Pierburg 2E3 problems - on-going faults, read this!

[silverbullet]

Time for me to ask for some help! A bit of background info:

2E3 on a 2.1 SS engine (same 9:1 compression as MV) in a syncro tin-top bus.
Timing set to 5 degrees as per V-notch on triple pulley (no pas or a/c) for 95 RON regular unleaded.
Got it warmed up the other day and drove a few miles, a bit hesitant but OK and the same as with previous DG and DJ engines (long story, not relevant) but to fiddle with the choke as it seemed to open too early. Holding it part-closed with my finger stabilized the idle, so I adjusted accordingly, along with adjusting the CO screw to improve the idle quality.
Fuel inlet filter on carb and main filter checked.
Vacuum hoses replaced inc. servo hose.
Carb gasket OK, backed up with sealant.

This evening in freezing fog: very reluctant to start, won't idle (splutters and dies unless on the pedal) plus is now popping and almost backfiring. Very sensitive to throttle, like it's far too rich. Once getting warm the idle is hunting very badly and only settles down once up to temp. I had to re-adjust the choke, which seemed to help a bit.

What is going on? Has the auto-choke failed or could it be the temp.switch in the thermostat housing?

PS This carb on any engine has always caused a rather smelly, acrid idle i.e always a bit rich, but on a run I've seen 26 mpg.

Any ideas? I'm desperate to get it sorted for offroading Sunday...

PPS Re-seated the inlet manifold at the heads, no change. Won't catch now. Wondering if the original VW TCI unit has let go? I have spares but it's flippin' cold out now.

[kevtherev]

The choke should open fully in about 5-7 mins, from fully closed.

The carb heaters are important this time of year
Big heater in the manifold
De icer in the carb body
Choke heater in the bi metal housing.

backfiring suggests it too lean.
Biggest culprit for air ingress is the choke pull down unit.
remove the pipe off the carb and suck, if you can continue sucking the unit has failed.
It should open the choke flap when you depress the accelerator during warm up.
Flap gap should be 3mm at idle (cold)

[silverbullet]

Ta Kev. The pull down unit is definitely working, it opens up with increased throttle under warm-up conditions as you say it should. Choke gap is ok at ~3mm and the springs are all correct.
I have a new heater switch so will check there first, along with swapping the relay and putting some more fresh petrol in it, the tank was pretty low and I only put a gallon in so this won't be helping.
I also have a new coil and TCI, time to swap one thing at a time...

I may have backed off the idle CO a bit too much for good measure

PS this engine has only ever had an earth strap on the transmission nose, should it have one on the block too? Silly question but it's starting to do me crust in!

[Ian Hulley]

PS this engine has only ever had an earth strap on the transmission nose, should it have one on the block too? Silly question but it's starting to do me crust in!

There is an M6 earth point for the ignition on top of the left hand bank as viewed from behind (where the oil cooler pipe is fastened to the head). In the course of your jiggery pokery have you dislodged a vac advance/retard pipe ?

Ian

[kevtherev]

I have never had a block earth strap on my two engines ..in contrast

The choke is only really there to assist the start and idle, it should open up in short time,

[silverbullet]

The choke does respond pretty quickly Kev, within a few minutes which is why I thought it was over choking. Must have been a red herring.

Ian, all vac hoses have been checked or renewed. The ign. earth is present and correct but I'm not sure that I remember tapping out the hole before the dob of copperslip. Aluminium oxide is a great insulator! Thanks, you may have just hit on the problem. Thinking about it this is just like a points distributor with a duff condensor, so a poor earth would do it.

I'll be tackling it this evening so any more thoughts gratefully recieved

[silverbullet]

So the evening went something like this:
All ready to get stuck in at 6pm, then friends dropped in for a couple of hours. Bloody cold out by then.
Ignition tag renewed, was looking a bit dicky. Struggled to solder in the cold. No change.
Coil swapped. No change.
TCI swapped. Duff spare!
Plugs swapped. No better.

Getting desperated by now. Something in the back of the grey matter said "pull off the vacuum pipe to the dizzy and suck to see if the capsule is ok" Lo and behold it's let go, passing air. That'll explain the hesitation that it's always had and the whiffy idle.

