mx5cartalk.com

or possibly a cam angle sensor..these usually break down after 100,000kms

fif111 wrote:Thanks for your reply.

How to test if the cam angle senor is faulty ? Cos I thought if they put the car on their computer, it will display codes about faulty senor ? Am I right ? Sorry, I have very very limited knowledge of car ...

there are a few forumites on here that have seemed to have similar symptoms. Sliq being one of them (shoot him a PM)

where abouts are you located? i have a brand new one sitting here which i will be installing in my when it goes back together. Feel free to swing by and try it if you want. Im in the Southern suburbs

I'm struggling to understand your symptom but here goes what happens with a Cam Sensor

Engine heat causes the problem!
As the engine gets hot, the sensor breaks down and the engine stops.
The sensor cools and the engine starts and runs fine.
Cycle starts again.

Getting the engine hot can be climbing a hill, giving it a bit of a flog or even a bit of heat soak in the engine bay may trip it.

The computer doesn't always record a code. (Mine did, Sliq didn't)

Fastest way to confirm it's the problem is to swap it with a known one (suggest you take Regie up on his offer)
The same sensor is used on both the NB8A and NB8B.
Takes longer to remove it from the box than to replace it on the motor
(1 x 10mm bolt and 1 x wire connection)

Another thought is possibly a crank thrust bearing problem, although yours is a bit out of the range and the people servicing it should have picked it up.
There is a video about it HERE

Could check it with someone watching the crank pulley as you try to start it and cycle the clutch. The pulley should move if that's the problem.

The more I read, the more I believe many of the random stop / start problems suffered by the NB8B is caused by the cam sensor.

Be a little cautious jumping on the dealer as it may not be anything they did. Many a person has been caught with this problem and spent heaps trying to fix it.

fif111 wrote:Many thanks for your reply, it is very good to know this. I apologise for my english as I am not a native english speaker .
I did quite a few google search, it seem like there are alot of people reporting the CAM sensor problem, I will discuss this with Mazda people.

Also, many thanks for Regie's offer too, but I dunno how to replace the sensor, I don't want to end up breaking his part. I very much appreciate your kindness

So, I assume, many of the NB8B would have cam sensor issues ?

if you can wait just over a week, im hosting a dodgey day at my joint. Head on down if you want. It takes literally 10 seconds to change over the cam sensor, take it round the block and hopefully its all back to normal.

viewtopic.php?f=63&t=41747

About the model having the cam sensor problems. I assume it has the sensor because of the VVt inlet cam. The sensor starts to break down around the 100,000km mark

I'd stick with Regie's offer. I have seen a 2002 with the cam sensor problem - it breaks down when a little hotter than normal. Once the engine cools down a bit it works fine again. Just buy the part and you will see how easy it is to fit.

it can take about 10 minutes of driving for it to start stalling if it is the cam angle sensor. i took my car for a good warming up/spirited drive and thankfully it stalled into a multi laned street, literally around the corner from me.

a way you can test it is (cheers to de bounce), start the car up, place a hair dryer over the cam angle sensor until it is pretty hot (for about 5 or so minutes), and the car should splutter and die because of the sensor over heating.

I think the sensor gradually becomes less tolerant to heat.
Mine only failed under extreme circumstances when the under bonnet and engine temperature was very high.
Once it cooled down it was fine.

I had the replacement in the boot and was waiting for it to fail to prove the point (as sliq has done)
I drove for another 2 months without issue before eventually replaced it.

If the car is never dríven hard or on a hot days, my guess is the sensor will degrade until it eventually fails once the engine reaches operating temperature.

There are some articles HERE and HERE on the big forum

You need to take it up with the repairer. The service mgr needs to be told that there is a fault and you want it rectified. By all means you can print out some of these suggestions and Euromazda should be able to check . If the car was ok when it went in then it should be ok now so it is fair to expect them to fix it. You do have consumer rights and a reputable repairer shoiuld assist. You may be able to get them to loan you a car if they need the MX5 for a few days. Most businesses will try and assist.

Hello there..
Re. Cam Angle Sensors.. (failing at around 100,000Km.)
Is this item found only on the NB8B/C series, or was it fitted to the NB8A as well?
Also how much do they cost, please?
With thanks from slowpoke.

I'm guessing its only on the 8b and later series due to the vvt on the inlet side. Not sure how much they cost, but I've herd they are a tad expensive if bought here. I got my new one from mx5parts.co.UK for roughly 70 bucks

slowpoke wrote: Re. Cam Angle Sensors.. (failing at around 100,000Km.)
Is this item found only on the NB8B/C series, or was it fitted to the NB8A as well?
Also how much do they cost, please?

Same sensor in the NB8A as the NB8B however it was repositioned in the NB8B
It appears it is not an issue in the NB8A's
Mine cost $150 from Mazda mid 2009

Regie and de Bounce...
Thanks for the info.!

slowpoke wrote:Regie and de Bounce...
Thanks for the info.!

did you sort it out?