LPG Discussion Forum

Update- ordered 2 3 bank injecters and did what you said knocked the retaining pins to remove the injectors from the rails, unscrewed the inlet pipes and swapped them along with the nozzles.
Misfire has gone and it's feeling smooth on gas which it hasn't for a good few mths but idle is a bit rough in park and drive.
So yes i think it needs a true up/mapping.

You did swap the nozzles at the end of the injectors too (for your old 3mm ones)?

LPGC wrote: Mon Nov 01, 2021 5:31 pm You did swap the nozzles at the end of the injectors too (for your old 3mm ones)?

Off course! Thanks

Thought you would have!

It will need calibration adjusting after changing the injectors.

Do you have an OBD live data reader you can use to see fuel trims?

Might also be worth running the 'injectors check' tests I mentioned in a post above but the results will be even less conclusive than normal if the engine isn't idling smoothly.

Bad news its running lean on bank!
Can't work out yet if it's lean on petrol as well.

I have a JOBD reader but can't remember if it reads fuel trims.

Did it seem to drive OK on gas?

Clear the code, drive it on petrol, see if the code re-occurs... Or better still check and compare fuel trims on petrol and on gas if your JOBD reader has the function.

Hi Simon, my JOBD reader can read voltage.
Cleaned codes and doesn't return on petrol but does on gas.
On cruise control at 70mph on gas bank 1 02 sensor voltage sets arounr 0.06 - bank 2 0.08v and petrol b1 and b2 0.60 - 0.80 it's idling rough on petrol and gas
Thanks

Does it look like i have a air leaking manifold?

It's possible the manifold has a vacuum leak but it's better to try to rule out other things before removing the manifold, lot's of things can give similar symptoms to a vacuum leak.
Another possible cause for a vacuum leak would be if one of the pipes between manifold and injector were leaking but this seams unlikely if it seems to idle OKish on gas (at least doesn't misfire).
To check for vacuum leaks you could use a blow torch... Don't light the blow torch but turn the gas on and go around the manifold 'squirting gas' at it, if you feed gas to a vacuum leak you'll probably hear a change in how the engine is running.

Other things include the engine running in openloop / limp home mode, this could be triggered by incorrect mixture when running on LPG. It is always a good idea and is often necessary to check/adjust calibration after changing injectors.

In your live data readings
What are the fuel system status's for bank1 and bank2? These may read openloop/OL, closedloop/CL or something similar.
What are the long term and short term fuel trim readings?

Hi simon, my JOBD reader is very limited, it can't read fuel status or fuel trims, can only see 02 voltage. The 2 after cats sensors are B1 0.12v B2 0.10v.

Thanks

You could do with having a code reader that can read fuel trims for this kind of diagnostics really mate.

For intents and purposes you can ignore the post cat sensor readings, though if they are hanging close to 0v all the time it probably does indicate actual lean running. But, again, that could be because the engine is running in open loop mode.

Update - after changing all lpg injecters, lower and upper inlet manifold gaskets its now running/idling fine on petrol, running fine on gas but the idling on gas is a bit up and down.

I found A/F AFPHA on my reader and on petrol it's always around 100% on both banks. On gas driving it's around 130% with idling dropped to 110%.

Also no engine light but do have fault code p0171
Cheers

Hi Simon, as said in phone txts having changed LPG injectors it will need calibrating.

If you've found AF/Alpha reading (fuel trims in Jobd terms) you should also be able to find 'fuel system status' (open/closed loop readings)? Check to make sure that the status reading is closed loop when running on both fuels, because if they read open loop the AF/Alpha reading will be 100% but it won't mean the mixture is correct.. It is possible to have another fault (say ua MAF fault) that sees AF/Alpha at 130% on LPG but would-be higher than 130% on petrol, in which case AF/Alpha will revert to 100% but only because it is running in open loop mode.

Hi Simon, my JODB doesn't show fuel system status, it is a import, just been fully through it again.
When on petrol the AF/Alpha does flicker around from 90-106%.

Are my dates any good for you?

Strictly speaking I am fully booked until April, that combined with you only having 4 days off work in December (including 2 weekend days) will probably mean we'll have to arrange either the Sat 11th or Sun 12th that you mentioned you'll be off work. But I won't know until closer to the time whether I'll be seeing my daughter on the Sat or the Sunday so we'll have to arrange the Sat or Sun closer to the time? If you had a few more Fridays off we might be able to pencil in a Friday afternoon but I'm booked on the Friday 10th December you mentioned (and booked on the Mon 13th).

Hi Simon, the 10th,11th, 12th and 13th are the only days i have off up the xmas I'm afraid.. if you could do it on that Saturday or Sunday would be good and leaving the arrangements to the last moment isn't a problem.
I am off between Xmas and new year if helps.

Now running sweet thanks to adjustment/remapping by Lpgc.
Thanks Simon.

Great stuff mate.

Simon

Just goes to show you can mess around yourself for weeks but a couple of hours with someone who knows what he's doing makes all the difference.

Didn't notice anyone had posted since my last post, cheers Gilbert.

I was sure I'd posted between 57Jam89's post numbers #56 and #57 to discuss the final date he was to come to me, have any posts been accidentally deleted? We did discuss dates on the phone too.

Will have saved a few bob for 57Jam89 since I converted it 5 years and 100000 miles ago. And I've converted another vehicle for him since which also gives no problems

These days I tell customers that if there's an LPG system related problem on a system I fitted I will drive to them (wherever they are) and fix the problem on their doorstep. So far I have converted around 450 examples of the 'other' vehicle 57Jam89 owns (which I converted) and have had to drive to 2 customers to fix problems (that developed with components so you could say not my fault, but I have to admit fault because I selected the components) on only 2 occasions. Once for a customer from Truro in Cornwall, once for a customer in Bristol. On both occasions I drove to the customer and fixed the problem on their doorstep. One of these problems (Bristol) was that the reducer inlet valve seemed to stay marginally open at all times, causing high pressure at changeover. I could have sent the customer an interface lead and got around the problem without leaving home... but that would not have been the correct fix, so instead I drove to Bristol and back the same day and changed the reducer. The other problem (Truro) was a fault that developed with the reducer temp sensor... I (we, because the missus came too) enjoyed a night in a hotel in Newquay for that one.

I could say that I don't know why more LPG conversion pros don't put their money where their mouth is and give the same sort of no nonsence straight forward good service that I do. After all, most of them claim to enjoy driving (like I do). Except I do know what their problem is - Their customers have so many problems, that they created by lack of knowledge/skill, that if they offered this sort of service (and honoured it) they would be continuously out on the road fixing the problems they created. I can offer it because my installs don't have problems, I make damn sure they don't.