FL5 stock exhaust valve: Fuse pulled/always open - exterior sound clips

[Jester04]

We're trying to tell you that multiple people (myself included) noticed some weird cold start behavior after keeping the valve open. When the valve is open a vast majority of the flow goes through the center pipe. You can see it for yourself if it's cold enough that all of the exhaust is coming out of the center pipe instead of the 2 side pipes.

• Maybe they were forced to add the valve to comply with emissions as the cold start is monitored heavily by the government? How quickly the catalytic converters warm up is critical for complying with emissions so a change in exhaust flow could definitely have an impact.
• If the flow of the exhaust has changed and the software cannot compensate for it this may lead to the feeling of stalling or shuddering.
• Your theory of it canceling out drones at cold start is a good one - that could be part of it too.

I don't know what the root cause of the difference in driving characteristics. I'm just saying it is happening. You are arguing telling us it makes no difference or we are imagining it or something. I made the decision to my fuse back in and keep the car running as well as it can.

There was a noticeable difference before and after. Maybe the ECU can learn around it but I wasn't willing to wait and see for no actual benefit.

Like I said without taking a look at some parameters its impossible to know for sure. And I understand and I have read all the comments, I understand why you guys would feel like that and if its a improvement for you then so be it. The open valve will flow through the center pipe only since its the path of least resistance.

I don’t have a Integra type S, but if anybody can confirm if it opens the valve in sport mode and it stays open on cold start and while driving? Please do chime in.

I’m not saying you are imagining it, never said that. Just said that it was probably not the valve that was causing it. Now on the testing front, if valve is closed and it did improve shuddering and hesitation. When it did act up was it colder or hotter? These are factors that we have to take into account.

Also on startup, even if flow is increased in the exhaust side. There should be no problems, how do other cars make it work? This is what points me to the software side specifically on the K20c platform. An engine is a air pump and almost all engines will perform similarly given conditions. There are some factors like airflow through the head and how well the intake and exhaust flow. But it should not cause a hesitation mechanically speaking.

If the integra leaves the valve open in sport mode and on cold start in sport mode it just further reinforces my point. Since they both have to meet the same emission standards and if it did cause a problem they would not install that function but we have to wait for confirmation of a type S owner.

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[sashimi]

The valve is there only for sound. There is no mechanical advantage for the engine with the valve closed.

Now when I say the valve is there for sound, its just one of its functions.

Someone is really confused. I think you are the only one trying to be smart here, Jester. Just cut the bs. Many have experienced and stated mechanical disadvantages with the valve open, and you are here trying to denounce it, why? Maybe I'm wrong about the atmospheric pressure theory, but the fact remains that the car is simply easier to operate with the valve functioning as the engineers intended. Also, I never said the car stalled with the valve open, it just shows more tendency to do so.

 

[Jester04]

Someone is really confused. I think you are the only one trying to be smart here, Jester. Just cut the bs. Many have experienced and stated mechanical disadvantages with the valve open, and you are here trying to denounce it, why? Maybe I'm wrong about the atmospheric pressure theory, but the fact remains that the car is simply easier to operate with the valve functioning as the engineers intended. Also, I never said the car stalled with the valve open, it just shows more tendency to do so.

Sorry I did not mention the increased flow, my bad thought it was obvious. Its there for sound, simple as that. The previous gen did not have a valve so the increased flow was already there. I’m not trying to sound smart and neither am spewing BS. I guess the engineers forgot to put the valve on the FK8. Must have been an oversight on their part but they can’t be wrong because they are engineers. Not everything they make works just fyi.

Have it your way, its apparent that I struck some chords with some people and you are obviously upset. Do what works for you, I will live happily with a deleted valve and enjoy my warm weather without a shuddering car. Not going to waste my time on this anymore. I will just sit back and watch.

 

[urbo73]

The AWE exhaust is non-valved. It works with stock tune/ECU. Are cars stalling?

 

[julianobl]

anecdotal evidence of n=1, my active valve fuse delete did not cause any issues whatsoever to my car except for mild sound increase

Now I have AWE Touring Edition and absolutely no issues either

 

[Jester04]

anecdotal evidence of n=1, my active valve fuse delete did not cause any issues whatsoever to my car except for mild sound increase

Now I have AWE Touring Edition and absolutely no issues either

Good for you! Time will pass and it will prove someone right. Either way I’m going with a valve less exhaust too just going the custom route. I don’t foresee any problems. I’m just a crazy person with delusions.

 

[TypeRD]

I agree with @Jester04 that there’s too many unknowns (as well as variables like fuel quality, air quality, temperature, time, location, etc.) to know what’s causing engine hesitation in some cases. That the valve is only there for sound and/or maybe emissions purposes are both reasonable hypotheses. At this stage, without more data, all results valve vs valveless (as related to hesitation) are really anecdotal. Comparing the FK8 to the FL5 is also not truly 1:1 (they’re not exact clones), so I agree that the ITS is probably the better data point to observe (despite the fact it has 1 less resonator and a different tune). I think AWE has done the most comprehensive study on the valve system to date, though I think it created more questions while providing some answers. Time will tell if folks report hesitation issues with the AWE exhaust. Regardless, I think with every single report of a hesitation problem, there will be 2 or 3 reports of people with zero problems. So then we’re back to square one with considering variables such as those listed up top. I guess what I’m getting at is that the best course of action for those experiencing hesitation is to have a diagnostic done (at least as a starting point) and see if it returns any useful information. Without more definitive info we’re all just theorizing…which leads to finger pointing and unnecessary arguments. I think everyone has good intentions here, so just keep cool.

