Need help diagnosing engine noise and misfire
 

Hi guys I have a bit of a problem with my 2013 BRZ. I am getting some engine noise (I don't think it sounds like rod knock) that is consistent with engine speed. The car is also showing code P0301.

I have troubleshooted a bit so far, this is what I have done and the result:

1)swapped out coils packs to the new 2015 revised ones (TSB issued on 2013 ones)
2)swapped cyl 1 spark plug with cyl 3 spark and the issue still resided with a P0301
3)visually checked the spark plug that came from cyl 1 and it looked fine/normal but was soaked in fuel

My vehicle is modified -
-short block from MAPerformance (10.5:1 - forged pistons and rods)
-stock heads n valves but upgraded springs and retainers (skunk2)
-STS remote turbo system with 14ish psi waste gate
-tuned from Delicious
- probably some more just cant think of them right now

Here is a youtube video that I took to show the sound. Any help is greatly appreciated.

[ame="https://www.youtube.com/watch?v=eKZrAImJA88"]Jordo brz - YouTube[/ame]

Is delicious a tuning shop, or the ecu flash or replacement ecu? What are you using to control ignition advance and afr? Any data logging?

Good job checking plugs and coil packs first. Are the plugs stock, or are they one or two steps colder and gapped appropriately if adjustable?

Delicious is a tuning shop and they are remote tuning with ecutek having me send them datalogs and then they send me back revisions until it's fine tuned. It has not been fine tuned as of yet. Me and delicious have agreed to get it close and wait till I get the final parts (boost controller, inter cooler, fuel system, etc.) until the tune is completed.

The spark plugs are completely stock


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I guess I could also explain exactly what happened:

Long story short I was messing with a mustang (about 750ish miles on this boost pressure setup before the cel popped). I was in second gear and I went wide open till about 7k rpms. I did not use the clutch but just let the engine die down itself - The CEL turned on while the engine was slowing down from that pull. I did not notice any noise or engine struggles at this time. When the engine went down to about 2500-3k rpms the CEL went away and everything acted normal. I stopped at the next red light (still everything normal) when the light turned green the CEL came back on and I noticed power loss. From that moment i pulled over checked for leaks or anything else that might be found visually - found nothing. I started the car back up and limped it home; about 3 blocks and this noise and problem has been there since.

14 psi on stock compression with no intercooler and partial remote tunes? Maybe it's just me, but I would never go wot under those conditions... it may have been difficult to hear pinging over engine and exhaust noise, but it is possible to exceed the knock sensors capacity if the detonation issue is great enough. I'm without sound at the moment, but I sure hope it's nothing serious and am interested to see what others have to say

stock compression is 12.5:1 I have lowered it to 10.5:1 - still a pretty high compression for a forced motor (no arguments there). The tune is good, when I mean finalizing the tune I am refering to advancing the timing to squeeze out more power.

I have been reassured from Delicious that the tune is not the problem - still a likely culprit until fully diagnosed... They also mentioned that they would like to see my car at 19psi boost controlled when I start looking into getting a revised tune.

I also agree with the non intercooler part - that was planned for next summer. As of right now Utah is always under 40 degrees and my charge pipe is a 8 to 9 feet long. Im thinking inlet air temp is not too big of a problem. Havent logged that on 14 psi but when I was breaking in the motor at 7 psi all my logs didnt show anything abnormal.

your video wont load for me. I run stock plugs gapped to .020 at 30psi no problem on e85, i doubt you would have a plug problem on pump, even with the stock gap. I have had one coil fail but the other 3 are original and have been fine. you have valve springs so i doubt a rocker pin has walked out. you should have a hole in your valve cover if that was the case anyway. what do you run for oil? monitor pressure at all?

Is that your BOV right next to your MAF?

If so, from your description of events, long rev down in gear under vacuum/no load. I think I know what happened.

Yes that's my bov and I think I put in 5w30 last change

Edit: that's a rhetorical question.

