2.1 DJ lumpy when coasting and 2nd throttle spring

[Tyrone Shoelaces]

My 2.1L DJ (1990) started suffering from a problem a number of months ago: When I’m driving along in gear under no load (i.e. coasting) the engine starts to lurch about when approaching low rpm. When I press my foot down to put the engine under load and accelerate, it recovers eventually. It’s a bit tiring driving along constantly accelerating and decelerating and using lots of clutch. Engine seems to idle reasonably well.

I’ve played about with many things on the engine like checking the throttle valve switch and airflow meter, tweaking the idle adjustment screw up and down, and checking the ignition components. The fuel filter was replaced about a year ago and I haven’t done a lot of mileage since then. The vacuum hoses are all new as well. I’ve looked all over this site and the rest of the net to see if a similar problem has been discussed, but no luck.

One thing I have found which improves the situation (not completely though) is to disconnect the long (damper?) spring on the throttle valve – the one which goes from the valve rearwards to attach to the back of the air inlet manifold. Before I go driving around with this permanently off I wanted to find out what it actually does, because I can’t really tell what it’s doing to the throttle other than to perhaps help the valve return to a more closed position (?).

If anyone has any info on this spring, or any suggestions about the engine problem I’d really appreciate some input. Many thanks. (This is my first post, so please go easy on me )

[tforturton]

Before we go looking at engine problems, have you done anything else - like change the wheels/tyres to a different size?

[Tyrone Shoelaces]

No, everything still as it was before the problem arose. Original wheels and tyre size. No work done on gearbox.

[MikeyVanagon]

Hi Tyrone Shoelaces

Have you sorted this problem yet? My 1980 Vanagon 2.0 petrol injection has come back from the garage and is doing the lurching in 2nd gear at low rpm.

Works that were done were:
- engine tune up
- new fuel lines (to the front areas of the camper only. rear lines to engine in good order)
- new fuel filter
- new rotor arm within existing distributor

Mechanic said I may want to change spark plugs and HT leads.

Any help much appreciated.

Mikey

[mark]

these old ladies suffer from electrical gremlins and poor earths.... clean up them all like new pins.... when was the air filter last changed......... have you googled vanagon stabilisation 2.1dj..........could be the temp2 sensor....don't spend any money until you are sure your electrical connections are clean and true also give amf a good clean but be careful swiss watch like inside......don't adjust anything

mark

[kevtherev]

Lurching is caused by a tiny air leak.
It's there somewhere...

[Tyrone Shoelaces]

Many thanks for the replies.

mark: air filter was changed relatively recently, and I've checked the air flow meter (presume this is what you mean by afm..?) - it didn't look dirty and seemed ok so haven't cleaned it so maybe I'll look at that. Temp2 sensor (at front LHS of engine?) was replace a couple of years ago following a period of very rough running (different to current problem I think). Have given all the connections accessible from top of engine bay a clean up and re-connected, are there any others I should be aware of? Haven't looked at vanagon stabilisation on web yet, but is this just for idling only? - as the idle doesn't seem too bad.

kevtherev: any tips on how to locate these air leaks?

[Tyrone Shoelaces]

I've been driving for the last 150 miles or so with that 2nd throttle spring disconnected and it's so much more enjoyable to drive. Still running quite rich though, but this has been the case for a while.

Any issues related to having the spring disconnected that I should be aware of?

[silverbullet]

Is this not a case of "Vanagon syndrome"?
Not an expert in anyway but interested to know!
Air leaks can be inlet manifold gaskets & hoses, crankcase breather/hose, servo hose... but air leaks usually make any engine run lean.
Unless the AFM has been got at in an attempt to mask a leak, in which case check everything.

[mark]

you have to carefully remove the top of the amf and check the track for wear and dirt and clean with a good blast of contact cleaner..... keep your pinkies out and re-fix with superglue................vanagon syndrome will happen suddenly, stop and wait a couple of mins and it will be gone until the next time it feels like occurring and most of the latter models have the upgrade...........if the amf is still the same one of course

mine had a similar problem cleaning all the connections, earths and the amf worked for me I also changed the temp2 this stopped the over fuelling and rough running, but I had a weird experience where the van felt like it was missing between 20ish to 30ish mph and if you pushed the throttle through it the missing/ lumpiness went............... jack up each tyre and give them a good spin anything egg shaped needs changing

E D I T....amf = afm

mark