Swapped intake, high knock control and check engine light after drive

[bay_hatch]

Flashed the car back to KTuner dual starter with the PRL Race MAF option selected.

Made a trip to the gas station to refill since i was at a quarter tank and figured it'll be good to do a data log.

I did a small pull on the highway ramp up to 4500 RPM and everything seemed to be ok. Came back to look at the log and it says that there is a misfire in cylinders 1,2, and 4. Should I be concerned?

@gtman, heres a link of the data log if youd like to take a look! Much appreciated

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[gtman]

Those "misfires" and few knock counts you had are no biggie.

The HUGE concern I have is that your short term fuel trims were a disaster. I saw as high as 45% at one point. I'm going to guess that you have the street maf. Also, your IAT is EXTREMELY HOT.

Revert back to the normal maf scaling and do another datalog asap!

You never did mention anything about the CEL. Were you getting an actual error code? I still wonder if that was just coincidental.

That top line on the graph is your short term fuel trims. They are supposed to fluctuate but the normal range is + or - 10.

 

[hobby-man]

Those "misfires" and few knock counts you had are no biggie.

The HUGE concern I have is that your short term fuel trims were a disaster. I saw as high as 45% at one point. I'm going to guess that you have the street maf.

Revert back to the normal maf scaling and do another datalog asap!

You never did mention anything about the CEL. Were you getting an actual error code? I still wonder if that was just coincidental.

View attachment 240407

That top line is your short term fuel trims. They are supposed to fluctuate but the normal range is + or - 10.

Based on the pic he posted its definitely a Race MAF he has... how was his MAP looking under heavy throttle? Maybe a boost leak, bad coupling somewhere in the intake?

 

[gtman]

For sure he has the race maf? Then why do you think his trims are running so far off?

He never came close to WOT (50% max), but he was basically hitting most of his boost targets if that's what you're asking.

 

[bay_hatch]

The HUGE concern I have is that your short term fuel trims were a disaster. I saw as high as 45% at one point. I'm going to guess that you have the street maf. Also, your IAT is EXTREMELY HOT.

Revert back to the normal maf scaling and do another datalog asap!

You never did mention anything about the CEL. Were you getting an actual error code? I still wonder if that was just coincidental.

That top line is your short term fuel trims. They are supposed to fluctuate but the normal range is + or - 10.

Those "misfires" and few knock counts you had are no biggie.

The HUGE concern I have is that your short term fuel trims were a disaster. I saw as high as 45% at one point. I'm going to guess that you have the street maf. Also, your IAT is EXTREMELY HOT.

Revert back to the normal maf scaling and do another datalog asap!

You never did mention anything about the CEL. Were you getting an actual error code? I still wonder if that was just coincidental.

That top line is your short term fuel trims. They are supposed to fluctuate but the normal range is + or - 10.

Yea, i confirmed that the intake was a race maf. Like @hobby-man mentioned can it be a loose coupler?

Also, in the rush of wanting the car to be back to normal, i forgot to pull the code prior to reflashing. Rookie mistake #2

 

[gtman]

I never saw your earlier post from today confirming it was the RACE MAF. My bad on that. I was offline for a while and got a notification that you requested I read the datalog and immediately checked it out.

I'm not sure about the boost leak. But your short term fuel trims are the worst I've seen on any datalog I've looked at. That 152 degree IAT1 is crazy high too.

When it comes to datalogs I can give you the basics I see but diagnosing them is not my area of expertise.

Hopefully PRL or JR or one of our tuning pros can give you some guidance.

 

[hobby-man]

I think in the meantime you should flash back to stock and put the factory airbox in

 

[bay_hatch]

I'm not sure about the boost leak. But your short fuel trims are the worst I've seen on any datalog I've looked at. That 152 degree IAT1 is crazy high too.

When it comes to datalogs I can read them but diagnosing is above my pay grade.

Something is clearly wrong.

I know SRIs are susceptible to heat soak, so could the possibility of 90 degree weather + the ambient temperature of the engine bay?
I have a 26 mile drive back home from my girlfriends later. Will it be okay to drive it back if I don’t drive it remotely hard ?

 

[gtman]

I think in the meantime you should flash back to stock and put the factory airbox in

I'd second that for safety sake.

For the pros...

There is one oddity on the datalog I've never seen before. Multiple times both fuel trims readings reset to 0% for 5-20 seconds and then start up again. Is that just a sensor issue or something else?

This gap lasted 20+ seconds. 10 seconds after that, short term fuel trims were at 25%.

 

[Linszter]

I'd second that for safety sake.

For the pros...

There is one oddity on the datalog I've never seen before. Multiple times both fuel trims readings reset to 0% for 5-20 seconds and then start up again. Is that just a sensor issue or something else?

This gap lasted 20+ seconds. 10 seconds after that, short term fuel trims were at 25%.

Fuel trims are 0% when you let off the throttle (fuel cut)

 

[bay_hatch]

For the time being, I flashed it back to factory base calibration still with RACE MAF scaling. Drove it home without any hard accelerations and everything seems to be normal. There were instances where STFT got up to 35%. LTFT seems ot be ok to my knowledge?

Here is the datalog for that if you can take a look again @gtman

 

[gtman]

Fuel trims are 0% when you let off the throttle (fuel cut)

I think you misunderstood my post. I understand STFT would do that. Look at the datalog and LTFT drops to 0 at the same time. Then goes back to normal. I haven't seen that before.

 

[gtman]

For the time being, I flashed it back to factory base calibration still with RACE MAF scaling. Drove it home without any hard accelerations and everything seems to be normal. There were instances where STFT got up to 35%. LTFT seems ot be ok to my knowledge?

Here is the datalog for that if you can take a look again @gtman

The fuel trims were still way off during many parts of the drive. hopefully JR can look at this datalog. Something isn't right. Look at this screenshot. For about a full minute STFT was at +20-25% meaning you were running super lean.

But here's the thing. You are also getting the frequent drop outs where STFT and LTFT both drop off to 0 at the same time only to go back to normal a second later and then drop off again. As seen in the screen below (top broken line on the graph). This combined with the unknown emissions error you were getting has me wondering if this is some sort of malfunctioning sensor?

Calling JR. Calling JR.

 

[KTuner]

The race MAF is too large to have a perfect MAF scale at all levels of flow. The flow dynamics simply don't allow it. STFT will swing both directions because of it. LTFT and the mean trend should be close to 0.

 

[bay_hatch]

Now i'm starting to worry if I ran the car too lean without tuning the correct maf scaling prior to learning that the intake is a race maf. Putting back the stock intake later today and will data log again.

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