[austinharper]

Hey guys, me and my mechanic are absolutely stumped. Had my Si in for a clutch change and when I got it back I’ve been misfiring in all 4 cylinders. 1 misfires while I’m idling, but the other three don’t until I take it to about 5,000rpms. On prolonged drives at 60mph the hotter the engine/electronics get, the more frequently it misfires, even with me keeping it below 3,000rpms the entire time.

The guy I bought it from had an Injen Xpedal throttle controller installed and my mechanic unplugged it and plugged it back in, but it only communicates with the TPS so I have doubts that had anything to do with it. It’s throwing Power Steering, Check Emissions, Check VSA systems lights as well. I put all new plugs in it, and the problem persists. Honda refused to even look at my car since it has “too many aftermarket mods”, so I’m hoping you guys can maybe help me out. Best guess we have right now is a problem in the ECU communicating to the VTEC solenoid.

 

[scottyrocks]

What you're probably going to see here is to bring it back to stock to see if the problem disappears. Then, add the mods back in, one at a time, to see what, or what combination, causes the issue.

It's called process of elimination, which should be done before spending more money, also known as throwing parts at it.

 

[jn2k108]

Did you put a lightweight clutch in?

What mileage are you at? Did you check inside the cylinder if there was debris?

Did you check your injectors?

Yes put your car back to stock and see if anything changes


Sent from my iPhone 13 Pro while on the toilet.

 

[kev604]

Most likely related to your new clutch being aftermarket.

 

[austinharper]

Did you put a lightweight clutch in?

What mileage are you at? Did you check inside the cylinder if there was debris?

Did you check your injectors?

Yes put your car back to stock and see if anything changes


Sent from my iPhone 13 Pro while on the toilet.

Its a lightweight flywheel, but the clutch was a stage 2, and it’s significantly heavier than the one I took out. The other was a stage 1 clutch with the factory flywheel.

My injectors are fine, besides the usual ticking from the weather changing. I did run a bottle of Techron through my system.

I’m at about 112k miles, the car hasn’t been tuned or anything, but no I haven’t checked inside any of my cylinders, but they all have compression.

 

[austinharper]

What you're probably going to see here is to bring it back to stock to see if the problem disappears. Then, add the mods back in, one at a time, to see what, or what combination, causes the issue.

It's called process of elimination, which should be done before spending more money, also known as throwing parts at it.

I don’t have any access to the stock parts, the clutch we took out was an aftermarket stage 1 that was “tuned” according the the guy I bought it from. I took it in the shop with no engine issues and left with a new clutch, flywheel, and master/slave cylinders so that’s all I have to go off of.

The closest I can get it to the state it was in when I bought it is to put the old clutch and flywheel back in, which are both toasted, and probably thrown out.

 

[kev604]

Lightweight flywheel requires a tune to run properly.

 

[austinharper]

Lightweight flywheel requires a tune to run properly.

I found some subie forums with people having misfire issues with lightweight flywheels. Would it seriously cause this much of a problem to misfiring in all cylinders? And would i have to get a proper tune with a hondata/k tuner?

 

[Allmotor]

You need to get either get ktuner or hondata and disable misfire detection.
It’s just a check box you un click and then flash the stock basemap on the car not the best tune but least it will not go into limp mode.

 

[scottyrocks]

I found some subie forums with people having misfire issues with lightweight flywheels. Would it seriously cause this much of a problem to misfiring in all cylinders? And would i have to get a proper tune with a hondata/k tuner?

You've got two similar but different concepts possibly a little confused.

A tuning issue doesn't cause a misfire, per se. An actual misfire is most often a result of the spark plug not firing at all, or with such a weak spark that little to no power is made in that cylinder. This can be the result of an actual hard mechanical part, or a software malfunction.

An improperly tuned system will have all the cylinders not making enough power due to, most often, an improper air/fuel mixture, usually due to mods, and/or a miss-timed spark signal, not to mention a dozen other possible things.

In other words, get it to a reputable tuner who can read your ECU's software to see what's what.

 

[jn2k108]

You need hondata and turn misfire detection off. The lighter than stock flywheel will cause all problems.


Sent from my iPhone 13 Pro while on the toilet.

 

[BWill9886]

I found some subie forums with people having misfire issues with lightweight flywheels. Would it seriously cause this much of a problem to misfiring in all cylinders? And would i have to get a proper tune with a hondata/k tuner?

Yes. You can find plenty of other threads on this forum as well regarding the issue.

 

[austinharper]

Well I have a hondata on the way, I’ll update when I get it in. The only thing that concerns me is that my car isn’t in limp mode, it stills drives perfectly normal until it misfires really bad.

 

[LogiFG4]

I found some subie forums with people having misfire issues with lightweight flywheels. Would it seriously cause this much of a problem to misfiring in all cylinders? And would i have to get a proper tune with a hondata/k tuner?

I have ACT stage 3 with ultra lightweight flywheel , ktuner tuned myself turn off misfire monitor and shouldn't have a problem

 

[EffBee6fromthe209]

Whatever happened to people doing some research before doing something blindly. We've been over this like hundreds of times in the last 10 years. Still people can't figure it out. Does no one research anything anymore? Smh.