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Misfire after Unitronic Stage 2 IS20

StorableComa

Autocross Champion
Location
Long Beach, USA
Car(s)
17 GSW S
OP, did you notice any issues with hesitation shifting from 3rd to 4th prior, or notice a hesitation on the shift that threw the CEL?

1.8T AQ250/09G 6spd Slush here too with IE stage 1. I've had something very similar to what you're describing to me happen to me once, and have yet to be able to repeat it.

Noticed while playing with the kickdown switch on the freeway in 'S' there seemed to be a delay or hesitation/buck when I'd let it roll out to 6.7k. So mashed it, let off, mashed it.. 3rd time the hesitation was worse and then BOOM EPC light, car is running like crap. I've got no power and it's trying to run out second at 4k. Limp to the side of the road to restart and the EPC is gone, power returns and she drives just fine on the way home.

Scanned codes I had misfires on Cyl 3 and 4, Cyl deactivation, Some implausible codes from the tranny. Cleared codes and have yet to be able to get it to return. Though I do notice it will still occasionally hesitate if I let it run out past 6.4kish. I've personally just got a feeling the Slush box doesn't like be running out longer toward the redline with power behind it, and the slush does have a built in torque limiter that causes issues with some tunes from what i've read/been told.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
OP, did you notice any issues with hesitation shifting from 3rd to 4th prior, or notice a hesitation on the shift that threw the CEL?

1.8T AQ250/09G 6spd Slush here too with IE stage 1. I've had something very similar to what you're describing to me happen to me once, and have yet to be able to repeat it.

Noticed while playing with the kickdown switch on the freeway in 'S' there seemed to be a delay or hesitation/buck when I'd let it roll out to 6.7k. So mashed it, let off, mashed it.. 3rd time the hesitation was worse and then BOOM EPC light, car is running like crap. I've got no power and it's trying to run out second at 4k. Limp to the side of the road to restart and the EPC is gone, power returns and she drives just fine on the way home.

Scanned codes I had misfires on Cyl 3 and 4, Cyl deactivation, Some implausible codes from the tranny. Cleared codes and have yet to be able to get it to return. Though I do notice it will still occasionally hesitate if I let it run out past 6.4kish. I've personally just got a feeling the Slush box doesn't like be running out longer toward the redline with power behind it, and the slush does have a built in torque limiter that causes issues with some tunes from what i've read/been told.
Yes. Tested again tonight, if I get into boost and then shift earlier than 5k rpm, its almost as though the car vibrates breifly (misfire) and then keeps going normally in 4th gear.

BUT, ff I even let it go to 5000 or 5500rpm under boost and shift with the triptronic, boom - hesitation, and then EPC and limp mode.

Trying to wrap my head around how it could be a stock inlet elbow and intake causing the WG duty cycle to go that high, and then cause misfire codes.. (according to Unitronic). They basically told me to upgrade those items as that’s the cause, but part of me has a hard time believing thats all it is.

I‘m about ready to go back to normal Stage 2 with my stock is12 when I had no issues. Although, now worried this problem will follow me regardless! I need some luck...
 

ZuMBLe

Autocross Champion
Location
NY
Car(s)
Alltrack 6MT
Yes. Tested again tonight, if I get into boost and then shift earlier than 5k rpm, its almost as though the car vibrates breifly (misfire) and then keeps going normally in 4th gear.

BUT, ff I even let it go to 5000 or 5500rpm under boost and shift with the triptronic, boom - hesitation, and then EPC and limp mode.

This sounds tune related. If Unitronic doesn't have a requirement to run their tune with upgraded inlet and intake, they need to fix their tune if you really do need those to run the tune. It makes zero sense to put out a tune that will throw a EPC and misfire codes because the stock TIP is in there. I now officially hate Uni like I hate IE. They are both jokes of software tuners. They should both stick to hardware.

EDIT: Edit because I'm so heated about this. The limp mode EPC is so fucking dangerous. Any tuner that puts out a OTS tune that throws a limp EPC because some stupid part is missing in the intake, can go fuck themselves. Go die in a fire.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
This sounds tune related. If Unitronic doesn't have a requirement to run their tune with upgraded inlet and intake, they need to fix their tune if you really do need those to run the tune. It makes zero sense to put out a tune that will throw a EPC and misfire codes because the stock TIP is in there. I now officially hate Uni like I hate IE. They are both jokes of software tuners. They should both stick to hardware.

