Transit MK6 - random petrol injectors firing whilst on LPG

Post Reply
Message
Author
adam.grafton
New member
Posts: 9
Joined: Mon Sep 16, 2013 12:53 pm

Transit MK6 - random petrol injectors firing whilst on LPG

#1 Post by adam.grafton » Tue Nov 01, 2016 9:46 am

Over the past week noticed slight intermittent misfire especially under load and twice switching back to petrol.
Quick check over and nothing untoward found on any of the usual culprits.
Plugged in diagnostics, found petrol injectors firing at the same time as running LPG, also managed to capture a change over to petrol at 120s, this while steadily increasing revs, at about 1400rpm
Scope capture below, traces from top to bottom:
RPM
Petrol Injector 1
Petrol Injector 2
Petrol Injector 3
Petrol Injector 4
Coolant volts
O2S11 volts
O2S12 volts
DPFE volts
Time ms
Image

ANY suggestions, no matter how obscure, welcomed.
Last edited by adam.grafton on Tue Nov 01, 2016 3:21 pm, edited 4 times in total.

LPGC
Installer
Posts: 3185
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: Transit MK6 - random petrol injectors firing whilst on L

#2 Post by LPGC » Tue Nov 01, 2016 10:56 am

Forget the changing back to petrol and O2sensors reading full rich for the moment - both likely due to the engine running very rich due to receiving both petrol and LPG fuelling at the same time.

Running on both fuels at the same time is the problem - Does this Transit have the relays under the dash that disable petrol injectors, and if so are they switching?

There is a sticky thread about how to post images on this forum, we can't see whatever you tried to attach.

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

Gilbertd
Advanced Member
Posts: 7957
Joined: Wed Apr 09, 2008 10:00 am
Location: Peterborough

Re: Transit MK6 - random petrol injectors firing whilst on L

#3 Post by Gilbertd » Tue Nov 01, 2016 11:30 am

I can, the picture appears in the post perfectly.
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.

adam.grafton
New member
Posts: 9
Joined: Mon Sep 16, 2013 12:53 pm

Re: Transit MK6 - random petrol injectors firing whilst on L

#4 Post by adam.grafton » Tue Nov 01, 2016 1:55 pm

not running "very" rich, just a little more so than usual,
plugs are dark tan centre, edges dark grey
rather than the usual dark creamy beige colour electrode

relays are under dash,
tested and all working ok when individually tested earlier this year
have moved all 2 slots along in sequence on Sunday, no effect
have probed outputs with Fluke 177, no response, DMM might not be quick enough to monitor change
may have to monitor with scope later

LPGC
Installer
Posts: 3185
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: Transit MK6 - random petrol injectors firing whilst on L

#5 Post by LPGC » Tue Nov 01, 2016 5:41 pm

Gilbertd wrote:I can, the picture appears in the post perfectly.
Ahh, then I suspect it was dodgy internet at my end while I was sat in a car in the yard! :roll:

Don't read much into plug colour while running on LPG.

If the engine was supposed to be running on LPG but also receives petrol, the standalone LPG system will attempt to lean LPG mixture right off, so only a bit flows to the engine - so it might be just a bit rich.

In what respect are relays working OK? Have you tried pulling those relays to see if the engine will run on petrol / on LPG? I was thinking more along the lines of the switching signal to relays not working.

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

Post Reply