GSlender's Track Beeotch!

toppertee · Postby **toppertee** » Thu Dec 17, 2015 6:26 pm

IMHO...
I daily drive on 949 track set up,
Never really had any problems.... Other than bone head suv, sized shopping speed bumps.

Must be honest though, mx5 handling is pretty bloody good. Would tend to think as long as your within the ball park with set up and not driving 10-10ths 99% of track rats are going to be fine.

gslender · Postby **gslender** » Mon Mar 21, 2016 1:36 pm

Had a great run out at Morgan Park and put down some good times, but unfortunately the engine ran foul after the 2nd run for the day. I lost a cylinder and I also heard a "pissst-pissst" noise that was in time with perhaps #4 piston compression stroke - it was definitely coming from that end of the engine and I assumed it would be a head gasket leak (or similar) .... :cry:

After a bit of investigation I found that #4 spark plug had the side electrode broken off - not sure where the bit of metal went, but the plug no longer had ownership of it !!

Anyway, after dashing into town (Warwick) to buy a set four (4) plugs, I swapped them over and the engine started to run better. I did another two (2) final runs for the day and it seemed to be ok - certainly pulling strong and not noticing any significant issues.

Upon loading the car onto the trailer, I noticed I was still getting an occasional miss and along with that, I'd hear a "pissst" noise similar to what was heard before. I'm now wondering if the bit of metal is bumping around inside #4 and getting caught underneath valves and what not ??

Not good, and next step is to grab an inspection camera and take a look inside #4 to see what I can see!!

I'll post back with the results.....

Magpie · Postby **Magpie** » Mon Mar 21, 2016 2:09 pm

Not good news. I had a spare set of plugs (and other 'stuff') however not a timing light or a CAS bolt. Seems all the ITB MX5's had different reliability issues.

madjak · Postby **madjak** » Mon Mar 21, 2016 3:08 pm

Damn... it's those little things that can really cause big issues (hopefully not in this case). I'd almost prefer a bigger failure that can be prevented in the future than something random like spark plug failure. It was an NGK I take it?

I'd do a compression test too to make sure there is no damage to the valve seat.

ndragun · Postby **ndragun** » Sat Mar 26, 2016 4:48 pm

gslender wrote:I'll post back with the results.....

How'd you go?

zero00 · Postby **zero00** » Sat Mar 26, 2016 5:39 pm

Gslender

Watching from the grandstand between turns 2-3 in the afternoon your car sounded sweet as and looked great, so hoprefully no issues from that :wink:

Grandstand? Not sure when i raised my umbrella [for sun protection] if you guys were ready to pit for wets!

gslender · Postby **gslender** » Mon Mar 28, 2016 3:57 pm

Good news!

I pulled the intake and exhaust headers off and checked the insides with a scope. Also peered down the spark plug hole and everything looks really clean and no damage seems present.

Also did a leak down on #4 and compression test on all others. Everything looks perfect and got excellent results across the board... so really pleased nothing is damaged.

The top of piston #4 has a scratch/tiny dent where the spark plug tip must of bounced a few times, but other than that... spotless.

I did find more melted intake vacuum hoses and so I'm putting it down to going lean and melting the tip of a plug until it broke off/failed. I've read that the Bosch Platinum plugs are prone to that type of failure and so I'd recommend against using them and given they are 4x more expensive... are not worth it!!

G

ndragun · Postby **ndragun** » Mon Mar 28, 2016 4:57 pm

gslender wrote:Good news!

I pulled the intake and exhaust headers off and checked the insides with a scope. Also peered down the spark plug hole and everything looks really clean and no damage seems present.

Also did a leak down on #4 and compression test on all others. Everything looks perfect and got excellent results across the board... so really pleased nothing is damaged.

The top of piston #4 has a scratch/tiny dent where the spark plug tip must of bounced a few times, but other than that... spotless.

I did find more melted intake vacuum hoses and so I'm putting it down to going lean and melting the tip of a plug until it broke off/failed. I've read that the Bosch Platinum plugs are prone to that type of failure and so I'd recommend against using them and given they are 4x more expensive... are not worth it!!

G

Phwew...
Ditch that rubbish Jenvey vac pipe!

Magpie · Postby **Magpie** » Mon Mar 28, 2016 5:17 pm

May need to consider some EGT/CHT monitoring, if it is hot enough to melt the tips (in excess of 900c) then it could do other damage very quickly.

Do the logs show how lean the engine went?

gslender · Postby **gslender** » Mon Mar 28, 2016 5:30 pm

Magpie wrote: if it is hot enough to melt the tips (in excess of 900c) then it could do other damage very quickly

It didn't melt the tip, but the tips are prone to premature break or failure which are assumed to be due to lean/hotter engine temps. Apparently those Platinum plugs have a narrow range they can operate at, so whilst they may last longer, they don't last long outside of their designed operating range.

I'll just stick to standard plugs which have never had a problem and was my foolish purchasing decision at the time!

G

ndragun · Postby **ndragun** » Mon Mar 28, 2016 5:55 pm

gslender wrote:I'll just stick to standard plugs which have never had a problem and was my foolish purchasing decision at the time!

G

Agreed... The only plugs I've never had a problem with have been bog standard cheap NGKs from Repco.
I haven't used platinums - but have been guilty of spending over the odds for iridium plugs. They just seem too fickle outside of ideal conditions. So tuning with them is a bad idea...

Magpie · Postby **Magpie** » Mon Mar 28, 2016 7:49 pm

I have used iridium plugs without an issue to date. Plugs always have had a nice colour to them and never a heat issue either. Only recent ignition issue was a COP failure. Not only was the loss of power obvious but the EGT's showed which cyl was not firing.