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[staticsan]

My '82 NA 924 went for an IM240 test today. Unfortunately, it failed. Just. The test engineer was really good, though (clearly, here was someone who loves their job), and helped explain what all the numbers meant and the sorts of things to do to fix it all.

Problem #1. NOx was too high by almost a factor of two. That was probably because my mechanic lowered the mixture to get the CO level down. But that raises NOx. So I go back to him and say it needs to be a tad richer to get the NOx down. I don't remember the units, but the CO was "11" and can be as high as "18"; the trick is my mechanic doesn't have a NOx sensor, just a CO sensor. However, these are the same numbers my mechanic was using with his much simpler tests. So.

(I'd like it bit richer, anyway, as it's hard to start cold when it's this lean.)

The test engineer also said the tappets were loose and fixing the would means lower emissions because the valves would open just that little bit sooner. I'll ask my mechanic about this, too, but I hadn't heard this before. Last resort is to actually put a cat on it, as it doesn't have one. My mechanic seems to think it's better without one, but hey -- it's good to have a fallback position.

Problem #2. THC. I needed to fill the tank before going to the test centre, but filled it right up. Bad move. I forgot until we got moving again that a full tank puts fuel vapour in the passenger compartment. This meant the reading was way too high. So now I've got to repair the fuel vapour system.

Dad and I managed to get into the fuel filler port and found a heap of extra hoses going hither-thither. :-O All look original, so I think some seals might have expired. It also looks like there's an expansion tank up in the C-pillar -- can it be replaced without cutting the body up? What about the "bleeder valves"? Who has those?

I found a useful diagram in the old parts catalogue (Haynes was useless); there seems to be a second expansion tank on top of the fuel tank. It looks like fun getting to that. How much can I get to and get done without pulling the tank? Is it even possible to pull the tank without dropping the transmission? (And then I've got to find a place to put 50+ litres of fuel...)

Postscript. The parts catalogue indicated that the Aussie versions had one of those charcoal canisters in the vapour system. AFAIK, mine doesn't have one, but I don't mind adding that, if that's possible, but Pelican list it for an awful lot. Is this even worth contemplating?

Wade.

[morghen]

you can set the mixture by yourself right there on the testing stand. i always do that...they say..well the numbers are not happy...so i take the little allen key and set the mixture to please the numbers on the screen.
i've got it to work at EURO 4 standards...thats like 20 years younger cars.
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[staticsan]