Lumpy running and yep the old favourite a misfire...

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Nigelg37
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Lumpy running and yep the old favourite a misfire...

Post by Nigelg37 »

Evening all,
This is my first Post so humble apologies upfront if I haven’t got used to how the Forum works yet. In advance of asking for your help I have ‘searched’ my topic and the results gave me things to check and having done that I still have the same issue so I would appreciate your advice please.
My issue is a familiar title ‘Misfire/poor running’ which for now I am treating as an electrical problem and having tried a few things already (listed below) I am next looking to either fit a new distributor or, swop out the ‘vane and pick-up unit’ in the existing one. But I have also had it in mind that it could be a mechanical or fuel issue, or, a combination of all 3! Finally, there are gaps in my understanding of how the LT/HT system works on my Van and that will be my first question below. But first up, a quick van intro - we have a 1984 1.9 W/C (DG engine code) with electronic ignition and she is normal aspirated. Our van is LHD and from the Westfalia factory it spent the first of its years in Sweden – I mention that just in case for that market there were set-ups/parts included for the expected climate. We have owned the van for the past 14 years and, apart from one collapsed spigot bearing and a perforated clutch pipe, through servicing it regularly we have had very few issues so have been very lucky.
Original issue and symptoms – after about 50 miles I could feel through the seat a ‘hunting’ started which then became an unhealthy misfire and finally a full-blown backfire followed by cut out. Tried roadside checks but no improvement so AA Relay back home.
Summary of what we have done so far:
Fuel and Mechanical checks completed - checked fuel pump and fuel filter etc were good and the carb was not full of grit. Completed a compression test on all 4 cylinders and for 175000 miles the readings were good – I wanted to make sure I didn’t have a valve seat issue leading to a hot spot pre igniting the fuel. I also checked the rocker settings just in case one had loosened off leaving a valve closed etc.
Ignition-Earth checks: The engine to chassis earth strap is good and tight. I have also checked, cleaned and made good the ignition system earth wire – Control Unit to engine block. The ignition timing was a couple of degrees off but following reset the running improved slightly but misfire still there.
Ignition parts changed so far: I have swopped out the following one at a time to see if any got rid of the misfire - Coil, HT-Lead set, distributor cap, rotor arm and plugs. I also bought in an ignition ‘Control Unit’ which, after fitting it the issue was still there and because the mounting holes to the heat-sink plate are not the same as the original then for now I have retained the original Unit.
Questions please
  1. according to the Haynes manual apart from the Ignition Control Unit there is also an ‘Idle stabilising unit (ISU)’ which in my case I cannot locate in the engine bay! Am I just not seeing it or does anyone know if the ISU unit is only fitted to certain models?
  2. Given the items I have swopped out so far would anyone agree that the next logical step would be to tackle either a new distributor or the vane and pick up unit? Or do you have another route I should follow?
 
Many thanks.
Nigel and Katie G

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maxstu
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Re: Lumpy running and yep the old favourite a misfire...

Post by maxstu »

Hello Nigel and Katie, and welcome to the forum.

On reply put up a photo of the engine bay. Use the black square with white i letter. Its next to two smiley faces.

Question one..ISU is normally fitted to fuel injection models 1986-1992. The unit is located behind rear right lamp. But as your van has a carb its unlikely to also have an ISU. However, as the vehicles are getting old, one often comes across the odd hybrid.

Question two...not sure of your terminology behind vane or pick up unit inside distributor. Do you mean the Hall sender unit?

Some reading for you...

https://club8090.co.uk/forum/viewtopic.php?t=172593

What was the last bit of van maintenance before misfire started? Replacing one bit at time is a sound idea. Yet some of the original ignition items you replaced could have easily been tested before buying new. Particularly coil and leads. But you have a good spares base now. :D
Are you running a normal rotor and not a rev limiter one.

Have you tested Hall sender unit attached to distributor? I see you have change ignition amplifier.

Have you check tightness of carb vaccum pipes?

