Rough idle on petrol smooth on gas MK

[ashlittler]

Help needed please, my Mk triton runs very rough when cold on gas and flick it over to gas when it's still cold and it idles fine.

Once it's warmed up back on petrol it still drops engine revs.

I have fitted a new air filter, cleaned throttle butterfly's.

It's strange it's just rough on the petrol - that couldn't be vaccume hose because that would be rough on both?
Possibly fuel filter?

Pretty stuck so help out is you can - thanks

[hvac guy]

How old is the fuel in the tank

[ashlittler]

There is a full tank of premium going in I would say once a month.

Could it be a dirty fuel filter or would that not make a difference?

[GLRkenny]

Spark plugs would be worth changing I think

[ashlittler]

Yer I did think that, but the gas would be ignited by the plugs aswell wouldn't it and it runs fine on that.

Today I have used the carby cleaner spray on vaccume hoses to hear for idle change - nothing
So then tried the gas torch on vaccume hoses again - nothing

So I am thinking it's fuel related just because it idles smooth on the gas.

Could it be the idle control valve? I have not cleaned that yet...

[GLRkenny]

One or the other (gas or petrol) requires a stronger spark, can't remember which way it goes.

Also gas or dual fuel cars should run a colder temp rated spark plug.

[ashlittler]

I have owned the ute for about 6 months now and unsure the last time the plugs were changed.

If anyone has fitted plugs into a mk triton that was on gas and petrol please give me some feedback

[GLRkenny]

Manifold has to come off, I would fit the LPG option plug - ngk number is PFR7A-11
Standard plug is PFR6J-11,
The 6 and 7 represent the different heat ratings of the plugs

[gregned]

I had a similar issue with a ford courier....ended up being a dirty air flow meter, my gas setup was a purely mechanical setup which bypassed all sensors.

[renotriton]

GQ patrol did the same. It was the changeover relay box or whatever they called it
(the thingy which switched between gas and petrol)

[ashlittler]

Thanks glrkenny I think plugs is something I am going to have to do to fix this problem.
Do the spark plugs play a part when the ute is running on gas?

Also gregned mine could be mechanical and could bypass all sensors, I am going to pull the throttle body apart this weekend and clean that and the idle air control valve - do the simple stuff first.

I have checked the engine for vacuum leaks and can't find any, would a plug and play computer (mechanics) say what the problem is?

[GLRkenny]

Thanks glrkenny I think plugs is something I am going to have to do to fix this problem.
Do the spark plugs play a part when the ute is running on gas?

Also gregned mine could be mechanical and could bypass all sensors, I am going to pull the throttle body apart this weekend and clean that and the idle air control valve - do the simple stuff first.

I have checked the engine for vacuum leaks and can't find any, would a plug and play computer (mechanics) say what the problem is?

Yeah the plugs still work whilst running on gas, I would change them first anyway just because they are a consumable which has to be changed eventually anyway.

I doubt the computer scan would really show much up

[GLRkenny]

Help needed please, my Mk triton runs very rough when cold on gas and flick it over to gas when it's still cold and it idles fine.

Once it's warmed up back on petrol it still drops engine revs.

I have fitted a new air filter, cleaned throttle butterfly's.

It's strange it's just rough on the petrol - that couldn't be vaccume hose because that would be rough on both?
Possibly fuel filter?

Pretty stuck so help out is you can - thanks

Have you disconnected the battery recently?

[ashlittler]

I have actually yeh, had the main battery stuff up the other month that I replaced.

[GLRkenny]

Has it run bad since then?

[ashlittler]

The battery stuffed up after a week or so of having it, I guess it did start r inning rough since then because I can't remember it idle'ing like that when I test drive it (from cold)

[GLRkenny]

Ok so don't worry about the plugs for now, the idle stepper motor (idle air valve) would have been reset with the battery change, you'll need to remove and clean the stepper motor with carby cleaner (be very careful of the o ring, it can swell and not fit back in) and then disconnect the battery to reset it again. After reconnecting the battery hold the revs at about 2000 for a couple of minutes (unless you have a scan tool that can reset base idle and timing) and this should fix the issue.

If you've only just bought the car and are unsure of service history, etc I would highly recommend the timing belt be changed or at the very least checked for piece of mind

[ashlittler]

You sir are a legend, well hopefully once it's fixed you will be!
So the stepper motor is that the idle air control valve? If not no worries ill google it and find out where it is and how you remove it.

The timing belt has been changed thanks, has sticker on the cover, ill get it checked though just for piece if mind. Thanks for the help

[GLRkenny]

It's the idle air valve located on the throttle body just below the opening, requires 2 8mm bolts to be removed, make sure your hands are free of oil when handling the o ring

[ashlittler]

Great stuff - so disconnect battery - remove idle air control valve, give it a good clean (using throttle body spray cleaner?) be carful with "o" ring.

Re-install it all - connect battery back up, start ute hold the revs at 2000 for 2 mins - that should reset the computer? Or idle control valve?

And then I guess next time I start it up cold after that it should run smooth -hopefully!

[GLRkenny]

When the battery gets reconnected the computer would think everything was in new condition so the cleaning makes it as new (or close to) and the disconnecting, reconnecting and revving makes the computer forget that's it was ever not new, if that makes sense

[ashlittler]

Sure does, thanks for that ill post on here when I get time do clean it all apart and let you know how it all went.

Thanks for your help.

[ashlittler]

I got around to cleaning the idle air control valve after work today, I was surprised to see a small amount of oil pooled in the housing and on the idle air control valve itself. The tip with the "+" was very dirty and after cleaning it didn't really come up much better, I got rid of the oil and used a throttle cleaner with toothbrush and cloth on everything else.

Once I re connected the battery and started the ute, it wouldn't let me hold the revs at 2000 because it was fluctuating so much, after the 2 mins of between 1700-2300 I let it idle for another min or so with it still dropping between 850 - 1100.

Flicked it over to the gas and so smooth, back the petrol rough idle.

Strange and annoying!

[hvac guy]

What's it like under load on petrol does it ping
How many ks on clock.

[ashlittler]

Goes fine under load and no pinging.

I am still thinking it could be the idle air control valve, even after cleaning its still rough and sutted up?

Triton has 178,000 on clock