Lex

stock BP (at least the protege and escort ones have injection setup like the firing order), so, 12, 34 IIRC.

muythaibxr

This is Ken from the msextra/msefi forums. James, Phil, and to a lesser extent, I and a few others developed the ms1/extra code (James and I are currently developing ms2/extra, and have about equal parts in that).

James and I were there when we got Jerry's engine to stop doing the "miss" thing on idle. All we really did was change the number of squirts, and the engine started running better.

I think Jerry, and Lex are on the right track. In fact, I suggested the 4 squirts thing to Jerry on the phone today, and I do the same thing on my 4 cylinder engines. (You can't run more squirts than there are spark events, so 4 is the max on a 4 cylinder). Wiring of the injectors is also essential to getting a good idle and smooth running characteristics. The ms1/extra code does not follow any particular order to its squirts... it squirts simultaneous on crank, then switches to alternating (if you want it to) once running. That means that sometimes it'll be in the proper phase for the engine to run well, and sometimes not (depends on your wiring, and number of squirts). If the engine enters alternating mode with inj1 squirting on cylinders 3 and 4 instead of 1 and 2 (which can happen), the engine might exhibit the odd characteristics (cylinders were examples... not necessarily the actual setup) where if it enters alternating mode with inj1 on 1 and 2, it'll run correctly.

This is definitely not a code issue, as the miata CAS is the most simple example of a wheel that ms1/extra can run with. The wheel decoder just counts teeth, and passes the "trigger" teeth down into the distributor code. This means that everyone who runs ms1/extra, whether wheel decoder or distributor, is basically running the same core code. If this code were broken, it would be broken for everyone, and we have not seen reports of these sorts of problems.

We also put a nice tek scope on various parts of Jerry's MS, and did not see anything wrong, or out of the ordinary.

Long story short, this is a tuning issue. Jerry and Lex are on the right track.

Ken

Lex

Thanks for the clarification Ken, I am not sure if the miata has the same injector wiring as the fwd version of the BP, but check that as well, I had to change one wire on my stock injector harness.

If you are running big injectors on a turbo setup like myself, on the MSI I can't have 4 simultaneous squirts because the PW becomes too small ... although such a setup would be ideal in conjunction with lowering the rail pressure at idle and part throttle.

Reverant

iTrader: (10)

Well, if time/wife/mood permits, I'll rewire the injector outputs in the weekend. I'm pretty sure that I have them Bank 1-> 1&3, Bank 2-> 2&4, so I 'll rewire them as Bank 1-> 1&4, Bank 2-> 2&3.

Just a question though. When I have the said problem, the ignition is also affected - ie the bouncing revs problem when I pass the ignition control to the MS. As soon as resync, it goes away. My coilpacks are wired IGN1->1&4, IGN2->2&3 (for a wasted spark setup).

Jim

cjernigan

iTrader: (13)

Sorry Lex when I said all of us have them wired that way i meant those of us that have wired up our MS systems outselves did it that way. Appears Rev didn't though, going to be interesting to see if it cures his problem. Dun dun dun

Reverant

iTrader: (10)

Well, I did wire it all by myself. You can tell that from my bloody scarred hands and rough fingertips (ain't wire stripping a bitch).

My homemade PnP box - see the 4 switches on the top left? Yellow wire for #1 & #3 (INJ1) and orange for #2 & #4 (INJ2):



Jim

cjernigan

iTrader: (13)

That box is wild, what will you have to change in order to switch your injector wiring? My little switchbox is no where near plug and play but it does allow me to switch between stock fuel, spark, idle and MS. It sucked enough, don't think I would tackle what you did.

Lex

All the has to do is swap two of the wires ... shouldn't be so bad.

FoundSoul

iTrader: (5)

No this change won't be too tough, but I don't envy the initial build .

muythaibxr

I believe the bouncing revs problem is probably because the stock ECU (as I understand it) varies the ignition timing and the pulse-width in an ocscillating fashion with the result of a stable idle... Take control of either fuel or spark from the stock ECU, and I'd expect weird things to start happening.

Ken

Lex

Yes, this regular timed oscillation of the stock ECU is what results in the stable leaner stock idle as I noted above.

Reverant

iTrader: (10)

Even when the MS controls both the injection and the ignition? (but not the idle valve). The bouncing revs only happen when I have the "misfire" problem, the idle is stock-perfect every other time.

Jim

muythaibxr

I'm no miata expert, but on most newer cars, if you leave the stock ecu in control of too much, you'll get weird results... I know that neons do the same thing because the stock ecu oscillates the ignition timing, AFR and idle valve with the result of a stable idle.

Ken

Lex

The MS should really have an "idle" mode where these variables can be oscillated/varied only when the car is idling because otherwise most cars won't idle near stoich.

Reverant

iTrader: (10)

I just tried the rewiring. Previously:

Bank 1 -> #1 & #3
Bank 2 -> #2 & #4

Currently:

Bank 1 -> #1 & #4
Bank 2 -> #2 & #3

Results: I first warmed up the car with the stock ECU and then switched to MS (fuel only) once the car was fully warmed up (coolant and IAT stabilised). At first it seemed like it worked. I restarted 6, maybe 7 times and it was smooth, around 14.0:1-14.3 AFR. I restarted several times again, and at some point, yes, the problem appeared again. It didnt matter how pich rich I made it (up to 12:1 at some point), it would still do the "slight misfire" thingy.

At this point, I'm just lost and dissapointed. I have a Hydra ECU which I bought on the cheap side to handle the idle and the VVT/VTCS and I'm afraid that it's going to replace the little squirt.

Jim

richyvrlimited

iTrader: (1)

Be gutted to lose your input Jim :(

Were you not tempted by MSII?

Someon's going to end up with a very clean MS install!

Reverant

iTrader: (10)

I'm not going to sell it, I paid like $600 for everything, start to finish, I can still get lots of things in my Innovate Datalog chain from the MS (coolant temp, intake air temp, knock, shift lights, baro readout, fuel pressure) plus a backup ECU "just in case". No one in their right mind would fork over $300 for a system that I claim to have problems.

The MS-II, I don't know. I still love the system for what it is and for how smooth it behaves overally - there were times that I would forgot than I don't use the stock ECU,p articularly in track days. It's just sad that a little problem like this can drive you nuts.

Jim

Lex

Just to add ... I advanced my idle timing by 3 degrees today and the idle was so smooth I could not feel any vibrations with solid motor mounts.

timk

Have you got (or is it possible to get) a video of it?

Lex

A video of the car idling ?