Can anyone recommend an exhaust gas analyser? I bought a Gunson one, but it was absolute poop! So much so I've sent it back to Amazon.
I looked at the Amazon reviews and they agree with you. This is a very old 1970s product dressed up as modern by slapping a cheaper digital display where it would have had a meter. For a tenner at a car boot or free they are worth having. For £114 its a lot for a tool with one job..idle gas mixture. These days you spend a bit more and get a lambda sensor based oxygen measuring kit - there are several around. For these you either make your own sampling kit or fit a "bung" in the exhaust for the sensor. PlX devices , innovate LM2. and the best : AEM UEGO. These work live and read several times a second. They can show misfires at idle. They can be connected to loggers so you can tune the carburettor for driving as well as idle .
So the mixture can be set by looking at the fuel mixture, instead of the CO reading? That might be an easier option seeing as I have a lambda plug on the VS exhaust.
You can, but you'd be better off blindly giving it whatever mixture makes it idle correctly though it would work for a single carb. How would you know which pot is rich/lean with a lambda measuring only all 4 at once?
I didn't mention it above, but this is for a FI bus, not carbs. So will the FI ensure that each cylinder is the same? At the minute, I have the idle mixture screen half way, and it idles ok. Tempted to just leave it and play ignorant!
I got one of these second hand years ago. It’s pretty primitive, and works by running the exhaust over a hot wire. The wire changes resistance depending on gas concentration. It takes a fair bit of fiddling to get it to stabilise, and then you get a read out in carbon monoxide percent. The number has to be treated with some suspicion, but it does indicate when you are lowering or raising the CO level, and I have used it to successfully pass the MOT emissions test after a failure. As Mike says, a tenner at a car boot sale OK, but not £114.
Having taken a fair number of random vans through MOTs, it's far from unusual to have to make the engine idle like a pig to pass CO test but for a carbed engine it's a sign of something other than the idle mix being amiss...obviously.
I couldn't get it to stabilise at all, really. When I eventually thought I had, and put it into the exhaust, the reading went from 2.0 to 2.8. I then screwed the fuel mixture screw in, nothing. I screwed it out, nothing. I then turned the engine off and removed the sensor. The reading went up to 3.8! I did buy it direct from Amazon as "used", at £80, so maybe it was just a bad one. But bit reluctant to give it another go at full price!
Would this kinda thing do the trick? https://www.demon-tweeks.com/racete...VQYBQBh2aDAMLEAQYCSABEgJbFvD_BwE&gclsrc=aw.ds
I bought a Gunston a couple of years ago & yes they are hit & miss and not very accurate. I set the CO at about 2% with it. Then checked it at the MOT garage with a decent analyser where it was reading nearer 3%. They do give you some idea but don’t take the reading as too accurate.
I think that is a narrow band sensor. They are slow to react compared with wideband. More accurate than a Gunston though.
This is a much better option if you can run to the price. Good thing is if you just want to set it up then sell the kit on they fetch good money second hand
Is this gonna do the job? Or is it just a gimmick? https://www.plxdevices.com/ProductDetails.asp?ProductCode=897346002870 Saves me having to fanny about with gauge wiring!
The fast acting AEM or my PLX will show uneven AFR at idle if there is a problem with a carburettor , air leak in. a manifold or a bad FI injector, if the sensor is somewhere that all four cylinders feed exhaust to.
You need to zero them in free air first , then they can take 10-20 seconds to settle on the reading assuming the mixture is constant , 2-2.8 is not an unusual fluctuation
I left it in free air for about 10 minutes, and it just kept going up and up. I'd dial it down to 2, but then it'd creep up. So I'd dial it down again. And so on. Maybe I just had a duff one.
