2018 Sti Stock Stumbles in WOT

[SDblitz858]

Hello Fam!

So I am new to this site (WOW)and also to this platform. It is my first Subaru and a lot of my friends and co-workers drive them so i wanted to experience a big boy enthusiast car also. But now I come across a problem. ..

2018 Subaru WRX Sti, STOCK 100% 19K miles again NO mods.

Regular driving city/highway it is fine cool and fun nothing is wrong at all but when i WOT around 4500-5500rpm 2nd,3rd,4th gear, it doesn't have that smooth acceleration, it jumps, it seems like it stumbles/hesitates/choke? like I'm hitting a dead wall, the rpms climb slowly after that, partial throttle no issues of that. I have searched this forum and other forums talked to other Sti enthusiast and nothing.

I do get it i still have warranty gold plus but this thing is driving me crazy/nuts. Sti is so fun to drive. Need your help guys.

Also, I know the stock tune blows. people just tell me to get AP and it'll fix it. but i want to keep it stock and be able to WOT anytime I want and enjoy the STI as is.

 

[Eagleye]

I'm surprised you found no info in searching or talking with other owners. If you are referring to what I think you are, this is fairly common on the stock tune. It sounds odd to say, but the stock tune leans out in that area. It has been speculated that it was for emissions purposes but I do not know for sure. There are several fixes you can do. All involve fuel system modifications or tuning through modifying the fueling tables or using an OTS tune from COBB for their AccessPort. You could certainly try taking it to the dealer, they will likely reflash the ECU. It may or may not improve from doing that.

 

[_Broken_WRX_]

Maybe fuel delivery? Only thing I can think would be to clean injectors and change your fuel filter. Hope you get it figured out soon.


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[SDblitz858]

I'm surprised you found no info in searching or talking with other owners. If you are referring to what I think you are, this is fairly common on the stock tune. It sounds odd to say, but the stock tune leans out in that area. It has been speculated that it was for emissions purposes but I do not know for sure. There are several fixes you can do. All involve fuel system modifications or tuning through modifying the fueling tables or using an OTS tune from COBB for their AccessPort. You could certainly try taking it to the dealer, they will likely reflash the ECU. It may or may not improve from doing that.

I have been reading all day about this problem back and fort from google/NASIOC/igotasti/Facebook ej or bust and other sub forums lol. its driving me nuts! normal driving she is fast! especially in S# but once i get on WOT 4500-6500 hek it dont even reach 6500rpm i stop it around 5500 cuz its that bad. its like loosing top end power. its kind of like hitting a rev limiter/choking/hesitates to go faster n reach redline. its not smooth.

 

[Eagleye]

I have been reading all day about this problem back and fort from google/NASIOC/igotasti/Facebook ej or bust and other sub forums lol. its driving me nuts! normal driving she is fast! especially in S# but once i get on WOT 4500-6500 hek it dont even reach 6500rpm i stop it around 5500 cuz its that bad. its like loosing top end power. its kind of like hitting a rev limiter/choking/hesitates to go faster n reach redline. its not smooth.

Yeah, I would be taking that in to the dealer. That does not sound like what I was explaining. I would suspect something is reducing your fuel flow, whether that is a partially clogged fuel filter or dirty/improperly functioning injectors I couldn't say. Has it been like this since Day 1 of your ownership? If not, have you ever allowed the fuel level to get pretty low, under 50 miles to empty? Sometimes your pump can draw debris from the bottom of the tank up into the filter if you let the fuel tank level get low enough.

 

[SDblitz858]

Yeah, I would be taking that in to the dealer. That does not sound like what I was explaining. I would suspect something is reducing your fuel flow, whether that is a partially clogged fuel filter or dirty/improperly functioning injectors I couldn't say. Has it been like this since Day 1 of your ownership? If not, have you ever allowed the fuel level to get pretty low, under 50 miles to empty? Sometimes your pump can draw debris from the bottom of the tank up into the filter if you let the fuel tank level get low enough.

Sadly i just got this car 8days ago from subaru of el cajon in sandiego. pre owned. had a good carfax all maintenance done from dealership and all. always gassed up didnt even try going WOT until yesterday. even my daughters and son said ?wtf was that dad? lol ?ur car shaking dad?

 

[Eagleye]

Sadly i just got this car 8days ago from subaru of el cajon in sandiego. pre owned. had a good carfax all maintenance done from dealership and all. always gassed up didnt even try going WOT until yesterday. even my daughters and son said ?wtf was that dad? lol ?ur car shaking dad?

Yeah I would stop asking questions on the internet and take that thing back in. Be sure to detail exactly what is going on. Good luck, and let us know what they do for you.

 

[IGOTASTi]

We can chime in here.

Our 2018 Hyper Blue STi had the same thing happen. It went back to the dealership for a recall to update the tune. After we got it back it was better but flashed it stage 1 with a Cobb Accessport and it ran way better!

 

[SDblitz858]

Yeah I would stop asking questions on the internet and take that thing back in. Be sure to detail exactly what is going on. Good luck, and let us know what they do for you.

