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Hey folks,
I just got back from out in the shed. I thought that I would check the timing, so I borrowed my mates timing light and started...
Shorted gnd and ten in the diagnostics block, on a warm engine, and checked that the idle was sitting at 800-900rpm. Trigger for the timing light was coming from the closest cylinder lead to the radiator....
I can see two timing marks on the crank pulley, one yellow and one white.
The white one is sitting at about 18 deg and the yellow (to the left of it ) is sitting off the scale at what I estimate at 24-26 deg!!!!!
I checked this twice, totally removing the timing setup between tests.
My car is not pinging (as far as I can tell) and I have not adjusted the timing since I bought it 5 months ago. It is an NA8.
It has done 4 track days since then and felt fine! I run only 98 octane BP fuel in it.

Does this sound weird to anyone else???

Should I be worried???

Cheers
Chris

EDIT just went out to check it again, got the same results but noticed that the timing seems to wander a little bit, not quite a steady mark, its moving a degree or so either side of being steady.

If it has two marks on the pulley, the right should be on zero and the left on 10 degrees BTDC with the correct timing. Seems like yours is set for about 28 degrees BTDC.

The exhaust cam could be out one tooth on the timing belt. Has it had a timing belt change? I saw this once on an NA6 - intake cam (CAS is on the intake on NA6) was advanced by one tooth.

JBT wrote:If it has two marks on the pulley, the right should be on zero and the left on 10 degrees BTDC with the correct timing. Seems like yours is set for about 28 degrees BTDC.

The exhaust cam could be out one tooth on the timing belt. Has it had a timing belt change? I saw this once on an NA6 - intake cam (CAS is on the intake on NA6) was advanced by one tooth.

JBT, the timing belt has been changed as the car has 125k km on it, unfortunately I don't have the details on who did it, as I only bought it 5 months ago.
I think I had go and borrow my mates knock sensor now..........
28 degrees can't be good....

Chris

the 2 timing marks won't line up with the notches on the pulley if you are seeing 28deg BTDC.

each notch to the left of either the \"T\" or \"10\" represents 2 degrees BTDC, and there are only 4 notches to the left of the T and 10. Therefore, you can only see 18degrees BTDC IF both marks line up with the pulley.

http://www.miata.net/garage/timingmarks_closeup.jpg

So if you are saying that both marks are lining up, then you were right in the first instance insofar as it's sitting at 18degBTDC, in other words, any more than 18degBTDC you will only see one timing mark lining up with the pulley (the right hand one) whilst the left hand one is hovering in mid-air so to speak.

It is rather extreme, but not too tragic.

Try and change the timing as per the instructions in the link. If you cant get it to move through the whole range of 20deg BTDC and 20 degATDC then you may have a timing belt issue like JBT stated.

1red5 wrote:the 2 timing marks won't line up with the notches on the pulley if you are seeing 28deg BTDC.

1red5 wrote:So if you are saying that both marks are lining up, then you were right in the first instance insofar as it's sitting at 18degBTDC, in other words, any more than 18degBTDC you will only see one timing mark lining up with the pulley (the right hand one) whilst the left hand one is hovering in mid-air so to speak.

Thats exactly what I mean, the white one is sitting on 18 deg and the yellow one is hovering in midair to the left of it. It seems to jump around a little though.......

Ok well that is obviously well past 18degBTDC as you thought.
The only thing you can do easily is the CAS twisty thingy and see what range you get BTDC and ATDC.

1red5 wrote:Ok well that is obviously well past 18degBTDC as you thought.
The only thing you can do easily is the CAS twisty thingy and see what range you get BTDC and ATDC.

I will have a look at it today, the other thing that I am thinking of doing is running down to AVO and putting it on their dyno to check for any knocking etc..... I am actually happy with the way the car runs.... purrs like a kitten.
If the exhaust cam was out one tooth surely it would not run well?

My car was the NA6 with one of the cams out a tooth that JBT speaks of; it run sweet as honey and hard. No pinging, no flat spots.

I lost power when we set it right again.

Everyone said \"it'll run like sh!t being a tooth out\"... They were wrong.

Boags

Boags'MX5 wrote:My car was the NA6 with one of the cams out a tooth that JBT speaks of; it run sweet as honey and hard. No pinging, no flat spots.

I lost power when we set it right again.

Everyone said "it'll run like sh!t being a tooth out"... They were wrong.

Boags

Thats why I am thinking of getting a power run on the Dyno at AVO.
If there is no detonation or danger I will leave it like that and just keep the 98RON up to it! If it's not broke... .don't fix it!

(speaking of 98...) I run BP Ultimate, and I just heard that AVO have 5 cars in there with blown engines that were all running BP. All have blown due to fuel issues, apparently a change in the formula in the last couple of weeks?
Chris

Boags'MX5 wrote:I lost power when we set it right again.

......but it stopped running hot too IIRC.

If the exhaust cam is out by one tooth advanced it may not detract too much from performance.

If you set the ignition timing back to around 10 degrees before TDC and it runs cr@ppy, the next thing to look at is the cam timing. This means you'll have to access the front of the engine as though you were going to do a timing belt change.

It will not be necessary to remove the belt to reset the cam timing. You can remove the cam gear wheel, set it back one tooth and re-attach to the cam to correct the timing.

JBT wrote:

Boags'MX5 wrote:I lost power when we set it right again.

......but it stopped running hot too IIRC.

Minor issue.

Boags'MX5 wrote:

JBT wrote:

Boags'MX5 wrote:I lost power when we set it right again.

......but it stopped running hot too IIRC.

Minor issue.

I am not seeing any heat problems in mine. The temp guage stays rock solid in the centre no matter how hard it gets dríven.

Can't get the car into AVO until next week...... I may just go outside and play with the timing a little.....

Chris

Boags' problem was intake cam timing, yours is (possibly) exhaust cam timing - two different animals. You'll have some degradation in performance but not necessarily overheating.

Okay, so I had some time on my hands this afternoon, rechecked the timing... Yep still 28 deg!
On closer inspection I found a secondary mark (liquid paper) on the front of the pulley that lined up with the rear white mark.
I am guessing now that someone has tried to time it to 18 deg but used the wrong mark.....
I have brought the timing back now, and will play a little more with it tomorrow.
Not sure whether it liked 10 degrees all that much, it did not really feel like it wanted to rev and I had trouble winding the idle back far enough for it to sit at 850/900.
It is now sitting on 18 degrees and feels a little stronger in the top end.
Another possible cause that I found was that when I first retimed it to 18, I tightened up the CAS and rechecked to find it at 28 again.... obviously I nudged it whilst doing the bolt up. Perhaps this would explain it too....
Hopefully I will get some dyno time at AVO next week to help sort it out.

Anyway thanks for all the help and advice guys, I will let you know how it turns out.

Cheers
Chris

I have the car booked in for some Dyno time at AVO next week to double check timing and Air/fuel ratios etc........
Meanwhile I know that I need to replace an o-ring in the CAS after all the timing has been sorted, but can someone tell me where it is located?
Sorry for the newb question......
Cheers
Chris