EDIT: Edit because I'm so heated about this. The limp mode EPC is so fucking dangerous. Any tuner that puts out a OTS tune that throws a limp EPC because some stupid part is missing in the intake, can go fuck themselves. Go die in a fire.
Unitronic’s website does list a turbo inlet and an intake as “required” for this stage tune. And at this point, I basically have to upgrade those two if I want them to continue helping me out.

for some reason I have doubts about that solving my issue, but it’s my next step nonetheless
 

ZuMBLe

Autocross Champion
Location
NY
Car(s)
Alltrack 6MT
Unitronic’s website does list a turbo inlet and an intake as “required” for this stage tune. And at this point, I basically have to upgrade those two if I want them to continue helping me out.

for some reason I have doubts about that solving my issue, but it’s my next step nonetheless

Okay that sounds like a rip off. I ran a APR IS20 tune with a stock inlet and filter. Never had a EPC or anything like that.
 

StorableComa

Autocross Champion
Location
Long Beach, USA
Car(s)
17 GSW S
Unitronic’s website does list a turbo inlet and an intake as “required” for this stage tune. And at this point, I basically have to upgrade those two if I want them to continue helping me out.

for some reason I have doubts about that solving my issue, but it’s my next step nonetheless
Just get an aFE dry drop in filter and call it day. If you want to go above and beyond you can replace the airbox hose with something wider.

My 2 cents on the intake upgrade.
 
Last edited:

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Unitronic’s website does list a turbo inlet and an intake as “required” for this stage tune. And at this point, I basically have to upgrade those two if I want them to continue helping me out.

for some reason I have doubts about that solving my issue, but it’s my next step nonetheless
You're right. It's too bad you have to do that just to play their game.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
Does anyone here think it could be anything to do with the PCV system causing the misfire under boost while shifting? Car has 45,000km (28,000 miles).

Briefly read about it, and someone mentioned to remove oil cap when engine is running and the engine should begin to stumble, which it does.
 

tigeo

Autocross Champion
Ok, I'm lost at this point in terms of the timeline w/r to the upgrades, tunes, etc. Uni has lots of tunes out there with no drama but certainly isn't playing nice here. I have to believe this is a hardware issue specific to the OPs ride at this point - turbo? boost leak? other? I recommended trying a few gal of E85 b/c I know through experience that their tunes aren't happy on some winter blend fuels but that is sorted now. It's happening only at this shift. There were no issues on the IS12/Stage 2 file. The turbo inlet/intake should have zero to do with this as a bazillion folks have run all manner of tuned 1.8s with stock intakes or the modified-stock jobs with no drama so that doesn't pass my sniff-o-meter. I believe this was recommended to another user that had some tune issues and it didn't sort it (of course).
 

tigeo

Autocross Champion
He said it was on an emix already.
Yes I am aware - that was b/c I recommended trying that. Just stating that it didn't fix it.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
Ok, I'm lost at this point in terms of the timeline w/r to the upgrades, tunes, etc. Uni has lots of tunes out there with no drama but certainly isn't playing nice here. I have to believe this is a hardware issue specific to the OPs ride at this point - turbo? boost leak? other? I recommended trying a few gal of E85 b/c I know through experience that their tunes aren't happy on some winter blend fuels but that is sorted now. It's happening only at this shift. There were no issues on the IS12/Stage 2 file. The turbo inlet/intake should have zero to do with this as a bazillion folks have run all manner of tuned 1.8s with stock intakes or the modified-stock jobs with no drama so that doesn't pass my sniff-o-meter. I believe this was recommended to another user that had some tune issues and it didn't sort it (of course).
They are saying that basically the stock inlet and intake aren’t flowing enough to the turbo, causing the WG duty cycle to go full bore (closed to try and hold boost) during the shift, and then causing a misfire. I’m just not sure I fully understand how that relates to a misfire only on shift. I’m about to spend a bunch of money on an inlet and intake, and I just have a hunch I’ll be stuck with something I hadn’t intended or budgeted at this point, and my issue will remain. At that point, I’ll be calling it a day and going back to is12. The issue is dragging out and I’ve been spending too much time on it. Only other thing I can think of is the PCV system
 

tigeo

Autocross Champion
They are saying that basically the stock inlet and intake aren’t flowing enough to the turbo, causing the WG duty cycle to go full bore (closed to try and hold boost) during the shift, and then causing a misfire. I’m just not sure I fully understand how that relates to a misfire only on shift. I’m about to spend a bunch of money on an inlet and intake, and I just have a hunch I’ll be stuck with something I hadn’t intended or budgeted at this point, and my issue will remain. At that point, I’ll be calling it a day and going back to is12. The issue is dragging out and I’ve been spending too much time on it. Only other thing I can think of is the PCV system
I'm with you/understand - I just can't see how those will change a thing. An inlet is super cheap (CTS) or similar (that's what I run) and is a great upgrade anyway. The rest could be handled with a modified stock setup - K&N/high-flow filter, snow guard delete, and a silicone inlet hose.
 
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