akaryrye

iTrader: (5)

ive been having issues with my car misfiring badly no matter what the heck i do. Ive tried many many maps as well as tuning to no avial. I was looking at a datalog today,going through the sensors, and noticed the coolant temperature fluctuating between 219 and 223 somewhat rapidly.

Here is a photo of the datalog:



Here is a closeup on the area where i had a major misfire. It popped like a gun! and my buddies said they could hear me misfiring from a block away ... pretty open exhaust though due to the glasspack.



And here is Al Hounos' datalog from the settings thread, it shows his coolant fluctiating 10 degrees all the time. He claims that his map works pretty well too. I was also surprised how much it fluctuated (150 - 200* over the course of a single boost pull!)




Ok, i am really not certain that the clt is the main cause of my misfires. Even though I have NOT set it up with easytherm to be perfect, it seems to be within 20 degrees of whatever the actual temp should be. Also, after seeing how Al's CLT fluctuates 10 degrees, the 4* that mine was going between, it seems like it shouldnt be a big deal at all.


--------------------
Now, there are some other things I would like you to look at:

First, on the top of the second picture, notice how my rpm signal jumps to 13,500 rpm! If my engine went that high and survived, i give major props to mazda. However, I dont think i went that high ... but why did it read this?

Second, take a look at the last graph in my 2nd pic. My pulsewidth is right on, but my dutycycle ... um wow it went up about as high as my rpm! Leading me to believe that my 550cc injectors dumped a LOT of fuel and led to my very loud misfire.

Finally, I believe it is an RPM signal issue (that little white wire). When i got my wiring harness for $60, I was pretty jazzed and hooked stuff up. I was not so jazzed when the white RPM signal wire fell out. Since then, i have fixed it with electric tape and an rtv like product called "Liquid electric tape". It stays in, but this really makes me wonder if all of my trouble could be traced back to a weak connection on the rpm signal!

In A Nutshell:

My Problem: I am misfiring a whole lot. I used to ping/knock/detonate a whole lot before I changed from 029t to 029q2, now I am misfiring a whole heck of a lot on 029q2.

My questions l: Could a weak RPM signal cause the issue I am having? Could a fluctiating Coolant signal cause the problem? Is there anything that you can see with what I have given you that might be causing my problem?

Well, sorry for the long post, but lets see what we can figure out over the next few days/weeks. It is not my DD so i dont need it to get me to work tomorrow, or ever. I really hope this brings some technical discussion to our forum also. I browse msefi.com as all MS users should, but we need to start bringing it back here as well.

akaryrye

iTrader: (5)

I forgot to include the MAP sensor data ... ya its kinda important too. Changed the sensors around a bit to so be wise.

Al Hounos

your rpm spikes to 15600 rpm? that's what's causing your DC to spike and probably causing tons of fuel to be dumped in. get rid of that tach spike, and it will probably solve the problem. also all those yellow lines going across the whole screen are instances where the MS isn't communicating for some reason.

Possibly Bad connection/ground somewhere.

oh yeah and don't worry about the clt. and as for the 50 degree jump, thats what 12psi and the puny stock rad will do!

akaryrye

iTrader: (5)

Ya I honestly was most concerned with the rpm spike, but was bored so made a nice long post lol

did you read this:

I dont think i have a good rpm signal, i think I am going to contact diyautotune for a replacement.

neogenesis2004

iTrader: (12)

Ya, I bought that same haness and one of my wires came out too. They assemble it with the wire WAYYYYYY too tight for the crimp fit they use. I just took the 37pin connector that the kit comes with regularly and ended up soldering the wires onto that one by one. It was basically a huge waste of money, I regret buying it regardless of part failure. The only plus of it is the metal housing, not worth $60 though. The boomslang extension harness I used though was worth every penny for not having to cut the stock harness.

Al Hounos

yeah sorry bout that. me - always looks at da pictures and reads the captions, skips the article.

Don't rule out the many other places that could have bad connections. harness, at the CAS, and solder joints on the board. also interference can cause spikes, as i had with my low impedance injectors before i put resistors in.

I'd just cut the place you had to fix out of the wiring and just solder it to the little connector in the db37 hood.

oh yeah and did you see about the yellow lines? that really takes the whole db37 into question, not just the tach wire. if not that, it's in your harness connections.