Racer74

Thanks to everyone for your thoughts, much appreciated. I'll have a trawl through the old postings to see if the reference data is there as it will be great to get a full set of readings.

What a pain this has proved to be but I've got there in the end. Pre Pscan I tried new lambda, new sensors with no luck (good old stab in the dark method) but no improvement.

Post Pscan I narrowed the fault to the fact that the lambda remained inactive and there was no fuelling compensation, more testing of wires, cleaning of contacts, removal of the misfire system (unique to the Elise 111s) but no progress at all. Tried a new (used) Mems 2J, no progress there either. #getting p*ssed off!

In short after eliminating all causes I've come back to what I assumed was an unlikely culprit....I replaced the new lambda I fitted a few months ago (genuine MG) with a new NGK one and some new plugs for good measure and....

After under 30 seconds the lambda goes active, the lambda voltage varies and I have fuelling compensation too! All looks well. It really does prove that old point don't assume it's good even if it's new!

Just need to fit everything together and give it a thorough road test before getting the emissions checked.

Thanks all.

That's right. Mems ECU in the engine bay, EFI technologies misfire unit in the boot.

On the Elise S1 VVC a recall installed a separate misfire detection unit following some misfire/cat fire issues on the higher performance Elise variants.

As I noted below the unit links into the standard car harness in three locations. Based on some wider research I think the unit looks at spark ionisation and lambda readings to detect the onset of misfire and then limits the rpm or cuts off the offending cylinders but how in interacts with the MEMS to cut the cylinders if misfire is detected is a mystery to me, I suspect it cuts the fuelling to the offending cylinders by intercepting the signals from the Mems unit. Details on the device are sketchy; I've dropped Lotus a note to see if anyone can shed any light on how it operates but in the current circumstances I'm not expecting a response.

If the misfire unit is triggering I would start by checking the usual electrical suspects, connectors, HT leads, plugs etc. as any of these could throw it a curve ball.

If that fails you could disconnect the unit from the car and reconnect the lambda, injection and coils to the car harness to see if it makes any difference, the car will then run as it left the factory (and in the same configuration as the MGF VVC) but obviously without the protection the system was intended to offer. At least you can rule it in or out.

If you do disconnect the unit do make sure you label what goes where as the injection and lambda plugs are not interchangeable reducing the scope for error but the plugs to coil one and two are...…

Stuart

Hi,

I've not got to the bottom of my 111s issues yet so I wouldn't put myself if the expert category.... but I think the Elise 111s has one difference over the MGF VVC.

Lotus did a recall in c. 2001 and fitted a misfire detection system. It's located on the LHS of the boot and is labelled 'EFI Technologies'. I've not managed to get any information on the exact workings of the system but it loops into the cars loom using a supplementary harness in three locations:

Lambda sensor connector
Fuel injection connector
Coil pack connectors (1 and 2)

It monitors misfire conditions and cuts the power (limit 5,500 rpm) and illuminates the dash light if there are issues. Pscan obviously can't read this system but you may have an issue there.

Hi all,

Apologies first of all, I'm an interloper with an S1 Elise 111s and this is a lengthy first post! The 111s shares the same engine as the MGF VVC so any thoughts are welcome on the issue below.

I have an issue with the cars emissions; it idles and drives perfectly but the engine's running rich with tell tale smell and black exhaust deposits but no smoke.

Pscan has highlighted the lambda sensor is inactive and remains that way. The lambda voltage is mostly static at 0.49v with an uplift in voltage only when on the over-run from c. 2,500rpm where it will briefly climb to c. 0.6v before falling to 0.49v again.

Measuring the output from the lambda using a digi multimeter shows an output of c. 0.8v which does vary a little with engine speed, I think this is telling me the lambda knows the engine is rich but the ECU is not responding to the lambda.

Prior to me owning the pscan the lambda, temp sensor, air temp sensor were replaced recently with genuine MG ones to try and address the issue so I'm reasonably confident they should be OK.

The harness has good continuity all the way back from the various sensors & lambda connector to the ECU (+ve and -ve) yet the ECU appears to not respond to the lambda. I've tried a second hand Mems 2J to rule out the ECU but no change to the lambda response.

A couple of questions:

1) Would anyone be able to share with me some baseline 'live' Pscan data for the VVC? As a newbie to this type of diagnostics it would be helpful to verify I'm interpreting the readings from all of the sensors correctly and importantly to understand what I should be seeing for the lambda, MAP etc.

2) Does anyone know if the Mems 2J defaults to a static voltage (0.49v) in the event of the lambda voltage being outside of a normal range (I'm guessing c. 0.5 to 1.0v)? I'm beginning to wonder if this is a symptom as opposed to the cause which may be caused by an issue elsewhere?

Thanks for any thoughts.

Stuart