Good luck and report back please.
MaxStu
1989 DJ 2.1 Auto Leisuredrive rusty bucket.
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ajsimmo
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Re: Lumpy running and yep the old favourite a misfire...

Post by ajsimmo »

Just to clarify in maxstu's response he refers to
Question one - idle control unit as being behind the RHS rear light, whereas I think you meant the one near the coil with two plugs that can be joined together. You don't have either.
The first is indeed injection only, and the second is fitted to air-cooled, DF and DJ, but not DG.

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maxstu
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Re: Lumpy running and yep the old favourite a misfire...

Post by maxstu »

ajsimmo wrote: 24 Nov 2020, 03:26 Just to clarify in maxstu's response he refers to
Question one - idle control unit as being behind the RHS rear light, whereas I think you meant the one near the coil with two plugs that can be joined together. You don't have either.
The first is indeed injection only, and the second is fitted to air-cooled, DF and DJ, but not DG.

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Well spotted Mr Simmons! Me and my initialisms, eh? :lol: I really should have known better.
ICU behind RHS light. ISU small white or green (normally) box with two cables, attached to wall next to ignition amplifier.

Perhaps the couple own a DF? Or it got replaced with a DG later on. 170K is achieveable on original DG engines but not common.

Back to Nigel and Katie. Have you a photo of engine serial number? Prefix DG or DH?
Is there a rebuild mark after numbers. I think usually a vw stamp or an asterix.
MaxStu
1989 DJ 2.1 Auto Leisuredrive rusty bucket.
"Blissfully happy in your presence".

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ajsimmo
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Re: Lumpy running and yep the old favourite a misfire...

Post by ajsimmo »



maxstu wrote: Well spotted Mr Simmons! Me and my initialisms, eh? Image I really should have known better.
ICU behind RHS light. ISU small white or green (normally) box with two cables, attached to wall next to ignition amplifier.

Perhaps the couple own a DF? Or it got replaced with a DG later on. 170K is achieveable on original DG engines but not common.

Back to Nigel and Katie. Have you a photo of engine serial number? Prefix DG or DH?

Maxstu, I think you're heading off at a tangent here. The OP said it's a DG, and they don't have an idle "thingy" unit of any kind, but Haynes suggests they should. It doesn't, and they shouldn't. So all is as it should be AFAICT. Image

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maxstu
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Re: Lumpy running and yep the old favourite a misfire...

Post by maxstu »

Oh dear! :oops: l need more sleep... :run
MaxStu
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"Blissfully happy in your presence".

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ajsimmo
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Re: Lumpy running and yep the old favourite a misfire...

Post by ajsimmo »

maxstu wrote:Oh dear! :oops: l need more sleep... :run
Ha! Image No worries. Meanwhile, back to the original question...
It's not all that clear to me whether the engine now starts or runs from cold, if it just misfires when warm, or misfires/backfires all the time now. If the latter it might be that the dizzy drive dog gear has worn and jumped out of mesh (if so, perhaps because the drive pinion below doesn't have the correct two washers at the bottom?). A good check is to see if you can turn the rotor arm by hand (beyond the normal amount of play/lash).

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Nigelg37
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Re: Lumpy running and yep the old favourite a misfire...

Post by Nigelg37 »

Please ignore this test reply - i just carefully replied to the two kind folks who responded to my Post and, my new 'masterpiece'! just disappeared when i selected 'Submit'.... i am hoping its awaiting approval for posting not that its lost for good!
Thanks,
Nigel (learning but slow!)

Nigelg37
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Re: Lumpy running and yep the old favourite a misfire...

Post by Nigelg37 »

Evening folks, first and foremost, thank you very much for replying, your guidance and clarification which is really good of you and much appreciated.

Ok, just to make sure I answer your questions first:
1. Vane and pick up unit - I lifted that description from the Haynes manual but since then when i went to the Just-Kampers site i realised that its called the Hall Sender unit so yep you are correct Sir.

2. Last bit of maintenance before issue arrived - was changing the Oil and Filter, Air Filter and cleaning the plugs but that was several weeks before and she was right as rain afterwards. In other words, the misfire just came out of the blue.

