Technical Ypsilon Misfire [intermittent]

[J25CLV]

hi. i have a '15 ypsilon, and for my troubles, it has a intermittent misife on idle.
pulling away is awful, chnging gear, when revs drop then come back up.
it's a 1.2 vvc engine, plugs changed, coil/leads changed, air filter changed.
sea foam ran through it. the oil is resonabaly new, etc etc.
without chucking money at it, i'm scratching my head.
any ideas would ne appreciated?

 

[lingottobuilt]

hi. i have a '15 ypsilon, and for my troubles, it has a intermittent misife on idle.
pulling away is awful, chnging gear, when revs drop then come back up.
it's a 1.2 vvc engine, plugs changed, coil/leads changed, air filter changed.
sea foam ran through it. the oil is resonabaly new, etc etc.
without chucking money at it, i'm scratching my head.
any ideas would ne appreciated?

Have you tried the OBD read....?......any lights on Engine management?, I assume not as you would have said.
Could be an air leak on induction, or an injector....

 

[J25CLV]

yes. i should have said. but have plugged my topdon into it. no dash lights, no codes stored.
have tried the 'spray carb cleaner over areas' to see if engine note changes.
it doesn't, so i assume [at least think], there's not a vac leak [but possibly could be].

 

[lingottobuilt]

yes. i should have said. but have plugged my topdon into it. no dash lights, no codes stored.
have tried the 'spray carb cleaner over areas' to see if engine note changes.
it doesn't, so i assume [at least think], there's not a vac leak [but possibly could be].

These faults can be difficult to fix if there is no clues via the obd check.Have you got the spark plug leads clicking home......what I do is to pull them off and put a little dab of petroleum jelly or vaseline....so that they sink onto the plug tops and make good electrical contact.....

 

[J25CLV]

have tried all that, too. strangley, it's exactly the same as before i changed plugs & leads & coil.

 

[lingottobuilt]

have tried all that, too. strangley, it's exactly the same as before i changed plugs & leads & coil.

What's the mileage.....and I always pull the VVT solenoid and give that a good clean, but yours could be faulty?....but I'm not sure what the symptoms are for one of those not functioning...

 

[J25CLV]

80k. c;eaned old vvc valve [no change]. fitted a new vvc valve [no change].
i have a 'proffesional mechanic' coming to look at it today. see what he [or her] makes of it.

 

[rmjbn1]

MAP sensor cleaned?

 

[J25CLV]

yes, cleaned that too.

 

[Herts Hillhopper]

Might not be under the bonnet at all… Build up of vacuum in fuel tank leading to fuel starvation? Theres a complex breather/vent arrangement in a unit inside the right rear wheel arch. Or a faulty fuel pump?

 

[J25CLV]

ok. thanks, didn't know about the breather. if it was the pump, wouldn't it do it all the time? not just intermittent.

 

[J25CLV]

an update. had a mobile mechanic look at it. plugged it in. reset codes to ecu [as parts had been changed??].
then it idled nice for about 10 mins. then it didn't.
back to same as before.
and he couldn't work it out.
so, i am going to book it in at a Fiat/Lancia specialist near me.

 

[Herts Hillhopper]

Try loosening the fuel cap and see if it runs then (as a bypass for the breather).

 

[lingottobuilt]

have tried all that, too. strangley, it's exactly the same as before i changed plugs & leads & coil.

Just thought, but its unlikely......contaminated fuel?

 

[AB100]

The only similar thing I saw was when I'd replaced the plugs with brand new Iridium ones. Then had the occasional misfire. Hooked it up to the laptop with MES and watched the firing and one cylinder was occasionally misfiring. Swapped the plug for a standard NGK and it was fine.

Worth a go.

 

[J25CLV]

Just thought, but its unlikely......contaminated fuel?

i filled it up when i got it. also added Sea Foam to tank.

 

[J25CLV]

The only similar thing I saw was when I'd replaced the plugs with brand new Iridium ones. Then had the occasional misfire. Hooked it up to the laptop with MES and watched the firing and one cylinder was occasionally misfiring. Swapped the plug for a standard NGK and it was fine.

Worth a go.

i didn't put irridium in there. just standard plugs. misfire was there before and aft.

 

[J25CLV]

Try loosening the fuel cap and see if it runs then (as a bypass for the breather).

it doesn't have a cap. the flap has a seal on it. tried running it with flap open, same.

 

[J25CLV]

a 'old timer' lancia specialist told me last night, might be ECU issue. gonna try unplugging ecu for a day. see how that goes. [after i plug it back obv].

 

[Greasytrucker]

Is it worth doing a compression test? I had a very similar issue on a Mini 1.6 petrol a few years ago (completely different I know) and it turned out to be a couple of cracked valves which a compression test identified straight away