Help! Engine problems...

[connico]

My Mechanic has a day off and don't want to disturb him while his getting his day of rest in...

Basically I went to St Alban yesterday for a drive with the missus. I filled up at a shell service station at Carlingford all was good and well till i got half way to Wiseman ferry. My engine while in forth started to splutter and when i pulled over and dropped it into neutral the engine stopped.

I let it rest for a few minutes, pop the hood and poked around. Nothing strange, no funny smells or leaks anywhere. I stood there for a few minutes scratching my head.

So I let it rest for a few more minutes and go ahead and turn the engine over, it sparks to life fine... Then after a few secs splutters again. This time I am listening intently. No Knocking nor is there any valve issues. So I am stumped, I am just about to call a tow truck to tow it back. But the missus had already gotten into the boot and taken out the picnic basket and was calling me over for light brunch.

Regardless it let it rest for another 20 and then turned it over. It sparked to life, let it idle for about 10 minutes and all seemed well. So i drove.... Yeah i drove the thing... All the way to Wiseman, and half way to ST Alban. It happened again.

Again we let it rest and it was. While driving I was thinking that it could be a loose igniter, some have been known in my previous cars to fail at temp. Then I realised that variable was that fuel. That was the only thing that changed about the car.

Regardless we got it going again and drove it the rest of the way to St Alban for lunch at local pub - The settlers arms Inn. Best battered fish in the country!

Regardless I let it rest for like an hour and drove it all the way back home with a stop at the petrol station at Wiseman, the local guy service guy said that I prob did get a bad batch of fuel and i should just let it run through. He did not have a pump to pump my fuel out anyways.

Took it for a spin today... everything was fine till I hit picnic point, again splutter and died. Did this for sometime and then let it rest for a bit again and it was working fine.

Now my questions.

I need to pump the fuel out and get rid of that variable before I assume its something else. I think water could of gotten into the fuel at the servo and its causing it. But i don't have a pump and no way to get rid of the fuel.

If i let it run through the car, how much damage could it cause.

If its not the fuel, what else is there... The car runs fine.. no lose of power, no knocking. Its not over heating, no crappy black exhaust. No smells or leaks visually.

Thanks everyone

[JBT]

What model car?

[connico]

01 NB8B

[Okibi]

It could be a coil pack on the way out.

I think people pour water over them to cool then down and see if the car suddenly starts again.

[JBT]

Could be the crank angle sensor (front of engine) or the sensor for your VVC system (see photo attached).

[connico]

Anyone got an opinion on the fuel issue...

[Okibi]

I'd be checking for loose connections to the AFM, loose hose from the cam cover to the intake, loose crank angle sensor ...

[JBT]

Anyone got an opinion on the fuel issue...

It would be a constant problem so I don't think so.

A guy up here had the problem you describe on a club run - it was the VVC (VVT?) sensor. When the car died it was a case of open the bonnet, let it cool and go again.

[Juffa]

You could have a bad batch of fuel, but I suspect that what the others have mentioned around the coil pack and CAS are probably closer to the mark.

The other possability is a clogged fuel filter. Does the problem happen when you need extra power such as climbing a hill or similar?

J

[Steampunk]

I don't think it's the fuel either, and why would you think you got water into it? Even if there is water present, it would have to be ALOT of water to cause damage.

http://mx5cartalk.com/phpBB-3.0.2/viewtopic.php?f=29&t=29104&p=368834&hilit=gearbox+neutral+switch#p368834
Check Craig's comments re: Gearbox neutral switch. Maybe....?

[connico]

The reason I think its the fuel is because its the variable before the problem started.

The other possability is a clogged fuel filter. Does the problem happen when you need extra power such as climbing a hill or similar?

I did think of this, but the problem is intermittent. I get it when it feels like doing it.

This afternoon I ran the engine for about 20kms then I started loosing the engine down a hill. Put it in third and cruised down and pulled over. It started dipping revs and then shutdown.

I stopped in that area for about 30 minutes trying the engine.

Looks like i'll take the car to an MX5 specialist, while my mechanic is awesome, his lacking in knowledge for MX5...

[Okibi]

Join your local MX-5 club, then you'll have a group of mates who might be able to help you diagnose it.

[connico]

lol that is very true..

Regardless Ill prob make a booking with a Mazda dealer service center.. Lets see how good or bad they are. I've been very wary of brand name dealer service centers as they tend to inflate costs...

[Hammer]

This is such a freaky coincidence.

I was about to post an identical problem in the forum to get some advice, then I saw this.

I too experienced this yesterday. As you know it was extremely hot in Sydney (33+ degrees). On constant speeds (anything 50km/h and above) all is fine, but at start/stop traffic doing anything from 10km/h to 40km/h, I did experience the same problems that Connico's mentioned.

My 5 stopped on me 3 times yesterday. Each time during the stop/go traffic conditions on Parramatta road. I put the bonnet up, leave it for about 5mins, then the thing will start again. On the M4 & M2, it didn't miss a beat.

It was obvious the heat is major factor to the cause but exactly what I didn't have a clue. At first I thought it was vapour lock. But I haven't heard it happen to a fuel injected car (only carb). Then i thought dirty fuel? But I just got it serviced 7k kms ago, and got fuel from my usual servo (Shell V-Power). I've had the car since new 6yrs ago, and it's never had this problem.

Having read some of your advice, I might check the VVT sensor, that could be one cause. Being an SP. it does get hot in that area. What should I look for with the VVT sensor?

As for the coil packs. Are the syptoms consistent with a coil pack on the way out?

Any advice would be appreciated.

[JBT]

Precisely the condition that the car here had the failure. Hot day, low airflow due slow hill climb = engine quit. Cause - VVT sensor failure at higher than normal engine room temperature. No problems at normal/highway speeds.