Judder / Misfire on LPG - Fine on petrol

Any posts regarding LPG to be posted here ONLY please.

Moderator: phpBB2 - Administrators

Post Reply
Eurostang
Newbie
Newbie
Posts: 13
Joined: Wed May 15, 2013 10:11 am
Location: Leeds

Judder / Misfire on LPG - Fine on petrol

Post by Eurostang »

Hi all,

My 3.9 Discovery 1 has started to misfire/judder really bad below 2000 rpm and at light throttle. Seems to go away at higher rpms

It is particularly bad on a cold morning and results in a big drop in power / judder.

The system is a Bigas Sequential (SIGN).

I have replaced the plugs to NGK BPR6ES and gapped to 0.8

New leads

New distributor, rotor, cap and ignition module

New coil

Could it be a sticking injector?

I have purchased a data cable to hook into the Bigas ECU.



Eurostang
Newbie
Newbie
Posts: 13
Joined: Wed May 15, 2013 10:11 am
Location: Leeds

Post by Eurostang »

I have taken a video, I apologize for the shakey video and background/road noise (It's an old squeaky land rover :/)

https://goo.gl/photos/j3eyGBk1VDk43atj8

User avatar
Rossco
Moderator Gold
Moderator Gold
Posts: 850
Joined: Sun Nov 19, 2006 11:33 am
Location: Too many to even keep count

Post by Rossco »

Air leak or poor electrical connection somewhere would be my starting point.

You say you have new HT leads, if they're standard then ditch them and get good quality 8mm leads.

LPG puts a lot more stress on the ignition system so any weakness will show up on LPG but may not show when on petrol.

User avatar
ChrisJC
Top Dog
Top Dog
Posts: 5039
Joined: Mon Nov 20, 2006 1:13 pm
Location: Northants / Cambs
Contact:

Post by ChrisJC »

I had a judder at high load / speed, which after replacing lots of ignition components turned out to be the MAF. Petrol was fine, LPG juddered.....

Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8

Post Reply

Return to “LPG Section”