LPG with vaporizor and 425 impco

[Ritch]

Hi there! I suspect this is a rare install.

With the cost of gasoline being twice of propane and the fact that old style LPG conversion kits are almost free used, I decided to try a conversion on my Yukon. It is a 2001 6.0L with 327000 km. Ha ha, now for the good part.

I have welded a plate to the end of an aluminum cold air intake tube and mounted an Impco425 mixer on it. I used a 10" round aircleaner from a 1988 throttle-body injected van and it all fit where the factory MAF and air cleaner used to be! Hopefully, I can still use the gasoline system to start the engine and then after it is running the propne vapor will be drawn through the tube. This saves some work as far as trying to get propane to the cylinders before start-up goes. The lock-off valve I am using is vaccuum operated, so that LPG only flows when there is engine vaccuum.

Any sugestions on how to turn off the injectors when the engine is running will be greatly appreciated. Also, I will not be using the MAF. I will need to use a IAT sensor at the air cleaner. Open loop tuned of course, and then the timing can be adjusted for the new fuel.

Ideas? Hints? Tips?

[swingtan]

Don't do it.....

Well, if you do, you need to at least address Fuel trims: The ECM will still try to run closed loop, but has no control over the gas mixtures. So it'll fail all the CL running tests very quickly, probably report the O2s as being faulty and may go into limp mode. You could just run OL, but there's other issues with doing that....

I've seen a couple of gas injection kits and they are OK, but only just. The LPG regulator is too slow in its operation to maintain good gas injection pressure and the mixtures dift as a result. The cars I've seen keep throwing O2 codes as the ECM tries to adjust for the slow converter.

You may get it working well, but it might be more effort than it's worth. To turn off the injectors, you may be able to just put a relay in the injetor supplu line that opens the CCT when the gas system comes on line.

Simon

[Ritch]

Oh oh, I already started. I like the idea of a vacuum operated relay that cuts power to the fuel pump. I have it running with the mixer on the intake and maf just sitting there by itself.
Picture as soon as I figure out how

[Ritch]

http://img.tapatalk.com/d/13/07/12/ahu3u2y4.jpg

http://img.tapatalk.com/d/13/07/12/upa3uta7.jpg