I've been trying to diagnose a problem i have when starting from cold and having little/no throttle response and rough running for a while now. It tends to clear itself after a minute or two.

On Sunday I took part in an off-road competition and during the day got the same symptoms when starting hot. I was on Petrol. As soon as I switched to LPG, the issue went away. Turn off LPG and it's back.

Immediate thought is an injector issue. Is this something I can diagnose/rule out with nanocom?

TIA

About the only things that aren't common to the two fuel systems are the injectors and fuel pressure. I can't see it being an injector problem or it would be there all the time. Nanocom will show if you have any fault codes (likely P030x code to show which cylinder is misfiring or simply a P0300 multiple misfires code) but will also allow you to look at the live data and see if one bank or the other is running lean or rich.

new problem - obd port is dead.... again...

Then problem is to do with log wiring especially where piggy back to fuel injectors

Could be although I would expect a wiring problem to be permanent not intermittent, but some Prins systems use a separate injector emulator so it could be a problem with that (if your system has one). In which case you'd get injector disconnected codes stored once you get OBD working again.

hoping the obd port is something simple. i'd already been repaired in the drivers footwell and close to the port itself!

and now the top tailgate isnt latching every time!!

lol, gotta laugh!

Is the OBD port problem due to lack of power at the OBD port or lack of coms? Same question put another way - Is there power to the OBD port? Does it's power pin use the same fuse as something else e.g. cig lighter socket?

Another thing that can prevent coms on the OBD port is if the LPG system is connected to OBD. This wouldn't be the case with a pre 2000 year Landrover vehicle but the LPG system may be connected to OBD on a post 2000 year Landrover. One way to test for this if just to disconnect the LPG fuse, see if the OBD port starts working again.

Good calls by Gllbert and Symes. Some systems do have separate injector driver units that can fail... Would add I have seen plenty LPG ECU's fail in a way in which they don't connect petrol injectors on a cylinder (or several) when they're supposed to (they're supposed to when the engine is running on petrol). On some (older) LPG ECU's such as older AEB2568 / Stag based systems this can be due to a bad internal relay, I have an old AEB2568 here at the moment that has failed in this way... some day I'll get around to changing that relay so I'll have an extra spare AEB2568 ECU.

Thanks. I’ll have a closer look tomorrow. Not sure how my lpg is wired in to be honest. Seems pretty well hidden!

Simon, if you look at his sig, it's a '99 fitted with a Prins system. Hence my mention of the emulator unit.

The OBD power pin is directly from a 5A fuse in the fusebox, don't remember which, but there aren't many 5A there ...
Before I fixed the intermittent, and very bothering, electrical failure in that connector by the A-pillar, I ran a direct cable from the battery.

A similar thing happened to me last week, poor tickover and a struggling throttle response and variations between normal and abysmal
Tested the battery voltage with the engine running - oh oh this doesn't look good.
Gave the alternator a whack with my trusty hammer -and she's been OK ever since.
As a precaution I've ordered up a spare alternator from a good P38 breaker on eBay and will get new brushes + voltage regulator (if available) to overhaul the existing

Gilbertd wrote:

Simon, if you look at his sig, it's a '99 fitted with a Prins system. Hence my mention of the emulator unit.

Sorry, yes I missed that.

Agreed the Prins injector emulator unit is likely causing the running on petrol problem.

Also the Prins system won't be wired to the OBD port.

hugh wrote:

A similar thing happened to me last week, poor tickover and a struggling throttle response and variations between normal and abysmal
Tested the battery voltage with the engine running - oh oh this doesn't look good.
Gave the alternator a whack with my trusty hammer -and she's been OK ever since.
As a precaution I've ordered up a spare alternator from a good P38 breaker on eBay and will get new brushes + voltage regulator (if available) to overhaul the existing

I've told the story about when I had to drive back to Yorkshire from mid Scotland using a generator to power vehicle electrics due to a failed alternator on a bank hol weekend a few years ago (different model vehicle but same problem) lol.. At first that alternator started working again if given a whack but the period of working between whacks became shorter and shorter until it wouldn't work even straight after a whack. When home I fixed the alternator myself the next day for pennies, just fitted new brushes but not available in Scotland on a bank hol weekend.

Lpgc wrote:

hugh wrote:

A similar thing happened to me last week, poor tickover and a struggling throttle response and variations between normal and abysmal
Tested the battery voltage with the engine running - oh oh this doesn't look good.
Gave the alternator a whack with my trusty hammer -and she's been OK ever since.
As a precaution I've ordered up a spare alternator from a good P38 breaker on eBay and will get new brushes + voltage regulator (if available) to overhaul the existing

I've told the story about when I had to drive back to Yorkshire from mid Scotland using a generator to power vehicle electrics due to a failed alternator on a bank hol weekend a few years ago (different model vehicle but same problem) lol.. At first that alternator started working again if given a whack but the period of working between whacks became shorter and shorter until it wouldn't work even straight after a whack. When home I fixed the alternator myself the next day for pennies, just fitted new brushes but not available in Scotland on a bank hol weekend.

I've had an alternator fail just like that. It really chose its time to do it - in the middle of Belfast the day before I had to drive to Dublin to catch the ferry back on the Saturday morning after. Finding an alternator over there off the shelf for the car seemed impossible, ended up finding a place that could either fix the alternator or get a rebuilt one (Also hampered by having no tools with me to take the alternator off to do anything about it). The replacement ended up coming over to them from Huddersfield!.

leolito wrote:

The OBD power pin is directly from a 5A fuse in the fusebox, don't remember which, but there aren't many 5A there ...
Before I fixed the intermittent, and very bothering, electrical failure in that connector by the A-pillar, I ran a direct cable from the battery.

Lpgc wrote:

Gilbertd wrote:

Simon, if you look at his sig, it's a '99 fitted with a Prins system. Hence my mention of the emulator unit.

Sorry, yes I missed that.

Agreed the Prins injector emulator unit is likely causing the running on petrol problem.

Also the Prins system won't be wired to the OBD port.

I think I have a 2000MY actually. It’s one of those ones that has a bit of 99 and a bit of 00!!

Where would I look for this Prins injector emulator and is there a way to eliminate it from enquiries?