Then retired pilot neighbour (on pension for more years than he ever worked) from across the road came over and had a moan about "the constant noise, 5 nights in a row, do you really have to do this at this time etc etc" Apologised profusely, lost track of the time (gone 10 by then...) I only have so many hours in the day, had a run of bad luck with breakdowns etc
Like he'd even comprehend such a thing! I didn't bother reminding him that it was me who went and got grit in the syncro to spread in the close last winter, ungrateful sod.

Packed up immediately and quietly, don't want to give him an excuse to phone the enviro. health

Think I've found the fault but a full test will have to wait until Saturday. In the rain, probably!

Thanks to the chaps for all the advice

[Ian Hulley]

Glad you've found the issue

[silverbullet]

If only...now all it will do is start and run for 2 mins max from stone cold, then die.
When cold, the choke is closed, as you'd expect. The slightest bit of warmth in the coolant and it opens up, which is what I see if I remove the inlet air duct immediately after stalling.
Further checks with ignition ON:
Pull bypass valve wire off and it clicks, so ok. Pull either wire off thermostat housing switch and manifold heater relay clicks, so both ok. 12v at heater feed, ok.
Unscrewed pilot jet to check for blockages, none found.

What the hell is going on?!!! I had it running a few days ago before this saga and drove a couple of miles once it had warmed up

PS checked the secondary choke cam (the white one) and it's ok, had one break off before on another bus and it wouldn't idle at all.

One thing I have noticed today is that now it's a bit milder - 8 or 10 deg C - the fast idle screw isn't finding it's cam at all, in fact the cam appears to be uncontrolled i.e it doesn't snap back to the next lowest idle speed setting when you open the throttle by hand, rather it's free do drift about. I can flick it to and fro with the air duct off.
What would cause this and is it fixable?

[weimarbus]

have you checked the vacume flexi pipe for the brakes? left end of the manifold as you look from the rear. this had me stumped for 2years high hydro carbons at MOT time. runs well now

[silverbullet]

Servo vac pipe replaced with new hose when engine was swapped. Starting to wonder if this is down to old fuel, but it had run and been driven although I did have to nurse it until it was warmed up that time

E D I T Maybe I'll swap the fuel pump for another in case it's emptying the float bowl because it's failing (strainer in the pump could be blocked?)

[silverbullet]

Just found this: Some pretty useful 2E3 info here at Club Polo, it would seem that 1.9 syncros use the Polo/Golf swirl pot version of the carb, whereas the 2wd version that has a more basic direct fuel return.

http://www.clubpolo.co.uk/forum/lofiver ... 52530.html

http://www.dellorto.co.uk/merchandise/p ... ctionID=90

http://www.carburettorspecialists.com/

[ermie571]

Hi Ian,

we have the 1.9 in the green syncro - behind the carb sits a small white plastic pot - is this the swirl pot? Is it because we don't have the breathers that the 2wd have? Is there a difference with the carb...I asked on the syncro forum and was under the impression that a 2wd carb could be used....

My carb isn't quite right either....once warm it seems to think that 1300 revs is about right!! But the idle screw is immovable....I am concerned that something like thread lock has been used to keep it in that position...

Still, it runs lovely else!

(for an industrial 30 year old vehicle!)

Em
x

[silverbullet]

Hi Em, yes that little yoghurt-pot thing is the swirl pot, I think it's used to de-aerate the fuel feeding the carb if there's a momentary loss of supply i.e low tank, steep slope angles, low rpm (low pump flow rate)

I'm going to lift the carb off and take another good look at it, I'm wondering if a fast idle cam spring has broken now, or if I've still got the choke set wrong. Easier to do on the bench! I'm going to renew the fuel pump hoses too, just in case it's pulling air in...

[silverbullet]

Carb off and now I can see the problem! That dizzy vac leak had really thrown all the settings way out, to the point that it was set with too much hot idle, so the cold idle screw was barely managing to touch it's cam unless stone cold. The slightest bit of heat and it was backing off and letting too much air in before it was warmed up, hence the stalling.
Schoolboy error

Swirl pot hoses were dated mid-85