Poor idle on petrol startup

[Bigrig]

Howdy

Tank has been running a bit crook since last weekend. ONLY when starting cold, and ONLY on petrol it starts and then idles up and down through the rev range (like it's confused! lol) and spits out a bit of black smoke as though it's running rich. Only does this till it's warm (literally a minute or so) then idles beautifully and no smoke whatsoever.

My first thought was dirty sensors, so I cleaned them with no success. My second thought is could my injectors be stuffed or at least on the way to being stuffed? I put an injector cleaner through it the other day and no change, but realise if they are going 'kaputsky' (Russian for 'up the shlt' lol) that it wouldn't do much.

Never having done injectors before, is this something a 'dual left handed' individual like myself should have a lash at??

Thoughts??

Thanks a million in advance!!

[Ben-e-boy]

I had a hilux that ran rough at idle when cold. it ended up being a vacuum hose that had come off. Its a long shot but give that a try.

Cheers

[Bigrig]

I had a hilux that ran rough at idle when cold. it ended up being a vacuum hose that had come off. Its a long shot but give that a try.

Cheers

Thanks mate - will do that also. Must admit, hadn't looked for leaks as figured it would do it right through the rev range and affect gas as well.

[tkn]

ONLY when starting cold, and ONLY on petrol it starts and then idles up and down through the rev range (like it's confused! lol) and spits out a bit of black smoke as though it's running rich. Only does this till it's warm (literally a minute or so) then idles beautifully and no smoke whatsoever.



Sounds as though it might be temperature related - my first thought is choke, but it looks like you are fuel injected?

Depending on how your gas is set up, the choke might not affect gas operation. But if injected I can offer nothing, except check the coolant temperature sensor.

What happens when idling rough if you give it a 'blip' of accelerator?

[the evil twin]

Doesn't sound like an injector problem to me... I'd be looking at the cold idle anti-pollution rubbish. Esp for vacuum hoses fallen off/cracked like Ben E Boy suggested

My TB42 effy always started better on Gas than Petty anyway so I used to start on LPG and switch to Petrol when it was warm... ROFL

[Bigrig]

Thanks lads - have checked all the hoses etc and all seems fine. What's the cold idle thingamajig I should be looking for??

[Bigrig]

Well, have booked it in for a health check ... no idea what is causing it and it's getting worse, so nothing to do other than have a pro look at it .. thanks to those above for advice, and I'll let you know the outcome.

[Bigrig]

Hey Tony (seeing as I know you're there! lol), for this problem, you reckon it could be that sensor again? Similar problem to last time EXCEPT this time it runs fine once warmed up. Could be on it's way out, but if so, what would cause it to go twice in such as short space? i.e. Is it symptomatic of another problem causing it?

EDIT: I'm willing to try changing a $40 part to save some time, effort and more dollars.

[YNOT]

The cogs are turning/grinding Scott, I'll get back to you soon.

Tony

[YNOT]

Can you start on gas or is it petrol only start with automatic changeover?

Tony

[Bigrig]

Can you start on gas or is it petrol only start with automatic changeover?

Tony

I normally start on petrol when it's cold as my LPG system doesn't do the whole squirt of petrol thing, and I don't risk it backfiring. On the odd occasion I have forgotten to change back and have started on gas, it hums, but not on petrol .. I let it warm up and then switch to gas.

[Bigrig]

I normally start on petrol when it's cold as my LPG system doesn't do the whole squirt of petrol thing, and I don't risk it backfiring. On the odd occasion I have forgotten to change back and have started on gas, it hums, but not on petrol .. I let it warm up and then switch to gas.

Thinking I'll go to Repco tomorrow morning and get one just to suss it out - would love it to be the coolant temp sensor, but still makes me wonder why two would go in the space of four months. I'll get some CRC MAF cleaner first though and give it a blast, just in case.

[YNOT]

Give it a try but I don't think that will be it, it would be affecting both fuels and would take longer for there to be enough heat increase to change its output signal.
What engine does Ryan have in his Patrol, you might be able to borrow his air flow meters to see what effect that has? You could also try his exhaust oxygen sensor.

Tony

[Bigrig]

Give it a try but I don't think that will be it, it would be affecting both fuels and would take longer for there to be enough heat increase to change its output signal.
What engine does Ryan have in his Patrol, you might be able to borrow his air flow meters to see what effect that has? You could also try his exhaust oxygen sensor.

Tony

That's true, but not sure he'll let me start pulling his car apart - he knows he'll get the crap part back!!! LOL ... I didn't realise the MAF affected gas as much? Or at least thought it affected petrol moreso. I'll give it a clean, and see if Derek is down the workshop in the morning and throw the diagnostic unit onto it ...

Thanks again