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[Webby the Bear]

As above, start the car and the idle is jumping around,

Two mins later it's settled right down but still kinda ticks over between 4 and 5 hundred rpm.

This coincides with what sounds like an exhaust leak.

Is it correct that an exhaust leak can cause this? I'm presuming only an exhaust leak pre O2 sensors would do this?

Had a look for vac leaks. . . None at all. And all vac lines on he correct order as per marks guide,

Would the disappearance of the lumpy idle suggest its a small leak that's ckosing up when it gets warmed up?

[Webby the Bear]

Just to add, breathers cleaned regularly and icv also.

When me and martin rebuilt the top end I did use the elring gasket which I'm aware some say not to use so wondering if it's the manifold leaking as I put a new down pipe gasket on only a few months back

[05omegav6]

Would have thought that wouldn't be an exhaust issue... Could be an air leak if it's seriously hunting rather than the occasional hesitation

[Webby the Bear]

Defo not an air leak mate.

I in ow that if the leak is before the O2 sensor it can mess up the fuel ratio and as it tries to constantly correct it = lumpy idle. Same symptom as a vac leak but for different reason.

And as it goes away after a couple of minutes that suggests it's a small leak closing up as it heats up.

A quick feel around the manifold revealed no blowing on my hand but I did smell exhaust from there. So I'm sold.

Hopefully it's just the downpipe gasket. But doubtful as that's new as per a few months ago.

[deviator]

Could the EGR pipe be damaged? Or something on the SAI? I'm trying to think of things that don't stay on all the time.

[Webby the Bear]

All in good working order. And this did just come on one morning and I was like. . . 'Oooook I got a lumpy idle'

Manifold leak or downpipe gasket leak makes sense to me. Anyone agree?

Ps, re vac leaks. Definitely not that as only the other day I checked the routing and that both vac boxes are holding vacuum. And they're all good

[TheBoy]

What are the trims doing at idle. Should be in the 125-131 on a 2.5

Intake airleak is most likely reason for a hunt, but exhaust leak may cause it

[Andy A]

What are the trims doing at idle. Should be in the 125-131 on a 2.5

Intake airleak is most likely reason for a hunt, but exhaust leak may cause it

Do you have the trim values for a 2.2 petrol please?

[Webby the Bear]

What are the trims doing at idle. Should be in the 125-131 on a 2.5

Intake airleak is most likely reason for a hunt, but exhaust leak may cause it

As I've never read trims am I looking at idle up to temp or from starting (open loop?). I presume from cold as that's when the issue occurs?

[Webby the Bear]

....and do you want STFT or LTFT details?

[Webby the Bear]

ooooook...

just been out. car wasn't completely cold (started it up and it was on 75o on the temp reading)

''my naff code reader'' tells me at this point I was in open loop and as I got up to temp I went in to closed loop.

o2 sensor 1 was switching between 120 and 820 MV at idle

[Webby the Bear]

presuming that means its switching correctly between 0.12v to 0.82v