what miata?

quick question guys.... i just installed ms1 on a friends 99 with a cas... i wired it up just as it saids in one of the other treads.. when i try to start the car when i first hit the starter its shows rpm sig on the ms main dash for a split sec then goes to zero. the sounds as it wants to start for that split sec that it reads a rpm sig... i double check everything on the wiring and the white wire is going to pin 24 and the yellow going to 25. got constant 12 volt... same 12 thats powering the ms.. and a good ground. the only thing i have tried another cas

any suggestions?

patsmx5

iTrader: (16)

I dunno but your grammar sucks as always. I understood about 1/3 of that, but I'm not rereading it.

Braineack

iTrader: (62)

im just going to guess its a wiring issue.

what miata?

here so you could understand a little....

The MS (megasquirt) is not reading rpm. It reads rpm for 1 second then shows 0 rpm and the car will not start. I am guessing it wont start because of no rpm input. The car is a 99 with a 96 CAS installed. I wired the CAS as illustrated in a sticky tread. I am trying to find out why it will not hold the rpm signal. because when it picks up the rpm signal for the split second the car seems like its about to start.

any info would be helpful

what miata?

they are 4 wires on the CAS ... what wire prob would you think i would have?
my 12v is the same power that im powering the MS
white CKP going to pin 24
yellow CMP going to pin 25
black ground

if there is anything miss im all ears

thanks

patsmx5

iTrader: (16)

Good. If you can type like that I'll help. Try removing the sensor and spinning it with your hand. See if you get a reading that way. Also, post up your ignition settings that you are currently running. Sometimes a weak or dying CAS will work on a stock ECU but not on a MS. Also a datalog of the described behavior would probably help. Post a datalog and msq. you're running.

what miata?

Well i just tried turning it with my hand and same thing. It read rpm for a sec then nothing. Ill log it but i dont think your going to see anything by lookin at that. Also the IGN settings are the same as DIY. I just loaded my msq file from my car to this one and tried to start it. I could send you my msq file if needed

Joe Perez

iTrader: (8)

The fact that it shows an RPM reading initially, but then lapses to zero for continued cranking, does strongly suggest that the MS is not correctly reading the CAS's output, most likely the second (CMP) trigger, which is the one typically connected to pin 25 of the Megasquirt, and internally wired from the IAC1A pad (which is what pin 25 connects to) to pin 11 of the processor (or JS8, which connects to pin 11) through a 1k resistor, and also from IAC1A to the +5 supply in the proto area through a 470 ohm resistor, with a 0.1uf cap additionally placed between pin 11 of the processor (or JS8) and ground.

Oh, just as an FYI- at this stage in the build, go ahead and remove all four spark plugs and disconnect the two plugs from the ignition coils- the three pin primary plugs, not the spark plug wires. This will make the engine easier to turn on the starter with less battery drain.

what miata?

you know i thought the same thing. So i stopped being lazy and pulled my CAS off my car and tried it same deal. Then tried his MS in my car and it worked. Also tried his CAS in my car and it worked. So something is going on with my wiring as earlier posted. The only thing i could think of is the shield wire going to pin 24. Its not shielded for about 1 1/2 to 2ft.. maybe im getting interference. Im heading right now to radioshack to pick up some shield and let u know how it goes...

thanks for the replys

xitsam

have you a spark, with your current spark plugs?
i ask this, because i had the same problem on my 93 miata...

i changed everything...

The yellow relais under the dash, the other in the main fuse box, the ignior, the cas.. the coil....
after 1 full day of searching i changed the BRAND-NEW Spark-Plugs as well.. and see.. the car starts on first turn.

Braineack

iTrader: (62)

doesn't need to be shielded...that's not the issue.

Braineack

iTrader: (62)

MS won't spark without the RPM signal. Unrelated.

Joe Perez

iTrader: (8)

In the OEM configuration, both CKP and CMP are unshielded over their entire length. That stupid piece of shielded cable that DIY includes in the kit is for cars using a VR sensor and a crank wheel (like mine.)

what miata?

Ok problem solved i messed up on the CMP to pin 25. I had it on 26.. my falt thanks for the help.