When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi, I need help. The car is a 2004 mazdaspeed miata.
During winter, I replaced the timing belt and put a new turbo. I started the car with the factory ECU and it was running... poorly but it was running. I built an MS3X using a megasquirt v3.0 I had with the car when bought 2 years prior.
I followed the instructions on trubokitty.com for the assembly. The only thing I didn't do was to solder a 100k resistor on the R52, instead I used the trim pot and turned it all the way counterclockwise. During assembly, I printed the component specification from this manual http://www.megamanual.com/ms2/V3assemble.htm Its for the ms2 but I assumed it was the same components. I desoldered evrything on the pcb and reinstalled the minimum for the miata.
As of now, the megasquirt is not reading crank signal. When trying to start, It feels like no fuel is being injected. I Did multiple start attempt with varying turns for trim pot r56. I tried to set it to 7 1/2 turns as the assembly said but it didn't do it. Someone told me to do a composite log and tooth log. The tooth log was completely empty. I'll join a picture of the composite log. I checked continuity on pin 24 (Crank in) for the sensor to the MS. I'm using the firmware and basetune for the MSM on trubokitty.com.
On a side note, I can hear a high frequency pitch noise coming from the engine bay when connecting the MS without the key inserted. The oem ECU doesn't do that.
I tried reconnecting the old ECU for fun and the car won't start. It tries and I can hear it buggles. i can smell gas coming out of the exhaust though. Could it be that the MS burned the ignition coils? I will be testing them wednesday.
I live in a rural area in a small town with no access to a local tuner. There could be a shop I can bring the car to but it's 400km away and the car must run for them to tune it and I feel like if it runs, I don't need to go there (paradox)?, I'll just pay someone to remote tune it. What would you do if you were me? I spend all my days and night on this and I cannot sleep anymore. I just wanna get it running. I feel like I am close but at the same time there is always something wrong.
A pic of the megasquirt v3.0 before I upgraded it to an MS3X:
The car now starts with the stock ECU, I might have drowned it under too much fuel and cranking without start.
Back to the megasquirt, it seems like I have the same problem as Saldua where whatever I do with the variable resistor R56 and R11 the voltage is always the same.
I now have a tooth log and the car starts! Here's what I've done:
-I reajusted R56 to get 2.5v over the top of R54 when the key was on.
-I replaced R52 with a 100K (99.4K) resistor because I couldn't get past 94.7k with the variable trim pot.
-I cleaned the board with alcohol
-I followed the diagram on page 199 with my multimeter and could, get a voltage of .88v to 4.88v on the vrout while moving the sensor close to metal back and forth here http://www.msextra.com/doc/pdf/MS3XV30_Hardware-1.5.pdf
Only to comment on the sound you heard. Is there any way that any of the devices or sensors are being powered when the key is off? I'm assuming you have a main relay in the car. That should cut power to all devices. If anything is powered when the +12 volt input is off to the MS, it could back feed power through any of the outputs of the MS. That does weird things like keep the MS running or coils or relays humming.
Only to comment on the sound you heard. Is there any way that any of the devices or sensors are being powered when the key is off? I'm assuming you have a main relay in the car. That should cut power to all devices. If anything is powered when the +12 volt input is off to the MS, it could back feed power through any of the outputs of the MS. That does weird things like keep the MS running or coils or relays humming.
Actually I found out recently that my headlights are on constantly and won't turn off even when my key is off. None of that was happening with stock ECU. Where should I start to diagnose the problem?
Connect a computer to your MS and find out if it is alive when you turn the key off. If it is, then start disconnecting connections to injectors and coils and sensors until it turns off.
Headlights don't seem like a ECU thing though. You need a wiring diagram for your car. Disconnect fuses and relays until you find the circuits that are stuck on.
Hi, the MS is not alive when the key is off BUT, the ECU drains my battery so I can't let the car sit in with the battery hooked for more than a couple of hours or the battery would be completely drained.
I'd like to mention that upon more analysis I found out last summer that If I turned the key exactly 3 times then tried to start the car then it would start every time so I ran with this for the remainder of the summer. This is not an ideal solution as I want it fixed for good.
Here's what I have done so far, with the key off and the MS not hooked in, I verified all of the stock pins to see where the +12v was coming. The only wire with 12v was the main relay.
After that, still with the key off, I hooked the megasquirt and checked all the pins. Here's a picture of the voltage for every pin:
Why is it that so many sensors receive electricity when there should be none with the key off. There is also something strange where the +12v should come, it only reads 3.8v. I followed this site and It shows for an MSM that the +12v should come from the 4s pin but when I looked upon the car manual it's supposed to come from the 4AF pin. Is https://trubokitty.com/#/ms3xassembly wrong? Is it the root cause of my issue?
I also checked all the power circuit using this diagram to see if everything seemed good, found nothing wrong:
There needs to be a main relay powering pretty much everything. The design of main board is crap imho. It feeds power right back from anything on the outputs and powers the cpu. The add on cards are much better. I use one of the newer outputs that doesn't back feed to power up the main relay. I put the 12 volt on the key ignition.
There needs to be a main relay powering pretty much everything. The design of main board is crap imho. It feeds power right back from anything on the outputs and powers the cpu. The add on cards are much better. I use one of the newer outputs that doesn't back feed to power up the main relay. I put the 12 volt on the key ignition.
Do you have some time to explain what to do for my situation? I don't have a well understanding of whats going on. The main relay is connected to the expander board so it should be programmable in tuner studio for it to switch on and off. The thing that I find strange is why does it take +12v from the 4s pin when clearly in the manual it should be 4AF for a mazdaspeed. If you look at the diagram on trubokitty for a 01-05 miata then it's at the right pinout.
06-13-2023, 05:35 AM
Ms3x no rpm while cranking
0
