ColorTune and Exhaust Gas Analyzer

[ronzi]

Moss has two tuning aids in their catalog, the ColorTune, and an exhaust gas analyzer, both I believe made by Gunson.
Does anyone have first-handknowledge of if and how well they work?

 

[Bret]

I tried the ColorTune once and thought it was a PITB. But I've heard folks with pre-emissions setups like them.

As for the Gas Analyzer? I’ve always been quite happy with the results of the gas analyzer and highly recommend it.

Some advice on it’s use for best results: All you need to do is hook it up to 12volts and follow the tune up instructions in the manuals. But while some folks like to hook it to the car’s battery, but I’ve found that the constant starting & stopping of the engine can give erratic readings if you don’t allow the analyzer to settle down & re Zero it again. So I like to use an independent 12 Volt AC to DC converter & leave it plugged into the wall outlet for about a half an hour or so before I zero it. That allows you plenty of time to warm the engine up to its normal operating temperature.

 

[DrEntropy]

ColourTune works fine on most old LBC's if the car has not been modified heavily. I've used 'em for years. Two of 'em, one per carb makes setting the mix a really quick job.

EGA is really better if you are trying to get a steady mixture across the acceleration range with needle profiles or re-jetting. If you are modifying the induction system or doing performance mods the EGA is the better way to go.

 

[ronzi]

Thanks for the feedback, guys.
Guess I'll take a chance on the ColorTune device.
Other opinions I have heard tend to agree with Bret that it can be difficult to "read". I had never heard the pre-emission distinction drawn previously, but since my car is a '64, it is encouraging.
One of the members of the local MG club had one of the Gunson EGA machines, and his comment was similar to Bret's in that he felt was unstable and produced non-repeatable results to the point of being useless. Could be that he did not follow the appropriate procedures to stabilize the readings, although he is an extremely meticulous aerospace engineer and I somehow doubt that.
Anyway, at $40 vs $300, I guess I'll try the ColorTune first.

 

[Nunyas]

I have the EGA. While I haven't had much success in using it, it does seem to work pretty well. I think my problem was in setting it up. I, like "most people", connected it to my battery, and let the EGA "zero" while my car was idling/warming up to operating temp. The problem that occurs while doing it this way is the EGA is not far enough away from the car to get a true "zero" reading; it's too close to the exhaust. So, your CO base will be too rich (i.e. your base CO reading will be higher than normal atmospheric)... I haven't attempted to use it again since my first tries... Instead, I've "played it by ear" and then made the mix a bit leaner for emissions testing.

 

[Bret]

Rob,

Next time try to hook the EGA up to an external +12V source like I did. This should elevate the biggest problem I see is that you have a stable power source whereas the car's 12volts is constantly changing between 13 & 14 volts as your fans and other accessories kick on & off throwing off your true zero.

Another bit of advice is that once you’ve connected it to the source make sure you position it in the location where you’re going to be testing the vehicle. Because the EGA doesn’t like to be moved around once it’s been zeroed. Once you’re sure the tail pipe sniffer will reach the exhaust pipe – take the car out for a quick drive to bring it up to normal operating temperature. Then when you return keep the car about 10-15 feet away from the EGA and insure it can idle properly. Once your confident about that walk over to the analyzer and adjust for zero and wait about a minute or so. Take this time to make sure you’re set to test by disconnecting the air pump as the manual describes. Once that’s done and the EGA stabilizes (no more adjustments needed) – bring the car forward to be tested.

I know it sound’s like a royal pain in the rear but if you do that and you'll be surprised at how accuracy improves.

 

[aroostok]

Just recently used the ColorTune to set up my 76B that was changed to accept 2 HS4's and removal of the air pump system. I though it really worked great. Made a difference of 25% (no kidding) in my gas mileage. I was really running rich at idle and with some tweaking of timing it really made a world of difference.
Highly recommend.