4g63 (4/2 CAS) Anyone Successfully Running True COP

[wes kiser]

I PM'd James and he suggested I asked in forum.

I have had a few friends attempt to use this decoder, and all switched to the yoshifab 24/1 disk before making the car run. I am currently helping someone who previously had the car running fine wasted spark, but after switching to COP it will not run. I had them put a timing light on it where they could see the cam gears, and it is most definitely 360 degrees out.

I have confirmed a tooth log looks "textbook" for the pattern, and their hardware/software matches documentation. Is there ANYONE who is successfully running this in a non wasted application?

I fully understand (and recommend) the 24 tooth disk is a much better idea. I ask this more specifically to help the developers if there is a problem with this specific mode.

[Peter Florance]

I assume it could be bench tested. I'd do it if I was sure what the decoder phasing should be over 720 degrees.

[prof315]

I PM'd James and he suggested I asked in forum.

I have had a few friends attempt to use this decoder, and all switched to the yoshifab 24/1 disk before making the car run. I am currently helping someone who previously had the car running fine wasted spark, but after switching to COP it will not run. I had them put a timing light on it where they could see the cam gears, and it is most definitely 360 degrees out.

I have confirmed a tooth log looks "textbook" for the pattern, and their hardware/software matches documentation. Is there ANYONE who is successfully running this in a non wasted application?

I fully understand (and recommend) the 24 tooth disk is a much better idea. I ask this more specifically to help the developers if there is a problem with this specific mode.

I've got an MS2 customer running COP w/4g63 successfully but I also have an MS3 customer with the same phasing issue i.e. car runs fine with wasted spark or wasted COP but not in COP mode

[jsmcortina]

Is it possible to insert the CAS 180 deg out?
I had a quick look at the Miata CAS I have, but I've already removed the drive dog (and mislaid it.)

James

[wes kiser]

James, that is what I asked. This particular one is on a miata, and the owner is telling me it is not possible to bolt it on 180 degrees out. I have no idea if this is true or not.

I know on the actual mitsubishi 4g63, it can be flopped 180, although people don't like to do it.

[prof315]

Is it possible to insert the CAS 180 deg out?
I had a quick look at the Miata CAS I have, but I've already removed the drive dog (and mislaid it.)

James

No I don't believe it's possible to install the CAS 180 out on a Miata. There is a slight offset on the drive dog much like a 90's Honda distributor.

Jeff

[Team DNR]

As the owner of the recalcitrant MX5 under discussion, I can verify that you cannot install the stock (unmodified) CAS 180 out. However there is a mechanical fix. Per Jeff's suggestion, I believe that you can remove the drive gear from the shaft (pin connection), rotate that 180 part and reinstall on the shaft. The offset in the drive dog and the cam only go together one way but this is a workaround to fix the phasing problem that I experienced. I did not do this myself, I got the 24/1 trigger wheel and installed it.

With the new trigger wheel installed, I went into TS, set generic wheel options etc and using timing light (coils disconnected) to set trigger advance. Over the phone, Wes had suggested 400 as a starting point and dang if that wasn't a real close in his guesstimate of what it needed. At 400 it fired, at 390 it runs!

This doesn't solve the issue regarding a possible glitch in the MS, but I am pretty certain that using the stock 4G63 CAS with the MS3X set to sequential COP produced a spark that was out of phase 180 cam degrees.

Thanks to Wes and Jeff for their help ! Since the resolution of the base question is way over my head, I'll leave it you gentleman to resolve at your leisure.

Henry

[jsmcortina]

Changing the phase in the code is trivial to achieve, IF (and only if!!) it is correct for the majority of engines.

James

[juansh2385]

I have run ms2 4g63 cas with the decoder as is but it was on a eclipse not a miata. It has worked for me with mitsubishi cas and with the new set up that uses crank/cam for the same pattern

[prof315]

Changing the phase in the code is trivial to achieve, IF (and only if!!) it is correct for the majority of engines.

James

Well as I posted earlier in the thread, I just upgraded an MS2 from wasted to COP and it worked fine. I have a local MS3 customer with a Miata and we have been thinking of going COP with him. I''l see if we can use him as a testbed.

