I’m looking for technical help or recommendations on: OBD2 checker and misfire
Can anyone tell me how to use one, I have an ELM 327 Interface which appears to be telling me there is no fault code even though when the car is hot (ie the problem doesn’t occur when driving at first) the car misfires as if it momentarily losses power then cuts back in and out again if I try to keep the revs high. Replaced cam and crank sensors no improvement, any help greatfully received thank you.
Dave
As with most modern manufacturers there is the legally required and the propitiatory ODBII connection delivery.
With the Mazda(Ford) the MS-CAN support is where you will likely get the additional propitiatory information your looking for, but its a CAN of worms , pun intended…
Take a look at this link and review what thy say about reading the Mazda(Ford) ODBII CAN-bus detail.
There is a free android app that should get you there with the correct adaptor or a modified one.
Hi eaa53, thanks I had a look at that link and realized just how little I know! To summarize does this mean that it’s possible it’s showing 0 faults when in fact there may be one? Thank you kindly for your time.
Dave
Good evening roadster Robbie, no engine light coming on, the car revs sweetly to 7k at the start of the drive but after a few miles the problem starts (heat related maybe ? ) I have made a visual check on the plug leads and coil packs an there is no furring or anything visually untoward (I guess though that may not mean a thing) the plugs were replaced by Wayne of Mazda menders who did a very comprehensive re commissioning job on the car as it had stood unused for 10 or 11 years, 15k 02 zero rot/rust, the tank was flushed and new filter fitted as well, it’s a strange problem and someone on here suggests maybe a temperature sensor? Also a strange thing is that sometimes the brake warning light comes on at about 70% luminosity (driving along handbrake off brake fluid ok) I wondered if it could be an abs fault causing the ECU to cut power ? Crazy idea probably. Desperate to sort it as the car is a peach otherwise. If your interested it’s on Mazda menders website “from unloved to reborn”. Thanks for the much appreciated help. Dave
Hi mk375, I have no idea about the Ford involvement re this issue but we did make parts for the I think 121 Mazda which I again think may have been a badged Fiesta probably 20 years ago ! Dave
To answer your question yes its very possible that the proprietary system used by Mazda could have faults recorded that are not shown as a MIL light. The legally required ODB connection will only show a sub set of faults usually the more serious faults. There is also a set of pending fault indications these are faults that are developing but not fully report as a MiL fault.
If as MK375 intimates it may not be the MS-CAN but it will be a propitiatory Mazda system that Mazda software can view. Other systems like Snapon professional readers sometimes can see them as well.
All manufacturers do this I guess to protect their trained service agents and provide a better service to owners, tongue in cheek…
As Robbie indicated it could be something basic like a plug gap, a cracked or broken pipe a failing coil or an intermittent sensor its not possible to tell you whats wrong without some testing so you need to check as Robbie has indicated.
The fact that it starts and runs is in your favour, the fact you report that the symptoms occur at working temperature means the cause is likely to be something affected by that temperature, spark gap is one.
Thanks for a clear concise and easy to grasp answer, I guess I will have to work through more of these things and if no luck take it to a good independent, I’m told freelance Mazda are good, a 75 miles round trip for me though!
Many thanks for your help, regards Dave
Sounds similar to the issue I had on my mark 2. Cleared the memory on on the ODB. Ran the car and then tested again. The sequence code indicated a faulty throttle sensor. I found a Mazda dealer who had the ODB knowledge and he confirmed my diagnosis. Replaced the sensor (£135 plus fitting). Problem solved. The price of the test kit was under a tenner from Autolink. I too had replaced coil pack, plugs and inlet sensor. Cheers John
Good evening John, that’s worth knowing I shall give it a try before seeing if there is any debris in the tank causing temporary fuel starvation, a good tip from you for which I am very grateful, once I have sorted the problem I will post my findings.
Kind regards Dave.