PLEASE reply if you have had an identical or similar misfire issue
 

Hey Ft86Club,

Twice in 2 years my MY13 FR-S experienced a problem that Toyota was unable to diagnose or repair. I want to see if anyone else has experienced it.

This problem occurred when my car was stock and also when it was tuned with an HKS V2 Supercharger on a factory fuel system --- as well as when I upgraded to aftermarket port injectors and HKS spark plugs.

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One day when normally cruising the car suddenly developed a brutal misfire. I pulled over and it became increasingly worse until the car stalled out and eventually refused to even start (likely became flooded due to ignition conditions)

The only code present was P0300.

Every last ignition component was checked over. The dealership "reported" an issue related to a TSB where the camshaft sensor can go out of spec. They performed the repair.. however I had never previously had any symptoms of this problem and after the repair nothing changed and the car still misfired and struggled to run. If you got it to fire up and stayed on the gas enough for it to find an idle it would just sit misfiring on at least 1 cylinder (however it managed to correct idle AFR perfectly)

Bewildered I took the car back. For no reason whatsoever it just started working properly one day. It ran fine. Datalogs were all good. I drove it the rest of the season, parked it for the winter, took it out next summer again.

There was no sign of the previous issues. I even tracked the car and it performed admirably, never missing a beat.

Then one day while simply idling and warming up in the garage the car started to do the same brutal misfire. It didn't get as bad as before but it was undriveable. It cranked fine but idled with a misfire / stalled most of the time.

We went over EVERY last component. No problems with plugs, coils, injectors, wiring, tune ... all fine. 2 weeks go by and the car is a paper weight .. then one day for no reason while sitting and staring at the scan tool I start it up and it's perfect again. It then ran perfect the rest of the season and is now parked.

Toyota was baffled. My own shop couldn't find anything actually wrong. My tuner and another giving a second opinion could gather no helpful information from the logs.

I feel like it's going to happy again and I'm so frustrated that an explanation cannot be found. Something is internally, intermittently, going wrong.

do you have lightened flywheel ? sometimes they upset car at idle


http://www.ft86club.com/forums/showthread.php?t=99994




is the DI computer under bonnet securely earthed to chassis.


Really weird stuff happens if it isn't earthed correctly its earth is via case not the wiring loom

I do have an ORC light weight flywheel.

My DI computer is grounded fine, if I feel like if it wasn't -- this would happen somewhat more frequently.

My idle is set to 900. I'm not sure how I could diagnose if this is due to the flywheel as it's a very infrequent issue.

Isn't that going to be true for any suggestions though? Hard to diagnose an issue that happens so rarely.

Well, there's no solid explanation I've ever seen of why a flywheel would cause this issue.

I've only ever heard of older Subaru's giving false misfire codes when using too light of a flywheel or a light flywheel in conjunction with a lightweight crank pulley.

I'm game to do any sort of diagnostic that actually makes sense.

Seeing as the issue lasts for over a weel -- I'd like to have some plan of attack next time it happens to maybe isolate the problem and prevent it from happening again.

Let us know if you ever figure it out. It is an intriguing issue but the explanation could be pretty simple if you can just catch it at the right time.

Ok, so it seems like I'm having the same issue with a completely stock BRZ. I'm pulling 0304 code. The engine was just replaced with a new short block during to oil change screw up.

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This issue was never resolved. If it returns I'll update but for now it's a total mystery that Toyota nor our own shop can figure out.

My next experiment is trying to see whether the weight of oil being used is causing issues with AVCS

This happened to my car the other day while warming it up in the morning. I walked out to leave for work and the engine sounded like it was limping. I turned off the car, and turned it on again and it was fine.


No CELs, completely stock car. I've owned it for 3 years and that was the only time it ever happened.

This may seem like a silly thought, but I assume you are tuned to a certain level of octane. Could it be that the gas tank somehow got filled with a lower grade fuel? Could this explain why the symptoms lasted a week and went away? Please don't take this as me saying you screwed up fueling your car, but I have heard of instances when the wrong fuel grade was dispensed at the gas station.

There is some electrical cable issue here. I'm going to give you two examples.

One, I have a Honda Pilot. One day the car decides to die, and not start at all. No lights on dash, battery was ok, checked fuse boxes and everything ok. Turns out there was an inline fuse in the body harness that blew (because there is a short somewhere). Replaced the fuse and blew immediately. I took it to a mechanic who started to move the cable around while doing continuity checks but couldn't find an issue. Replaced the fuse, all good and dandy. Kept the car for a few days to trouble shoot, shook the harness good, nothing, all perfect. This happened over two years ago and it has never happened again. Whatever cable problem is present, its currently sitting in a position as to not short the connection.

I have a friend with a 16 BRZ, who out of nowhere developed a misfire. This has actually happened twice to him. He left the mechanic first time, thinking he didn't have any issues and it came back (so it's a similar intermittent problem). Changed coilpacks, spark plugs, changed injector and injector plug position, nothing. Mechanic found that if he shook the engine harness connector to inside body harness, he could make the misfire appear and disappear. The broken cable is not visible or apparent, but the issue is there. The solution for this gentleman would be a new engine harness, but he still has not been able to come up with the funds for it, as the 16 harness is different than the 13-15 and it's rare to find a used one.

Unfortunately given the circumstances of when the misfires began (once during idle after startup, once during slow cruising speed on smooth surface) this would be a poor, yet maybe last ditch effort to cure this.

The car has seen plenty of rough roads and also full on track use -- none of which caused this issue to arise so it seems like movement in the harness aggravating an existing fault is at least largely unlikely.

Also -- diagnosis while misfiring did not reveal any electrical or signal issues at ignition components or timing related sensors etc