S1 tickover control

[neptune26]

Help please,

What controls the tickover in a '97 Elise S1. Is it just the IACV? My elise starts fine on autochoke, but after a while she hunts for an idle and then dies. Time can be anything from 1 to 10 minutes, no obvious temperature when it occurs. Then the electronics lock me out for a few minutes, such that I cannot start her at all. I then hear a click in the engine bay and then I can start her again. I have taken the IACV off and wiped it clean, no luck. Do I need a new IACV? Any other advice please??

Thanks - Mark

[djroadboy]

Sounds like it could be the Multi-function relay unit. Its the little black box next to the ECU. Or it could be the IACV.

HTH

Dan

[KarlosFandango]

When it cuts out does it just die, or splutter then cut out? When it has cut out and you try the ignition can you hear the fuel pump prime?

As mentioned could be the MFRU or with me, my problem turned out to be the immobiliser. Easily bypassed if need be though.

[neptune26]

Revs stutter - about 500rpm, then up to 1500rpm, then die - seems more like the ecu has a cut off which prevents the ignition engaging the starter motor as all other noises and electrics sound fine. Just this one click - like a relay opening - then the starter motor turns again - before that no starter motor turns with the key.

It appears that the revs don't drop as fast after a blip of the throttle as normal, either. In fact if I restart the car as soon as allowed after it has stalled, then it may die again, even with the throttle being applied!

Could I have got some bad petrol? Could the fuel filter be blocked? I have put in some injection cleaner wth my last fill up to see if that could help - no joy!

Open to all suggestions!!

Thanks - Mark

[neptune26]

I just tried running it with the IACV disconnected (pulled the electrical connector out.) It started and ran fine for about 5 minutes - 90'C operating temp. Throttle response was good - only the tickover stayed around the 1000rpm mark. The car then tried to reduce the idle and stuttered and stalled as it has been doing. Can I conclude that the IACV is knackered. Any fuses / relays I should check first?

I thought I could check the cable to see if any signal was being sent to the IACV. What should I expect?

What should you look for when cleaning the IACV?

Thanks - Mark

[fergusd]

First : If you ran it with the IACV disconnected and it still died . . . then it ain't the IACV that's causing the problem, I'd expect it to run almost indefinately with the IACV disconnected, but with a high idle (as you obselved).

Second : The ECU never 'locks out' the starter - I'd look to the immobiliser if something is stopping the starter turning.

The timing of things may point to the ECU switching over to lambda control of the mixture (which takes a while after startup - but I'd have thought less time than you are describing).

The "lock out" thing sounds like an MFRU/Immobiliser problem, but insufficient data to understand exactly what.

Fd

[Neptune26]

Changed the MFRU but still the same problem. Fuel filter to change next. Any other suggestions?

[tuscan_thunder]

lambda sensor I'd say. maybe fuel pump?

[tomgoll]

Had a similar problem recently - sometimes idling at around 500, stalling, then hunting between 1500 and 2000.
Everyone told me it is just a characteristic of the Sport 160.

But, traced it to the brown water temp sender to the ECU. Changed it, and perfect idling.

I DIDN'T get the electronic 'lock-out' that you experience, but I guess that the temp sender could be telling the ECU that the temperature is so high it should cut out???????????

Try it, under a tenner from Hangar 111

Best of luck

Tom

[Neptune26]

I have changed the fuel filter and still have the same problems. I tried unplugging the brown sensor for the water temp whilst the car was running. The radiator fan come on as I believe it should. Does this mean that the sensor is behaving normally or could it still have problems. Was your fan on before you changed it?

The car starts and runs fine on start up from cold. It ran through until 90'C then cut out! Then was a real pig with no tickover!!

This is getting to me now!!

HELP - thanks