I’m looking for technical help or recommendations on: __
So, I return to Nc1 in a crowded, chaotic Lidl car park and it starts but immediately dies. This is completely ‘out of the Blue’: not a hint of a pending failure.
Return an hour later in our other car with an a OBD scanner but it won’t read the car for some reason and won’t even fire now.
So get it hauled home for £180.
Given the palaver the solo pickup guy had to go through and the chaos he created in the car park it went some way to sweeten the bitter pill! Completely aware that supermarkets are all about speed and throughput, he shared with me anecdotes of when he had, doing his job, had slowed the world around him to a more sensible pace and no one could could do a moan about it! Mellowed a bad day for me I have to say…
Anyone point to a methodical way to approach this in one post I can follow?
From biking days I’m looking first to check for a spark and then smell for fuel but in the search it’s all about sensors, crank and cam.
Any direction for a dinosaur would be much appreciated! Thanks
If you have a fault light on then first step is find an obd tool that works, otherwise old school, check fuses, loose connector plugs, are you getting a spark at plugs ? Is fuel up to injectors ?
Wiring to crank sensor runs close to belts, check for any fraying.
Tried two scanners and both report no fault!?
Reading around it looks like under some conditions the crank sensor and/or the cam sensor can be faulty without being flagged.
This in itself could be diagnostic so I’ve got a new crank sensor for £20 and a functioning old cam sensor for £14.
All I can say is it’s beats depreciation if all goes well…. Wish me luck fellas!
Prime holiday time, not sure if / how it is possible to tell if you are a member or not anyway. I am in an NBFL with no NC experience but the usual procedure is check battery terminals tight and for any corrosion, corrosion around earth straps baterry and engine, alternator and starter connections for corrosion, then main fuse for integrity and any signs of corrosion around the fuse and relay boxes. Not sure NC’s are as rusty and NB’s there may be one or two NC peculiarities I am not aware of.
To be fair, it doesn’t seem that you need much assistance at this point. You’ve stated that there are no fault codes and have ordered a camshaft and a crankshaft position sensor. Report back with the results of changing those I’d say. I’d also follow @rutlandsurfer advice and check fuses as a next step if required. How many keys have you got? If more than one have you tried another one?
Both cam and crank sensors have been replaced with new items. Both keys have been tried and all fuses have been checked. The resistance of the injectors are equal and within spec (12.6 ohms in all four). Good spark on cylinder 1 so assuming the others are good. Fuel relay has been swapped.
I’m inclined to think fuel problem as it started then died. Given it’s pressured at 2 bar I’m a bit nervous how to check the fuel system. Any tricks todo the business without a gauge ?
I see ways to de-pressurise then disconnect the injector rail and see if it fills up a container perhaps?
Ignorance is expensive. For just six quid I could avoided this rabbit hole of cam/ crankshaft sensors that cost £50….
Just get a can of cold start, spray a bit into your intake, I found it easy to break the hose just behind the air box. Start the engine. If it runs for a few seconds then it nothing to do with the ignition side of things or timing issues.
Conclusion? You have fuelling problem.
Hope this saves the days I wasted when someone else sits wondering why it their pride and joy is suddenly a very expensive paperweight
Fair point. I did check the resistance of the injectors and they are all 12.6 ohms. That’s obviously not conclusive but that consistency in that component is reassuring. I’ve discovered a broken tag on the fuel pump. This could have happened with the trouble I had removing its connector but the simple circuit from battery/ fuse/relay/pump shows no faults so new /old pump first before another dive.
Battery kept charged when not diagnosing.
Engine fault light has always been on but no fault codes when scanned.
So the scanner you are using is definitely connecting yet refusing to show the code that the car is convinced is present? If so, this would suggest that the code is present in a specifically Mazda programmed module and would require the use of Forscan or such to actually read.
I recently purchased an ECU kit for around 50 quid from Sportscarandspares on Ebay after buying a non-starter with an immobiliser fault. Your immo seems fine since you mention no abnormality with the security light, but I am suggesting that you could eliminate/solve any potential problems with the ECU by swapping those parts out, should it come to that. I have it on good authority that occasionally NC ECU’s fail with little rhyme or reason and no visible signs of failure.
