NB8B engine cut out

[JBG]

Last Sunday, returning from work, my NB8B ( Igrushka ) cut out on me.

I was cruising at 60 or so on Epping Road when there was a serious loss of power. The initial feel was alike that of a rev limit cutoff. Thereafter the engine did not responded to throttle inputs. Just some shuddering low rev intermittent stuff. Then it would not start.

After arranging a tow etc, 40 minutes later it started and ran perfectly. $80 bucks to get a large truck to follow me home in case it happened again.

I generally drive to the city to work (is there a better way to bookend long stressful days yet invented than an MX-5, even in bumper to bumper Victoria Road traffic?) so this is a major issue.

I book it in at Artarmon, with a couple of other issues (neither of which have yet been resolved, plus the car came back with greasy fingerprints at the top of the door and on the A pillar). Expensive service later...

Next day, today, the same thing happens. After the initial loss of power it is hard to work out whether there is too much fuel, too little or some problem with the air or oxygen sensors. Or bad fuel. It revs spasmodically and lumpily then dies if slightly pushed.

Given 20 minutes to sort itself out (and two hazard flash stops on Epping Road at early peak time) the car ran fine all the way home.

Anyone else with an NB8B had anything remotely similar happen?

Jonathan

[Russellb]

Sound like a heat related Problem
Proberbly the cam sensor most common problem on the NB8B

[de Bounce]

See if the OBDII has recorded a code

Mine recorded an Error Code P1345 Cam Position Sensor
Appears to be a common problem in the NB8B's at approximately 60 - 70k miles (100K km)
From memory there was a couple of cars died in the heat in Sydney last summer.
Read more here and here

I believe it is heat related due to the relocation of the sensor from the front of the motor in the NB8A to the rear cam cover in the NB8B
Both NB8A and NB8B use the same sensor Mazda Part No. BP4W-18-230 sensor, camshaft
Cost from Mazda $150.00

Held in by 1 10mm bolt and takes about 2 minutes to change.
Could try swapping with another and see if the problem goes away.

[Garry]

What they said though it doesn't always show up as an error code in the ECU. I decided to avoid the rip of Mazda AUS price and imported one from MX5 parts UK. http://www.mx5parts.co.uk/product_info.php/products_id/1173 It will take about 5 days to get here if they had any in stock though. Probably not much help to you.

[Benny]

It could also be signalling that your fuel pump is on its way out.
I had a similar problem with my Clubman many years ago.
The car would be driving perfectly, when all of a sudden, the engine would cut out and refuse to start.

Leave it for a half hour or so, and then it would re-start and run perfectly again.
The cutting out started to become more and more common, until eventually it got traced back to the fuel pump.

I hope it isn't your fuel pump, as these can cost around $600 to replace.

[Hellmun]

I've had my NB8B cut out 5-6 times for no discernable reason. I worked out that if I lock and unlock the doors..the car works perfectly again. I assume it was the immobiliser. Hasn't happened in a long time for me but simple enough to try next time it happens.

[JBG]

Thanks all for the replies.

As I need new front rotors and pads (which I have already paid for), which have to ordered in, I have to go back to the dealer within about two weeks.

I'll raise the cam/temp sensor and the fuel pump issues. Igrushka has done only about 83K kms though I bought it second hand with 64k on it.

This is really annoying me.

I may take Mr Pink with me, if he is free, next time I put the car in. Which means we'll come up to the showroom and hassle you Craig!



Jonathan

[MrsB]

mr b here -

we had the same problem on mrsb's na6 after picking up from the mechanics - turns out there is a couple of fuses that earth through a screw inside the fuse itself that if they aren't there or are loose the car cuts out. Only isolated the problem after getting them out and one of them remembered playing with the fuse and couldn't remember about the screw and it ran fine and hasn't missed a beat since.

Hope this helps

[Hammer]

I vote for the cam sensor needing replacing. The symptoms where similar to what happened to me last year. Replacing the cam sensor fixed it.

