RESULT! CU running lean, what could it be?

[81AirCooled]

Spoke to the garage again.

Compression test is reading 9.5, 9.6, 10, 9.6 bar but the CO value is between 0.17 and 0.23 at full output. As far as power goes the vans getting 39,4 bhp @ 4000rpm which is shocking.

I don`t think the garage is going to be able to work on it for a couple of days either

[kevtherev]

So no O2 reading...
Does it have the Twin Solex carburetor 34 PDSIT carb with twin venturi?
is the second venturi opening? (I think it's vacuum operated)

CO content @ idle 0.0 ±0.3 % volume
HC content @ idle 500 parts per million

So your mixture is spot on

[sarran1955]

Hello,

Following your thread,

I take it you have standard Solex pdsit 2/3 carbs.

These are somewhat unusual as a pair setup, both having idle/mixture pre setting screws at the very base of each carb, almost at the inlet manifold junction.

If these have been closed up in the past to reduce the tickover....people do the strangest things

Try to get the settings as per the factory original settings.

If your man does not have these, I can help.

Just to help the sanity level.....

2 little video clips shot recently in my barn.


Before:
http://www.youtube.com/watch?v=4qayyc9Z ... re=related" onclick="window.open(this.href);return false; (click here to see carburettor set up for a shed )

After:
http://www.youtube.com/watch?v=dsfo5ATg ... re=related" onclick="window.open(this.href);return false;

Cordialement,

[kevtherev]

Further info regarding timing
this would affect performance

5°±1° ATDC with vacuum
Mechanical ignition advance checks
0°-1° @ 1150RPM w/o vacuum and basic timing
9°-13° @1600RPM w/o vacuum and basic timing
21°-25° @3400RPM w/o vacuum and basic timing

When setting ignition timing on vehicles with DIS (digital idle stabilisation) the two connectors of the DIS unit must be removed and plugged together.

Disconnect engine crankcase breather and plug on side of air cleaner.

[81AirCooled]

I´ve got the standard carbs and the Haynes manual says the CO to gas content should 0.3 to 0.9% at idle so surely I´m way below that. I'm a bit apprehensive about making too many suggestions about what to look at as the place at least appear to be top notch as far as VW vans go and he had 3 people checking it out Saturday but the more heads providing input the quicker it`ll get sorted so thanks for the suggestions everyone, I'll be speaking again to him tomorrow and I'll go through the next steps with him over the phone. I think he wants to check the valves next. The problem is I only got the van in August and I´ve got no previous history on it so for all we know someone could have done a proper botch job on the engine.

[kevtherev]

CO content @ idle 0.0 ±0.3 % volume
what is yours?

have they said?

[81AirCooled]

Yes he said the CO value is between 0.17 and 0.23 at full load but that´s not what the Haynes says it should be. No idea what he meant by "full load" though

[kevtherev]

Yes he said the CO value is between 0.17 and 0.23 at full load but that´s not what the Haynes says it should be. No idea what he meant by "full load" though

I doubt full load is idle speed.. pity... it would have told us a lot

[81AirCooled]

I'll ask him to do it again tomorrow at idle and see what we get. Still, he tells me the carbs are getting enough fuel, he's used other carbs too with the same result, low CO and no power. I'll ask him to check the sparks as well while I´m at it as I changed them in winter and it hasn`t really run since. I'm hoping I messed that up and 1 of them is loose but tbh the van doesn`t behave any worse than before the change so I guess I´m clutching at straws

[kevtherev]

lack of power is lack of fuel and/or poor timing.
if the other carbs produced the same result then you can only assume they suffer from the same lack of fuel and the same poor timing.

It is very difficult to diagnose remotely without being there.
You have my sympathy but that's no help is it.
good luck, maybe some others have some fresh ideas

[81AirCooled]

Cheers Kev, I'll have to go around to the place on Friday or Saturday I guess and ask him to show me everything. I won`t know what I'm looking at as far as the timing goes but at least we can check it against the Haynes etc

[toolsntat]

My old favourite is the fuel pump pushrod wearing down causing lack of fuel but doubt that it affects this problem (worth checking though)

This garage should from what your saying be on top of this problem by now
Are they getting things mixed up somewhere with CO CO2 AND O2 values ?

My old engine was well gutless and did suffer with low compression on No3 but even without fixing that problem when I went to Vanfest in it those German guys played with the carbs and improved it no end....

I tend to think this is down to the carbs and like Sarran said setting them right means making sure ALL those little adjustment screws are right.

Really hope they get it sorted soon as your bill could have paid for a new engine
Andy

[81AirCooled]

Ok so I'm due to call the garage in a couple of hours and I'm just going through a couple of things in my head to check with them;

Timing set to 5° with vacuum attached?
Sparkplugs not loose?
Tappets ok? I honestly don't know if this could have any affect but I changed the pushrod tube seals on the right last autumn: I did them one at a time and as far as I know I have the hydraulic kind I didn't adjust or reset anything. The left hand side also needs doing badly as it`s leaking a lot - would this affect power/CO value?

[kevtherev]

no it wouldn't.

[81AirCooled]

Shame that as I could get it fixed easily. Crap news is that I the van is not being looked at for a couple of days so no new until Thursday earliest. Only 1 week until we should be gogin on holiday