Running lean on warm starts

[Patches]

My car starts as it should when cold but if i drive for a while then start it within the next hour or so it will idle a bit rough. Nothing too bad but noticable and the AFR car be between 17-19 :/

If i tap the throttle it comes right down and once i get moving for a bit it will slowly get back to normal. Its really strange if i sit with the engine running and let it get hot it never seems to go past 15.5 so im confused why it happens on warm starts.

Any ideas?

Edited April 26, 2014 by Patches

[AdamB]

What ecu are you using mate?

[brendonware]

Mine does exactly the same, but probably worse, I can start it first time but if I turn it off and try and start it again it doesn't start or it does the lean and rough idle as you described. I'm running emanage blue by the way.

Brendon

[TurboTobz]

I uses to have this but I swapped my fse rrfpr for a new sard unit and it didn't ever fail me. May have be coincidental.

[brendonware]

I borrowed a mate's one and I thought it fixed it but a day later it was back to its usual self so swapped it back :/ might have to buy a new one as I think the one I bought from someone is a copy :/

Brendon

[mikey4410]

they do rarely pop up to 16.8 ish. normal. and most importantly not an issue whatsoever.

WOT is what u wana worry about.lol. idles feck at to worry bout

[GP82]

I run 16 + A/F on idle at operating temp. It actually burns more cleaner, aswell as being more fuel efficient. Any leaner then 17:1 A/F and it tends to eventually decrease the idle speed or cut out. If you don't have a catalytic convertor then it is fine to run this lean on idle. The car will run stoich (14.7:1) on the stock ecu so the cat does not overheat from the hotter exhaust gasses.

It sound's like maybe possibly a sensor is starting to go duff causing this issue on your car, but as mentioned, the A/F is more crucial when the car is on load.

[JayJ]

I'm currently running a stock ecu and got this issue too. Could it be water temp sensor playing or what?

[brendonware]

I changed mine water temp sensor and for me, it was no use

Brendon

[JayJ]

Good to know, have to check the FPR then.

[mech5107]

It's due to the stock lamda sensor not getting up to temp after the restart. If you drive more gases are produced so the sensor gets up to temp.

[JayJ]

It's due to the stock lamda sensor not getting up to temp after the restart. If you drive more gases are produced so the sensor gets up to temp.

So would a new lambda help as mine just started doing this some time ago?