Hitting rev limiter to early?

s300 and SManager software questions & answers
simon21
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Hitting rev limiter to early?

Post by simon21 » Sun Jun 14, 2015 7:00 am

Hi Guys,

I was having a weird problem on the dyno a few days ago, the car was hitting the rev limiter way too early,
3 times in a row, on the 3 last high power pulls.
The limiter was set to ~10500-10700 in the ecu (and 10000 on the dyno), but it was hitting the limiter at around ~9200-9700
according to the dynapack.

Does anyone has a clue why the rpm all of a sudden jumps 1000-2000 rpm in the logs? (mostly on high power levels)

Worth mentioning, the car was on the same dyno last year pulling good to ~10200 without a issue (before I lost 4th gear) at around 900 whp
and I haven't changed anything other than increased the coil dwell times to exactly match kpro dwell times, and a new liberty dogbox for that matter.

My setup is a 84mm GSR, GT42, ID2000cc, Pro1 cams, S300 V1, CPR with RRA Coils, tuned on E92 at around 950 whp/800 wnm.

Thanks // Simon from Sweden
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AREA876
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Re: Hitting rev limiter to early?

Post by AREA876 » Sun Jun 14, 2015 9:05 am

Looking at your calibration the rev limiter is actually set at 9715rpm

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Sun Jun 14, 2015 11:04 am

AREA876 wrote:Looking at your calibration the rev limiter is actually set at 9715rpm
no shit!? ;)
it was set at 10500, even 10700 at the time being, to AVOID going into rev limit in the dyno, the dyno lockup was set to 10000

forevertrj
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Re: Hitting rev limiter to early?

Post by forevertrj » Wed Jun 17, 2015 12:17 am

very bizarre as it looks as if you're within all the parameters of the calibration then all of a sudden your injectors shut off, the RPM spike a bit but your still WOT on the TPS sensor, and your max speed is like 13Km/h below the maximum limiter for speed, the injector duty cycle is pretty high, reaching a whopping 97% duty cycle, possibly reaching their maximum output maybe there is a duty cycle limiter somewhere built into hondata we are unaware of? also the activation rpm for the rev limiter is set to about 100rpm below the maxium as stated in the help file, maybe set this to late instead? I'm really curious about the injector duty cycle though and whether or not there is a limiter hidden somewhere for this.

forevertrj
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Re: Hitting rev limiter to early?

Post by forevertrj » Wed Jun 17, 2015 12:34 am

you can see in the datalog that yes the rev limiter is switched on at about 9566RPM, my only recommendation would be to set the rev limiters even higher than 10500RPM, and make sure that speed limiter is increased past 158MPH.

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Thu Jun 18, 2015 5:54 am

I doubt its related to injector duty cycle, because last year it was running ~100% all the way from ~8250 to 10000 without an issue (log attached), 4th broke before we had any chance to lean it out.
I'm more into that it's ignition related, because when I recalculated the coil dwell times I completely missed the rpm compensation...

for an example, the values for 9000+ where 60 (dwell angle, cam degrees)+14.74 (rpm compensation) +15 pre-ignition = 89.75 degees total,
maybe that's too tight in the 90 degree window between cylinder event, and then maybe the ecu loses itself because of the huge variation in engine rpm? (which in turn may depend on all vibrations?)

you can see in the logs that every time it goes in the rev limiter, the pre-ignition goes up to 16 deg... and then your out of the 90 degree window...
is it possible that the ECU and the CPR gets lost because of this? and goes into rev limiter...

// Thanks
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run 1 20140812.s3d
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Spunkster
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Re: Hitting rev limiter to early?

Post by Spunkster » Thu Jun 18, 2015 9:43 am

What is the reason that you changed the dwell angles? DId you have a problem that this was compensating for?

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Thu Jun 18, 2015 11:19 am

Misfires... Last year we started out with 0.03" gap - misfires. Gap them down to 0.02 - misfires. Gap them down to 0.014 - STILL misfires!
Also worth mentioning, the car was running e100 last year.

Then we added 5 deg dwell angle at 6019 rpm and 10 deg to 8976, misfires totally went away!

This year I wanted to be able to go back to ~ 0.02" gap by increasing the dwell angle to exactly match kpro dwell angles.

To give me 3.55ms at 3000, 3.05ms at 6000 and 2.701 at 9000 rpm. (calculated, as in Kpro)

// thanks

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Spunkster
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Re: Hitting rev limiter to early?

Post by Spunkster » Thu Jun 18, 2015 12:46 pm

You will need to post new datalogs with the calibration being used as this calibration has a lower revlimit set than what you are trying to reach and the posted datalogs make sense with the calibration posted.

You may not be hitting a rev limit, but are getting too weak of spark from having gaps that are too small and getting misfires. What spark plugs are you using?

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Thu Jun 18, 2015 2:02 pm

Well... that's easier said than done as I'm not in the dyno anymore.

But can't you see in the sensor list that it actually hitting the limiter, regardless what the calibration tell you? And that the rpm shifting from 9500 to 10500 even 11500.. (in one jump)

Because I'm telling you, the limiter was set to 10700 at the time being (when the log was recorded) and lowered to 9700 when we were finished.

And according to the film that was recorded, 
it is hitting the limiter, no doubt about it! No misfires..

I'm using bkr9eix right now but bkr8eix and bcr8es were also used/tested
Last edited by simon21 on Sat Jun 20, 2015 9:27 am, edited 1 time in total.

forevertrj
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Re: Hitting rev limiter to early?

Post by forevertrj » Thu Jun 18, 2015 9:39 pm

not sure if it's worth mentioning, i know the traction control isn't enabled in the calibration but as soon as the rev limiter kicks in, i see the ECU enable 60% traction control, practically mirrors the rev limiter, super weird what could this mean?

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Re: Hitting rev limiter to early?

Post by Spunkster » Fri Jun 19, 2015 11:15 am

Do you have Traction control?

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Fri Jun 19, 2015 11:51 am

No, I haven't, why?
But it doesn't seem to engage every time it hit the limiter, when the rpm spikes?

simon21
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Re: Hitting rev limiter to early?

Post by simon21 » Mon Jun 29, 2015 10:14 pm

Ain't it nobody that has an idea?

forevertrj
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Re: Hitting rev limiter to early?

Post by forevertrj » Mon Jun 29, 2015 10:54 pm

Try checking in your options-> sensors settings and look at rpm mine was set to 9500 as a max value, try increasing it to 11000rpm? Also that dwell angle hypothesis seems legit but it didn't look like you were out of parameters, is too bad the sensors list doesn't have more sensors to display under datalogging

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