Hi Robbie,
I replaced both the front and rear sensors for piece of mind, thinking if one is broken chances are the other isn’t far behind.
I replaced the rear one with one of these available on autolink: Temperature sensor Mazda MX-5 1 6 mk1 ECU rear of engine 857418840
Do you know what else may be causing it to run rich ?
What I find really odd is how intermittent the fault is. When I first started the car it ran fine (Albeit idling a little high), and it was only after I depressed the throttle and revved it to around 3,500 RPM that it suddenly started running rough & rich, making me wander whether it’s something like the oxygen sensor or AFM ? I’m thinking about testing the AFM and seeing whether the flap inside it is getting stuck maybe.
Hey @Roadster_Robbie, just wondered if you caught that last update ?
Sorry to be a bother, just curious if you have any thoughts at all.
Got a lot going on so not had time to give a considered response, sorry. You could probably do with doing some proper testing rather than making assumptions and swapping parts, how handy are you with a multimeter? And more to the point, are you in a rush?
Thanks for taking the time to look. I’m by no means an electrician, but I have got a multimeter and managed to use it to test the battery voltage, calibrate the TPS and test the resistance on the idle. control valve, so I should be capable of using it to carry out further troubleshooting.
One of the things I’m going to try and do next before replacing any more parts is to test ground/earth points around the engine bay to ensure they are stable for all the sensors and inputs around there.
I’m keen to get it fixed up and back on the road quickly just because it’s been like this for a while now.
For the benefit of anyone else experiencing similar problems now or in the future, I managed to resolve this in the end by replacing the AFM.
Turns out that the flap inside my original AFM was getting stuck occasionally and not closing, therefore giving the ECU a bad reading and causing the car to run rich. With the new AFM all is as it should be.
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