what cause backfire on mx5

[wun911]

Just changed the spark plugs today I use NGK ones (BKR5EIX-11) they have done only 50,000 km and look like this.

Here is a pic of the plugs: any opnions?

One of them is slighly oily around the threads?



Getting new leads in tomorow.

[Matty]

It happens on the main straight at 6000 rpm (im in 3rd gear im thinking about changing to 4th but I havent done so yet) just happens all of a sudden my foot is planted to the flor. Loss of power exhaust pops loudly crackles and it stalls, I turn the key it starts up I ease it off the track.

I scratch my head, 20 min later get back onto the track, happens again after after about 8-9 laps, same thing on the straight, friggin frustrated now, lots of track time but car not lasting the distance happens a few times thoughout the day etc.

I was thinking heat issue?

That doesn't sound like backfiring to me.

From that information I would guess that the coil pack or cam angle sensor (or their associated looms) is playing up.

[Matty]

plugs look fine. The oil would at worst be a leaky cam cover gasket

[wun911]

Just an update...

Went to chaddy watched max payne. came out car wouldnt start. (Has fuel has power)

Took it to tony's full tech, we think it might be fuel pump.

(I do run around on 1/4 tank as often as I can)

[wun911]

Figured it the solution to the problems Iv'e been having.

Fuel pump died on friday night (after watching max payne) got it fixed at tony's fulltech.

A fuel pump on its way out could explain the symptoms Iv'e been having I guess.

I drive around with 1/4 tank and near empty all the time to save weight I probably cooked it.

[bensale]

I'm glad you've got it sorted Wun. Perhaps keep a little more fuel in the tank in future? Surely the extra few kilos of half a tank isn't too much to bare...