 

[urbo73]

I haven’t heard of any on here, Facebook or Reddit. AWE also did extensive testing and I doubt they’d release an exhaust if it caused stalling or shuddering.
I’m on the side of “the valve does nothing” like Jester, but it’s just personal anecdote for me. I never had issues with my valve open.

Exactly my point. The valve being open is not causing any of the issues posted IMHO. My post was in jest.

 

[Noize]

I have not touched the fuse and forced my valve open, but I also get this odd cold start behavior. I do have Hondata, and it does it on the basemap as well as the TSP stage one map. I have not bothered to flash the car back to stock to see if the behavior continues.

It is warm where I live, but if the car sits a couple of days, it does not like to be below 3000 RPM for the first minute or two on a cold start. The best way I can describe it is it runs a little rough and will buck a bit between 1800-2500rpm. This clears up very quickly, I don’t have to drive more than half a mile and it goes away completely. I just chalk it up to the car is fussy when the engine is cold. My FK8 did not do this at all.

 

[ne_typer]

I have not touched the fuse and forced my valve open, but I also get this odd cold start behavior. I do have Hondata, and it does it on the basemap as well as the TSP stage one map. I have not bothered to flash the car back to stock to see if the behavior continues.

It is warm where I live, but if the car sits a couple of days, it does not like to be below 3000 RPM for the first minute or two on a cold start. The best way I can describe it is it runs a little rough and will buck a bit between 1800-2500rpm. This clears up very quickly, I don’t have to drive more than half a mile and it goes away completely. I just chalk it up to the car is fussy when the engine is cold. My FK8 did not do this at all.

That’s normal on a cold start. Timing is significantly retarded to heat up the catalyst, which results in rougher behavior.

 

[Jester04]

That’s normal on a cold start. Timing is significantly retarded to heat up the catalyst, which results in rougher behavior.

No dude its the valve, did you not hear the other people? No way its the cold start timing retardation or cranking and startup fuel calculations, this is all just heresy.

 

[dandaman15]

No dude its the valve, did you not hear the other people? No way its the cold start timing retardation or cranking and startup fuel calculations, this is all just heresy.

Don't take it too hard. People do appreciate your thoughtful posts (like me). Im a mechanical engineer and work with fluid dynamics, worked with Honda engineers, was on Formula SAE in college working with Ford and FCA engineers. People give these guys too much credit, but your information is pretty much spot on from an insider perspective and just the basics of how exhaust flow/ engines work. The factory tune does have some weird inconsistencies and Im sure this is part of it.

Edit: I have put about 3500 miles on with the fuse pulled and have no issues. People thinking the stock exhaust is so sensitive to cause shuddering would mean nearly no aftermarket downpipe, exhaust etc would work and have cars stalling from too much flow. Now that its getting colder Ill see if I notice it more as itll be 50s some mornings. Maybe I just learned to drive around it by now.

 

[Jester04]

Don't take it too hard. People do appreciate your thoughtful posts (like me). Im a mechanical engineer and work with fluid dynamics, worked with Honda engineers, was on Formula SAE in college working with Ford and FCA engineers. People give these guys too much credit, but your information is pretty much spot on from an insider perspective and just the basics of how exhaust flow/ engines work. The factory tune does have some weird inconsistencies and Im sure this is part of it.

Oh I’m not, just being sarcastic cause I tried to share some thoughts and almost got burned at the stake when I was just trying to help. Good thing its not the middle ages cause the inquisition would have burned me for sorcery of forbidden knowledge.

That is awesome that you do mechanical engineering! People always tell me I should have gone for that since I’m very passionate about cars and knowledge. Instead I went into medicine and fixing people’s mechanical problems instead of inanimate objects.

 

[Jester04]

Don't take it too hard. People do appreciate your thoughtful posts (like me). Im a mechanical engineer and work with fluid dynamics, worked with Honda engineers, was on Formula SAE in college working with Ford and FCA engineers. People give these guys too much credit, but your information is pretty much spot on from an insider perspective and just the basics of how exhaust flow/ engines work. The factory tune does have some weird inconsistencies and Im sure this is part of it.

Edit: I have put about 3500 miles on with the fuse pulled and have no issues. People thinking the stock exhaust is so sensitive to cause shuddering would mean nearly no aftermarket downpipe, exhaust etc would work and have cars stalling from too much flow. Now that its getting colder Ill see if I notice it more as itll be 50s some mornings. Maybe I just learned to drive around it by now.

Yeah we can only do testing and report findings to see if we can figure it out. In October I’m getting Hondata so I will be able to monitor start up and check if I see anything out of place and if it shudders will make sure to log it to review it.

 

[Noize]

It’s definitely a tuning/mapping thing. But my FK8 didn’t have cold start retardation anywhere like this.

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