[jsmcortina]

Well as I posted earlier in the thread, I just upgraded an MS2 from wasted to COP and it worked fine. I have a local MS3 customer with a Miata and we have been thinking of going COP with him. I''l see if we can use him as a testbed.

Please do and keep us posted.

James

[wes kiser]

The person I was helping swapped to a 24/1 disk and we tuned the car yesterday. I will see If I can get him to swap back after this weekends race for "R&D" purposes.

[wes kiser]

James, would it be feasible to have two "options" for the 4/2 CAS? Perhaps call one standard, and one inverted?

[prof315]

James, would it be feasible to have two "options" for the 4/2 CAS? Perhaps call one standard, and one inverted?

We are going to need 2 options for the 4g63(Miata) CAS. But call them 1.6L and 1.8L because I know why the phasing is 360*out. The car Wes was working on (I did some minor repair work to the mainboard and have been helping the customer via phone and email) is a 1.6L, while the car I converted successfully to COP with MS2/extra was a 1.8L. The 1.6L CAS is driven by the intake cam and the 1.8L CAS is driven by the exhaust cam so of course the phasing is different. I will still try COP on my local customer but he's got a 1.6L so I am sure the phasing is wrong.

Jeff

[Peter Florance]

James, would it be feasible to have two "options" for the 4/2 CAS? Perhaps call one standard, and one inverted?

We are going to need 2 options for the 4g63(Miata) CAS. But call them 1.6L and 1.8L because I know why the phasing is 360*out. The car Wes was working on (I did some minor repair work to the mainboard and have been helping the customer via phone and email) is a 1.6L, while the car I converted successfully to COP with MS2/extra was a 1.8L. The 1.6L CAS is driven by the intake cam and the 1.8L CAS is driven by the exhaust cam so of course the phasing is different. I will still try COP on my local customer but he's got a 1.6L so I am sure the phasing is wrong.

Jeff

I think Mazda didn't care because stock they're wasted spark.

[prof315]

I agree Peter, although the 1.8L engines are factory sequential fueling. And to further confirm things, we had already switched to sequential fueling on my local 1.6L Miata customer's car and ever since we did it starts harder than it did with untimed batch fire. I just switched fueling back to batch and it starts easily again!

Jeff

[Peter Florance]

I agree Peter, although the 1.8L engines are factory sequential fueling. And to further confirm things, we had already switched to sequential fueling on my local 1.6L Miata customer's car and ever since we did it starts harder than it did with untimed batch fire. I just switched fueling back to batch and it starts easily again!

Jeff

May not be related, but I never could get Marelli mode working full sequential. I thought I was 360 out, but it wouldn't work when I clocked output by 360
Wasted mode works fine.

[prof315]

So just to remove any ambiguities here I did a little research concerning 89-97 Miatas using a 4g63 style CAS and here's what I got;

89-93 1.6L EXCEPT California emissions : Batch fire fueling and waste spark CAS is on the intake cam
89-93 1.6L WITH California emissions : Sequential fueling and waste spark CAS is on the intake cam
94-97 1.8L ALL : Sequential fueling and waste spark CAS is on the exhaust cam

[Peter Florance]

Ahh...

[prof315]

Well as I posted earlier in the thread, I just upgraded an MS2 from wasted to COP and it worked fine. I have a local MS3 customer with a Miata and we have been thinking of going COP with him. I''l see if we can use him as a testbed.

Please do and keep us posted.

James

Ok I definitely believe we need 2 4g63(Miata) versions. I have tried COP on my local customer's 1.6L Miata and phasing is 360*out i.e. it won't run in COP mode but runs fine in wasted COP. We went so far as to try 2 different CAS's with no change and then removed the drive dog on one of them, reinstalled it 180* out and reinstalled the CAS. That DOES work with COP.

To summarize; Even though the 89-97 Miatas all use the same CAS, 2 versions of 4g63 code are needed for full sequential operation. The current 4g63 works perfectly on 94-97 1.8L Miata's. The CAS on these cars is driven by the exhaust camshaft. The current code will NOT run sequential on 89-93 Miatas which came with a 1.6L engine. The CAS is driven by the intake camshaft on them and the phasing is 360* off.