[Caffeine]

Could be the EGI main fuse. It's the big green one in the underbonnet fuse box. I had 4 die a few years ago (my car has some serious electrical gremlins) and the symptoms were as you described (before it cut out entirely and wouldn't restart)

Should be $25 for a replacement one from a wrecked, same fuse in all NB or earlier MX5's

[Uncle Arthur]

I'm now having a similar problem on MAX (bloody cars!!! ) Car starts, car runs, I open the driver's door and close it and the car just cuts out. Then won't start - at least not at first - it just cranks and then decides to fire, although it also chugs and misses a bit sporadically if I lift off the throttle. When it won't fire there seems to be atong smell of fuel from the exhaust, although could it be the pump cutting in and out?

mr b here -

we had the same problem on mrsb's na6 after picking up from the mechanics - turns out there is a couple of fuses that earth through a screw inside the fuse itself that if they aren't there or are loose the car cuts out. Only isolated the problem after getting them out and one of them remembered playing with the fuse and couldn't remember about the screw and it ran fine and hasn't missed a beat since.

Hope this helps

Can you remember which fuses in which fusebox? I'm assuming you mean the one in the driver's footwell?

What other symptoms might stem from the green fuse inthe engine bay?

[93_Clubman]

Can you remember which fuses in which fusebox? I'm assuming you mean the one in the driver's footwell?

What other symptoms might stem from the green fuse inthe engine bay?

UA, on NA6 & NA8 at least the fuses that are screwed in are in the box in the engine bay.

Caff & one or two others have posted some good info ref symptoms & fixes which might assist:
search.php?keywords=egi&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

[Uncle Arthur]

Further update.....

Checked all the fuses in the engine bay on the NA6 this afternoon - all seemed in order.

1. Car starts fine.
2. Car runs fine (for about 15 seconds)
3. Car cuts out (seems to coincide with some change in electrical load - this afternoon it was turning on the radio, this morning it was the door light).....
4. Car cranks but doesn't fire.
Repeat
Repeat
Repeat
5. Car fires.
Car runs - must keep revs up or else car cuts out.
Go back to number 3.
6. Car eventually runs - keep revs up, and all seems fine to drive.
7. Pull into driveway - lift off accelerator - car cuts out (but will now start again straight away).

What do people think? Does this sound like the fuel pump cutting out? Funnily enough my car actually has a kill switch on the fuel pump - the symptoms here are exactly as if I flicked the switch to off..... except that I haven't.

Are there any particular recommendations regarding a replacement pump? The Walbro is a well recognised unit, but are apparently noisy accodring to many posts here.

Someone in Brisbane was selling a NB8A fuel pump late last year - are they the same as the NA6 to fit?

[93_Clubman]

UA, I'm assuming you've checked the fuel cut out switch, & also that it's been installed, as when you turbo'd you removed the AFM & fitted a standalone aftermarket ECU? If so, then the fuel cut out switch would have been installed as the NA6 AFM incorporates a fuel cut out which kicks in when no air is sensed to be passing through the AFM. May be if the switch is wired back to the old AFM harness or connector there's a problem there?

Ref noisy Walbro fuel pumps, you could always fit the jumbo thickness rubber sleeve to it to quieten it down - these guys sell all the bits separately: http://www.apeusa.com/html/kits.html

[manga_blue]

Just figured out the same thing in my NA8 today. All fuses inside the engine bay and below the dash were OK but no power to the ECU.

It was the Main Relay. That's the big black thing in the main engine fusebox. It is responsible for power to the ECU and a host of engine devices. As it starts to fail it becomes prone to knocks and bumps, e.g. shutting the doors will bring it back to life. I found it virtually by accident when I accidenatlly touched the fusebox and it went click and turned the radiator fan back on.

Try turning the ignition on and off and listening for a soft click. If it doesn't click then try tapping it gently while the ignition's on. If you can't get a click out of it then it's dead.

Mazda part no B6S8 056700-9000 or JE16 056700-8780 for NA8s.