MFI part load CO settings

[Jay Zollinger]

I've reviewed the eariler posts, but don't quite feel confident about the answers. Is it a concensus that the part load CO setting should be 7-8% at 3,000 rpm while the car is stationary, with the idle CO set close to the same?

Also, has anyone tried to use a Gunson with the car moving to get a more accurate part load reading? Given how fickle the Gunson is, and given the problems that I've had with a melting tester tube, I doubt that it would work, but am tempted to try. I know that I should just break down and get the LM1, but I'm too cheap (and too married).

[David E. Clark]

These pages are right out of CMA. Is this what you are looking for?



Copyright Dr. Ing. h.c. F. Porsche A.G.

[David E. Clark]

Here's the page out of the factory manual supplement -- says the same thing.

Copyright Dr. Ing. h.c. F. Porsche A.G.

[Zeke]

The instuctions on the Gunson say to calibrate it in a stationary, no wind environment each use. Then bring the car to the test area for testing (you don't want the car anywhere around during calibration, or any other source of fumes, for that matter).

So, I doubt if it will work well in a rolling test. I don't know, I have a GTT, but have only read the instructions. I'd rather beat on metal.

Although MFI is marvelous, so are PMO's.

[Jay Zollinger]

David: The issue is how to set the part load without a dyno or a way to take an accurate reading on the road. I agree with Zeke that the Gunson won't work on the road. The closest thing that I have seen in prior posts is one from John Walker saying that you need to set it at 7-8% at 3,000 rpm, but it wasn't clear that this was a stationary reading. John says he doesn't know how these cars ever ran right at the factory recommended CO specs.

Thanks, by the way, for compiling the MFI resources--its great to have it all in one place.

[David E. Clark]

Without a dyno and with only the Gunson it depends on how creative you want to be. I've never tried this but could you block the car up with 6 or so jackstands (how many it takes to be safe), set the throttle to 9 degrees and get 2400 rpm in second using the brake to simulate a dyno? I know it sounds crazy, and it is probably better all around to spend a buck and get the LM1, but it might work.

By the way, do you use the "self made" tool to set the throttle? With or without the protractor? If yes, can you post a picture of the tool you made and describe how you made it? If no, what method do you use?

[Jay Zollinger]

David: That doesn't just sound crazy, it is! I did, however, recently see a set of rollers for the rear wheels advertised in a car magazine. I'm sure there's no way to adjust tension, but someone might be able to figure out a way to simulate a home dyno using them. If I were smarter (or less married), I'd just buy the LM1.

I also haven't been able to find a set of protractors, so I haven't even bothered to think about a tool to set the throttle angle.