Club 80-90 Forums

Hi,

I'm new on the board. I'm a 33 years old man who drived a 1.6 TD panel van for 11 years. Now it's time for restauration. In the meanwhile I bought a high top camper with a 1.9 wbx petrol engine and pierburg 2e3 carb.

I have renewed:
- fuel hoses
- pull down
- checked vac and are ok
- bought a carb rebuild kit
- the fuel pump is new
- checked ignition
- choke is working correct

The van starts good (cold and warm) both the acceleration and the speed of the van are good (better then my 1.6TD) . No oil or water leaks. Driving motor temp is ok.

Problem:
The engine cut off on idle when you get high in rpm and get off the accelerator (for example when you stop on a crossroad).
without the pancake on the carb the motor won't even idle.

I've read a lot and it's likely a common problem with the wbx's but everyone has a different cause. Someone here who recognize these symptom and had the solution?

Greetz

Hi and welcome.

you could try increasing the throttle stop screw and see if it helps as a temporary solution, it may run a bit fast but better than it keep stalling.

Check vac unit on distributor is working (suck on pipe rotor arm should move a little)
check idle cut off valve is working ( remove connector, replace and you should hear it click)

Sounds like the fuel mixture is too lean. Possibly a small air ingress leak or the carb has been adjusted too lean. Try unscrewing the mixture screw a tad and see if it improves the idle.

Thanks guys but it's a weird problem.

This morning I split the carb en cleaned the hole to the idle cut off valve and put them together: idle ok, cold and warm. This evening I start the bus: no idle.

The weird thing is: last week I did also a split of the carb to check everything: idle ok. I drove to my parents, no problem. After 3 hours I returned home: no problem. A couple of days later I tried again: no idle.

So when I split the carb I "reset" something. I'm thinking on a mechanical problem

could be an air leak as said above
gasket leak perhaps, I assume you didn't fit new gaskets every time and tye lower gasket to manufold usually isn't in kit, you can make this one easy enough.

an old trick, when it won't idle, stick a brick on the throttle to get it to run, then spray wd40 type spray around the gaskets apparently if you have a major leak it gets sucked in and revs increase.

I take it you have changed the fuel filter, didnt see it mentioned in your list

Hi,

All gaskets are allready replaced and all vac's are tested and ok. The idle cut-off is working correctly.

But I think I found the problem. I tracked it down to the idling fuel/air jet.

The only "problem" was the top of the screw was broken so I've drilled them out and replaced him with a good one: ilde is back again


Now 2 problems left:
1. when I accelerate in 1st gear, the van holds 1 second (like a soft brake), then I hear a "bam" and then he accelerates.
2. acceleration in 2nd - 5th gear also holds 1 s before acceleration

Almost there ...

Hesitation could be down to failing vacuum advance on distributor

Accelerator pump?

Sent from my SM-T210 using Tapatalk

Hi Lievenn,

Your post is very informative so thanks especially the illustrations!

I was just about to post an idle problem question on here but your symptoms sound exactly like mine which are completely intermittent.

My van's a Canadian Import with a 2.1 DG on a carburettor conversion (unknown carb but I think it's from a 1.9-2.0)

I'll try out some of these suggestions off here.

Thanks,
Mike.

Hi Lieven and respondents, just to second what Mike said, thanks for an informative post particularly bc of great illustration and annotated pics.

Posts like these seem like good candidates
For addition to the wiki. I'd be interested in helping as I enjoy/am reasonably good at technical writing

This is on a 1988 1.9 syncro wasserboxer. As I understand it, , on starting, a bootful of throttle should set the choke and give 1500 -2000 rpm until it warms up and the pull-down closes down to normal idle speed.
BUT this is what's happening: Boot the throttle (cold start) and it spins up to around 800 rpm. leave it to it's own devices and the revs rise steadily over about three minutes until settling on 1400+ rpm. Sometimes there's a dip at around 1000 rpm, then it rises again. Under normal running the idle stays at !400.
Greatly daring, I ran it (static) until warm and turned the idle screw down to 1000 rpm; 800 with all lights and blower running.
Following morning stone cold, boot throttle, clean start, 800 rpm, rising again to 1400. Blip the throttle to about 3000 rpm and revs drop to 1000.
To be fair it's running sweetly, but that frantic tickover worries me and clearly something's not working as it should. Is it running on choke all the time?
i'd welcome your insights and advice.

BosunDoug wrote: To be fair it's running sweetly, but that frantic tickover worries me and clearly something's not working as it should. Is it running on choke all the time?

That sounds like it's working (almost) as it should. The 'frantic' tickover, that gradually disappears when you blip the throttle as the engine warms up, is just the fast idle/choke mechanism doing it's job - there's a stepped cam that the fast idle screw sits on and as the choke gradually comes off as the engine warms up that screw moves down the steps in response to the pulldown unit. Eventually that screw drops right off the stepped cam and idle speed is then controlled by the idle screw - the one you adjusted to get the warm idle down to 1000rpm. If adjusting that screw changes your idle speed, then by definition it means that your choke has disengaged.

The bit that doesn't sound right is the initial 800 rpm - as you said, it should be faster than that after setting the fast idle with the throttle pedal. So it sounds like your choke housing needs to be rotated clockwise a fraction. If it's not set far enough round the fast idle screw won't reach the top step of the cam and you won't get that initial fast idle.

Rather than waiting 24 hours between each test, you can check that this is working without even starting the van. Take off the pancake and the flexible rubber hose that connects it to the airbox, so that you can see the mechanism to the right of the carb. Then press the accelerator all the way down and check whether the fast idle screw is on the very top step of the cam - tricky to see, but possible with the pancake removed.



If it's not, slacken the three screws that hold the choke heater to the carb and rotate the choke heater clockwise by a few millimetres. There should be a scratched line on the heater that should line up with another mark (incidentally, I've read somewhere that the choke can be backed off a bit in the summer, i.e. turned anti-clockwise, but the VW documentation says only that the marks should stay aligned, and in fact if you do back it off in the summer then the chances are that the fast idle will stop working). Once you've rotated the choke heater housing a bit, try setting the fast idle again using the throttle pedal. If it reaches the top step of the cam you should get a much faster idle speed than 800rpm next time you start the engine from cold.

The other adjustment you can make is the speed of the engine when the choke mechanism is engaged. You do this by winding the fast idle screw in or out. Chances are there's a tamper-proof cap on this screw, and that it doesn't need adjustment, but I've had a carb where it was way off. Because this screw is so difficult to get to they advise not to do this while the engine is running (you have to lean right over the engine), so it's a matter of trial and error. And because cold engine speed will vary depending on the amount of choke, the adjustment is specified with a warm engine, i.e. choke fully open. So warm up the engine and turn it off, then, with the airbox and hose removed, set the fast idle screw on the *first step down* (not top) step.



Make sure the choke flap is fully open (vertical), then start the engine (no throttle pedal, or you'll knock the screw off that first step). Engine RPM should be ~2300. If it's not, turn off the engine, adjust the screw in or out to raise or lower that speed, then start the engine again and check it. As I said, the chances are that you won't need to adjust this screw, but it's a possibility.

One other possible reason that you're not getting the proper fast idle could be that there's slack in your throttle cable. I had this when I first got my van - great for fuel economy. You'd see any slack at the carb end where the cable wraps around the quarter-pulley on the throttle mechanism. To adjust it you have to take the front offside indicator off to get to the clamp screw.

Following this post for a friend.