Help about RPM figures

[HA11S]

Hi everyone.

The trouble is that the RPM figures of ECU is doubled, comparing to the tachometer which picks up the signal from plug cord.
(We used it last year and confirmed it shows ture RPM)
We use DTA S60 with 2cyl-engine.(KVF650,V2 engine)

For the mean time, I doubled the range of RPM of ECU, but duty cycle soon reach 100% http://fsae.com/groupee_common/emoticons/icon_frown.gif

DTA says ECU doesn't wrong RPM but ECU says 6000rpm when 3000rpm.

Does anyone experience similar problem or know how to fix?

thanks in advance.

[HA11S]

Hi everyone.

The trouble is that the RPM figures of ECU is doubled, comparing to the tachometer which picks up the signal from plug cord.
(We used it last year and confirmed it shows ture RPM)
We use DTA S60 with 2cyl-engine.(KVF650,V2 engine)

For the mean time, I doubled the range of RPM of ECU, but duty cycle soon reach 100% http://fsae.com/groupee_common/emoticons/icon_frown.gif

DTA says ECU doesn't wrong RPM but ECU says 6000rpm when 3000rpm.

Does anyone experience similar problem or know how to fix?

thanks in advance.

[pengulns2001]

theres no way your ecu is wrong or your engine wouldnt be running its gotta be your tach

[pengulns2001]

actually i guess it could still run as a wasted spark system and spraying fuel at closed intake valves which would make it run like shit (the fuel part) most likely you have your calibration setup wrong im not sure what ecu your using so i dont really know how to change it but im guessing you entered the wrong number of teeth on your crank sensor (half of what you should have) thats the only way i could see it still running

[HA11S]

I changed the setting seemed wrong but it didn't run.
So, the calibration is most likely correct.

I think again and wonder why RPM of ECU is doubled when tachometer from plug cord is correctly.

ECU send correct signal to coil though RPM is doubled http://fsae.com/groupee_common/emoticons/icon_confused.gif

We gave up FI and returned to carb http://fsae.com/groupee_common/emoticons/icon_frown.gif and FSAE Japan starts tommorow.
What a shame..

[Chris Boyden]

A divide by two circuit will work
if you can't adjust the pulse input setting on
your tach to two pulses per revolution.

[Marshall Grice]

perhaps i'm missing something, but why does it matter if your tach says the right rpm? We've run several years with no tach installed at all.

[absolutepressure]

You're from Pamona, the school that Jimmy Newtron went to. You should be smarter than that. He's saying that the ECU thinks the engine is spinning twice as fast as it really is.
(I thought Pamona was a made up school until I saw your location, lol)

[Chris Boyden]

It sounds like the tach is getting two pulses for every rev, but treating it like one pulse per rev which doubles the reading. The tach needs to be setup for the number of pulses the ecu issues per revolution.

The ecu you were using before with the same tach probably only put out one pulse per rev, that's why it seemed to work. was it a DTA as well?

[Bill Kunst]

It is weird why we question everything about an accel run, but nothing of any significance on a topic such as this.

You said the ecu is showing it doubled, but the company(DTA) says that is impossible? Where are you reading it, on a tach output, or in the computer interface? How are you verifying it? If you are reading it off the tach, which one do you have? Is this the stock computer? Are these the stock injectors? Too many questions, so tell us all that you know.
Bill

[pengulns2001]

well thats because this isnt an engineering question really its obviously something extremely stupid.... not to say its easy to figure out, it could be something buried in the options list but its nothing complex for sure

[VFR750R]

Is it possible to have the polarity reversed on your trigger so it is picking up the teeth wrong (gaps instead of rising edge)?

[Bill Kunst]

Quick question, I have had a long day, so maybe I am crazy.

Would there be any more ignition events form gaps versus teeth? Something tells me know, and that the ignition would be off by the degree of spacing between teeth, or spaces.

Penguins- I wouldn't call this stupid, as ecu issues have ended plenty of teams chances at driving for comp. Is the problem stupid, yes. Is it likely that in the confusion of learning the system, and the panic behind it, that there is a user error, yes. Have we all done this, yes.

Just my $1.50 worth of opinion.
Bill

[murpia]

A quick glance at the manual shows the DTA S60 has a fairly comprehensive set of options for crank trigger setup, including a 'self-learning' cranking oscilloscope system.

It also says the minimum number of supported cylinders is 4, but OFRAC seem to be using it on a 2 cylinder vee. This may be the problem!

It should be possible to use an ECU designed for up to a V8 on a V2 but you may not be able to use the automated setup options. Instead you have to carefully decide which of the V8 cylinders corresponds to each of the V2 cylinders and pay very careful attention to firing order and crank (and cam?) sensor timing.

I suggest a very very careful read of the manual is in order. OFRAC, you may need to find someone with good technical English and a lot of experience with electronic engine management systems to help you out. Good luck!

Regards, Ian

[pengulns2001]

read my post thats exactly what i said. The reason theres not a million responses is it doesnt intrest anyone. its a stupid problem i didnt say it was going to be easy to figure out, im not saying i couldnt make the same mistake but its not engineering i was just responding to the above post about the lack of responses Vs the accel run topic which is obviously far more interesting

[HA11S]

Thank you all for reply.
I just returned from FSAE Japan.

As Bill says, DTA says there is NO possibility the ECU is wrong if the engine is running and any setup(teeth number etc) is wrong, the engine doesn't run.

In the competition, I set the ECU 8cyl mode and it seemed work correctly.
(I confirmed the figure on PC)

It's a shame that I don't understand why this happened but I will ask DTA about the ECU's system and find out what is really problem.

[pengulns2001]

well that proves the problem is that you specified the wrong number of teeth, all you had to do was halve the number of teeth in the cal and you would have been fine (halve or double i dont feel like thinking)

[murpia]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by OFRAC:
In the competition, I set the ECU 8cyl mode and it seemed work correctly.
(I confirmed the figure on PC)
</div></BLOCKQUOTE>
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by pengulns2001:
well that proves the problem is that you specified the wrong number of teeth, all you had to do was halve the number of teeth in the cal and you would have been fine (halve or double i dont feel like thinking) </div></BLOCKQUOTE>
No, doesn't that prove that a 'V' engine needs to be specified as such when configuring an ECU?
Regards, Ian

[pengulns2001]

not really just that its a 2 cylinder unless it has an odd firing order like a harly

[BryanH]

DTA firmware needs trigger count per CYCLE, not 1 rev. Eg. 24 teeth in cam driven sensor is same as 12 teeth on crank, 24 per cycle.
changing to 8cyl divided count x 2 which corrected the rpm reading,(on the right maps at least) but depending on how timing algorithms work in DTA Ign advance might be half of indicated, but the fact that the tacho reads correctly off the spark plug leads me to believe that all is well. Do a timing lock check at 10degrees and 30 degrees. If both are correct at same software settings then leave settings alone and map the thing
Bryan H
RMIT fan club

p.s. Saw latest Aprilla 450 V-twin Enduro bike racing few weeks ago, running in the top 3 and was fastest thing down the straights. Best of all it sounded just like a.........VFR750R !!