Turbo BRZ strange driving issue has me stumped..

[Olson1288]

So I have an issue I've been chasing for a while now with no success. 2014 BRZ with a SBD turbo kit, car has around 100k miles and has had zero issues with the turbo kit being on for nearly 40k miles now.


I'm running into an issue where while driving, the car will stumble/surge pretty bad around 2.5-3k rpm. Vacuum/AFR's fluctuate hard while this happens, and seems to happen regardless of how light or heavy I am on the throttle. I am still able to drive the car carefully, but after around 10-15 minutes, the throttle almost stops responding completely, as if in limp mode. I was forced to pull over, and I was able to disconnect the battery and let the ECU reset, which allowed me to get it home (original issue still persisted however, just no more "limp mode").


The car has never once thrown any sort of CEL or any other light, even when the "limp mode" comes in, if that's what that was. Now the strange part, this only happens to me after driving somewhere and allowing the car to sit. I can start her up in the morning, drive 20 minutes to work or the gym and she will drive/pull perfectly. After sitting for 2 hours at the gym, the car will begin to stumble on the way home. Also, the car is able to idle perfectly, pulling normal vacuum + normal AFR's.


I have thoroughly checked for vacuum/boost leaks, cleaned the MAF, checked for any sort of injector or fuel leak, and I am honestly at a loss as to what is causing this issue, as it literally appeared out of nowhere. Car has been running perfect with the same tune for ~2 years, so I know it's not a tuning issue. I don't know if it could be an O2 sensor or something, but I would think the car would throw a code if that was the case. I plan to replace the MAF even though it has been cleaned and looks fine. I honestly don't know what else to do.


Also, it doesn't feel like a misfire, as I've dealt with that in the past. Car has aftermarket coil packs + OEM plugs that only have around 15k miles on them.



If anyone has any thoughts or ideas, anything else I could check, I'd truly appreciate it. I don't have much money to randomly throw at parts in an attempt to fix this unfortunately.

[DarkPira7e]

I had a similar issue with my turbo car and it was a coil pack - passenger side, closest to the front of the car. Mine happened in the same range, neutering interstate merges.

"Aftermarket coils", what brand? I know it seems silly but I would stick stock coils back in to see what happens.

[Olson1288]

Originally Posted by DarkPira7e

I had a similar issue with my turbo car and it was a coil pack - passenger side, closest to the front of the car. Mine happened in the same range, neutering interstate merges.

"Aftermarket coils", what brand? I know it seems silly but I would stick stock coils back in to see what happens.

I knew I would get some flak for saying “aftermarket” coils lol, they were from Delicious Tuning. Supposedly they have a higher heat range vs stock, but now I’m beginning to wonder if perhaps I should have just replaced them with new OEM coils. I’m not ruling out that it could be a bad coil pack, it just doesn’t feel like a misfire and I’ve never had a CEL but it could be. It’s definitely on the list of things to possibly swap, just wish they weren’t so expensive.

[dragoontwo]

Would upgrading to the 15+ coils be a help in this application?

Also, hi neighbor!

[Olson1288]

Originally Posted by dragoontwo

Would upgrading to the 15+ coils be a help in this application?

Also, hi neighbor!

Hey! I honestly haven’t thought about getting the “upgraded” coil packs from a newer model, but I have heard they are more reliable. I’m just not 100% sure if all I’d need is some sort of wiring adapter or what.

[dragoontwo]

Originally Posted by Olson1288

Hey! I honestly haven’t thought about getting the “upgraded” coil packs from a newer model, but I have heard they are more reliable. I’m just not 100% sure if all I’d need is some sort of wiring adapter or what.

There is an adapter harness out there to make it plug and play.

[Olson1288]

Originally Posted by dragoontwo

There is an adapter harness out there to make it plug and play.

I might try new coils if it comes down to that, but the current ones on there only have 10k miles. Just don’t want to spend $400+ and have that not be the issue ya know 😞

[DarkPira7e]

After re-reading your post, you say you're not getting a CEL, but have you checked for stored DTCs? I am assuming ECUtek is how your car is tuned based on your post history.



The tuner may have hidden some codes to help with emissions / peace of mind. I wonder if you have a p0016 or something the tuner disabled that is triggering limp mode, but won't illuminate the light.


Can you check stored DTCs next time you start the car please?

[Olson1288]

Originally Posted by DarkPira7e

After re-reading your post, you say you're not getting a CEL, but have you checked for stored DTCs? I am assuming ECUtek is how your car is tuned based on your post history.



