Brenspeed issue, or SCT issue?

[ExSRT8Guy]

Or (C), none of the above?

Motor "mods" are limited to K&N drop-in, opened-up air box, and Borla Tourings. Car has 46K miles, and is driven "spiritedly" for lack of a better word, but not abused.

I've had an SCT X3 with Brenspeed tunes for a couple of years. There are two issues:

- Pinging, occasionally on tip-in, and WOT. Not a death rattle, just a couple of ticks before the ECM pulls timing. This is in spite of running gas 2 octane points higher than the tune calls for; i.e. 89 on the 87 tune, and 91 on the 89 tune. If I run the same octane as the tune, pinging's much worse. Contacted Brenspeed, and they were useless; "Can't be the tune".

- Speedo calibration. I have the tuner at 765 tire revs per mile. Speedo reads ~1% fast, so changed it to 770. Holy shit... the speedo's now almost 30% fast! Tried 775... same thing. Changed it back to 765, and we're back to 1%.

If I need to kick down and have Lito do a tune, I'll do it, but with the car more-or-less stock from a drivetrain standpoint, I was thinking it really shouldn't be necessary.

 

[stkjock]

I'm leaning (c)

are you getting your fuel from the same place consistently?

 

[ExSRT8Guy]

Same brands, but not always the same station. Always top-tier, usually Chevron or Shell.

 

[stkjock]

have you logged the knock or is just by ear?

 

[ExSRT8Guy]

By ear. I'm assuming that the ECM's pulling timing when it hears the first bit of ping.

 

[joedls]

- Speedo calibration. I have the tuner at 765 tire revs per mile. Speedo reads ~1% fast, so changed it to 770. Holy shit... the speedo's now almost 30% fast! Tried 775... same thing. Changed it back to 765, and we're back to 1%.

Within ~1% isn't good enough for you?

 

[stkjock]

my .02, I would data log it and see what you're getting

 

[ExSRT8Guy]

Within ~1% isn't good enough for you?

Normally, sure. But given that the tuner has the ability to adjust in fine increments, why not get the delta close to zero? The adjustments worked fine up to 765 revs/mile, and then go wack in the opposite direction after that.

my .02, I would data log it and see what you're getting

I can do that. Figured I'd see if anyone had had similar experiences, to get a running start.

 

[joedls]

Normally, sure. But given that the tuner has the ability to adjust in fine increments, why not get the delta close to zero

IMHO 1% is close to zero. I don't think you're going to get any closer than that since the RPM are in increments of 5.

 

[ExSRT8Guy]

IMHO 1% is close to zero. I don't think you're going to get any closer than that since the RPM are in increments of 5.

Understood. It's actually closer to 2%. I'm more curious why the tuner goes wack in the wrong direction at revs/mile over 765.