Dear FChat tool gurus: I have decided I need to purchase some form of exhaust gas analyzer. I now have three cars with carb set ups (a single DGV on one Fiat, twin IDFs on another Fiat, and the 4 DCNFs on my Dino), and tuning by ear only goes so far (though it's gotten me through emissions in CO). With the "sniff tubes" on my 308, I could theoretically tune each cylinder perfectly. If my girlfriend really does buy an old Porsche 356, I'll be tuning four cars! There appear to be two types out there - one that is a lambda sensor and reads A:F ratio, an the classic broad spectrum analyzers. These analyzers seem to come in two styles as well = huge and small, costing several thousand or several hundred. The AF ratio readers seem to hook into laptops, and as I have a Macintosh, I'm not sure they would work with my computer. What equipment do you recommend, and why? Any troubles fitting nozzles into the small exhaust analysis tubes on a Ferrari? Your expertise and experience wanted. Thank you. Jonathan in Denver [email protected]
As an amateur guy, I have had luck with the Innovate LM-1 and LM-2 product, a wide band O2 sensor based unit that gives A/F or lambda. It's on the lower end of the cost scale at around $300, and I have bungs welded into my exhaust near the headers to help in optimizing the carb jetting. You don't need a separate computer, but it helps in analyzing. I particularly like these as you can take them on the road with you and monitor real time real world mixtures while driving. Good luck!
I've not been impressed by the cheaper ones on the market. What you are better off doing is finding yourself a good used trade-specification 5-gas off EBAY or from an auction site from a closed business. i have the classic SUN 5-gas, that model has been around for years and there are plenty of used ones available on the market for a very good price. If you go for a used one, try and get to see it working, sometimes the gas-bench board inside fails, and they are prohibitively expensive to repair. Just fire it up and check it goes through the calibration procedure (can take up to 15 minutes) and that the vac. pump runs o.k.
The problem with the air fuel or lambda only units is the lack of CO2 or HC readings. A cylinder that is not running properly puts O2 and HC into the cylinder and the O2 sensor will pick up the unused O2 as a lean condition when actually the other cylinders may be running properly. Snap On makes a very nice hand held unit, I have two in the shop and you can even take them on a road test for actual readings.
On my 308 most of the sniffer tubes were blocked although some of them could be cleared by ramming bicycle type brake cable down them. I could then adjust these with confidence but was reduced to guesswork sniffing at the two exhausts for the others. I had a cheap CO meter which was good as far as it went but in the end I had to go to a professional to get it through the local fairly strict emissions test. All round a tricky business.
