had a eye terminal too big for the bolt and so the white wire eyelet of the proper size was dished by being pulled down into the larger hole of the heavy cable. Will toss a washer in between to correct this until I can redo the heavy cable in the spring with the correct size. Cleaning the engine block wasn't as easy as it is down past the spark plug wires and the A/C compressor is in the way. Wrapped some 120 paper on the end of a dowel and chucked it in an electric drill. It took three changes of the paper, but finally the area where the grounds connected were 75% shiny. I sharpened the end of a flat bald screwdriver and was able to scrape the final bit of rust and created a shiny area where the bolt attached the grounds.

BUT, the bolt had fallen out of the socket wrench and disappeared under the unreachable and seeable area by the number 3 spark plug. Put a mag on the end of a bendable wire and wiggled it around. Nada. Crap. Pulled out the jar of misc. vanagon fasteners and found some allen seat bolts that looked right. Taped one to a wooden dowel, buy it only threaded in about 2 turns. Wrong pitch. Found another with a coarser pitch, but is also fetched up after a couple of turns. I suspect the second try was actually an SAE 1/4-20 lurking in the wrong jar. Didn't bother to try a 1/4-20 nut on it as it's moot. By then it was dark and the temp was down to 17 and the bare fingers needed to deal with bolts were gone, so done for the day.

The Ms S biggies hasn't been acquired yet, so at 0 dark hundred tomorrow--today actually, I'll go out and paste the two grounds together with as heavy a chunk 'o wire I can find and toss a ground on some spot on the engine in different easy to get to place and make sure the bolt/nut doesn't play hide and seek.

Climb into the seat and............."in God we Trust". If it runs, ill be in great shape. If not, then I have to ask the Ms on bended knee if I can borrow her Volvo. That will cost about 98% of the merit points the biggie should gain. If she doesn't like the biggie, then,,,,,,,not good and canine residence time. First stop at the hardware store to get a bolt. Will buy as many as there are with a head that fits a 10 mm wrench and about a 1/4" shank with both a coarse and fine pitch thread. 3 of each to make sure that at least one will wind up in the right spot. And while I'm at it will reroute the white wire away from one of the high tension plug wire it was rubbing noses with.

So that's all the news from Lake Wobegone for today.

Duncan

[DuncanS]