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Misfire after Unitronic Stage 2 IS20

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
Another misfire thread!

I was previously on Unitronic Stage 2 (downpipe and intercooler upgrades only) and never had an EPC light.

Just installed a basically brand new IS20 turbo and flashed to the Unitronic Stage 2 IS20 file, and now got an EPC light and some codes under boost:
Cyl 1 Misfire Detected P030100 (intermittent)
Cyl 3 Misfire Detected P030300 (Static)

Figured it might be bad plugs after 44,000 km (27,000 miles).
Bought some new NGK PLFER7A8EG plugs in, gapped to .025.
Seems to run better overall, did some pulls and it seemed okay. But then went to do a highway pull in 3rd and now have a code for Cyl 4 Misfire P030400 (intermittent).

Before spending money to try new Coils, does anyone have any suggestions as to what could be causing this after an IS20 install and tune?
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Another misfire thread!

I was previously on Unitronic Stage 2 (downpipe and intercooler upgrades only) and never had an EPC light.

Just installed a basically brand new IS20 turbo and flashed to the Unitronic Stage 2 IS20 file, and now got an EPC light and some codes under boost:
Cyl 1 Misfire Detected P030100 (intermittent)
Cyl 3 Misfire Detected P030300 (Static)

Figured it might be bad plugs after 44,000 km (27,000 miles).
Bought some new NGK PLFER7A8EG plugs in, gapped to .025.
Seems to run better overall, did some pulls and it seemed okay. But then went to do a highway pull in 3rd and now have a code for Cyl 4 Misfire P030400 (intermittent).

Before spending money to try new Coils, does anyone have any suggestions as to what could be causing this after an IS20 install and tune?
Before you buy coils move the cylinder 4 coil to a different cylinder and see if the misfire follows it.
 

tigeo

Autocross Champion
Uni tunes are sensitive to fuel quality. Try a few gal of E85. I know this through experience....winter blend fuel could be the culprit.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
Uni tunes are sensitive to fuel quality. Try a few gal of E85. I know this through experience....winter blend fuel could be the culprit.
Interesting. I guess that could be a possibility... our “Chevron 94” here in Vancouver Canada has actually been proven to really suck.
 

jeffdemara

Passed Driver's Ed
Location
Vancouver, BC
Cleared the codes, swapped cyl 4 coil with cyl 2.

The EPC light came on and went into limp mode during a pull, but only when I shifted from 3rd to 4th at about 6000rpm. From 3000 to 6000rpm held boost fine and pulled great.

Now it shows misfire cyl 1 and 2, and “random/multiple cylinder”
 

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tigeo

Autocross Champion
Cleared the codes, swapped cyl 4 coil with cyl 2.

The EPC light came on and went into limp mode during a pull, but only when I shifted from 3rd to 4th at about 6000rpm. From 3000 to 6000rpm held boost fine and pulled great.

Now it shows misfire cyl 1 and 2, and “random/multiple cylinder”
Try some E....it's easy (if you have it available). 2 gal.
 

CaptainRatty

Drag Racing Champion
Location
Winston-Salem, NC
Car(s)
MK7 GTI
Interesting. I guess that could be a possibility... our “Chevron 94” here in Vancouver Canada has actually been proven to really suck.
And other tuners have said exactly that about Chevron fuels.
 

tigeo

Autocross Champion
And other tuners have said exactly that about Chevron fuels.
Folks always assume misfires = plugs/coils (which it certainly can be) but I've had the same issue with knock and the ECU/tune adjusting for it by running richer to cool it down until which point it taps out and goes into limp mode. Running 2 gal of E85 is so easy to try.
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
I think the problem stems from the tune. OP what is your actuator voltage?
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Yes. Which should be plenty enough for this tune according to many who have been running it for a long time. And my car has low kms, so nothing should be tired or worn out yet.
All I can tell you is that when I got an EPC light it was because the HPFP I added wasn't properly tuned for.
 

TwinDad

Drag Racing Champion
Location
Fort Lee, NJ
All I can tell you is that when I got an EPC light it was because the HPFP I added wasn't properly tuned for.
You also didn't get an EPC for misfires. Not sure why we are looking at fuel pumps and actuator voltage when he has misfire codes. It's pretty common in the Uni tunes to misfire with bad fuel quality.
Your hpfp issue can be solved easily with a tune from Reflect. A few of us went down the hpfp road a couple of years back to test it out and see what the issues were with it. Then Ian was able to work it out and make it work
 
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