I will update the page for sure for future reference for other people in the future. Thanks alot. few hours ill be heading to stealership. i hope they dont say the infamous ? we cant replicate your problem ? i havnt been in any stealership service in yearssss.

 

[Eagleye]

I will update the page for sure for future reference for other people in the future. Thanks alot. few hours ill be heading to stealership. i hope they dont say the infamous ? we cant replicate your problem ? i havnt been in any stealership service in yearssss.

Sounds good. Ask if one of their mechanics/service manager would be willing to ride with you so you can demonstrate the issue. I have done this with the dealership I work with. It allows you to explain the issue directly and show them what is going on. As [MENTION=1]IGOTASTi[/MENTION] mentioned, your issue may get better but not go away until you bite the bullet and get an AccessPort tune for it. It is a sad situation honestly where we feel the need to spend $600+ to fix a factory issue, but that fix voids your warranty...righhhhtttt. :roll:

 

[SDblitz858]

We can chime in here.

Our 2018 Hyper Blue STi had the same thing happen. It went back to the dealership for a recall to update the tune. After we got it back it was better but flashed it stage 1 with a Cobb Accessport and it ran way better!

Hey thanks for chiming in!! i appreciate that! uou had same thing happen? wow , do i tell them they need to update the Si Drive tune or something? what recall is that? and did you leave your car overnight for them to fix it?

 

[SDblitz858]

We can chime in here.

Our 2018 Hyper Blue STi had the same thing happen. It went back to the dealership for a recall to update the tune. After we got it back it was better but flashed it stage 1 with a Cobb Accessport and it ran way better!

Where can i find this recall? i dont see it anywhere.

 

[Alin]

Is this the same fuel stumble problem that the GR's have or is this a whole new issue that the 2015+ models have?

 

[Eagleye]

Is this the same fuel stumble problem that the GR's have or is this a whole new issue that the 2015+ models have?

I thought he was referring to that problem as well, but what he is explaining sounds like a bigger fueling issue.

 

[Alin]

Since he bought a used car, the realm of possibility exists that the car was modded in some way, form or fashion and the dealer didn't catch it. We can't assume, but we can't prove nor deny either. I don't have enough knowledge on 08+ with their multiple driving modes. Then, there's the case if the 08-10,11-14,15-17, and 18+ all have different parameters of their own built into the driving modes.

The GR fuel stumble is what, 3,400-4,400 RPM?
[MENTION=6944]SDblitz858[/MENTION] , in which driving modes have you attempted WOT? I also don't want to assume, but the car is properly warmed up as well before you attempt WOT, correct?

 

[SDblitz858]

Since he bought a used car, the realm of possibility exists that the car was modded in some way, form or fashion and the dealer didn't catch it. We can't assume, but we can't prove nor deny either. I don't have enough knowledge on 08+ with their multiple driving modes. Then, there's the case if the 08-10,11-14,15-17, and 18+ all have different parameters of their own built into the driving modes.

The GR fuel stumble is what, 3,400-4,400 RPM?
@SDblitz858 , in which driving modes have you attempted WOT? I also don't want to assume, but the car is properly warmed up as well before you attempt WOT, correct?

Hey! appreciate the response sir! yea the GR fuel stumble is around that rpm. I have done. I,S,S# offkourse the car is warmed up properly and also before i get on it im around 3500-4000rpm before i WOT. im at stealership right now waiting for someone to drive with me so they can replicate the problem. im amazed how helpful this forum is. just wow.

 

[Eagleye]

Hey! appreciate the response sir! yea the GR fuel stumble is around that rpm. I have done. I,S,S# offkourse the car is warmed up properly and also before i get on it im around 3500-4000rpm before i WOT. im at stealership right now waiting for someone to drive with me so they can replicate the problem. im amazed how helpful this forum is. just wow.

Stick around and spread the word. We'd like to hear more about your car outside of its problems haha. Post up pictures if you haven't already.

 

[Alin]

Hey! appreciate the response sir! yea the GR fuel stumble is around that rpm. I have done. I,S,S# offkourse the car is warmed up properly and also before i get on it im around 3500-4000rpm before i WOT. im at stealership right now waiting for someone to drive with me so they can replicate the problem. im amazed how helpful this forum is. just wow.

Then, we'll wait for you to finish up at the stealership and report back to us as to what they say!

 

[SDblitz858]

Then, we'll wait for you to finish up at the stealership and report back to us as to what they say!

UPDATE - Drove with a subaru specialist, replicated the issue in i S S# mode. thank you for the advise. Now the waiting of diagnostics. he was saying it felt like misfiring, might be coil packs/sparkplugs or a ecu flash is needed like what some1 advised earlier. Also i have no engine light or whatsoever. Ill keep you guys posted.

 

[SDblitz858]

Stick around and spread the word. We'd like to hear more about your car outside of its problems haha. Post up pictures if you haven't already.

offkourse i will stick around! just waiting here in stealership. might get lyft to comeback to work tho.