Rough idle after new headers installed
03-10-2023 | 01:11 PM
#16
Burning Brakes
Joined: Apr 2017
Posts: 864
Likes: 353
@ShawnM981 mine does what's shown in your vid, just way louder. Once the cold start sequence is done, it settles down and no longer bounces. No tune on my car.
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BabyNSX (03-10-2023)
03-10-2023 | 01:16 PM
#17
Burning Brakes
Joined: Apr 2017
Posts: 864
Likes: 353
Sorry guys - I’m having a disconnect with technology today, working on getting the video to upload correctly but @avera is correct in the “bouncing” being what I’m experiencing. You’re also correct in that it’s certainly louder with the new headers/cats but that’s not really what’s drawing my attention at this point.
I brought it to the installer who was able to scan for codes but nothing came up. Also asked about 02 sensors but they didn’t seem to think that would be the issue.
I also consulted someone with the exact same setup (softronic + fabspeed headers) on a GT4 without this “bouncing” situation.
Does anyone know if there are lines or hoses that are removed and replaced during install that could cause this?
I brought it to the installer who was able to scan for codes but nothing came up. Also asked about 02 sensors but they didn’t seem to think that would be the issue.
I also consulted someone with the exact same setup (softronic + fabspeed headers) on a GT4 without this “bouncing” situation.
Does anyone know if there are lines or hoses that are removed and replaced during install that could cause this?
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Larry Cable (03-18-2023)
03-10-2023 | 01:21 PM
#19
Thread Starter
Rennlist Member
Joined: Apr 2021
Posts: 129
Likes: 131
From: Boston/Naples
Only thing removed are the 02 sensors, and if they were installed backwards you'd be getting 02 sensor warnings. I'm assuming once the car warms up the bouncing idle stops? If so, mine did exactly the same, and I'm sure you can send Softronics some logs and they can smooth that out for you.
03-10-2023 | 02:36 PM
#20
Burning Brakes
Joined: May 2018
Posts: 816
Likes: 462
From: Minnesota
Yes! This was an issue I encountered after a shop did my install.....discovered after chatting with Jonny and looking at the info, corrected with DC021's help. It's common for them to be swapped if you aren't thinking exactly about the path/routing of the Air (at least in my JCR setup with my installer....). Mine doesn't bounce around, but it is at a higher rpm for the first 45 seconds or so, as others stated, it is to warm up the cats so they are more efficient and able to be cleaning things quicker for emissions.
03-10-2023 | 02:40 PM
#21
Burning Brakes
Joined: Mar 2021
Posts: 1,065
Likes: 607
The only thing removed which I see as a possible cause are the exhaust loud valve vacuum lines, assuming the muffler box was R&R. To be fair, after installing the JCR, mine aren't clamped as tight as I like; I will try changing their clamps at some point and see if it stops the bouncing. But since it never bounces at any other point in the drive cycle, I suspect it's an artifact of the OEM tune, not a leak.
03-10-2023 | 02:41 PM
#22
Racer
Joined: Aug 2021
Posts: 377
Likes: 362
From: Chicagoland, IL 60134
03-10-2023 | 02:58 PM
#23
Burning Brakes
Joined: May 2018
Posts: 816
Likes: 462
From: Minnesota
We're supposed to get a few more inches of snow tomorrow, but I'll try to grab a recording of mine at startup. Maybe mine does bounce and I'm just so used to that I don't even think of it? it's definitely an event upon startup, although the 970.2 Panamera GTS with the 4.8 still takes the cake...nothing will wake you or your neighbors up like the crack of that thing turning over with the valves wide open because no vacuum!
03-10-2023 | 04:13 PM
#25
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Joined: Nov 2014
Posts: 629
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From: S.Fla.
Hey guys - trying to diagnose a problem after having new (to me) @Fabspeed Motorsport headers with sport cats installed. Car is a 2023 Spyder 6mt. I had the fabspeed OAPs installed at delivery, did @Softronic tune around 1200 miles, and added the headers at 1800 miles. Since the header install I’ve had a rough idle on cold start. It goes away once warmed up, it’s just during that first 20-40 seconds. I’m up to 2075 miles now without any change. Any ideas??
It is a known issue when you remove cats.
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DerekHK (03-11-2023)
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jwr9152 (03-11-2023)
03-10-2023 | 07:58 PM
#28
Instructor
Joined: Mar 2016
Posts: 175
Likes: 121
From: Phoenix, AZ
Just for reference my GTS 4.0 after the cold start cycle finishes but the engine is not yet up to temp idles rough, it sounds like an ignition miss. I often will move it to sport so the idle speed goes up an it seems to idle smother. Until reading this thread I did not consider this was done on purpose to help the cats warm up, that sounds very plausible.
Do these cars have a secondary air pump that is running during that first 30 seconds of cold start when the rpms are held high?
Do these cars have a secondary air pump that is running during that first 30 seconds of cold start when the rpms are held high?
03-18-2023 | 06:08 PM
#30
Thread Starter
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Joined: Apr 2021
Posts: 129
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From: Boston/Naples
For me it’s what I now believe is called an idle surge. The car idles at around 1600 right at start up, then drops to 1100ish and bounces for about a minute before settling in. It does it regardless of sport exhaust being off or on. I’m convinced it’s something that can be tuned out but @softronics doesn’t seem to agree or just doesn’t care to help with it, I was told it’s because of my headers with sport cats are “bad” but many others with the same setup don’t seem to have the same issue.