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[stealthiskey]

D16z6 na.
Been going on for over a year.  Rev limit comes on at 6500 instead of 7400.  Did it on the old engine as well.  ECU is chipped, rev limit is set to 7400 in crome.  On a stock p28 bin now, but I think it was doing it on the boosted map as well.  I'll play around with it a bit more, just thought I'd ask the braintrust...

Ever heard of that, any ideas?

[HiProfile]

Cold rev limiter? My guess is the ECT sensor isn't reading correct, which is separate from the gauge sensor, so the ecu keeps the limiter low. Also check the ignition timing in the vtec map, crome sometimes puts big blocks of values to -6 degrees. Also check the cat converter, sometimes a plugged cat does this.

[HiProfile]

Someone just posted something similar on H-T, their tach was off by more than 1000rpm. They figured out what rpm it should be at 60mph in 5th, and it was off by the same percentage (600rpm low at that speed). http://www.zealautowerks.com/transcalc.php

See what a datalog would say, or try changing the rev limit on the chip.

[turbohf]

mine always seem to be off more at higher rpms.

my car datalogs 850rpms at idle and cluster shows around 1100-1150... hits revlimiter at indicated ~6500rpm. should be 7200....

car runs out of gas when you hit the E line... think the speedo is so wrong it ended up being right with the car on 17's..... and i never trust that oem coolant gauge does anything.... OEM clusters are pretty useless. 

[ratcityrex]

None of my cars have ever been off by much. Maybe a couple hundred rpms at rev limiter but other than that it's been fine.

[HiProfile]

The tach is usually off by a percentage, the speedo is usually off by a set amount plus percentage. If you limit yourself to 10mph over the posted limit (posted = 65, speedo says 75, actual = ~71), you'll stay under the proverbial radar of 99% of traffic cops. I've verified my odometers are spot-on with the correct tire, so they probably built it into the speedo to err on the side of caution. Similar to the stupid idiot anti-lockout on the driver's lock.

The coolant gauge is accurate for what it's designed to do. It basically tells you if the motor is NOT w/in optimal temp range instead of telling you relative temp. It will rise linearly up to ~160F, then barely move from that spot until 220F or so then rise linearly again. I know those numbers are off, but I think the actual values are in the helms manual.

[ratcityrex]

Similar to the stupid idiot anti-lockout on the driver's lock.

Easy, pull door handle and while handle is still opened, flip the lock.

[stealthiskey]

Hmm popped a fresh P30 stock bin on and drove it today.  Same deal, rev limit set to 7411 it cuts at 6500 on the cluster. 

Tried dropping it down to 3500 and it seems to cut right at 3500, although it seems slower to catch back on than at higher rpm.

Tried bumping it up to 8400 and now it cuts at around 7000.  So... you think the gauge off or is it the ECU?

Maybe I should also mention it's been doing this surging idle pretty annoying lately.  turned the IACV compensation down to -20% and that seems to fix it (whatever that actually does I don't know.)  The "target idle" value in chrome doesn't seem to have any effect on anything, I don't think it ever did though.

[HiProfile]

Take a cheap tach from autozone and tap into the blue tach wire (cluster or underhood), test, return gauge.