NA 1.6 "wandering" timing issue..... seeking some insights..

Uncle Arthur · Postby **Uncle Arthur** » Fri Mar 09, 2012 9:55 pm

OK - I have an odd problem with the timing on the MX5 - the timing mark is wandering around, while the timing itself doesn't appear to be changing (based on how the engine is running)....

The timing was done at MX5 Plus a while back, with a replacement pulley. The timing hasn't changed. The marks on the CAS remain in the same place, yet the timing marks on the pulley wheel are shifting around. They now appear to be more than 90 degrees anti clockwise off the TDC mark - which puts me at in the order of 100 degrees AFTER TDC!!!!!

Now you would expect the car not to even start with that level of timing - so can ANYONE suggest what it could be (remembering this is a long nose crank engine), and that it seems unlikely that the replacement AND the original pulley wheel could be slipping - or is it?!?!?!?

toppertee · Postby **toppertee** » Fri Mar 09, 2012 11:00 pm

Uncle Arthur wrote:OK - I have an odd problem with the timing on the MX5 - the timing mark is wandering around, while the timing itself doesn't appear to be changing (based on how the engine is running)....

The timing was done at MX5 Plus a while back, with a replacement pulley. The timing hasn't changed. The marks on the CAS remain in the same place, yet the timing marks on the pulley wheel are shifting around. They now appear to be more than 90 degrees anti clockwise off the TDC mark - which puts me at in the order of 100 degrees AFTER TDC!!!!!

Now you would expect the car not to even start with that level of timing - so can ANYONE suggest what it could be (remembering this is a long nose crank engine), and that it seems unlikely that the replacement AND the original pulley wheel could be slipping - or is it?!?!?!?

Check your timing light gun. grounding could be a issue.

Postby **NitroDann** » Fri Mar 09, 2012 11:37 pm

Have you used the right cylinder for the timing?

Check if the pulley slipped? Do you need a quick explanation of how to do this easy?

Dann

Uncle Arthur · Postby **Uncle Arthur** » Sat Mar 10, 2012 10:01 pm

Can't be sure that it's the timing light, as the timing is reading different EACH time I check it....

Am using Cyl 1 for timing.

Would love an explanation of how to check for pulley slip.

Postby **NitroDann** » Sat Mar 10, 2012 10:21 pm

Take cam cover and top timing cover off.

Remove plug number 1.

Insert a rod into cylinder number 1.

Turn engine until rod indicated top dead centre, check alignment of cam gears on rear timing plate.

Look at pulley, is it aiming at the 'T' on the lower timing cover..?

Dann

Uncle Arthur · Postby **Uncle Arthur** » Sun Mar 11, 2012 5:10 pm

Thanx Dann - that was the simple explanation I was "almost" expecting - I was hoping to get away without having to pull the timing cover, but well - the proper solution is the proper solution. By the way - so you know in future - I'm no noobie when it comes to this car....

I've had more grease under my fingernails than baked dinners. I'm typing with grease under my nails now.....

Soooooo - having now checked the timing, it appears the factory mark has miraculously found its way back to being the right mark. When I checked the timing the other day it was reading at 0degBTDC. Checked it again today having confirmed as per your method Dann, and it seems that the timing mark was reading correct. I also took the opportunity to change the spark plugs - they were looking a bit on the "worn" side when I pulled all 4.

I have now set it back to 10deg BTCD which is my usual base timing, and the car feels good. Before anyone says "but it will run better at 14", yes - I know, IF I was running atmo opposed to boost.....so 10 it is.....

Temps are good, no apparent misfires, and plenty of zing for my jinbai ittai. Here's hoping it stays that way.

Postby **NitroDann** » Mon Mar 12, 2012 12:31 am

Great.

Glad it all worked out. BTW... do you have a garage thread?

Dann

Uncle Arthur · Postby **Uncle Arthur** » Mon Mar 12, 2012 8:26 am

I won't know if it has worked out as such until I check the timing again after another week of driving

As for a garage thread - not as such.

I do have a cardomain page - that I haven't looked at in ages. It would take me a looooong time to capture in one garage thread page the 11 years of modifications I've done to the 5........

Postby **NitroDann** » Mon Mar 12, 2012 10:10 am

Well I for one am interested.

Dann

NMX516 · Postby **NMX516** » Mon Mar 12, 2012 7:37 pm

UA what ECU are you running? It could be a problem with the base timing set in the ECU... I had that problem with the ET, and just had to go back to basics and set it up again.

Uncle Arthur · Postby **Uncle Arthur** » Mon Mar 12, 2012 8:37 pm

Trust me - if I had an ACTUAL timing issue as far out as it has seemed to be, the car wouldn't even start, let alone purr like a goddam kitten.....

For the record, I'm running the stock ECU + Greddy Emanage Blue (piggyback).

Base timing has always been set at the CAS, at 10D BTDC, where it "should" be back to now.

I'll check it again after a week of driving, but it certainly seems to be behaving itself again.