Erratic idle speed advice please

[timski]

Engine: 2.1 DJ (1991) that has an LPG conversion by VW Elite/Gasure a year ago (starts on petrol and switches over to LPG).

Problem: When you start the motor the idle speed is all over the place. It will be fine then suddenly rev really high without pressing the accelerator and then drop and then back up again and so on. There's no apparent pattern, rather random, but generally over-revs. The problem is intermittent but happens regularly. The problem is present on petrol and LPG.

Action so far: Removed idle speed control valve and cleaned with carb cleaner and replaced. Problem persists.

So got mechanic to have a look when doing the MOT. He came recommended and used to work on these vans lots although I think mainly air-cooled. He suspects an electrical fault such as a bad connection somewhere or faulty ECU/ISCU. He said he'd rather leave that to an auto-electrician. He suggested another route is to by-pass the fuel injection by fitting a carb. He said at this age (21 years old) the electrics on these vans tend to deteriorate and cause recurring problems.

I'm sure I've read that some of you have done this. I'd be interested to hear your opinions on the matter.

I had considered tackling the job myself and started by cleaning the idle speed control valve but reading the WIKI and forum I think tracing this problem is probably beyond my very limited knowledge

I need to get my LPG serviced soon so I could look at getting VW Elite or Gasure to fit a carb when I get that done. Presumably they'll need to make some adjustments to the LPG setup too. Any idea how much that might cost?

Thanks,
Tim.

[icosahedron]

The most likely culprit is a dry solder joint in the idle stabilisation control unit that sits behind the offside rear light. Well worth taking it out and having a quick look.

[PetenAli]

The most likely culprit is a dry solder joint in the idle stabilisation control unit that sits behind the offside rear light. Well worth taking it out and having a quick look.

What he said ^^^^^^. Or the same unit could have got some water in it. I had the same problem as you and it turned out that water had got into it. I had to carefully separate it and then dry it slowly with the boss's hairdryer. Then put it back together with a bead of silicone and cable tie it up out of the way. That worked for me and never had problems since.

[timski]

Ok that sounds worth checking first.

In fact, I did try looking for the ISCU before as I had read it might be related to that on the forum but my van has been gas'd and they put part of the LPG system behind the off-side rear light. Everything I could see looked like part of the LPG system, i.e. it was connected to it. So I suspect they may have moved it elsewhere when they fitted the LPG. And to be honest I don't know what one looks like so I wouldn't know I'd found if it did

What does it look like? Or even better has anyone got a piccie?

Thanks,
Tim.

[mark]

what i did with mine was to clean every electric contact with electrical contact cleaner and tooth brush (twice) took a couple hoursish each time, but the difference after was really noticeable (1st time anyway second time was due to a wobbly tyre. long story) and its been smashing since. i also did the afm as well the ecu, cleaned up the earths with a bit emery paper.

this led to me buying a spare afm, ecu and all manner of electrical nicnaks that now are part of the must be carried everywhere spares.

mark

[timski]

Thanks Mark. Sounds like remaking all the connections and checking they are clean is a good place to start if I can't find an auto-electrician.

Is there a diagram I could use to identify the connections/components I would need to check/remake?

Been looking at the Haynes Manual (sections 4.B, 12.27 and 12.28) but there a bit cryptic
Cheers,
Tim.

[Wychall]

The big fella below is the idle stab relay.

[timski]

Thanks Wychall.

And this would normally be found behind the off-side rear lights cluster, i.e. the drivers side on an UK model. That right?

Cheers,
Tim.

[Wychall]

Correct.

[mark]

Thanks Mark. Sounds like remaking all the connections and checking they are clean is a good place to start if I can't find an auto-electrician.

Is there a diagram I could use to identify the connections/components I would need to check/remake?

Been looking at the Haynes Manual (sections 4.B, 12.27 and 12.28) but there a bit cryptic
Cheers,
Tim.

i just started at one side and unplugged cleaned and put back together everything with a wire and connector, one at a time steady as you go
i doubt an auto sparks would want the faff of it, it will cost a couple of quid for the cleaner nick your mrs's toothbrush (rember to give it a rinse before you put it back) and bob might be your relation.

mark

[timski]

Thanks Mark. Sounds like remaking all the connections and checking they are clean is a good place to start if I can't find an auto-electrician.