The tuner may have hidden some codes to help with emissions / peace of mind. I wonder if you have a p0016 or something the tuner disabled that is triggering limp mode, but won't illuminate the light.


Can you check stored DTCs next time you start the car please?

First time checking for DTC's but I busted out the ol' laptop and used the vehicle DTC function in ProECU which I'm assuming was the correct method, but the only thing I saw was a B1693 airbag DTC, which is weird because I have no knowledge of any sort of airbag issue so I cleared that. No other DTC's were found.


Also got in contact with Delicious Tuning and they were nice enough to provide me with an RMA for my old coil packs, and are going to be sending me some new ones so that's pretty cool. I'm still not entirely convinced that is the issue here considering the current one's have around 10k miles but it's possible, guess I will find out soon when they arrive and I swap them in.

[DarkPira7e]

Originally Posted by Olson1288

First time checking for DTC's but I busted out the ol' laptop and used the vehicle DTC function in ProECU which I'm assuming was the correct method, but the only thing I saw was a B1693 airbag DTC, which is weird because I have no knowledge of any sort of airbag issue so I cleared that. No other DTC's were found.


Also got in contact with Delicious Tuning and they were nice enough to provide me with an RMA for my old coil packs, and are going to be sending me some new ones so that's pretty cool. I'm still not entirely convinced that is the issue here considering the current one's have around 10k miles but it's possible, guess I will find out soon when they arrive and I swap them in.

Glad to see there's nothing nasty in DTCs, hopefully the issue is something simple like those coil packs.

[Olson1288]

Well I swapped in 4 brand new coil packs yesterday, and unfortunately the issue still persists..


Drove it last night after replacing the coil packs, and everything seemed fine. Drove for like 45 minutes or so and the car was great, however I never turned it off during that process. Idled perfectly, drove fine, pulled fine.


Today I took the car to the gym (20 min drive) and it was perfect all the way there. Car sat for about 90 minutes, came out and started it up. Idled fine, but as I went to pull out of the parking lot, I had zero to little throttle response, once again as if in limp mode. I was able to shut it off, let it sit for a bit, and drive for maybe 5 minutes before the throttle response completely disappeared once again. This happened to me roughly 3 times on the way home, and I was almost to the point of calling a tow truck but I was able to get her home.


Car did not want to idle properly after this happened a few times, and would idle very poorly/die, but I was able to hold it at ~2k rpm and just go, and I got home. Definitely leads me to believe its some sort of fueling issue, but it still doesn't explain why it would drive fine and then only do this after sitting for some time. One thing to note, I use the torque app to read boost/afr (I know its not nearly as good as a dedicated/hard-wired gauge) and occasionally my boost gauge would shoot up to like 25 psi, as if over-boosting or something, but I definitely never felt such a surge in power at all. The vacuum/boost gauge would also randomly stop working for some time, and then re-appear as well.


I don't know if this could be some sort of sensor gone bad.. maybe fuel pressure sensor or something, honestly not sure anymore. Thought perhaps a bad injector but the car is fine sometimes, and awful at others. If anyone possibly has any other ideas to try or check out I'm all ears, but also don't have the cash to really just be buying random parts in hope that they fix the issue so idk. This issue just sucks

[CSG Mike]

Do you have a datalog?

[Olson1288]

Originally Posted by CSG Mike

Do you have a datalog?

Not at the moment, but I can try and get one. Only issue is that it’s gotten kinda sketchy to take the car out and drive, because I’ve had this throttle issue happen randomly in the middle of traffic, but I’ll drive near the house and see if I can duplicate the problem.

Starting to lean towards throttle position sensor possibly as that makes the most sense but not sure.

[Olson1288]

So I took two logs tonight, one "normal driving" log of around 15-20 minutes, and another log roughly 2 hours later also normal driving but where the issues start to persist. First log where the car was acting normal was slightly too large for datazap, so hopefully it is still usable through excel or something.


First log:


https://drive.google.com/file/d/1HJ4...ew?usp=sharing


Second log:


https://datazap.me/u/hoirc88/log-166...?log=0&data=31


Like previous drives, I was able to start the car and it idled/drove perfect for 20 minutes. I then parked it and left it sitting for about 2 hours. Second drive, idle was a bit hesitant at first but the car drove ok for a bit. Then the "hiccups" started occuring, idle would occasionally bounce around at stop signs/lights, and I had the throttle completely stop responding once about 10 minutes into the drive, but it almost instantly returned after pulling over.


Still can't wrap my head around why the car would drive perfect and then only act up after sitting for a while, but hopefully some of the information in these logs may help. Thank you!