3. Rotor arm - its a (new) rev limiter type which I put on at the same time as the dizzy cap and leads. 

4. Hall sender unit - nope i haven't tested it yet mainly because i am not sure how to! but, funnily enough i was going to ask a question about this Unit please: Am i right to say that these units either work or they don't? i.e. is there a middle ground with them where they start to fail and after a bit longer they completely pack up? If the answer is 'they work, or they don't' then as the van is still starting (literally at the turn of the key) and running - if not lumpy and missing - then it suggests the Hall Sender is functioning? To be honest i am really hoping that your reply is that they do fail slowly, and a symptom is misfire!

5. Carb Vac pipes - yep both from the dizzy to the carb and from the carb to the airbox etc. Interestingly I thought I had cracked my issue because one of the vac joints at the back of the carb had split and opened up so all excited i trimmed the tube back and refitted snug and guess what... the misfire/lumpy running was still there! but the upside was i had improved the connection.

6. Idle Control Unit - Many thanks both for the clarification re the Idle Control Unit and which engine types it is fitted to - again i picked this off the Haynes schematic. But, as ours is a Carb model and its water cooled then in which case it doesn't have one.

7. Engine serial number - i am working away from home this week so will confirm at the weekend, but, i appear to have noted the engine number in my Haynes manual: DG071886 * is what i have written down. By chance I know the last two owners before me and neither of them had a rebuild job done which from the compression test suggested that an overhaul has happened. However what i should add here is that when i did the compression test 1 of the cylinders was not as good as the other 3. From the four cylinders I got 12, 11, 10 and 8 Bar. The 8 reading being the back right cylinder.

Parts changed so far - because we are hoping to set off next March for a 3 month trip I am really quite happy to swop out old for new as in theory its one less item that might pack up en-route. But that's not the main driver which really is to try and hit on the problematic part through a process of elimination. 

One thing i have not checked yet - up to now i am assuming that the ignition switch and the wiring from the ignition switch to the engine bay is good but it has struck me that if i have a poor connection somewhere en-route then perhaps the LT/HT ignition system is struggling from the off with a lack of solid connection?

Request - please let me know what your experience is of Hall Sender units, is malfunction a creeping thing or it works/doesn't work. And, how do i test mine to see if its ready for a swop out.

many thanks again,
cheers,
Nigel & Katie



 

ash1293
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Re: Lumpy running and yep the old favourite a misfire...

Post by ash1293 »

Nigelg37 wrote: Request - please let me know what your experience is of Hall Sender units, is malfunction a creeping thing or it works/doesn't work. And, how do i test mine to see if its ready for a swop out.

 


I had a few odd moments over the space of a year which I couldn’t quite put my finger on.
Initially I would have the very occasional misfire/cough. It was so random and infrequent I didn’t give it much thought.

I’d then get the odd cut when coasting to a junction etc. But every time it would start straight away.

New plugs, leads, cap, rotor arm etc and I would convince myself it was sorted. But again it was infrequent & random so was never quite sure.

Then things worsened......

Would go for a reasonable drive then park up for an hour. Typically a few miles after restarting it would cut out coming up to a junction.
First time I wrongly trouble shooted to the coil as no detectable spark. Nipped home and picked up spare, got back and swapped it over and started straight away. New Bosch coil ordered & fitted.

Few weeks passed and same symptoms...... again as close to home nipped back for spare (yes it should have been in the van)
This time in my return I tried and it started no problem.

By this point the only original parts of ignition system were the ignition amplifier & distributor. Although the amplifier by all accounts works or it doesn’t it points towards dizzy.
As the van is a keeper for the foreseeable I thought bugger it and ordered a new amplifier & halls unit so all ignition parts are renewed. Brickwerks JP group kit was not bad to fit. Dizzy body needs slight modification and terminal connector changing.

So far so good, but limited miles since due to work and needing a new throttle cable.


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Nigelg37
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Re: Lumpy running and yep the old favourite a misfire...

