onfireTTS

Is it catless ?

Big Swole

Yes. Tubi w/ no cats.

onfireTTS

That is key. GIAC did not shut off all of the potential codes from the rear O2’s as should have been. Take a quick look. Probably spacers as noted above. No biggie. Will not hurt performance and might never come back.

Pdtp#16

GIAC has pretty specific tunes for the equipment you are installing. If someone installs their tubi with cats and thereafter you change to catless, it will show the code and the tune was meant to be used with the cats. I have seen this happen several times. Also there tunes varies depending on the equipment it was meant to be used with which is why they usually sell specific tunes with specific equipment to be used. One neet thing that i remember them doing was that they adjusted the boost display to show the actual boost and not stop at the max allowed by Porsche. I wish COBB would do the same.

onfireTTS

Actual boost would be a killer feature that is needed on Cobb.

Pb Pedis

Just want to echo this comment. My tuner (Champion Motorsports) advised that my GIAC tune (which is currently set for an otherwise stock vehicle) will need to be revised when I upgrade intercoolers.

Also, I did notice that the stock boost gauge with the GIAC tune was reading more boost now than when stock, but is that not the case with COBB? Said another way, does the factory boost gauge read less boost that actual when using the COBB tuner?

2fcknfst

That seems a little like a cash grab - I cannot see why there needs to be a programming change due to cooler, denser air; that is like saying you need a summer, and winter tune.

Steve Cole

COBB's current tunes are utter trash. I lost 6-10mph in the 1/4 with their stage II tune and their stage I tune was right on par with stock. I tried the 91 octane stage II tune, ran a 124mph trap speed with my 991.2, I tried the Stage 1 93 tune, ran the same as stock (10.59@131.78 which is an average trap with my car, not its best). Low end power just barely may be more substantial than stock. Over 20C ambient temps, the tunes ran much better than at lower temps (15C and down) but still not faster, just better response to the throttle. I think the exhaust has more to do with that than the tune (Kline 7670 with 100 cell cats).

Before you ask, logs show no additional boost with their OTS tunes. Their own web site confirms my findings - at BEST - that there is no additional power in their current OTS tunes. If you don't get a custom tune with your COBB, the tunes are worse than worthless, they may make your car slower like they did mine. Their Stage II tune never logged higher boost than stock, and usually was less.

pfbz

@Big Swole noted elsewhere that he passed a plug-in OBD emissions test, which IIRC looks for OBD readiness flags, which I believe will never set (pass) if the rear o2 sensors are coded out, so I speculated that the rear sensors on his car are *not* coded out and spacers were likely used instead...

I think if you run a catless setup, you have to be ready for this sort of thing to happen, but hopefully only occasionally. Rear o2 sensor faults don't seem to ever effect the running of the vehicle and a quick reset usually fixes things.

Anecdotally, my 991 Turbo has run flawlessly with cat eliminators and spacers for ~5K miles, not a single sensor fault with stock ecu tune.

On my 996 Turbo, when I went catless (and Cobb tune, but rear o2 sensors not turned off), one rear o2 would trip every week or two... I swapped side-to-side and the fault remained with the sensor, replaced the sensor and hasn't faulted in thousands of miles. The rear o2 sensors were fine prior to the cat elimination, so one either got slightly damaged in the r&r or it was just on the cusp of failing and the cat elimination took away whatever margin it had. It also passes the OBD emission "readiness test" without issue.

pfbz

If heard this before, that on the 991 Turbo platform the Cobb off-the-shelf tunes aren't 'optimal' and that a custom tune is really needed, but that guys like Sam deliver really awesome custom tunes with the Cobb platform.

It's a bit disappointing to me considering how good the OTS tunes are on the 996/Mezger Turbo platform. Maybe it's a result of Kevin leaving Cobb and going elsewhere?

Steve Cole

Losing 6+ mph in the 1/4 is a whole new level of "not great." 11.1@126 was my best run with my 991.2 Turbo S with fresh BMC filter, COBB 93 Stage II tune and Kline 7670 exhaust with 100 cell cats. Hell, I ran 10.5s and 10.6s @ 134+ with my 20k mile filter, dead stock right down to OEM tires. All zero prep, even to the manuals in the glovebox. Same day I tested Stage II, the Stage 1 93 octane tune ran the same as stock.

Can't defend that. If you are going to buy COBB, you need to get a custom tune immediately or you are just lighting your money on fire. Even better, your car will be slower.

(FWIW if you follow the threads on here and 6Speed, you will find that I'm not alone and I've received some DMs from others asking me to share logs etc.)

2fcknfst

And this is the reason why:

https://www.epa.gov/enforcement/deri...act-settlement

None of the major players are taking any kind of risks after this, Cobb included.

pfbz

LOL... I agree, that is a big hit. It is a bit curious that Cobb did so poorly with the OTS tunes when it doesn't seem much of a challenge for their custom tuners to knock it out of the park, even on an unmodified or exhaust-only car. And more curious that they haven't fixed the problem..

Especially since Cobb charges $2,500 for the 991.2 Turbo platform and only $900 for the identical system for the 996 Turbo platform (which again, performs really, really well with OTS tunes). That extra $1,900 I'm sure is to recoup the R&D for the platform, but how about completing the R&D?

2fcknfst

See post above...

pfbz

Cross-posted... Seems a likely explanation.

But if that is the case, and @Steve Cole is correct (and I assume he is) that the OTS tunes really move performance in the wrong direction, why not sell the tuner with zero performance tunes installed, just stock and perhaps a valet tune, and hand over all expectations of a performance tune to the custom tuner?