Vibration/judder/misfire- Map?

Post Reply
Message
Author
57jam89
Member
Posts: 466
Joined: Sun Jun 21, 2009 5:14 pm

Vibration/judder/misfire- Map?

#1 Post by 57jam89 » Thu Jul 02, 2015 6:02 pm

Hi all,
I have a very light vibration/judder/misfire about 2000 rpm under light/normal load. There are no fault codes stored and runs fine on petrol.
I had this new ecu and injectors set up by Tubbs a few months ago and has been fine up to now.
I had a look at the maps and this is what I found-

Image

I don't know why the 2 lines are so different, they were ok. And whys does the gas line just drop straight down?
Is this why it's not running right?

Thanks.
Nissan Skyline 350gt Lpg fitted by Lpgc.

LPGC
Installer
Posts: 3323
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: Vibration/judder/misfire- Map?

#2 Post by LPGC » Thu Jul 02, 2015 10:11 pm

:lol: Are you sure you haven't clicked on each dot on the map and randomly moved each up and down while blindfolded?

I'm betting this isn't how Tubbs set it. :roll: More likely the 'active multiplier assistant' and/or 'active rpm assistant' have been left on and made a mess of things. The multiplier map is indeed a mess, show us your rpm correction table - they might be compensating for each other..

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

57jam89
Member
Posts: 466
Joined: Sun Jun 21, 2009 5:14 pm

Re: Vibration/judder/misfire- Map?

#3 Post by 57jam89 » Fri Jul 03, 2015 8:13 pm

Hi Simon,

No I was not blindfolded! And the map was fine then I left Tubbs.

Image

I did find Autoadaptation was on so I turned it off and also pressed 'calculate multiplier' and this is what the map looks like after 100 miles-

Image

Do you think this is ok now or do I need more adjustments?

Thanks.
Nissan Skyline 350gt Lpg fitted by Lpgc.

LPGC
Installer
Posts: 3323
Joined: Wed Sep 29, 2010 6:01 pm
Location: Yorkshire
Contact:

Re: Vibration/judder/misfire- Map?

#4 Post by LPGC » Fri Jul 03, 2015 10:19 pm

It still looks wrong.. Unless there is something wrong with vac reference (unlikely) or you're running too much pressure (doesn't seem so) / poor performing injectors. Would usually expect to see a rise from about 2.5ms, a peak at about 4ms, a fairly steep drop from 4.5 to 6ms, a drop that levels out to near flat at 16ms where the multiplier should be near 1. The point of the peak will depend mostly on gas injector spec and then on petrol injector spec, is usually about right for a vehicle that idles (no load warm engine) at around 3ms Pinj.

Another example of a thread that would have been better not as a new thread but as a continuation of an existing thread that lists what actual parts are fitted on what vehicle... You do have threads that contain all the relevant info mate!

Clear the rpm map, get someone to drive the car with a code reader showing fuel trims while you manually adjust the multiplier to achieve fuel trims at all loads that add up to zero. Then check mixture driving flat out (using lambda reading on code reader) and adjust the high load multiplier. If mutliplier at flat out Pinj isn't very near 1, adjust pressure accordingly and redo from start (with adequate injectors).

Depending on what injectors and vehicle this is, pressure won't be far out, so I don't think you'll be far out on calibration first attempt. Anyway, you've visited Tubbs who will have sorted that out. A few us us pros just do a very rough cal to start with, point being to get the 1 multiplier at flat out so we know the pressure to calibrate at.

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