So I’m doing a routine service, and I thought I’d check the timing and adjust if necessary.
I find it’s 14 before TDC, or maybe even a bit more.
I know this is the setting that is supposed to be the one to go for on a normally aspirated car, but since mine has a turbo, I thought this seems a bit too advanced, and maybe I’d pull it back a bit.
But I find that the CAS won’t move any further “backwards” than its present setting! If I wanted to set it back to 10 or even less (as typical turbo installations call for) it wouldn’t be possible.
How can this be? Does it mean the CAS is wrongly installed? Or could it be the ECU is bad? Any other explanations?
Do give me your thoughts!
Dave
(1991 1.6 import with Greddy turbo, intercooler, fifth injector and MF2 conroller)
The CAS only goes one way so you can’t get it wrong. Could be the cam timing is one tooth out, although I’d expect the engine to be really flat if that was the case. Maybe the turbo is masking it?
It’s a mechanical check, you need to remove the cam cover & upper timing belt cover, set the crank to TDC on the marks on the timing belt cover then check the 2 marks on the cam pulleys are aligned with the marks on the back plate (about 4:30 on the intake cam & 7:30 on the exhaust cam. I & E).
There’s an article here about changing the cam cover gasket http://www.mx5oc.co.uk/forum/forums/t/158.aspx
It’s always worth changing the gasket if you don’t know how long the one on the car has been fitted, they tend to harden with age. MX5 parts can supply them but make sure it’s a genuine mazda part, there used to be problems with the fit of some after market gaskets.
Re the avatar, just select the image that you want using the browse feature, it will be automatically resized [100 x 100 is the max size]
All posts have the tags on the end, it enables you to highlight things of a technical nature, not to be confused with the sig. option
HTH
One remaining possibility is that the problem is with the crank pulley where you read the timing: The pulley’s actually made in 2 parts with a rubber antivibration damper sandwiched between the inner and outer parts. If the bonding of the rubber fails, it’s possible for the outer pulley to turn relative to the inner, and that means that the ignition timing notch will be in the wrong position.
You can test that by replacing the pulley and the cover which has the timing scale while the engine’s in the TDC position shown in your photo. If the timing notch on the pulley doesn’t line up with the scale on the cover, the pulley’s probably the culprit.
(Depending on what year of car you have, the pulley might have one notch at 10°BTDC or two notches - one at TDC and another at 10°BTDC)
Having failed to find anything wrong in accordance with the various suggestions here, I decided to consider the possibility that the problem was not real – so I went back to the CAS adjustment to confirm that I truly couldn’t move the timing back any further. And guess what? – at first it did seem as if I’d reached the end of possible movement, but then I slackened the screw off a bit more and applied some serious effort and hey presto! the CAS moved back further.
So – it seems I dont have a problem after all. Sorry for causing all that brain work unnecessarily, but thanks for the input. It was an interesting exercise from my point of view.
Just to hijack this thread. If looking at the lower pulley with it set at TDC, where on the accessory pulley does the timing mark appear? (1 o’clock, 2 o’clock etc.?)
I can’t seem to find mine and I think I have set the timing to a dink in the pulley rather than the correct mark
When the bottom timing-belt pulley is set with the TDC notch aligned (as in the 2nd photo of my 28/2/09 above), the timing mark on the crankshaft pulley is about 1 o’clock (speaking from memory) and should align with the zero degees calibration (marked “T” I think, again from memory) on the timing scale. On my car, the mark on the crankshaft pulley is a very tiny knick, not even worthy of being called a notch – I highlighted it with a dab of liquid paper so I could be sure I was seeing the right mark when checking timing with strobe.
My mark is just to the right (ie clockwise) of the T mark on the timing cover when the crank is at TDC. (Just checked) So I guess I marked it right after all (there are no other notches near the mark I painted with correction fluid.
