I am continuing this string from April because I could not find if anybody had resolved this minor but troublesome issue. When I downshift my 5AT from 3rd to 2nd (usually at low RPM's), the transmission is *sometimes* jerky... Interestingly, this does not happen between any other gears. Granted, this does not happen often (maybe 20 times in the 6 months I've had my G), but it is annoying nonetheless. I mentioned it to my service guy and he'll take a look at it when I bring it in, but I wanted to see if anybody else had any feedback so I could know more about this issue beforehand. A previous poster suggested that I would need to have the ECU reprogrammed.

I will of course update you with what the delaership has to say, I am sure I am not the only one with this problem.

Thanks!

 

Hmm...I don't have the AT, but could this be due to the auto's gear ratios? Maybe just an anomaly that occurs within this system due to the programming and the ratio? Just a guess, and I could be WAY off...Anyone have any input?

"All the Power in the World resides in the Eyes..."

 

It happens to me. Best thing to do that i found out, is when you downshift to 2nd give it a bit of gas, keep it same acceleration as it was in 3rd when you downshift. Usually that does the trick for me. It only seems to happen when I slow down quickly and downshift without any gas.

Crawford Plenum / Z tube + Stillen Hi-Flow / Borla Dual Exhaust / Stillen Xdrilled+Stotted Rotors
Best 1/4 mile 14.371 @ 100.29, 60ft 2.347

 

I might be wrong but i see a huge performance gain on the manumatic when you let go of the gas really quick when shifting gears... the gears catch quicker... but i might be wrong...

 

Ahhh I see you've found one of the secrets of the MM mode... Yes it is true. I noticed the same thing but thought it was all in my head. You get more boost into 2nd gear. It works best when you release the gas during the shift because you don't get any lag.

5AT- premiumpackage /performance package/ K&N

 

To answer the original question, I agree with the other poster that giving it some throttle removes the clunks from any downshift, except sometimes 2 to 1. Taking your foot off the gas and downshifting in low gears will clunk it. Thus, it's probably better to let the car downshift itself when you're coming to a stop. If you want to downshift into a turn, you just need to do all your braking in the higher gear and wait until you're ready to power through the turn to downshift.

With regard to the other thing people are talking about, releasing the throttle to get a faster shift, what do you mean exactly? Is it catching the next gear closer to the ideal spot in the power band, or just shortening the shift lag? Are you pulling off the throttle before or after the "tap"? Do you stomp the throttle again before or after the shift is complete? If it's before the tap/after the shift, aren't the performance gains offset by whatever amount of time you spend with your foot off the gas? Would love to test this out, but the dragstrip here is closed until April.

-Jack
Obsidian '03 G35 Sports Coupe
Titanium '03 MX-5 Shinsen #532

 

KAHBOOM but isnt it bad for the transmition?

-------------------------------------------------
04 Maxima

 

The only time mine is jerky is when it's cold. Once the tranny is warmed, the downshifting is smooth.
Are you downshifting at too high an rpm?
If the tranny oil is low, it may cause abnormal shifting, but the dealer will have to check your oil level because US automatics have no dipstick.
Good luck with the dealer, and let us know what he says.
GSM

<font color=red>GSM</font color=red> <font color=black>Silverstone Coupe</font color=black>

 

Thanks for the replies so far... anybody else with thoughts keep it coming. Usually the problem occurs when I am downshifting at low revs, I'm talking less than 1500. I have this bad habit of downshifting at every stop or turn, so if I let the automatic downshift by itself I would not encounter this issue. This was just never a problem with my A4's tiptronic...

 

Yea, I wish they made a tranny ecu reprogram so it doesnt downshift on its own. Id rather do it myslef in MM. And as far as letting off the gas and shifting then stomping it again, yes it can be fun if you get it perfectly right. I do it sometimes when accelerating through the gears and I can feel a sharp push when the gear engages.

Crawford Plenum / Z tube + Stillen Hi-Flow / Borla Dual Exhaust / Stillen Xdrilled+Stotted Rotors
Best 1/4 mile 14.371 @ 100.29, 60ft 2.347

 

It happens to me also...just let the car downshift on its own before a stop...do not do it yourself..it usually only happens downshifting into 2nd...if you notice the car, when downshifting on its own, never downshfts into second only from third to first but never from third to second..it weird

 

Well, it appears there are problems with downhifts in mm mode - both automatic or manual downshifts.
When in mm mode my car usually only downshifts to 1st automatically and only at almost a complete stop. What I have happen occasionally, and I know others have mentioned it on this forum, is the automatic return to 1st gear is "jerky." This and the problem you are having shouldn't happen and seem to be a problem with mm mode. Why should there be any jerky shifts in mm mode, whether due to automatic downshift or manual downshft? If the same transmission is working perfectly while in "drive", why should it jerk in mm mode?
I am going to mention it at my next service and see what they say.

 

I've brought it up with a local Infiniti dealership before, all the guy did was look up the TSBs and say that there were none on that issue.

I've found that after a ground wire install to the transmission, and the transcooler and filter, that the 2-1 shift is much much less harsh now. The shift is still harsher than the rest, but I never get that scary CLUNK anymore.

 

What you're feeling on a slow speed downshift from 3rd to 2nd is the engine idle speed surging (especially when it's cold out). I'm not sure why it does this but sometimes it does!

Solution: Why are you downshifting under these conditions in the first place? At low speeds, it better to pop it back into auto. This also avoids the occasional first gear "clunk", and you're ready to accelerate in full auto mode.

By the way, I have noticed the MM gives fairly reliable double downshifts if you shift quickly. This can be significantly faster than waiting for the auto kickdown when you want to go from 3rd to 1st (a blast) or 4th to 2nd (still decent). My theory is the "learning" electronics cause the kickdown problems. If I've been driving hard, the transmission seems very responsive. If I've been cruising and suddenly floor it, the transmission seems surprised and is reluctant to give you the downshift you want. Sometimes you have no choice but to cruise gently, and now the tranny goes into vacation mode! A sport mode (latching switch that you didn't have to press on startup) would be a much better solution.

 

JDMAN, It's kinda hard to explain...
I tap up from 1 to 2.. (There is naturally some reaction time from the tap until the tranny shifts)... As soon as I tap up I release the gas (just slightly[not even 1/4 distance from the floor]) At that time you get a slight kick in the butt while the RPM,s are dropping in response to the engagement of 2nd gear (My MX-6 used to do the same thing, I was toldthat the torque converter in engaging and producing more torque-thrust because you are confusing the computer[ I'm not sure if this is the case in the G but it feels similar]) . Just before you feel 2nd gear engage, go full throttle again (you will feel a continuation of that boost until 2nd gear is fully engaged and oftentimes your engine will sound as if you are double clutching a manual.. In response to wether it causes tranny problems...I did this a lot in my MX6 but didn't have any tranny problems. I had 190,000 miles on my Mx6. But I changed the tranny fluid every 7500 miles.


5AT- premiumpackage /performance package/ K&N