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-   -   No spark on start up with VVT swap (https://www.miataturbo.net/megasquirt-18/no-spark-start-up-vvt-swap-83007/)

shuiend 02-23-2015 08:21 AM


Originally Posted by Ryan_G (Post 1208606)
Its definitely mechanical timing. Here are some pictures to illustrate the problem. All of the exterior markings line up perfectly and I was able to verify that cylinder one was at TDC when it was suppose to be.

Well that is not right.....the intake cam should be pointing to the 9 O'clock postion and not the 12 O'clock position. How the fuck did that happen. If I remember correctly there is a guide pin and the cam gear can really only slide on one way. I need to take it off and figure out the problem.

With VVT the cam gear should only be able to go on one way. I am not sure how you fucked that shit up to get it off like that. One 90-00 motors there are 3 holes that the guide pin could go in, so those make more sense of screwing off up the intake cam gear.

Ryan_G 02-23-2015 09:25 AM

I don't know how it is on wrong to be honest. When I put it on the first time it was clear that it could only go on one way and I am pretty sure I got it on the guide pin. You would think if it wasn't on the guide pin that it would stick out a little bit but it is as far back as possible without these bolts on the back of the gear making contact with the head. I wasn't able to take it off on Sunday to check because I had some family stuff going on.

There was one bit that might need fixing that I have been thinking about. When we were taking the motor apart originally, Miata2fast was curious how the vvt mechanism worked so he decided to open it up. There was a bit of an oh shit moment but he put it back together and was pretty sure it was correct but I am not thinking I might need to reopen it and take a look. I'll have to analyze a parts diagram to make sure I get it back together correctly. Not sure if the cam could advance itself this much if it was assembled incorrectly but I won't know until I get it off.

shuiend 02-23-2015 09:34 AM


Originally Posted by Ryan_G (Post 1208787)
I don't know how it is on wrong to be honest. When I put it on the first time it was clear that it could only go on one way and I am pretty sure I got it on the guide pin. You would think if it wasn't on the guide pin that it would stick out a little bit but it is as far back as possible without these bolts on the back of the gear making contact with the head. I wasn't able to take it off on Sunday to check because I had some family stuff going on.

There was one bit that might need fixing that I have been thinking about. When we were taking the motor apart originally, Miata2fast was curious how the vvt mechanism worked so he decided to open it up. There was a bit of an oh shit moment but he put it back together and was pretty sure it was correct but I am not thinking I might need to reopen it and take a look. I'll have to analyze a parts diagram to make sure I get it back together correctly. Not sure if the cam could advance itself this much if it was assembled incorrectly but I won't know until I get it off.

I don't think Mazda makes a parts diagram for the inside of the VVT gear thing. You can only buy it fully assembled from Mazda. If you search on mt.net there are a few threads from people who have taken them apart and put them back together. At least we now know why it is not working.

Ryan_G 02-23-2015 09:48 AM

The thread 18psi linked in my build thread has pictures of when he took his apart. I'll probably use that for reference.

Davezorz 02-23-2015 03:25 PM

I took one apart and documented for posterity:

https://www.miataturbo.net/engine-pe...or-pics-80407/

Is the gear locked? you should not be able to spin the cam independent of the gear/belt

sixshooter 02-23-2015 03:50 PM

Hmm. 4 lobes inside.
It could have gone together 90 degrees out? Stranger things have happened.

Ryan_G 02-23-2015 04:14 PM

If it was put back together 90* off I would be kind of impressed seeing as how the single large lobe also has a significantly larger space to fit in. No one knows but Troy! I do believe the gear is locked.

sixshooter 02-23-2015 10:36 PM

All I can do is guess. . I'm trying.

stefanst 02-25-2015 08:59 PM

Not sure anymore, but didn't you at one point say there's no spark? Verified with a timing gun?
This would not be caused by the Camshaft- no matter how far off it may be.

Ryan_G 02-25-2015 10:10 PM

Spark was verified in test mode. Timing light was not picking it up but I saw it with my eyes.

Ryan_G 02-28-2015 03:59 PM

IT'S ALIVE!!!!! The physical cam alignment was indeed the problem. However, It appears as if something else is going on. We used the little dot mark to line it up as it was 90 degrees off of the slot mark on the cam gear. Every VVT timing picture we have looked at show that the markings I had originally used should have been correct. The VVT actuator can only bolt to the gear one way due to bolt spacing and the cam has to be seated on the peg due to spacing. I am not sure why mine runs perfectly while using the other gear mark.

sixshooter 02-28-2015 07:24 PM

You are doing it wrong.

curly 02-28-2015 07:33 PM

From his build thread, he installed the cam gear ~90* off, which sounds right according to his issues.

sixshooter 02-28-2015 09:08 PM


Originally Posted by curly (Post 1210922)
From his build thread, he installed the cam gear ~90* off, which sounds right according to his issues.

I know. I was kidding with him. I was there and the one who found it, haha.


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