Strange Problem

[Beechy]

Morning all
I have a strange problem with my car. It's an S2 51 plate Elise.

All the coolant disappeared and the garage said it was the water pump which they replaced for me, they also performed a service on the car, and a cam belt replacement as the coolant had apparently sprayed all over the original one.

When I was driving the car out of the garage, when ever I took my foot off the accelerator peddle it stalled which I was latter told was the ECU. After doing the old 5 good revs then turn it off trick it now idles ok most of the time but sometimes the revs fluctuate between about 500 and 1500 revs and sometime stays really low and the engine really shakes. There is also a worse problem that is quite worrying. If I stop the car and then start it again shortly after, say the amount of time it takes to fill up and pay for petrol. It starts and then stalls straight away, even if my foot is holding the accelerator all the way down it won’t hold any revs. I then have to leave it for approx 10 – 15 mins and it then starts although usually with the fluctuating or low revs mentioned earlier.

It's never had these problems before. Any idea what it could be?

Thanks

Edited by Beechy on Friday 10th August 11:14

[Gooby]

I would say the timing is out, the alignment of the timing belt is not correct. It may be able to be adjusted out by adjusting the distributer timing (even on ECU cars dizzy timing has a lot of influence) or the timing belt has jumped a few teeth.

[Beechy]

Thanks Gooby. IS that something I could do my self or is it a back to the garage type of job?

[rfoster]

Sounds to me like your throttle position sensor has had it. This is a small resistor on the side of the throttle body (which is reset by doing the 5 pedal presses thing) and a dodgy one may give the symptoms you indicate - I've had it myself. Very, very easy to replace. You can buy them from Eliseparts (it's called a throttle potentiometer there). However before buying one, do you have access to another friendly Lotus driver who will let you try theirs out first? It's simply a matter of unplugging the sensor, undoing the two screws (sometimes with torx head) and fitting the new one. Under 2 minutes to change.

Other than this there may be an airleak that the ECU is trying to control, or it's possible that the timing may have slipped but I'm not sure if this last option is likely, particularly if the TPS reset procedure fixes the problem (albeit temporarily.)