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Thu Apr 03, 2014 4:30 am

Just went through airfare with my new rebuild engine, passed everything but idle... high HC.
Engine seems to run good, idles around 900
Any idea's Guy's
Thanks

Thu Apr 03, 2014 6:48 am

How good is your cat?

http://www.smogtips.com/failed-high-hydrocarbons-HC.cfm

Thu Apr 03, 2014 8:17 am

I had the same problem last year, with all new exhaust and cat.
I had it tuned at a shop and went through a second time and the results were worse, but they gave me a conditional pass but let me insure it for a year!

Thu Apr 03, 2014 1:16 pm

What were the other figures, including the pass/fail threshold?

Even without knowing those figures, there are a couple cheats you could use if your HC at idle was close to a pass:

1. If the oil was not fresh, change it, filter also;
2. Disconnect the crankcase breather line into the intake manifold and plug the manifold side and put something on the crankcase side to control oil spray;
3. Disconnect the connection of the fuel tank evaporative system to the intake and plug the intake side.
4. Disconnect the electrical connection on the idle stabilizer valve and use the idle speed adjustment to raise the idle to 1,000 or even 1,100 or 1,200.

If you pass, immediately restore all the above to normal.

The reasons this will help are:

1 & 2 Dissolved gasoline in the engine oil is sucked into the intake tract through the crankcase breather, but also, to a lesser degree, in blow-by going past the rings and valve guides;

3. The fuel evap system on Vanagons is pretty primitive and can cause overly-rich conditions, especially at idle.

4. These engines are old and worn, including the throttle shafts. These air leaks (and other causes) can cause an intermittent miss at idle which the Oxy sensor interprets as a lean condition (due to the unburnt oxygen in the exhaust from each miss) which then causes the lambda system to enrich the mixture to where HC is too high. At higher engine idle speeds, the probability of miss is drastically reduced. The testing facility does not look at any of your engine components nor measure the idle speed. There is no "fault code" system. This is why you can get away with these cheats.

If the above does not do the trick, you need a new cat converter. Call VM Autohaus in Burnaby (604) 298-9637 for best price and quality VW parts.

BTW, you didn't hear any of this from me!

Thu Apr 03, 2014 1:52 pm

schoonerman wrote: Just went through airfare with my new rebuild engine, passed everything but idle... high HC.
Engine seems to run good, idles around 900
Any idea's Guy's
Thanks

You'll need to post all your numbers, including year/model/engine, if you're looking for informed responses. ;)

Thu Apr 03, 2014 7:24 pm

1987 Vanagon rebuilt performance engine to 2.2

all new stainless cat and stainless exhaust system

oil and filter changed

copy of Aircare attached

thanks for replies

Thu Apr 03, 2014 9:06 pm

A good shop with a sniffer should be able to dial in the CO to read ~0.10 - that would help your HC as well. Retarding the timing slightly might also help. Again, you'll need a tailpipe sniffer to dial it in.

The only guys I recommend are Vancouver Transmission at 604-590-8404

Obviously, running Mohawk Premium would help, too, unless you have a hot cam?

Thu Apr 03, 2014 11:11 pm

Given that the high HC is with in limits but it is just the low idle HC that is way high you may have a missfire at idle. There is no Lambda reading on the print out that I see. That is always my first suspect in high HC. If it is not working and not sending a signal the CPU reverts to default "engine protection mode" and enriches the mix to avoid too lean a mix damaging the engine.

Thu Apr 03, 2014 11:49 pm

Jake de Villiers wrote: A good shop with a sniffer should be able to dial in the CO to read ~0.10 - that would help your HC as well. Retarding the timing slightly might also help. Again, you'll need a tailpipe sniffer to dial it in.

The only guys I recommend are Vancouver Transmission at 604-590-8404

Obviously, running Mohawk Premium would help, too, unless you have a hot cam?

The engine is fitted with proprietary cams, could that cause any problems?

Thanks for all the replies Guy's I will be taking her in next week to Adria Motors who do re-builds

Fri Apr 04, 2014 8:09 am

schoonerman wrote: Jake de Villiers wrote: A good shop with a sniffer should be able to dial in the CO to read ~0.10 - that would help your HC as well. Retarding the timing slightly might also help. Again, you'll need a tailpipe sniffer to dial it in.

