My MX5 94 Eunos has just failed its MOT on the Lambda sensor. I have now replaced this and after doing so the car will turn over but will not start. The sparks, petrol and battery are all ok and the readings on the emmisions, CO2 and HC all past. The car does not appear to have a CAS, as this was going to be my next step.
Has anyone else come across this before, is there something I’m missing, maybe a cut out switch I’ve knocked in the process of changing the LS? The car was running ok up until changing the LS, now the car is stuck in the garage and I’ve missed out on a gorgeous bank holiday!!
Sorry to hear you missed out on the bank holiday weather.
My first thoughts are that the Lambda sensor itself isn’t very likely to be the problem (the sensor doesn’t operate till it heats up, so it’s not needed for the car to start) unless of course it’s miswired and is causing a short circuit somehow. Did you replace the sensor with a new one complete with plug, or did you splice the new one into the existing wiring loom?
Also, it’s extraordinarily unlikely that your car doesn’t have a CAS - you should be looking at the back of the exhaust cam, with the electrical connector on top, right beside where the lambda sensor plugs in (coincidence?).
The new lambda sensor has been fitted into the existing wiring loom, do you think I should have fitted it with a new plug? I will look again tomorrow for the CAS now I know where it is, could this be causing the none start?
Thanks for your help so far, I will re-post tomorrow with an update.
There’s no need to fit a new plug, I just wondered if there was any opportunity for a wiring error to have crept in. If the CAS were disconnected, the car definitely wouldn’t start.
Found the CAS and that all looks ok, so I’m still at a blank with it really. I called the MX5 centre today to see if they could give me any advice, they said even if the wiring was incorrect for the LS the car should still start but would sound and drive rough so without taking it down to them they dont have the equipment to come and check it, so looks like I will have to get it down to the garage, some how.
I’ve unplugged it and the car still wont start, the spark plugs are ok, the petrol pump is clicking so seems to working, Ive taken the jets off thinking they may have been blocked but they seem ok. Ive called an MX5 expert who is supposed to be coming out to look at the car, if he doesnt come then a toed trip to the garage is needed.
Never thought of that, it could be the imobiliser, I can hear a clicking noise when trying to start and I have had the battery off. An MX5 expert was supposed to come today, I was going to ask him, but he never showed! I might try re-setting the imobiliser, I have the instuctions! Will let you know. Thanks for your help.
…But I dont have the imobiliser code and the MX5 expert who was supposed be coming over to look at it never showed!! Think I will need to take it to a garage (somehow) and have the imobiliser re-set!
one other thing… if your getting clicking when attempting to start… is it not just a dodgy battery without enough power? (usually the dash lights will fade in this instance) otherwise get the imobiliser checked as you thought.