Slow RPM Buildup and weird shifting sound

[86TOYO2k17]

Originally Posted by Blackedout86

im currently using demineralized water + a little prestone super concentrate for coolant, should i replace it with prestone prediluted 33% instead ? will it help somehow ?


i have actually done atf change once last year using total mvlv, because i was trying to fix this issue. apparently it doesn't help, so i doubt its an atf issue.

i even tried unplugging the Piggyback, so the car is basically stock tuned, but the problem still exists. so thats not a tune-related problem either.

Your coolant will have nothing to do with this.

so you followed the leveling procedure exactly?

A data log is one of the best tools for finding and narrowing down mechanical issues. not just tune issues. Regardless stock tune or not. It is a good starting place. Not to mention you said you are using stock tune with aftermarket header and no cats?

what piggyback where you using?

Using tires that are so far off from normal stock diameter tires and especially different diameter front and rear. Can cause the ecu to calculate thing weirdly causing weird issues. Especially how the ecu calculates torque values for the AT shifts. When did you get these tires in correspondence to noticing this issue?

also you have an NA auto 86 with 10% taller tire (which presumably is pretty heavy vs stock wheel/tire) you just don't have any power now in 4th gear with 10% taller tire, your mechanical torque to the wheels is so low now any incline in the road and or gust of strong head wind can actually cause you to temporarily decelerate especially between shifts specifically 3-4.

The only noise i hear is possibly an exhaust leak that is exacerbated when exhaust is warmed up and when shifting because it "blips" the throttle.

[Blackedout86]

Originally Posted by 86TOYO2k17

Your coolant will have nothing to do with this.

so you followed the leveling procedure exactly?

A data log is one of the best tools for finding and narrowing down mechanical issues. not just tune issues. Regardless stock tune or not. It is a good starting place. Not to mention you said you are using stock tune with aftermarket header and no cats?

what piggyback where you using?

Using tires that are so far off from normal stock diameter tires and especially different diameter front and rear. Can cause the ecu to calculate thing weirdly causing weird issues. Especially how the ecu calculates torque values for the AT shifts. When did you get these tires in correspondence to noticing this issue?

also you have an NA auto 86 with 10% taller tire (which presumably is pretty heavy vs stock wheel/tire) you just don't have any power now in 4th gear with 10% taller tire, your mechanical torque to the wheels is so low now any incline in the road and or gust of strong head wind can actually cause you to temporarily decelerate especially between shifts specifically 3-4.

The only noise i hear is possibly an exhaust leak that is exacerbated when exhaust is warmed up and when shifting because it "blips" the throttle.

i forgot exactly how since it was last year, but it was something like 3x fill and drain, according to the complete atf guide on this forum. I will try to get data log from my tuner for accurate results, but it takes some time, in the mean time i'll try to find any exhaust leaks.

im using dastek unichip, and yes the tyres mess up those things but i can barely feel it, and they were replaced just last month, this problem much longer than that. i was using 225/40/18 before.

The rpm drop was more like the car hesitated to rev and held for a few seconds, because i also tried WOT on downhill roads, it still occurs always after shifting at high rpm, not necessarily redline shifting. but after that it accelerates just fine, going up all the way to 210kmh+ on speedo (prob. 225 actual).

It goes like (roughly) : WOT 3rd gear =>shift to 4th on 7,2k rpm which drops to 4,5k =>going UP to 4,8k then boom it drops back to 4,5k => Going up again normally

not to mention the awful intake growl sound from 4k rpm and up.

[86TOYO2k17]

Originally Posted by Blackedout86

i forgot exactly how since it was last year, but it was something like 3x fill and drain, according to the complete atf guide on this forum. I will try to get data log from my tuner for accurate results, but it takes some time, in the mean time i'll try to find any exhaust leaks.

im using dastek unichip, and yes the tyres mess up those things but i can barely feel it, and they were replaced just last month, this problem much longer than that. i was using 225/40/18 before.

The rpm drop was more like the car hesitated to rev and held for a second or two, because i also tried WOT on downhill roads, it still occurs always after shifting at high rpm, not necessarily redline shifting. but after that it accelerates just fine, going up all the way to 210kmh+ on speedo (prob. 225 actual)

The leveling procedure is different then just drain and fill x times, it requires getting the trans to a specific temperature range (between 108f-117f) and then leveling it to the specifications by pulling the leveling plug. Not something you would really forget if you did it or not.

A datalog could help narrow this down a lot, either finding the issue, or eliminating several possibilities.

You can also tune how the Auto shifts, making it shift quicker, and bite harder/firmer, etc.. Alternatively an upgrade valve body will accomplish this as well, but even more so.

Depending on mileage and how you drive it is possible clutch packs could be wearing and slipping. but i think something else is at play here.

[Blackedout86]

Originally Posted by 86TOYO2k17

The leveling procedure is different then just drain and fill x times, it requires getting the trans to a specific temperature range (between 108f-117f) and then leveling it to the specifications by pulling the leveling plug. Not something you would really forget if you did it or not.

A datalog could help narrow this down a lot, either finding the issue, or eliminating several possibilities.

You can also tune how the Auto shifts, making it shift quicker, and bite harder/firmer, etc.. Alternatively an upgrade valve body will accomplish this as well, but even more so.

Depending on mileage and how you drive it is possible clutch packs could be wearing and slipping. but i think something else is at play here.

i took the car to my regular workshop for the atf change, i showed the complete DIY atf change on this forum to them and asked to follow it completely including the levelling, which as far as i remembered they did.

If it means anything, i just remembered the car went on limp mode once because of backfiring tune (which apparently this car hates so much), and the car goes exactly like the video, minus the CEL. after clearing the code it went back to normal after a few hours, and it never happened again until this problem occured some 2years ago.

Also in limp mode, the car held back when downshifting, similar to fully disengaging the clutch on a manual car on high rpm, but it doesnt happen on my current problem.

So basically my car is in constant limp mode minus CEL and hard downshifting kickback.