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-   -   Timing question. (https://www.miataturbo.net/general-miata-chat-9/timing-question-76403/)

Wastemore 12-04-2013 01:19 PM

Timing question.
 
2 Attachment(s)
'99 10AE

Car's running like garbage-
Timing marks on the cover show 10BTC and 5 hash marks to the right.. no designated TDC on the cover, but it's assumed the 5th mark would be TDC.

I have two engraved marks on my pulley/HB. How in the world does the left engraved mark on the pulley read TDC and the right engraved mark completely off the grid? Yes, I jumped 10/gnd with no load.

Mine looks like this running.

Oscar 12-04-2013 01:26 PM

Did the outer ring shift? Have you found true TDC with the dipstick down the no.1 plug hole? Do the marks line up then?

18psi 12-04-2013 01:41 PM

why are you jumping 10/gnd on a NB to check timing? that's for NA's

did you recently do the belt? its way way off
unless the tensioner is loose and it jumped like crazy

Leafy 12-04-2013 02:08 PM


Originally Posted by 18psi (Post 1079546)
why are you jumping 10/gnd on a NB to check timing? that's for NA's

did you recently do the belt? its way way off
unless the tensioner is loose and it jumped like crazy

Whats the base timing check mode for NBs? Or do you just kind watch it move around in the 17* neighborhood at idle?

Wastemore 12-04-2013 04:00 PM


why are you jumping 10/gnd on a NB to check timing? that's for NA's
? The internet mislead me.... again.


did you recently do the belt? its way way off
unless the tensioner is loose and it jumped like crazy
Yes, belt/WP two months ago. Pulled the upper cover and everything seems to be in order.. Belts tight.

I'm wondering if the pulley slipped.

pdexta 12-04-2013 04:21 PM


Originally Posted by Oscar (Post 1079538)
Did the outer ring shift? Have you found true TDC with the dipstick down the no.1 plug hole? Do the marks line up then?


Originally Posted by Wastemore (Post 1079602)
I'm wondering if the pulley slipped.

I would doubt it, but you can do what Oscar said to verify.

I would bet the exhaust cam is off a tooth (which would be about 10 degrees) and the cam sensor is throwing the timing off. When you check the cam gears it's tough to tell visually if they're correct, use your finger to feel if they're lined up with the "I" & "E" and that will tell you for sure.

18psi 12-04-2013 04:48 PM

19 teeth between the gears if I remember correctly

williams805 12-04-2013 06:25 PM


Originally Posted by pdexta (Post 1079611)
I would doubt it, but you can do what Oscar said to verify.

I would bet the exhaust cam is off a tooth (which would be about 10 degrees) and the cam sensor is throwing the timing off. When you check the cam gears it's tough to tell visually if they're correct, use your finger to feel if they're lined up with the "I" & "E" and that will tell you for sure.

He said '99 10AE. Cam sensor is looking at intake gear.

pdexta 12-04-2013 06:34 PM


Originally Posted by williams805 (Post 1079661)
He said '99 10AE. Cam sensor is looking at intake gear.

You're right, not sure why I was thinking it was exhaust side. That actually makes more sense as the crank pulls directly on the exhaust and any slack would likely be on the intake side.

Also, as I thought about the gear sizes, I'm changing my bet to it being off by 2 teeth on the intake side.

Wastemore 12-04-2013 07:39 PM

Thanks for the responses.

I pulled the upper cover and the I/E line up perfectly, so the belt didn't slip. HB/Pulley slip?

pdexta 12-04-2013 07:56 PM

Did you check top dead center with the dipstick in cylinder 1 against the timing cover (remove spark plug in front cylinder, stick dipstick in hole, turn motor over until dipstick is as high as it goes, check to see if timing marks line up with top dead center)? The pin in the crank pulley pretty much guarantees that it does not slip without completely destroying your crank... unless you forgot to put that pin in when you put the pulley back on.

Leafy 12-04-2013 07:57 PM


Originally Posted by pdexta (Post 1079697)
Did you check top dead center with the dipstick in cylinder 1 against the timing cover? The pin in the crank pulley pretty much guarantees that it does not slip without completely destroying your crank... unless you forgot to put that pin in when you put the pulley back on.

The outer ring and the inner ring on the crank pulley are only bonded together with rubber, and its been known to fail.

Wastemore 12-04-2013 08:54 PM


Did you check top dead center with the dipstick in cylinder 1 against the timing cover (remove spark plug in front cylinder, stick dipstick in hole, turn motor over until dipstick is as high as it goes, check to see if timing marks line up with top dead center)? The pin in the crank pulley pretty much guarantees that it does not slip without completely destroying your crank... unless you forgot to put that pin in when you put the pulley back on.

I didn't and here's why. unless my thinking is skewed( and it may be, so correct me, please), it would be next to impossible for the belt to slip and have the cam gears (I/E) still line up to the hash marks perfectly. If the belt slips one, or both of those cam gears would be off.
I'm pretty certain the woodruff key hasn't sheered..

mellowout 12-05-2013 12:50 PM


Originally Posted by Wastemore (Post 1079714)
I didn't and here's why. unless my thinking is skewed( and it may be, so correct me, please), it would be next to impossible for the belt to slip and have the cam gears (I/E) still line up to the hash marks perfectly. If the belt slips one, or both of those cam gears would be off.
I'm pretty certain the woodruff key hasn't sheered..

The crank could slip a tooth and the cam gears would still look aligned.

Finding TDC using the dipstick and checking the alignment of the cam gears and crank gear should tell you whats wrong.

Seems to me like it could be one of these few things (assuming timing belt marks on cam are correct)
  1. Crank pulley outer ring slipped
  2. Woodruff key sheared/mangled (I've had a similar problem)
  3. Crank slipped a tooth

18psi 12-05-2013 01:09 PM

Bottom line is: the BP is one of the easiest engines ever to set timing on. So pull the front apart, and set it right like you sould have from the start.

To me it sounds like you're being lazy, pulled off the vc and glanced at the marks, and say its all good. If not then my bad.

Godless Commie 12-06-2013 06:11 AM

You have to jumper GND and TEN on (at least some) NBs.
My NB is OBDI, for example.

richyvrlimited 12-06-2013 06:31 AM


Originally Posted by 18psi (Post 1079546)
why are you jumping 10/gnd on a NB to check timing? that's for NA's

It's still valid for NB's. You have to lock the ECU timing to a static amount, otherwise the ECU will be varying it to maintain idle speed/quality.

You need to jumper TEN and GND to set the idle speed correctly and verify base timing on my NBB/NB2

18psi 12-06-2013 09:04 AM

Maybe you're right, I've always set timing with MS installed and not stock ecu.

DNMakinson 12-06-2013 11:09 AM

Yes, timing is wrong. Yes "TEN" (which stands for something and not the number "10") to ground. One mark should be on 10*BDC and one should be on 0*


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