Hi all,

Last week I discovered my wifes (dual fuel) EF had a huge hole top and bottom in the plastic intake plate on top of the rocker cover. Not having a spare EF one, I put the entire intake and mixer assembly from my EL onto her car as we have three kids to shuttle around and the EF wagon can't be out of commission.

This required me to assemble and "innovate" a replacement arrangement for my car late on a Sunday arvo with what I could find around the house..

(just FYI, my PVC assembly is 75mm round all the way so it's a dramatically better flowing than the original so I'll be cleaning it up and painting it black and leaving it in place.)

Anyway, her LPG system with my mixer seemed to work well enough.. better throttle response as my mixer was less restrictive than her old one. However.....

I was taking her car for a drive on LPG to evaluate it... and I stopped and idled at a traffic light for about a minute and a half. When the light turned green, I put the boot in a little bit and the result was a huge intake backfire and the car stalled.

When I started it again... it would not idle on LPG properly... seems the backfire caused the LPG idle speed to drop 200rpm or so.. just borderline idling and it would die in about 10 or 15 seconds of struggling along. Petrol it still works fine.

The balance hose and all over connections are fine.. no looks or holes or hoses off are apparent.
I am assuming the backfire after idling was caused by a too rich mixture of gas?

Can anyone tell me what in an LPG system effects idle speed that could have been changed by an intake backfire?


regards

Frank

fiddling with the adjuster on the side of the converter seems to have helped a little, but it's a long way from perfect.

I'd say it has either caused a vacuum leak some where or it damaged the second stage diaphragm.

Thanks dude,

I screwed the adjuster on the converter in about a turn and it seems ok now..

I was wondering if changing the mixer from the restrictive EF one she had to a much bigger holed EL one from my car would cause issues.... so I put hers back in..(had to modify it to get it to fit as the EF one wasn't designed to go in the big rubber intake knuckle.)

Ironically, the pulsing I've been complaining about on here a couple of times is gone now.. turns out that was caused by the EF intake pipes... once I swapped to the EL setup the pulsing stopped. (I had thought it was the converter so I'm pretty happy the pipes solved it.)

I think once I find her an EL mixer like mine... I'll take the car in and have the LPG system tuned properly.

The bigger mixer with no retune would have caused it to be lean, which is what caused the back fire.

Check the MAP sensor hose has not popped off.

ahhh.. I didn't know to lean could cause backfires.. I thought maybe gas had been accumulating while idling and ignited when I planted my foot in.

The gas system has a complex converter with a dumb mixer and en electric stepper motor connected to a lambda module if that helps anything.

Twase, balance hose and map sensor were the very first two things I checked.

Had that hose pop off on me once. On petrol it wa spitting out black smoke like you wouldnt't believe from running so rich.

Yes from what i have seen petrol will not run very well at all but gas will just see the vacuum leak and idle funny if at all.