Can't rev-match with ARC features
 

I've had a very unique issue that I can't seem to get an answer on.

My Z has the Uprev ARC features. Pretty extensive mods. Tomei cams, GT-R injectors, walbro 255, and plenty of other bolt ons.

I've noticed that the car won't allow me to rev match properly now if the rpms pass through or over 4500rpm, which is the starting point for launch control/2-step.

Example: Cruising in 3rd at say 4000rpm, clutch in, pop throttle while going into 2nd. The rpms will not smoothly travel up to the required level for a smooth downshift. The throttle will "pop" at the 4500 mark and cause a jumpy downshift.

Same thing happens if I am ABOVE 4500rpm. Car will stutter/pop momentarily as if it's trying to 2 step.

It's gotten to the point where I'm about to have the features removed as it will cause issues with spirited driving or potential future track days.

Anybody else had this issue before?

Well, yeah. Two step is engaged by the clutch switch. If the clutch is depressed, it won't rev over 4500 rpm. If you're not at the 1/4 mile track, why do you need a 2-step? If you HAVE to have a 2-step, install a second clutch switch with an inline toggle switch.

I was under the impression that with the features you also have to have the car in 1st gear. After talking with Z1, they don't seem to be having this issue.

Did you install some type of switch to let the car know it's in first? From the factory, the 350Z has no 1st gear position switch, only neutral and reverse position switches.

That's a great point. Next question is if it (2-step) has to be engaged at WOT only. I might be able to try rev matching without doing a full WOT throttle blip. Might take some practice.

I'll try that next time I'm in the car.

Nope. Most rev matches are done at almost if not always at WOT.

Just accept it’s either 2 step or you get rev match. Pick one.

This was my exact thought as well. Considering how I want the car to perform, I'll likely have the features removed.

Install a MPH switch to disable it.

https://www.lingenfelter.com/product...l#.Ws5joy7wbcs

Or a simple toggle.

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Howzat?

Can't say I've EVER been close to WOT for gear match, heel/toe NOR normal (brakeless) downshift. Or am I missing the point completely here?

What exactly would I be toggling on and off? The ARC features are in the tune itself, and I imagine the ECU still needs to know what's going on with the clutch switch and throttle position.

Thanks for the help on it. Would be a cool feature to toggle the ARC features on and off if I can.

I think the idea is the throttle blip itself. That moment I am switching to a lower gear when I go to blip the throttle, it's a "full throttle" blip (i.e. I quickly mash the pedal to the floor to get a rev match for the lower gear)

That's where I have my problem. Instead of rpms climbing quickly and smoothly to match the lower gear, they "stutter" as if trying to 2-step.

Which makes sense because clutch switch is engaged, and WOT is seen during the throttle blip...possibly resulting in a "I want you to 2-step" scenario...but this is not the case.

Make sense?

I think they are talking about downshifting to increase speed not to decrease speed. I'll WOT and downshift without the use of the clutch for rpm matches, but it's a very rare occurrence.

To be a bit more technical, I should be able to smoothly rev-match downshift without changing speed at all.

Same example as before: 3rd gear at 4000rpm or so, I should be able to clutch in, blip throttle up to maybe around 5500rpm (depending on speed), and move into 2nd without changing my mph at all, but will smoothly be in a lower gear at a higher rpm.

The issue I describe above in the original post is "bucking" by trying to 2-step when pushing the car hard when downshifting on a track or on a road like the Dragon, which I do not want.

Hmmmm, I must be looking at this from a weirdly different angle...still having trouble wrapping my fat head around this.

S'far as the clutch switch engage/disengage position, I'm almost certain that in 75% of my downshifts, I'll never push the pedal far enough to trigger the clutch switch - nearly but not quite - as while in motion and doing a heel/toe downshift coming into a corner, say, full clutch disengagement is not necessary if the pedal work (coordinating the three pedal and shifter dance) is done correctly.

But I guess if I'm downshifting to get the revs up for immediate acceleration (like a roll start vs geardown to be in the correct gear for acceleration out of a turn) :confused: it kinda makes sense but somehow my mind is disconnecting between logic and practice. Hmmmm..... gotta go sit in the corner to ponder this cuz it's bugging me. :icon17:

Hell, writing that trying to be intelligible in describing the actual practice even confuses me. Laff....

Yeah, I get that. It's like there's a wall at the lower of the two rev limits and downshifting at or below the lower limit still triggers the car to two step even though you're already at speed, not launching.

Guess my confusion stems around the "WOT rev match" which still bewilders me. Even pushing at higher speeds, I never hit WOT but that might be just me too light on the pedals to be taken seriously. Hahahahaha! :icon17:

Mic it all depends on the engine, car and set up.

Perfect example my tractor trailer I drive for work 100% needs a FULL WOT double clutch downshift for a good few seconds before you can downshift. If you don’t youre looking for a grind fest if you get it in gear at all. But these are heavy sluggish engines. VQ’s obviously aren’t that bad but there are a number of times I WOT or 3/4 throttle rev match my cars. Just depends on how hard I’m driving. It’s always better to over rev than under rev as far as weight transition when downshifting. Under rev and your weight transfers to the font. Over blip and you just slip and drag the RPM down instead of the trans trying to pick the RPM up from being too low of RMP’s for the down shift.

But yes I was referring to rev match via downshifting again compromising OP’s Rev limiter switch to hit rev match by using the clutch while on the throttle. We can assume hypothetical “it should hit the switch, it might not” all day but the easy answer is just pick onenover the other.

Or like Uprev pick a map to house your 2 step and allow for the rev match to be on a completely different system of engagement.

That last piece was my initial thought...two different maps. Apparently that can't be done with the ARC features. You either got 'em or you don't.

I do want to try and "finesse" my methods for a downshift and see if I can remedy what's going on. I'm typically very deliberate and fast with the downshift and throttle blip. I could just be causing and issue with "blipping" using a quick 100% throttle input during downshift. I wonder if a less-than-100% throttle input will give a different result.

A less that blip with 100% give a different result. But not necessarily a negative one. It will just result in a slower raise in revs making you wait a little more to rev match or under rev the down shift. But like I gave the example of my work rig if you don’t give it a solid rev not even a blip a full rev you’ll flat out miss a gear. (Using this as an extreme example of course)

I mean you can down shift with out any gas blip at all. It won’t be fun for either you or your driveline tho but it could work.

I’m not saying you have to stand on the gas pedal to rev match. I’m just saying the firm blip is close to a use of a 2 step being you have the clutch in and rev the motor using the throttle to raise RPM. The car doesn’t know what you’re trying to do just what you’re telling it to do. So if it’s set it up to 2 step you can’t just magically make it not 2 step if you begin the process it’s programmed and mechanically set up to start the 2 step.

But from the sound of it you’re doing a proper down shift. Like above you just set your car up to do another process in doing so. This the downside of missing a car, to gain one thing you usually have to give up another.

I have NEVER gone to WOT to rev match, and I've done many track miles in cars and on bikes.

That's great and all, but I just always have blipped the throttle to floor on rev matching. It seems much faster and the revs climb to exactly where I want.

However, I'm definitely going to try it differently to see if I can remedy my problem without having to flash the ARC features off of the car.