S2 rough idle only first mintue from cold

[Parko]

Hi folks and HNY to all

Only a few days into the year and the first Lotus problem has emerged....all advice welcomed with open ears.

S2 Toyota lump...been running 100% until:-
- Thurs am (frosty) start....engine started, but on idle hunted 400 to 900 rpm....decided to tickle the throttle (~+1k) and that seems to even things up...until i released and it was the same. Left it hunting to defrost and I would say 1min max and it sorted itself out. Off to work.

- Thurs pm (cold) start...same as above (60seconds)!

- Fri am (frosty) .. engine started, but this time died. tried again..same. So I gave it little gas and held it about 1k for 30 secs and runs like a sweety!!!

I'm thinking it's something to do with the cold start system....but it's got a fly by wire throttle so I think cold start is all done electronically??
What inputs hold the cold start cycle?
+ air temp / mass air flow
+ eng temp (but don't think this will register in 60secs?)
+ lambda's ?? (have I damaged it whilst changing the exhaust - see PS below)
= All controlled by the ecu (i'm not even going to think about it!!)

King regards
Ian

PS...(Also need to mention that I changed the exhaust on tues night back to standard...I can't see that I've disturbed anything and all the Lambda sensor wiring looks ok (and it did not have a problem Wednesday) ..I've sort of dismissed this as coincidence).

[duggiesmith]

Can't offer much help I'm afraid, but I've experienced something similar a couple of times, accompanied by the MIL coming on and staying on for a day or two.
Is your MIL on?
The problem always seems to sort itself and doesn't seem to be temperature/weather related.
I'll get it plugged into a code reader next time it's in for a service.

ETA If it's the lambda sesnor, the MIL should come on and stay on.

[mwmackenzie]

Possible Lamda at a guess?

[Stu160]

If it was a k, i would guess early hgf, not sure about yota?????


Stu

[Parko]

Quick update . . . 'Since it's got warmer, it's bin 100% fine'...coincidence me thinks
Gonna get chilli later this week, so I'll keep yer updated..

Guys, thanks for the thought thus far....

PS....the MIL light does not come on....................yet!

[robin]

My knowledge of toyota engines is slim.

Lambda is ignored for cold start - only used once engine (and O2 sensor itself) is up to temp.

Is the air intake standard or a 3rd party air box thing?

It could be moisture in some actuator getting frozen, but given it's DBW I would expect the only important actuator for cold start to be the throttle, which you say works OK.

One for the code reader (faults are still latched even if they don't cause a MIL, I believe).

Cheers
Robin

[dirkpitt]

hi ian,

if it helps ....i get a slight rise and fall at idle as well when its cold ...when warmer it drops to 800 rpm and holds....i have the same induction as you also VIS piperx right?

im guessing that its quite normal on the yota lump for this to happen...in your case sounds like its the same but more server

i have notice with these yota engines that any sudden demands when she is cold and you get some resistance from the ECU and what not.....when she is warm and happy, shes runs sweet....

leigh

[Parko]

All sorted (I think).

The crank vapour tube from the rocker cover to the inlet manifold (just next to the throttle body) has a 'valve' screwed into the rocker cover. I think this valve was freezing up with a little vapour retention, thus drawing un-metered air into the induction.

Changed the valve and pipe (just in case that had a crack) and all seems well.

Thanks for all the help