Have you experienced a misfire like mine?

[Stinky]

Hello, Im Andrew. I have a 2016 ST (58k miles) with an s280 turbo, HPFP upgrade and injectors, FBO, and I’ve been having a misfire issue under WOT for months. I have tried getting new coil packs (NGK, one failed recently after being used for maybe 3k miles), I’ve gotten my intake valves and throttle body cleaned, compression is good, gas is good, all temps are good. I have step colder iridium plugs (less than 3k miles on them), I’ve tried .028 (undrivable, misfires in every gear at any boost), .026 (only misfires in 4-5-6), .025 (4-5-6), .024 (4-5-6), .022 (more misfires than .026, but still 4-5-6), .019 (about the same as .022). Car seemed to misfire much less after getting my valves and TB cleaned, and I should also mention the misfire seems to get worse after the engine gets warmer. Dizzy tuning can’t see the issue on their end, and my mechanic wasn’t able to find the issue yet. If anyone has any advice for me that would be great, I don’t wanna spend any more money on fruitless diagnostic. Thank you!

 

[TyphoonFiST]

Hello, Im Andrew. I have a 2016 ST (58k miles) with an s280 turbo, HPFP upgrade and injectors, FBO, and I’ve been having a misfire issue under WOT for months. I have tried getting new coil packs (NGK, one failed recently after being used for maybe 3k miles), I’ve gotten my intake valves and throttle body cleaned, compression is good, gas is good, all temps are good. I have step colder iridium plugs (less than 3k miles on them), I’ve tried .028 (undrivable, misfires in every gear at any boost), .026 (only misfires in 4-5-6), .025 (4-5-6), .024 (4-5-6), .022 (more misfires than .026, but still 4-5-6), .019 (about the same as .022). Car seemed to misfire much less after getting my valves and TB cleaned, and I should also mention the misfire seems to get worse after the engine gets warmer. Dizzy tuning can’t see the issue on their end, and my mechanic wasn’t able to find the issue yet. If anyone has any advice for me that would be great, I don’t wanna spend any more money on fruitless diagnostic. Thank you!

Dies the check engine/ MIL light illuminate?? IF SO are there any codes?

Sent from my SM-S908U1 using Tapatalk

 

[Stinky]

Dies the check engine/ MIL light illuminate?? IF SO are there any codes?

Sent from my SM-S908U1 using Tapatalk

No codes, never had any either. Maybe I should also mention my car is currently making 32-33 psi and I am on e40, tune is not finished. The misfire first started some time at the end of last summer, and I was on 93 then.

 

[TyphoonFiST]

No codes, never had any either. Maybe I should also mention my car is currently making 32-33 psi and I am on e40, tune is not finished. The misfire first started some time at the end of last summer, and I was on 93 then.

Is it WOT....When it happens? Is it catted? Have the O2 sensors been changed lately?

Sent from my SM-S908U1 using Tapatalk

 

[Jabbit]

I'd try new plugs.

 

[TyphoonFiST]

I'd try new plugs.

I buy mine from Rockauto....change every 10k

Sent from my SM-S908U1 using Tapatalk

 

[the duke]

How do you know the fuel is good.

 

[Stinky]

I'd try new plugs.

I have tried new plugs, multiple sets of iridium and ruthenium, and many different gaps.

 

[Stinky]

How do you know the fuel is good.

I can't be certain it is good, but I have a few reasons to think it is not bad fuel. For one, I use an ethanol blend and I have a sensor and a gauge, so I know my blend is consistent and such. I also have always used the same gas, and I had no issues with it last summer. I noticed no difference when I tried using gas from many of the other stations around my area. I go to kroger to get 93 and e85.

 

[Stinky]

I buy mine from Rockauto....change every 10k

Sent from my SM-S908U1 using Tapatalk

Got mine from whoosh

 

[Stinky]

Is it WOT....When it happens? Is it catted? Have the O2 sensors been changed lately?

Sent from my SM-S908U1 using Tapatalk

Wot, and a lot of times even at partial throttle in 4th-5th-6th gear at high rpms. I have a catless DP and a o2 sensor defouler, and as far as I know, the sensors are factory.

 

[TyphoonFiST]

Wot, and a lot of times even at partial throttle in 4th-5th-6th gear at high rpms. I have a catless DP and a o2 sensor defouler, and as far as I know, the sensors are factory.

Mileage?

Sent from my SM-S908U1 using Tapatalk

 

[Stinky]

Mileage?

Sent from my SM-S908U1 using Tapatalk

58k miles

 

[TyphoonFiST]

What's the Low Side Fuel pump pressure doing when this happens? What is its High and low pressure?

Sent from my SM-S908U1 using Tapatalk

 

[TyphoonFiST]

What intercooler are you running? What are the intake Temps when the "misfiring" starts to happen?

Sent from my SM-S908U1 using Tapatalk

 

[Stinky]

I only have third gear logs, and after getting my valves cleaned the misfire stopped happening in third, but it stays around 100 psi at WOT in 3rd, lowest was 97, highest was 106. AFR stays around 12-12.3. Charge air temps are close to ambient and FRP is between 2500 and 2900.

 

[rcnut14]

I would get a second opinion on the datalogs/tune if it were me.

Not saying it's Jason's fault, he knows his stuff, but it doesn't hurt to have a fresh set of eyes looking it over.

 

[Stinky]

I will get some 4th gear logs next time I have the chance, the misfire in 4th usually happens at 6000 rpm or so, and it makes the car stop accelerating almost like hitting a hard cut rev limiter.

 

[TyphoonFiST]

I'd be running a Richer mixture* seems pretty lean too me.

Sent from my SM-S908U1 using Tapatalk

 

[Stinky]

I would get a second opinion on the datalogs/tune if it were me.

Not saying it's Jason's fault, he knows his stuff, but it doesn't hurt to have a fresh set of eyes looking it over.

I have had a local mechanic and someone online look at the logs, and they both said they didnt see anything strange.