Is there a diagram I could use to identify the connections/components I would need to check/remake?

Been looking at the Haynes Manual (sections 4.B, 12.27 and 12.28) but there a bit cryptic
Cheers,
Tim.

i just started at one side and unplugged cleaned and put back together everything with a wire and connector, one at a time steady as you go
i doubt an auto sparks would want the faff of it, it will cost a couple of quid for the cleaner nick your mrs's toothbrush (rember to give it a rinse before you put it back) and bob might be your relation.

mark

Thanks Mark.

I'll give that a go. Did you disconnect the battery first?

Cheers,
Tim.

[ermie571]

Tim,

you also asked about the carb

Yes, we have 3 vans running a 2.1 DJ on the 1.9 carb, all on LPG. (converted from 1.9 to 2.1) they are also elite units and Gasure conversions.

Don't even start on petrol. Even in winter.

Just so you know if the issues persist, and you want to try that option. Think you would need some other changes - manifold might be different, and you will need 12 to the fuel cut off solenoid. Not sure if you have that on the injection

Elite would give guidance on how easy

and they charge around £40 for a gas service

Em
x

[timski]

Tim,

you also asked about the carb

Yes, we have 3 vans running a 2.1 DJ on the 1.9 carb, all on LPG. (converted from 1.9 to 2.1) they are also elite units and Gasure conversions.

Don't even start on petrol. Even in winter.

Just so you know if the issues persist, and you want to try that option. Think you would need some other changes - manifold might be different, and you will need 12 to the fuel cut off solenoid. Not sure if you have that on the injection

Elite would give guidance on how easy

and they charge around £40 for a gas service

Em
x

Thanks Em,

I am going to try cleaning and remaking connections as suggested by others already as that will be a cheaper option if I get lucky.

If I don't have any luck I might go the carb route so thanks for your info. VW Elite did my LPG conversion too so I would probably go to them as you suggest.

Maybe going the carb route is worth considering in the longer term anyway? I'm guessing the reasons some go the carb route are:

1. It's easier to maintain? I've had this current job turned down by one mechanic already.
2. The electrics begin to deteriorate at this age so are likely to cause recurring problems?
3. Difficult to get the electrical components?

Why did you go that route Em?

I'd be interested to hear other peoples' opinions as to the pros and cons too.

Thanks,
Tim.

[mark]

Thanks Mark. Sounds like remaking all the connections and checking they are clean is a good place to start if I can't find an auto-electrician.

Is there a diagram I could use to identify the connections/components I would need to check/remake?

Been looking at the Haynes Manual (sections 4.B, 12.27 and 12.28) but there a bit cryptic
Cheers,
Tim.

i just started at one side and unplugged cleaned and put back together everything with a wire and connector, one at a time steady as you go
i doubt an auto sparks would want the faff of it, it will cost a couple of quid for the cleaner nick your mrs's toothbrush (rember to give it a rinse before you put it back) and bob might be your relation.

mark

Thanks Mark.

I'll give that a go. Did you disconnect the battery first?

Cheers,
Tim.

yeah discontect the battery.
from what i read on here and the samba, the manifold and carb offof a dg is a straight enough bolt on. it might become noiser with the induction roar and could be a bit thirstier, i dont know if it would effect the bhp as ive never been able to find any info about anyone ever having rolling roaded one with a carb. i did think about it myself but once running right they are a dream

mark

[ermie571]

Tim,

sorry, didn't make it clear. The 1.9 engine in the bus started leaking water, and dripping oil, so went to elite for a new unit - we payed a little extra and upgraded to the 2.1 unit. Therefore, the engine bay was set up for the carb and other 1.9 auxiliaries.

There are pros and cons to each I guess....but it runs well on the lpg, and as you stated, there are many of us around who have upgraded from the 1.9 to the 2.1 running the original carb etc

regards

Em
xx