Questions, questions, questions

Gentlemen (and Ladies)
It’s finally my turn to have problems…
Car has been misfiring lately and a bit low on power over 6000rpm. and now it won’t start at all, even after charging battery overnight!
Got a new battery on order - siver plus. But it does’nt turn up until Tuesday. How does the old battery come out?
Think I’ve sourced problem with misfire and non-starting - the air control valve bracket has failed - half of it has gone awol with the pinch bolt, the valve is hanging down on it’s two hoses and wires. Guess the wires have rubbed through on the chassis and shorted out taking the control fuse with it. Without jacking car up and taking under tray off its a right s*d to get at!
Booked into Lotus garage in Bournemouth for a week Tuesday!!
They should fix it - but does my diagnosis sound plausible?

Hi Tony,
Its quite probable that the fault with the IACV would cause those problems.

Good luck


I guess you need to sort out the obvious first then see how it goes. But it seems plausible to me that your fault could lead to these symptoms… if there were wiring shorts or false earths then anything could have been happening i guess… but i’m not sure how the IACV hanging loose would lead to misfires???

Let us know if the dealer does anything else to get it up and running.
BTW - how do people connect all the bit n bobs back together when they remove the IACV ?? Mike Lane… you done this yeh ?? how do the origonal pipes n wires get left after removal?.. can this only be done with a mappable ECU ?? will our GEMS work at all without IACV ??

GEMS Rox ??? Its a Lotus K4 controller

The ECU will not like the IACV removed, the amount of air it lets in is part of the fueling map.

With the Lotus breather kit you get a couple of plugs that fit over the throttle outlets.


So could i simply remove it as long as I bung the holes up on the underside of the Throttle bodies? what about the electrical connections?

Yep you can just remove it, idle may be rich so it could struggle at MOT time and make starting from cold difficult but just bung up the holes

The connector can be left where it is or sealed up with some silicon sealant to stop the water getting in.

So it’s only an idle air control valve?
This is the one half way up the rear of the engine with two blue silicone hoses on it?
That valve should’nt cause misfires at 6000rpm as it only adjusts idle air - or am I missing something.

If the IACV wasn’t closed then too much air would be present causing a lean mixture and hence a misfire.

Thanks Phil - that makes sense.

All fixed again
The valve wasn’t the problem…
far to embarrassing to say what really stopped it!!! But it involved new engine oil and a spark plug recess.
Put new battery in too - bosch silver plus no longer available and bosch have changed their part numbers again.
But it don’t 'arf spin the engine!!

oops spilt a bit did we lol

I’m not saying nuffin!!
Otherwise someone will laugh at me!

dont worry, you secret is safe with me…

Whats the advantage of upgrading to that silver plus battery? I see a few people are doing it.

the bosch or the varta equivilent batteries have a higher amperage capacity, and as tone says they spin the engine over much quicker when starting

Whats the advantage of upgrading to that silver plus battery? I see a few people are doing it.

Try a search, there was lots of discussion on it (becasue we’re not at all sad! ).


I take it they help cold starts then? Do you know what sort of price they are? Would you agree its worth upgrading the battery then? Sorry for all the questions.

Only if it’s a problem. I understand most who don’t use them regularly keep them on a CSI Airflow trickle charger (the type Lotus brand and double the price of), then it’s never a problem.


and today it’s back
cost me a set of plugs and a new set of leads
and a reset to ecu
Forgot how much I loved it!!!
Use a funnel to put the oil in with!

thanks Tone