d00d

There are plenty of other threads that show dynamometer graphs of the gains.
My state doesn't measure emissions at the tailpipe, instead it uses the ODB port to scan for ready codes, so as long as the tune has prevented these you are good.

d00d

A tune didn't cause this, it's caused by the stock tune not beng able to compensate for the ~20% increase in flow using the bigger TB.
COBB is working on it, and I believe Ehresmann may already have this solved.

okie981

Ahh...ok, good to know.

ShakeNBake

+1 - it's a hardware compatibility issues, not a tune issue. Cobb is working on it. And it only really happens at the track - not an unintended acceleration problem, it's an unintended free-revving problems and rev-sticking problem. Porsche did a lot of things to make the rev decay helpful to heal-toeing and throttle lift oversteer...and that tuning gets messed up when the TB is giving the car more power than expected. My guess is that the Porsche feature tuning is a function of throttle position, not air pressure in the manifold.

Jimmy-D

Air filters should be part of the TB/Plenum upgrade which should also go with some kind of ECU flash or ECU upgrade. IMO without the TB/Plenum/ECU upgrade they will do nothing. Right now there have been some reports of problems with upgraded TB but hopefully these will be solved as it's key to increase the size of the TB in order to make some decent increase in power and torque. A local tuner tested a COBB on his personal GT4....full stock....and on a mustang dyno they could only measure 1-2 HP increases, so probably not worth it if you at least haven't done the exhaust mods.
jmartpr is offline Report Post

Can you please elaborate - So some one with the upgraded throttle body, plenum, and tune only saw 1-2 HP gains??- or are you just talking about the air filters??

If the latter, how much more HP/Torque will one probably see with the throttle body, plenum and tune

Jimmy-D

But if this person had the Cobb tune what would anything have to do with the stock tune or are you saying this individual had not tune??

ShakeNBake

What most tuners focus on is creating a map that tells the car how to deal with increased air flow, by adjusting fuel rates and timing as mapped to manifold pressure (I'm sure I'm over simplifying), helping the ECU go beyond what was originally expected - beyond the range of what was thought originally to be feasible by the factory. When you get off the throttle, a lot of other things come into play. Keeping the throttle open for idle (even when you think the throttle is closed, it's not), dealing with how the car responds to off-throttle commands in terms of upsetting the chassis, holding the throttle for down shifts (not blipping)...lots of what I call feature programming. There is absolutely no doubt that with a tune, the car makes HP (maybe not 10K worth...but 1st world problems), and even more as a delta at lower RPMs, with the right parts, vs sticking with the stock tune. The trouble is with the feature stuff and the bigger TB. Tuners are not used to addressing this, so it's coming. Net is that Tuners will fix it, even though it's not their problem.

Bardman

Its probably also worth noting that a tune is not a complete replacement of the stock ECU parameters. Essentially they take a copy of the stock file, and tweak some of the parameters to get the outcome they want.

This means you need to understand what all the parameters do, and it doesn't come with an instruction manual for obvious reasons. So to fix an issue like this, there is a little trial and error / educated guessing that needs to take place so that the correct parameters can get the right values to fix the issue.

Bardman

First I have heard of heat issues with headers. Good to get this feedback. So it seems ceramic coating is pretty much mandatory.

Bardman

As I predominately use my car on the street, my priority is to smooth out the torque curve in the low rpm range (remove that 3.6k dip) and perhaps give it a small boost down low.

It seems headers and a tune are a good way to achieve this. Any comments from those that have done this?

ShakeNBake

Yes, you need to be diligent with keeping the harnesses away from the headers, or go with a wrap or shielding. If you metal zip-tie the cables to within an inch of their lives you'd probably be ok. But when you are going through trial and error like I am, you melt some things. And again, the duty cycle on a car on the track is very different from the road. It gets much hotter...it never gets a chance to recover and cool down.

jmartpr

Did you fixed both O2 harnesses to their stock position? There are 4-5 points on each side. I had to play a bit with this when installing my Cargraphics headers. Reaching some of the harness fixing points is a PITA but necessary or it gets too loose and could come into contact / close to the header. On the dyno my headers glow Red of all the heat accumulated on them so not surprised that under racing conditions if the harness gets too close you will have problems.

jmartpr

+1 on headers....long tube ones. The Tune I'm not so sure will give you a substantial increase but I'm trying to be the guinea pig for the local COBB dealer and see what results we get with sports headers and the Cup exhaust.

jmartpr

I was talking about a full stock car....no other mods...except installing the COBB AP. They used COBB stock maps, did custom maps (lots of them) and at the end it's only 1-2 HP on a stock car.....not sure how COBB got those gains for stock cars advertised on their website.


This coupled with the issue of the TB made me hold on the COBB. Don't want to spend +$1K and then find out I need the full ECU from Germany or some kind of other ECU solution.


I'm trying to convince the COBB tuner (who is the owner of the stock GT4 tested) to lend me his COBB AP (after erasing his car from the system if possible) and test on my car that has the headers and exhaust and see if we can get anything extra with a ProTune and these mods.

KingSize.Hamster

Personally I don't get the point of catless header unless the car is a dedicated track car. It's not worth the health hazards involved ... And plus the headaches with emissions/police.

I see people with no cats rolling up the windows when parking and staying in the car for a little longer for health reasons. It just looks silly to me ...