Timing question

[Hasbeen]

Do you have the air pump still fitted & working? That most cynical bit of kit does nothing to reduce the stuff coming out the exhaust, but by adding volume it reduces the ppm reading of the nasties.

Then the EGR valve. Is it working. It is another of those pretend solutions that can get you past inspection.

Triumph bean counters would never have paid for them if they had not been essential to passing exhaust tests.

Hasbeen

[jeffremj]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Can't get through emissions testing. The engine runs really nicely - very smooth - but the HC is really high at idle. If I lean it out to almost a lean misfire, I can get the CO levels down to almost 0 at idle, but the HC goes up past 550ppm. If I bring up the CO levels by richening the mixture slightly, the HC comes down, but only to 450 or so, then starts to rise. (I need 416 to pass.) I've tried fiddling the timing by a few degrees and re-adjusting things, but I just can't get the HC down to where it needs to be. I'm thinking of putting in a small catalytic converter, as that should get me roadworthy.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">The car seems to be performing correctly - for an UK car! The TR7 UK spec only has to pass these requirements in the UK:

From 1/8/75 and before 1/8/86 - max. figures:
CO: 4.5% HC: 1200ppm

Also, if car is over 1200ppm at idle, the figures can be tested at fast idle and if below 1200ppm, it will pass.

So, your car is tuned correctly for a non-emission fitted car.

[sheetsofsound]

The way the car performs I figured it was tuned pretty right. Emissions testing here is done at idle and at driving speed - which means above 2500rpm or so. For the driving test, my readings are almost 0 for HC and the CO is at around 1 percent - no problem. At idle I'm supposed to be 4.6 percent CO and 416 ppm HC.

None of the emissions stuff was on the car when I got it, so I don't have an air pump. The other car that I've been trying to sell doesn't have an air pump either. There is an EGR valve that I have not hooked up, so I could try that. There is a guy selling a small cat for $100 that would solve my troubles once and for all.

The really funny part of all this is that the government is phasing out emissions testing here in December because they say it's done it's job of cleaning up the air. Comedy, that. If I don't want to drive the car this summer,I could just wait and put it on the road in the winter. Not drive a convertible in the summer? Where's the fun in that?

[jeffremj]

IIRC, the EGR is only for NOx, so won't help. You need the cat so you can change un-burnt HC to water and CO2. This needs oxygen to work correctly, but if you are lean at tick-over, there maybe enough oxygen in the exhaust to help you out - worth a try. Tell us how you get on - don't change any tuning so you know if the catalyst has an effect. Can't you use a second-hand cat and splice one in - must be loads in scrapyards.

[FI Spyder]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jeffremj</i>

Can't you use a second-hand cat and splice one in - must be loads in scrapyards.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

For the short term (which is all you need) that might be the solution. My FI is a California car and had a cat to make the strictest of emissions (at the time). It doesn't come with the air pump and EGR as the FI did away with that.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[sheetsofsound]

My plan is to get a used one, although I got a used one at a wrecker yesterday and it was no good; once it was on the car, it didn't change the emissions even a little. The wrecker was good about taking it back and I'm am presently trying to source another one.

[Workshop Help]

Here's an idea or two. Try using my 'Free Decarbonizing' trick as shown in The Workshop Manual to clean the combustion chambers. Perhaps some carbon buildup is causing incomplete combustion which would skew the CO and HC levels. Then, there is that snake oil concoction juice that claims on the bottle to guarantee your car will pass an emission test. This miracle fluid is sold at most every auto parts store I've been into.

If nothing else, it will be a cheap bet on your part in lieu of a catalytic convertor and the labor to install it.

Mildred Hargis

[sheetsofsound]

I have tried putting methyl hydrate in the tank prior to the emissions test before. I don't imagine the snake oil you're talking about is much different. I may give that another go if I don't turn up a cat pretty soon. I will also try decarbonizing, but I'm kind of curious to see how the readings change with the cat in place first.

Scrapyards are not exactly swimming in catalytic converters. From what I hear, it's one of the first things the wreckers cut out of the cars here due to the valuable metals. I've been trying Craigslist, but so far no luck. Tomorrow I will be trying some local scrapyards again.

[sheetsofsound]

For those enquiring minds that want to know...

Fitted a new catalytic converter that I got cheap. I also did the decarbonizing as described in Mildred's thread. HC at driving speed was almost 0 and the CO was at 0. This was much as before.

At idle the HC was down to 380 ppm and CO at around 4 percent - not a huge change, really, from before the cat was installed and before decarbonization. Enough change that it passed emission testing, though. I am now legal and insured. Luckily, today was warm and clear, so a perfect day to be out and about.

Thanks again to all for sharing their invaluable knowledge.