The only guys I recommend are Vancouver Transmission at 604-590-8404

Obviously, running Mohawk Premium would help, too, unless you have a hot cam?

The engine is fitted with proprietary cams, could that cause any problems?

Thanks for all the replies Guy's I will be taking her in next week to Adria Motors who do re-builds

Was it Adria who built the engine?

Fri Apr 04, 2014 9:38 am

No, they didn't, but they do WBX rebuilds and service loads of Vanagons
Who would you recommend Jake?
Mike

Fri Apr 04, 2014 3:30 pm

Jake de Villiers wrote: A good shop with a sniffer should be able to dial in the CO to read ~0.10 - that would help your HC as well. Retarding the timing slightly might also help. Again, you'll need a tailpipe sniffer to dial it in.

The only guys I recommend are Vancouver Transmission at 604-590-8404

Obviously, running Mohawk Premium would help, too, unless you have a hot cam?

I disagree. CO was not the fail, but any base CO adjustment done on the AFM is base only and gets corrected by the Lambda system, so no matter the base setting you do, after warm up, the lambda system controls CO (indirectly, of course, through programmed stoichiometric AFR). If the lambda system is not working, the WBX will not pass emissions testing - - a new engine might get close, but only with a great deal of luck.

This problem is clearly caused by a misfire, which is obvious in light of the other test figures. Assuming the engine was fully warmed up at testing, the NOx reading is on the low side (which is good), but this means you could crank in a bit more spark advance. That is not, however, something that will clean up the HC readings, though.

Since your dynamometer test figures (as opposed to idle figures) were good, this fail is linked only to things occurring at idle and it is clear the Lamda system is working as designed and at good efficiency.

For the $30 test fee, and considering how close the fail was to a pass, you will likely pass just by raising the idle speed to say, 1,200 rpm as described in my post above. Worth a try, IMHO. The reason this works is because at the higher rpm, the air leaks at the throttle body bushings and butterfly (and elsewhere) become insignificant due to higher air flow and they therefore no longer cause the miss. This is why your higher-load chassis dyno figures are a very clean pass, by comparison.

Remember, every miss puts unburnt oxygen into the exhaust system. The oxy sensor senses this and the ECU interprets this excess oxygen as an overly-lean condition and adds fuel. The lambda system CANNOT do its job if there is a miss. The lambda system uses the oxygen content as a proxy for the air fuel ratio (AFR). It does not measure AFR. So a miss not only puts unburnt HC into the exhaust stream from the miss event(remember that the oxy sensor DOES NOT detect unburnt HC), but then the lambda system compounds the problem by adding fuel to ALL the cylinders.

The WBX does not have cylinder-selective fuel trim like some of the highest-tech sports cars. It does not even have sequential injection - - all the injectors open at the same time. This fact does create a tendency for one cylinder in particular to be more likely to miss at low idle speeds - - whichever cylinder is getting its injection event right after the intake valve closes.

Hope this helps.

Sat Apr 05, 2014 12:54 pm

Thanks Howesight,
I have just checked the vacuum lines and sprayed WD40 as per Tencents suggestion while running the engine, all is good.
I have all new coil, distributor cap and rotor, plugs and leads, so next step before taking her in to a shop, is to have the injectors overhauled
Thanks again
Mike

Sun Apr 13, 2014 11:20 pm

Before I take her in to the shop I started checking.......

Removed the afm and the spark plugs, the plugs were all in good shape, sort of white color on the electrodes

Removed the injector electrical plugs and cleaned, checked the wiring, all ok
Cleaned out the filter box and checked the air cleaner, ok.
Checked all vacuum pipes, ok
Checked rubber between afm and throttle body, ok

Replaced everything and started up, I was amazed to find that she started on the first turn of the starter, usually takes 3 or 4 turns, I found I had forgot to plug in the afm electrical plug, could that be a CLUE as to the idle problem?

I checked the allen screw adjuster on the afm and found it to be turned 13 turns out, shouldn't it be only 2 turns out? another CLUE?

When at idle the engine does seem to shake a little bit, indicating a miss?

She drives and runs very well, no indication of a miss.

Tomorrow I intend to remove the injectors and have them overhauled.

Any idea's on the above Guy's?
Thanks