So in test mode firing injectors individually manually, 1 and 3 fire but 2 and 4 don't. Switching the injectors around, all the injectors work. How do I check the signal coming out of the ECM?

 

Can someone please move this to the mspnp category. Clicked the wrong one.

 

With an oscilscope.

Sequential injection?

Test for continuity between ECU and injectors.

 

What year Miata is this? And can you post the MSQ? It is possible to accidentally switch injector outputs off.

 

'91

If you're poking around other areas, this tune is a free rev tune only so far. The tune Scott Clark helped us with was for E85 and we are breaking this engine in on pump gas so I was starting from scratch. Car was started and running and free reving on this tune last year but destroyed the thrust bearing in the engine due to a faulty throwout bearing. We seemed to be having occasional injector misses at that point as well, so we decided to dry test them in TS before we actually finished assembling for start up this time and discovered that 2 and 4 aren't firing.

 

BTW, continuity is good on all wires. Firing in test mode we get voltage on the yellow trigger wire coming from the ecm which runs 1&3, but not getting voltage coming out of the yellow/black trigger from the ecm for 2&4.

 

Does INJ3 / C fire in injector test mode?

 

Yes

 

If it works in test mode but not when running, please post a data log and a composite log of an attempted start. This will give me more to go on.

 

1&3 work in test mode. It's 2&4 that don't work and that are on the same trigger. There is no data log as the car has not even been started. No point in trying to start a car with only 2 injectors firing.

 

hence "an attempted" start.

turn off the fuel pump while you crank. he just needs to see what the MS is seeing when you're cranking.

 

My bad. It didn't seem like there was a clear understanding of which injectors were and were not firing.

I'll attempt that tonight. Never run a composite log. Is that something different than a data log? Do I need to do something different than just start a data log and then crank the engine and then end the log?

 

 

click the diagnostics tab.

check save to file.

click start.


go WOT for flood clear (if you have a vTPS installed/setup) or unplug the fuel pump relay or injectors, and then crank for like 20-30sec.

 

Alright, I'll let you experts give me your thoughts, but I think my ecm has issues. Let me explain.

Well first let me give you a little background that I probably should have mentioned earlier. A while back (not sure, maybe even late 2014) the ecm just basically went dead. A couple of screws had come loose inside the case and apparently shorted things out. Scott Clark called, I think maybe you Matt, and we pulled I think a 2 pin thingamajiggy and plugged it somewhere else as a jumper or bypass and it seemed to take care of the problem. I didn't bring this up before, because after that the car ran and drove and seemed that the ecm was fine. Then it was last year we were having some miss issues and after some testing determined we had a bad ignitor. While that fixed most of the issue, we were still occasionally having some issues and discovered all the injectors weren't consistently firing. That's why we decided to test them before we even finished hooking things up this go around.

Ok, that brings us to this thread and after attempting the composite log tonight I'm thinking that the above may be relevant.

The first 3 times I attempted the log, it displayed no action and no results. I shut down TS and tried again. Nothing. I keyed on and off. Nothing. I shut down TS again and when I tried again, I got nothing for the first 5-6 seconds and then I got the little blue squiglies (not data but above the graph just showing signal connection and activity) and it displayed some data but then it all disappeared and the log only had three entries. It did this 3 or 4 times. So then I hovered over the stop button and when it started the little blue squiglies and flashed the data, I quickly hit stop and captured the first of the two logs attached. I then did another log and just let it go and it did the same thing. Flashed some results and then it all disappeared. In the sidebar it only showed three entries again, but as you can see, the log actually recorded more values than that, unlike all the attempts before.

I'm thinking I have some sort of short or something has failed within the ecm.

 

The second log attached, the battery was starting to struggle. Just an FYI

 

You are getting a good cam signal. Can you email me (support@diyautotune.com) with purchase info so I can look up when this one was built and if it's under warranty?