Windstorm

Was accelerating in 4th gear, around 5K RPM the car jerked rather abruptly (as if I instantly let off the gas). Luckily I was logging at the time and when I look there is a 14 knock count. Is there anything obviously wrong in my log? I've had this happen occasionally, maybe once or twice a month. But pulls usually log fine right up to redline.
Car is a 08 GSR, bone stock, running Naji's map on 91 oct.

momostallion

iTrader: (1)

wow, that's bizarre. it looks like you hit some kind of limiter. did you let off the throttle after that happened? tps goes from 96 to 76 but not immediately.

i cant think of anything else that would make your load drop from 255 to 185. the knock was probably a result of going from 7 degrees of timing to 16.

richardjh

Is this the tune you're running?... NJ_R35_52680020.HEX ? ...


Naji / nj1266:
Appropriate for a stock Evo X that needs to run on 91 octane gas. It is tuned for 1-2 counts of knock. The AFR starts at 11.8 post spool and tapers to 10.8 by redline. The boost peaks at 23.5 psi and tapers to 17-18 by redline. This map also contains a modified GST mivec map with some DTC's disabled.

Boost: Peak 23.5 psi and tapers to 17-18
Fuel: AFR starts at 11.8 post spool and tapers to 10.8 by redline
Timing: Timing is modified to be more aggressive
Mivec: modified GST mivec map

From...

http://www.evoxforums.com/forums/showthread.php?t=22385



Your boost peaked at 27.7psi at 4800rpm.

Your load was:
@4700rpm : 265
@5000rpm : 263
@5136rpm : 255

...and that took 1000ms.


On that ROM, "Boost Limit" loads are:

@4500rpm: 260
@5000rpm: 255
@5500rpm: 250

...and "Boost Cut Delay Timer" is 1000ms.


So... over-boosting. You're running a ROM that is described as intending to hit "Peak 23.5 psi", but you're hitting 27.7psi.


Note that this ROM uses 100% ActiveWGDC from 2250rpm to redline, and 100% PassiveWGDC from 5000rpm to redline.

You nailed that throttle at 4650rpm, and walked right into a sea of 100% duty cycle awesomeness (or not).


Another note: I'm not a pro tuner, and my wee RA doesn't even have a passive bcs. But I've got 400+ ROM revisions under my belt... and half of those were related to boost control, lol.

Actual tuners, please feel free to comment.


Rich

AndyCT9W

Note: I'm not tuner either

I think the short of what Richard said is that it is likely you are hitting boost/fuel cut. The cut is the engine's defense mechanism against the turbo producing more boost than the engine can cope with.

I'd advise you stop using that tune and get it done by a pro.

momostallion

iTrader: (1)

dang it! i glanced right over 27 psi. good eye rich..

there is your answer andy. what was the temp outside? i know you said you are stock but have you messed with the boost pill/solenoids at all?

Golden

iTrader: (1)

No need to comment with Rich's statements.

Rich, you may not be a pro tuner, but there aren't many tuners out there that tune their car by disassembling the rom and tracing stuff until they *know* what it does. In many ways, you know more about our cars than some of the best tuners.

sLowEvX

iTrader: (1)

I had the same problem once and what cause it was my cone filter fell off the intake pipe some how. I'm sure you checked under the hood but just incase you didn't it could be something as little as that.

Windstorm

Yes that's the one.

I also suspect that I hit fuel cut, that's exactly what it felt like. I'm wondering if that can cause the knock reading, as opposed to actual knock. And yes I let off the throttle immediately.
The high PSIG is worrisome, though I'm not sure how reliable it is - I'm logging with standalone Open Port, and the scaling factor is just what came in the sample config file, I've never verified if it's right.
No hardware mods at all on the car.
I'm attaching another log file with some 'clean' pulls, the logged PSI is consistently above the map targets that Rich stated. But 99% of my pulls are fine with just the odd knock or two here and there.
Thanks for the help so far!

richardjh

You really need to get tuned properly...

Rich

Windstorm

Good advice I think

But I still have questions... after looking at the log again I saw what you mentioned, I did exceed the boost limit table, and sure enough 1 second later the knock. So it seems like fuel cut caused the knock reading, it wasn't actual knock.

So biggest question is, if the car pulls fine and doesn't knock what is wrong with running 27-ish PSI?

If i raise the boost limit table slowly, say by 5, then log thoroughly and don't see any signs of knock, am I still working toward a blown engine?