Help me diagnose a misfire please

[blueka]

Hi,

So, 1999 UK Spec 4.0 SOHC.. has been LPG/propane converted

Runs fine on LPG/Propane, switch back to petrol, misfires..

So, I would assume, it's an injector fault... but, it isn't throwing any codes...

How do I fix this?

Please help

Thanks

Si

 

[Fix4Dirt]

can you clean the i jectors? i wonder if thats the issue. any codea?

 

[blueka]

no codes at all, Ideally I want to know what injector has failed before I take it apart so I can replace it

It's not my explorer, it's been sent to me to fix

Si

 

[Turdle]

Could it be fuel pressure when switched to gas? Might check that

 

[blueka]

last time it was here, it had a code for a misfire, can't remember what cylinder though and the owner didn't have enough money to get the work done, so it went back, this time though, the battery was flat, so all the codes have gone and now it has no propane in it

Si

 

[Turdle]

Also, just a hunch, bad fuel?

 

[Turdle]

Might need to drive it a bit to get the code to reappear

 

[blueka]

it won't drive, just dies

Si

 

[Turdle]

Ah, fuel pressure check

 

[CDW6212R]

How long has it been driven without using the fuel injectors? They may be at fault, if unused for a long time, it might be better to replace them with rebuild units, $10-$15 each.

 

[blueka]

I have no idea, most people would just run on petrol till warmed up then switch to propane

Si

 

[CDW6212R]

I have no idea, most people would just run on petrol till warmed up then switch to propane

Si

That would be a decent life cycle for the injectors, and they could be just fine. How old are the O2 sensor, the front pair? With the battery having run down, there may be codes that won't show up unless it can run for a few cycles.

 

[blueka]

looks to all be factory

Si

 

[Josh P]

I'd start with an infrared thermometer pointed at the exhaust manifold on a cold start. The cylinder missing won't heat up as quickly as the others. Then I'd use a multi-meter to check the injector against the others. It could be an injector or a wiring issue to the injector.