Tune necessary after LT headers?

**jimbo98z** · 03-13-2006, 01:30 PM

Originally Posted by foff667

i know i just wanted jimbo to explain his reasoning...I like to

I've heard that it's the coating that fouls the O2's. Guess I should not take people's word on these kinds of things... Oh well.
I've heard that what supposedly happens is that when they spray the coating on the outside of the headers, some gets into the inside and it burns off, contaminating the O2's... Did a little more research and can't find a definite link between the headers and fouled O2s. I guess its just a quick thing to point fingers at.

Another thing I didn't think of: Couldn't the reading errors be caused by the fact that the O2's are getting as hot with an LT setup due to the fact that they are further away from where the combustion actually takes place?

**GottaHaveLS1** · 03-13-2006, 01:49 PM

Originally Posted by WS6TNT2K2

I am new to the board, I have a 02 WS6 with a 6 speed. With the LT's I am having a problem with the SES light. I had the code read and it's shooting 3 o2 codes. I replaced the o2's and reset the light but it came back on in three days. Any suggestions as to how to fix this problem?

Go to an AutoZone or Advanced Auto Parts to have them scan it. It's free.

**WS6TNT2K2** · 03-13-2006, 06:14 PM

I went to Autozone and thats how I Found out what the codes were. That is why I replaced the o2's but that didnt help. I am trying to find out if a hand held tuner will help by changing the air fuel ratio. Any help is appreciated.

**oneBADDz** · 03-13-2006, 08:18 PM

You're sure it's throwing frotn O2 codes right, not rears? Do you have cats and rear O2s?

**WS6TNT2K2** · 03-13-2006, 08:43 PM

It's definetly the front o2's I have sims on the back and they work great. My set up is headers 1 3/4" primaries to dual 2.5" straight pipe out the back. No mufflers or cats. Its a little noise but I want the car to breath freely. So far no one can tell me if changing the air/fuel will help or if I have bigger problems. I was holding off on buying a tuner and was hoping someone could tell me one way or the other if the tuner is now needed.

**oneBADDz** · 03-13-2006, 08:47 PM

you need to know if your a/f is off first. . . .some people say that the lower temps make a diff, some people say that's rediculous. Mine was running very rich

**WS6TNT2K2** · 03-13-2006, 09:12 PM

As for running rich I think that is a big misconception. Think about it if the o2's are to lean they tell the ECU to richen up therefore when you think your car is rich and have the raw smell its really running lean. It's like a reverse psychology theory. I have found numerous comments of ppl claiming to be running rich when in fact they are lean but are not fully understanding the system or cycle of the o2 sensor. Electronics are so hard to understand and pin point a diagnoisis. But that is just me thinking out loud
I am not sure what to do in my situation it seems no one has had the same problems.

**oneBADDz** · 03-13-2006, 09:32 PM

Black smoke and poor mileage = rich in my case

**WS6TNT2K2** · 03-14-2006, 04:39 AM

I dont have the black smoke and the car definetly seems to be running crappy. So I am figuring that its not getting the right A/F mix

**98-NBM-Z28** · 03-14-2006, 08:17 PM

Originally Posted by WS6TNT2K2

It's definetly the front o2's I have sims on the back and they work great. My set up is headers 1 3/4" primaries to dual 2.5" straight pipe out the back. No mufflers or cats. Its a little noise but I want the car to breath freely. So far no one can tell me if changing the air/fuel will help or if I have bigger problems. I was holding off on buying a tuner and was hoping someone could tell me one way or the other if the tuner is now needed.

so you don't have any x pipe or anything to create backpressure??? that might be why the car isn't running well. our cars do need backpressure in oreder to get the desired response from them. I know someone will correct me if I am wrong.