So did you actually do the easy start thing? Bear in mind that that is not always a conclusive test, but of course it does eliminate things like spark condition. And what do you mean by broken “tag” on the fuel pump? Another way to check for fuel is to just take out a plug, crank it over and use your nose! Or crank it over a good few times, then pull a plug and see if it’s wet.
If your fuel pump wasn’t working I would think you’d see some OBD2 codes on the scanner, if not for the pump then further down the line, maybe even a misfire code. This is why I’m wondering if the ECU is ok, since I don’t see why you can not read the codes.
I generally use my ears for fuel pump testing before anything else. Just turn ignition to on and listen for the whine behind the passenger seat. Make sure you check the fuel pump’s earth and any grounds further down the line that might be involved. And, of course, the fuel filter! Easy to test by simply bypassing the filter, bearing the risks of doing so in mind.
It certainly sounds like some sort of fuelling issue, but the thing that puzzles me is the unreadable code! I’m not aware of anything fuel related on these cars that wouldn’t just be a standard OBD2 code, but hey I’m willing to admit my knowledge is often lacking!
Fuel pump has four male connectors. One, the earth, Is simply missing. I can’t see it in the female connector. There is some blackening on the nylon on the female connection of the earth pin which suggests overheating. It’s not massive but overtime may have waekenined the male connector.
Yes, I did the easy start spray into the inlet. Pretty conclusive when the engine runs sweetly for a few seconds!
Yes, I’m bemused by the lack of codes too. If the whole fuelling system is down it’s fair to assume something should show up on the simplest OBD2 scanner.
On the NC I think the filter is built into the pump assembly?
Just to put your mind at rest the blackening on the conector is most likely some water proofing Mazda put on to protect the connection. One sees this question of is my connector burnt all the time on MX-5 forums see third post on this link for a photo :- Passenger side dipped headlights and side lights failure - #2 by Foxcompaq
Sorry I cannot help with diagnosis of the fault with your paper weight, hope you find a fix soon.
I would assume that a fuse would be blown before enough heat is produced to damage connectors or wires, since this is precisely what the fuses are specified to do, but of course there can be anomalies.
Have you listened for the pump?
Filter could be in the assembly, I’ve not had an NC for long. There’s a flap on the older models near the tank where the lines run under the body, a quick google shows that it does seem to be the same part as older cars, so it will be there under that flap. It’s worth disconnecting that and catching some fuel out of the tank (careful here, be prepared) to make sure that everything at the tank end is hunky-dory, maybe bypass the filter to answer that question. Possibly even running the fuel pump with your filter line disconnected entirely to see if you get a good gush would provide some answers. If the fuel pump is failing, you should get some sort of standard obd code, even though it won’t specifically describe fuel pressure. The presence of the engine light seems to suggest that there is a standard obd code present at some point, again this is why I wonder if your ecu is suffering from something.
I know you’ve done a crank and cam sensor swap but there is still the possibility that this is a timing/communication issue. I would definitely pull the injectors and see if they squirt under their own volition if you’re certain you can’t hear the fuel pump or the pump won’t run with a direct 12v feed.
I’m feeling generous so here’s a way to test an injector on a bench if you’re unable or averse to testing them in the engine bay (Just because they have resistance doesn’t mean they work, because you’re just measuring resistance in the coil): Prepare a can of very thin solvent like brake cleaner, either in a syringe into a plastic tube that fits on your injector OR in a spray can with a little straw, which you can wrap tape around until it fits snugly into your injector. Prepare some wires connected to a 12v battery. Connect your wires to the injector (I’ve heard you shouldn’t do this for too long as they are designed with a very short duty cycle, but others have said they routinely open injectors this way for several minutes and have never had a problem, I’m inclined to believe you can hold the solenoid open for a good while before anything untoward will happen. If in doubt, “pulse” the injector) and the solenoid in the injector will actuate and the injector will now be open, in its spraying state as such. Spray the can or push the syringe until you get a nice triangular spray from the injector. However, I doubt injectors are your problem because it’s so unlikely that all 4 will fail at once.
Have you checked your MAF and MAP sensors? I know from experience that an NC will run without the MAF sensor connected, but I don’t know about the MAP sensor. This is why easy start is not a conclusive test, as you may find it could be the air ingredient (or at least the sensors involved) that is amiss. Not overly sure on this for an MX5 but sometimes faulty oxygen sensors can do some very strange things. Even a lot of cheaper OBD scanners can have the function that shows whether your air sensors are happy.