The RevXtend issue only occurs with TBW bikes. My '07 (cable) shows correct RPM's all the way to the redline (6250). I haven't actually witnessed this, but I understand the tachs of TBW bikes with RevXtend enabled will stop at ~5K RPM while the engine climbs up to the redline.

 

The RevXtend issue only occurs with TBW bikes. My '07 (cable) shows correct RPM's all the way to the redline (6250). I haven't actually witnessed this, but I understand the tachs of TBW bikes with RevXtend enabled will stop at ~5K RPM while the engine climbs up to the redline.

I don't know of any data that gets transferred from the PCV to the ECM. What I believe is happening with the REvXtend issue is that in stock form it stops at 5K or thereabouts, and the limiter also kicks in at that point. My understanding is that the tach function is unaltered unless you have a flash performed at a Harley shop, or with one of the flash-based tuners (TTS, SEST, etc.) using a computer, and apparently the PCV intercepts and alters the rev-limiting signal from the PCV, yet the tach signal is not something the PCV can change.
If I'm mistakened I hope someone will correct me.

 

What I read from this thread is that Jamie is saying the it does not make any difference if you wait or not, the PC-V is on. However, most users are stating that their bikes start better if they start their bikes immediately and do not start well after waiting. I find that pretty interesting. I'm having a PC-V w/autotune installed later next week. Guess I'll see first hand how it works.

 

What he said.

 

I've tuned quit a few PCIII on cabled bikes and you're right, it's not a problem. The PCV I had the problem with was on a '09 Road King, so yes, TBW. In stock form his bike hit the limiter right at 5500 PRM, with rev Xtend enabled it might be getting to 6000 to 6250 RPM, somewhere in that range, but the tach does stop at 5000 RPM. So that leaves me to believe that the Rev Xtend is running off the tach signal wire. It seams like the PCV is shutting the tach off at 5000 RPM's to fool the stock ECM into thinking that it's not reving higher, then the PCV is shutting it off at 6000 RPM's or so. Either way its a real pain in the ***, nothing worse than racing a guy and hitting your rev limiter sooner than expected, that puts him about half a second late in his shift. Problems solved though, I have a TTS on the way for him to take care of it. We'll run the TTS and the PCV both on is bike, use a MAP switch and run the PCV auto tune on one and a zero MAP on the other for the tuned MAP it'll have when I get done tuning it.

 

The PC's strategy of driving the ignition, allowing us to actually adjust it, and also raising the rev limiter is actually pretty complex, it actually picks up from the crank signal which runs right thru the Power Commander. The tach wire is simply an output from the ECM.

To quote myself from from an earlier post in this thread:

"The PC III and PC-V read input channels from the ECM and use a microprocessor to interpret this data and in turn drive the injectors and igntion timing. They do not use sensor or signal offset as the original PC and PC II did previous to 2003. Due to specific strategies of the 08 and newer DBW ECM and where the tach signal picks up from, when RevXtend is enabled the tach will only read to 5K as above that the PC is driving the igntion."

 

Roger that, thanks Jamie.

 

Great read, thanks for the info Jamie, now I feel like less of a dumb azz, I have a pc v on my 2010 SEUC. Dont usually ride hard, but on the rare occasion that I did, the tach would stop at 5000 rpm, but the motor was still pulling, and I didnt hit the rev-limiter. I wanted to post this question why? on the forum but never did. I had enough of the trained Harley techs at my local shop. I wasnt about to ask them the reason, even though they installed the PCV, because they couldnt tune a SEPT on the dyno.

 

I'm changing my answer from earlier. I took the time to wait for the fuel to prime and the bike turns over 2 times while starting. If I hit the starter while the fuel pump is doing it's thing the bike starts up immediately. I verified the PCV has power the entire time no matter what method you choose.

Crazy ain't it... My bad.

lp

 

On my 08 Ultra SE3 I removed my PC5 and went with the MasterTune TTS....awsome power and smoothness, no vibration at 2200 RPM. Used the canned map that best fit my bike, you won't believe the performance and smoothness and now has the Harley idle !!