**oneBADDz** · 03-14-2006, 08:23 PM

Originally Posted by 98-NBM-Z28

so you don't have any x pipe or anything to create backpressure??? that might be why the car isn't running well. our cars do need backpressure in oreder to get the desired response from them. I know someone will correct me if I am wrong.

some people say that's right and some people say it's rediculous. An x or an H either one is a really good idea. It smooths out the sound and helps with scavenging for a little more power over straight pipes

**WS6TNT2K2** · 03-15-2006, 05:15 AM

At this time I have no X or H pipe but after finishing with this exhaust I plan to add on soon. I have 3" dies on the way so the 2.5" will be getting replaced this should give a deeper more mellow sound and I plan to put an X in the new exhaust. I haven't heard of any problems due to the lack of back pressure.

**WS6TNT2K2** · 03-15-2006, 09:43 AM

I recieved my Predator and 160 stat this morning thanks to overnight shipping. I have put the basic performance tune to start, if I'm not happy after that i'll adjust accordingly. Took car for test drive seems to be alot happier and that makes me happy.

**rotwiler** · 03-16-2006, 11:50 PM

After I put in the LT headers the car ran great, then a few days later some back firing and could almost watch the gas needle moving as I drove. Put it on the dyno and did A/F at same time. My A/F was 10 something to 1, ajusted it with my Predator tuner at WOT and best power was made at 12.9:1. My gas mileage returned, backfires stopped and gained around 20h.p more than before adjusting the A/F. I'm going to get a custom tune from a local tuning guy and should see over 350 rwhp, now I am low 340 SAE rwhp which makes me happy since it is a A4 car.

**WS6TNT2K2** · 03-17-2006, 05:46 AM

Did you have any problems with the predator install? I thought my install went fine then I was going to modify the tune but when I tried I got 2 errors the first one said Install failed incorrect origin and the second error said Incorrect header found. Any idea how to fix this problem?

**rotwiler** · 03-18-2006, 04:23 PM

I have been using the Predator tuner since about March of 2003 and never once did I have a error. I even downloaded some custom tunes and installed them without a problem. You may have a bad one.

**WS6TNT2K2** · 03-18-2006, 07:34 PM

I called and talked to one of the Diablo techs and he had me send it back so they could make some alterations to it. Apparently there have been a few updates for the car but I havent had the car into a shop to have them updated so they said they would put the updates into the tuner and send it back to me.

**tblu92** · 02-13-2007, 07:00 PM

You deff. need a tune with LT's-- At PT the LTFT's will correct themselves up to a point. However at WOT you are at the mercy of your stock tune. Headers 99% of the time make you rich--so if at WOT you are at 11.8 stock and now you've richen'ed it up even more---you are way rich !!! A negative LTFT will lock on "0" just before going to WOT so it won't be taking out fuel as it does at PT to corrrect the commanded AFR. At WOT you don't have the 02's correcting the AFR --Even though the stock program is commanding an 11.8- it doesn't neccesarily mean thats what you'll end up with--Any mods you make will change the WOT fuel ratio and the actual won't match the commanded AFR---And that takes us to VE tuning which is a whole other mess to deal with but it is the way to make them match.

**9t8z28** · 02-13-2007, 07:42 PM

Originally Posted by jimbo98z

I've heard that it's the coating that fouls the O2's. Guess I should not take people's word on these kinds of things... Oh well.
I've heard that what supposedly happens is that when they spray the coating on the outside of the headers, some gets into the inside and it burns off, contaminating the O2's... Did a little more research and can't find a definite link between the headers and fouled O2s. I guess its just a quick thing to point fingers at.

Another thing I didn't think of: Couldn't the reading errors be caused by the fact that the O2's are getting as hot with an LT setup due to the fact that they are further away from where the combustion actually takes place?

Ceramic Coated headers are coated inside and out! Always! The coating does not burn off!

**unkind** · 02-19-2007, 05:42 AM

Originally Posted by rotwiler

I have been using the Predator tuner since about March of 2003 and never once did I have a error. I even downloaded some custom tunes and installed them without a problem. You may have a bad one.