Post by Nigelg37 »

ajsimmo wrote: 24 Nov 2020, 21:26
maxstu wrote: Oh dear! :oops: l need more sleep... :run
Ha! Image No worries. Meanwhile, back to the original question...
It's not all that clear to me whether the engine now starts or runs from cold, if it just misfires when warm, or misfires/backfires all the time now. If the latter it might be that the dizzy drive dog gear has worn and jumped out of mesh (if so, perhaps because the drive pinion below doesn't have the correct two washers at the bottom?). A good check is to see if you can turn the rotor arm by hand (beyond the normal amount of play/lash).

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Hi, sorry i missed the fact you had added another reply - much appreciated.

The van starts really easily i.e. a couple of turns and it fires up straight away but without holding a decent throttle it is hesitant. I put this down to fair wear and tear of the engine etc, and, once the auto choke has done its job it does tick over reasonably well.

ref backfire - perhaps through timing adjustments and the parts now replaced the backfire issue seems to have gone but the misfire is still there - as i work away in the week my plan this next weekend is to get up early and take the van for a fast drive (locally just in case) and get her warmed up. Before i do that though I will as you suggest check the drive pinion play/lash to see if it seems excessive... memory says it seemed fine. Then when i get back I am thinking to introduce 12V direct from a spare battery to the ignition system just to make sure that its not a wiring fault from the ignition switch/wiring.

Hall sender - would appreciate your experience on whether this item does deteriorate over time or drops off a cliff?

thanks
Nigel
 

Nigelg37
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Re: Lumpy running and yep the old favourite a misfire...

Post by Nigelg37 »

ash1293 wrote: 24 Nov 2020, 22:08
Nigelg37 wrote: Request - please let me know what your experience is of Hall Sender units, is malfunction a creeping thing or it works/doesn't work. And, how do i test mine to see if its ready for a swop out.



I had a few odd moments over the space of a year which I couldn’t quite put my finger on.
Initially I would have the very occasional misfire/cough. It was so random and infrequent I didn’t give it much thought.

I’d then get the odd cut when coasting to a junction etc. But every time it would start straight away.

New plugs, leads, cap, rotor arm etc and I would convince myself it was sorted. But again it was infrequent & random so was never quite sure.

Then things worsened......

Would go for a reasonable drive then park up for an hour. Typically a few miles after restarting it would cut out coming up to a junction.
First time I wrongly trouble shooted to the coil as no detectable spark. Nipped home and picked up spare, got back and swapped it over and started straight away. New Bosch coil ordered & fitted.

Few weeks passed and same symptoms...... again as close to home nipped back for spare (yes it should have been in the van)
This time in my return I tried and it started no problem.

By this point the only original parts of ignition system were the ignition amplifier & distributor. Although the amplifier by all accounts works or it doesn’t it points towards dizzy.
As the van is a keeper for the foreseeable I thought bugger it and ordered a new amplifier & halls unit so all ignition parts are renewed. Brickwerks JP group kit was not bad to fit. Dizzy body needs slight modification and terminal connector changing.

So far so good, but limited miles since due to work and needing a new throttle cable.


Sent from my iPhone using Tapatalk
Thanks Ash, its good to know I am not the only one chasing shadows! I think i am going to do the same as you have, i already have a new Control unit but have not pertinently fitted it yet as when i tried it the misfire was still there so decided to keep the new one as a (new) spare. But, after some more wiring checks I am going to try the Halls unit to rule it out as being the issue.
cheers
Nige
 

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maxstu
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Re: Lumpy running and yep the old favourite a misfire...

Post by maxstu »

Hi Nige,

Got your email thanks. Not changed a Hall sender myself. Suggest you start a new post (linking this one in new post) asking advice. Seems a little tricky as dizzy requires removing from engine.

Have you check Wiki on here?


https://www.bing.com/videos/search?q=vw ... ORM=VDRVRV
MaxStu
1989 DJ 2.1 Auto Leisuredrive rusty bucket.
"Blissfully happy in your presence".

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