Fordmods Logo

Won't idle on LPG after backfire. 

 

Page 1 of 1 [ 9 posts ] 

 
 Post subject: Won't idle on LPG after backfire.
Posted: Sat Sep 22, 2012 2:31 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 3440

Joined: 23rd Dec 2007

Gallery: 32 images

Ride: BA XR6T (mix of BA, BF and FG)

Location: Perth
WA, Australia

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..
Image
(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
Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Sat Sep 22, 2012 5:24 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 3440

Joined: 23rd Dec 2007

Gallery: 32 images

Ride: BA XR6T (mix of BA, BF and FG)

Location: Perth
WA, Australia

fiddling with the adjuster on the side of the converter seems to have helped a little, but it's a long way from perfect.
Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Tue Sep 25, 2012 7:38 pm 
Getting Side Ways
Offline

Posts: 6449

Joined: 11th Nov 2004

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

 

_________________

PERMANENTLY BANNED

Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Tue Sep 25, 2012 8:14 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 3440

Joined: 23rd Dec 2007

Gallery: 32 images

Ride: BA XR6T (mix of BA, BF and FG)

Location: Perth
WA, Australia

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.
Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Wed Sep 26, 2012 9:03 pm 
Getting Side Ways
Offline

Posts: 6449

Joined: 11th Nov 2004

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

 

_________________

PERMANENTLY BANNED

Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Wed Sep 26, 2012 9:20 pm 
Getting Side Ways
Offline
User avatar

Posts: 2644

Joined: 6th Nov 2004

Gallery: 8 images

Ride: 2007

Location: Mount Annan
NSW, Australia

Check the MAP sensor hose has not popped off.

 

_________________

BF Fairmont Ghia Series II update.
GQ XR6T ghia patrol.

,======o00o
//__|__|_,\_____\,___
|_/--\'_|'__|_/--\_[]IIII[]
_( o ) )_____( o ) )=o=) )__

Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Thu Sep 27, 2012 1:41 pm 
Getting Side Ways
Offline
User avatar

Age: 45

Posts: 3440

Joined: 23rd Dec 2007

Gallery: 32 images

Ride: BA XR6T (mix of BA, BF and FG)

Location: Perth
WA, Australia

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. :-)
Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Thu Sep 27, 2012 3:10 pm 
Getting Side Ways
Offline

Age: 36

Posts: 9453

Joined: 9th Nov 2004

Gallery: 4 images

Ride: Fordrunner 5.0 Turbo

Location: Wollongong
NSW, Australia

twase wrote:
Check the MAP sensor hose has not popped off.


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.
Top
 Profile  
 
 
 Post subject: Re: Won't idle on LPG after backfire.
Posted: Thu Sep 27, 2012 8:01 pm 
Getting Side Ways
Offline
User avatar

Posts: 2644

Joined: 6th Nov 2004

Gallery: 8 images

Ride: 2007

Location: Mount Annan
NSW, Australia

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.

 

_________________

BF Fairmont Ghia Series II update.
GQ XR6T ghia patrol.

,======o00o
//__|__|_,\_____\,___
|_/--\'_|'__|_/--\_[]IIII[]
_( o ) )_____( o ) )=o=) )__

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 1  [ 9 posts ] 

Who is online

Users browsing this forum: No registered users and 4 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Wed Dec 13, 2017 7:12 pm All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names