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*^&^%!!! Cheap Chinese timing light was the culprit!
Borrowed another timing light to find the timing was way off- advanced. Reset the timing, synced it to the DIYPNP. MAP went up, idle smoothened out after some VEAL. Some video of it below (ignore the hammering in the background LOL.) The engine sounds much smoother- and sounds like it is sucking in a lot of air! Still a little lumpy though. Will open the cam cover tomorrow to verify the lobe positions. A fantastic thing I did not expect was- since base MAP went up, the AC compressor engagement hardly fazes it anymore! I dialled the PID WAAAAAAAAAY down. Got this: P30 I 15 D400 Attachment 186973 The increased MAP values meant that my breakpoints were all wrong. Spark advance is all over the place. Gotta rescale the bin values to reflect the increased MAP. |
Most uneventful videos evar.
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If I'm not misreading Maruha's Engrish reply to you they want both cams set up at 110 degrees at max lift (ie the "center" of the lobe). Worst case you can set them to the factory specs. The thing about timing aftermarket cams/sprockets is you just can't trust that the cam machining or the pulley machining/marking is accurate. I've seen both be off personally.
If this were my engine I'd clarify what exact spec Maruha wants to see at max lift on each cam. Then I'd put a degree wheel on the crank and a dial indicator on the lifter and set it up at max lift so you know exactly where the cams are in relation to the crank. If you don't know how to set up cams this way or lack the tools I'd find someone who does. Anything else is just guessing... |
Thanks bill! I do plan to do that- I just opened it up and did my crude measurements as part of my (forced) education. I actually did understand it better after the exercise. I do know that the protractor from the bookstore taped to the cam wheel is not the correct tool for the job :laugh: But as a learning exercise, and as a sanity check that the overlap is not waay off, I'd say the time was well spent. ;)
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Originally Posted by Greg G
(Post 775475)
Thanks bill! I do plan to do that- I just opened it up and did my crude measurements as part of my (forced) education. I actually did understand it better after the exercise. I do know that the protractor from the bookstore taped to the cam wheel is not the correct tool for the job :laugh: But as a learning exercise, and as a sanity check that the overlap is not waay off, I'd say the time was well spent. ;)
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Noob question- if I adjust the intake cam pulley, I have to redo my timing syc again right? I retarded the intake cam 10 crank degrees to see what a little less overlap would do. Idle seems subjectively more sedate- but then I realized I may have retarded ignition timing 10 degrees across the board by doing so. I did, didn't I? :facepalm:
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Originally Posted by Greg G
(Post 776722)
Noob question- if I adjust the intake cam pulley, I have to redo my timing syc again right? I retarded the intake cam 10 crank degrees to see what a little less overlap would do. Idle seems subjectively more sedate- but then I realized I may have retarded ignition timing 10 degrees across the board by doing so. I did, didn't I? :facepalm:
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These are the last 2 logs from the car idling with no load, AC engagement, and AC plus headlights (marked with red lines).
PID settings P 20 I 25 D3000; min rpm 900 max RPM 2200- much tamer than I had before the cam install. This is with the cam wheels in stock orientation: Attachment 186939 I believe the oscillating MAP values are due to the large overlap. This is with the intake cam retarded 10 crank degrees, to reduce the overlap. Note that I forgot to re sync the timing, so the spark advance is actually -10 across the board from what is reported. In any case, the MAP oscillations have been reduced (lower min/max values, sorry forgot to fix the range). The idle seems subjectively better/smoother. Attachment 186940 |
Doing some more reading... Would adjusting the map sampling angle improve the jitter on the map signal?
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Possibly. What're the options?
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Quick update- advancing the exhaust cam 4 degrees, reducing the overlap has significantly reduced the oscillations. Idle is much more behaved at no-load idle. Turning on the AC seems to bring out some oscillations.
https://www.miataturbo.net/attachmen...ine=1321699538 |
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