I would move that post-haste. I bet money that the spark plug was soaked in fuel because the MAF still saw a ton of airflow over an extended rev-down, (as the BOV was likely hanging open for a while) and the engine ran richer than hell.

If that is the case, then you are going to have serious AFR problems every time that valve opens.

As for the specifics on the damage you may or may not have caused, I have no idea. Just speculating on the initial cause. I have no audio at the moment.

Good catch. I hate MAF sensors now and always switch to a standalone ecu and map sensor when converting to FI for reasons such as this

that makes sense. Let me try and make sure I am getting this correctly.. to solve this in the future I should move the bov farther back from the MAF or should I move the MAF closer to the intake? If moving the bov back; how far are we talking about?

STS so far is the worst decision I have made on my car. Nothing but problems so far and they went out of business right after I purchased the kit so finding technical help is hard. I have been playing around with the idea taking it to a local FAB shop to have them cut everything up and make a custom front mount setup.

Also you should sell me the engine for dirt cheap since it's totaled

I'm liking the custom work idea. I heard about STS quite a bit before they disappeared. Not many success stories.

Either way moving either the valve or the sensor would work, as long as the pipe is the same diameter you won't need returning if you move the MAF. IF I was doing it I'd move the MAF sensor right around the corner closer to the throttle body. Make sure it's on a straight section of pipe. I can't see the rest of the charge piping but if you move the BOV I'd advise you to replace the section with the MAF housing. The MAF won't like the turbulence from whatever is left after you cap off the BOV flange.

Just got access to audio. Not the best quality but your noise sounds exactly like a bad exhaust leak. In fact I'd bet money on it. How's she smell?

Well it smells rich but it has been that way since being tuned. It was left slightly rich to help safely break in the motor. (My knowledge of tuning is a little short). Sounds like your thinking a burnt or bent exhaust valve? I haven't had time off from work to go buy a leak down tester.

Bingo. Sounds like you roasted a valve in the misfiring cylinder. Which is likely why its misfiring. Slightly rich is no issue but massively rich due to absurdly high MAF voltage at high rpm/low load means burning mixture with open valves.

Also it sounds like a leak to atmosphere. That's the ticking that sounds like a Waterpik shooting air. You may have also roasted an exhaust gasket. I can see the stock header down there so I seriously doubt you warped a flange.

You may want to get rid of those ceramic cats though before they break down and eat your turbo. Just idle advice now that you're on low comp and high boost. Metal cats are a good idea when your turbo is downstream.

The valve was what I was thinking it was. I was just hoping someone has heard of the noise or had a similar problem that could rule the valve out before I pull the motor back out.

The cats are on the list for the next steps. Full exhaust with high flow cats then I was going to heat wrap everything to get that heat all the way to the back where the turbo is. But now I am asking around local shops to see how much/if they can build me something custom. Keep in mind that this new motor is only 500ish miles outside its break in period. Thus, I was trying to work at all the bugs then start upgrading items to increase boost pressure.

_I know stuff all about turbo,s

And its hard to tell from video but it sounds a bit like an exhaust leak to me.

I agree that having the bov so close to maf is likely to cause issues, but so is moving the maf to close to throttle body.

Maybe use a long screwdriver or similar as a sthethoscope and listen to different areas arroind motor to se if you can isolate the noise ( one end on motor and other end to your ear

coil packs are a known failure item and can be intermittent

The other thing that happens with turbo and sc guys and even heavily tracked na cars is the front cat disintergrates sometimes rear one as well. sometimes the bits of the front cat block up the rear cat

burned valve most likely,
Possible blown DI seal or exhaust gasket leaking
But it sounds like you are losing compression going with valve
https://www.google.com/search?q=burn...4QsAQIIQ&dpr=1

I pushed 29psi on 10.5 compression using Delicious Tuning Flex Kit so it is NOT the tune