ShawnM981

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??

dnimi123

maybe need the stage 2 tune? Id call ST. Or perhaps somehow the cats are bad... Know how many miles were on them prior to your purchase? Do you smell anything bad from the exhaust?

jwr9152

I noticed more vibration when I added headers and sport cars. One thing to double check is that everything on the exhaust is tight. If a flange or connection is loose it makes it worse and can increase drone.

BabyNSX

For what it's worth, after installing my Dundon Headers and OAPs the first 30 seconds after a cold start are very loud and one might say "rough". The OE engine tune is optimized to fire up the catalytic converters during a cold start and that is (I believe) the reason you/we experience this.

LISsailor

Yea, I think cold start defaults to valves open. It’s loud AF with just OAPs. Maybe with headers it’s even louder?

Avera

@ShawnM981

Not sure exactly what you mean by ‘rough idol’ but I am going to take a stab at it by suggesting you mean the following . . . Cold start . . . LOUD at about 1500 RPM . . . after about 15-30 seconds idol drops a bit and ‘bounces’ for another 15-30 seconds . . . then decibels drop and idol ‘settles to a few ticks below 1000 RPM (cats warm).

By ’bounces’ I mean it sounds like you are lightly applying and releasing throttle over and over. I am assuming this is what you mean by ‘rough’ idol?

Since you have aftermarket headers/OAPs I would suggest the cold start in discussion is largely a result of a stock phenomenon being amplified in terms of decibels. . . and completely normal. I experience the same with my Dundon headers/OAPs.

I relate this to my experience after adding JCR Race Pipe to the mix. The drone was absolutely insane. However, it was not just a single drone range, e.g., at 2500 to 3200 RPM. There were other insane ‘resonances’ that were mind altering at idol and with varied throttle intensity above 4000 RPM.

Once I removed the Race Pipe, ALL these resonances remained acutely apparent to me but completely benign and non-problematic because their ‘intensity’ was significantly reduced. Stated differently, I never noticed them with OEM exhaust or just the Dundon components because they were not bothersome.

What I am SUGGESTING is the ‘roughness’ you report is a normal cold start phenomenon that has been amplified by your aftermarket headers/OAPs . . . if I am interpreting your ‘roughness’ properly, I too experience it with my Dundon setup.

The potential flies in the ointment are (1) we are not talking about the same thing in terms of ‘roughness’ and (2) your aftermarket tune is at play. The latter should be very easy to test by simply uploading the OEM file (tune).

Avera

ShawnM981

It’s not that it’s much louder. It’s more of just a bouncing RPM situation while in that cold start phase. It’ll bounce between just over 1100rpms and just under 1100. It feels like an air/fuel combo issue.

I’m going to take a ride down to the shop that installed the headers today. Will report back.

DC021

Silly question, but are your o2 sensors installed in the correct positions?

I’ve seen them the pre/post cat o2 sensors installed in incorrect locations before.

Avera

If your cold start is not that much louder with aftermarket headers/OAPs, then I would suggest something is wrong with your headers/OAPs . . .

At any rate, that 'bouncing' is not a problem

Avera

ShawnM981

jwr9152

Seems pretty normal with headers. Mine would do the same thing. Not sure if you have a tune or who's if you do, but I have the M-engineering tune and they removed the high idle at start up and mine doesn't do that anymore. Scared me a little, because the first start up after the tune actually idled worse, but has been great ever since.

jwr9152

And it might be just me, but I had to cut and paste the link for the video to get it to work.

enduro

Mine does exactly this. Behaves almost like a small vacuum leak, then stops when it settles to 'normal' idle. Whenever my car gets out of warranty, I intend to tune out the cold start mode. Obnoxious, and unless there's an electric oil pump and pressures are already up, the initial bark can't be good for bearings.

enduro

@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.

edit: to clarify, I'm running Dundon headers + JCR muffler.

ShawnM981

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?