Tune necessary after LT headers?

**Wheeler99WS6** · 02-19-2007, 06:22 AM

Originally Posted by tblu92

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.

tune can wait if you plan on doing more mods soon such as heads and cam. if not then i would suggest tune but not because you have to but just to get all you can performance wise out of the longtubes, yes you are running rich at WOT but not to the point you are harming anything necessarily. like i said you can wait if you have the mod bug and are doing more mods soon. No a hand held tuner is not going to cut it. You will need tuning software and laptop such as HPtuners or EFI live type. or pay a tuner to do it for you.

**7camaro7** · 02-20-2007, 10:44 PM

what could happen from running lean and without a tune?

**oneBADDz** · 02-21-2007, 08:02 AM

Originally Posted by 7camaro7

what could happen from running lean and without a tune?

Severe sudden death. Lean isn't a joke, a little rich is fine but lean is unacceptable

**Wheeler99WS6** · 02-23-2007, 05:31 AM

Originally Posted by oneBADDz

Severe sudden death. Lean isn't a joke, a little rich is fine but lean is unacceptable

+1.....lean does mean more power but if you are too lean.......well it wont be pretty hows that. Running too lean is very risky.

**firesilver** · 03-06-2007, 08:07 PM

well i got my car tuned after lts, but they said my air fuel ratio was almost right on. But it was worth it because i gained about 15rwhp and got the codes tuned out. It also sounds and feels alot crisper at wot.

but if your gonna do more mods it can wait.

**oneBADDz** · 03-07-2007, 07:48 AM

Originally Posted by firesilver

well i got my car tuned after lts, but they said my air fuel ratio was almost right on. But it was worth it because i gained about 15rwhp and got the codes tuned out. It also sounds and feels alot crisper at wot.

but if your gonna do more mods it can wait.

that's unusual though

**WARP211** · 03-09-2007, 03:42 PM

lean is all bad...

Rich will foul out plugs and can destroy cats..

lean= ping and detation.. if its way high like 15:1 or 16-17:1

Stoci= 14.7:1 that's the middle where you wana be at part throttle or cruise..

Rich= 13:1,12:1,11:1,10:1 and so on..

02's info....

Vaccum leak or running lean will send the signal to PCM to add FUEL= RICH

Stuck open injector or running Rich will send the signal to PCM to SUBTRACT FUEL= LEAN

hope this helps kids...

**7camaro7** · 03-10-2007, 01:39 PM

so in my situation where I just put on lts with the ory and the rear o2s are just hanging up in there, what kind of signal would my computer send to make the engine run? rich or lean?

**WARP211** · 03-12-2007, 08:43 AM

Originally Posted by 7camaro7

so in my situation where I just put on lts with the ory and the rear o2s are just hanging up in there, what kind of signal would my computer send to make the engine run? rich or lean?

If you don't have 02 simulators.. then your PCM will see that your cats are not working.. And that will throw a code.. The rear 02's are to look at catalytic efficencey.. Since you don't have cats.. you need the 02 simulators..

**7camaro7** · 03-16-2007, 05:51 PM

rich or lean though?

**SSr8d** · 03-18-2007, 11:28 AM

Originally Posted by tblu92

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.

hello names nick

in SD, CA

01 SS no cats, flashed the O2 sensors

need a little tuning

716 940 1259 Cell

619 303 8991 Home

Please hit me up soon!!

**WARP211** · 03-19-2007, 10:48 AM

Originally Posted by 7camaro7

rich or lean though?

Most likley you will be running rich.. Cuz of the excess of air in the exhust. But, the PCM will compensate and try to keep the A/F ratio around 14.7:1..

**WARP211** · 03-19-2007, 10:51 AM

Originally Posted by SSr8d

hello names nick

in SD, CA

01 SS no cats, flashed the O2 sensors

need a little tuning

716 940 1259 Cell

619 303 8991 Home

Please hit me up soon!!

you might wanna try looking up some Local Tuners in your area.. Try the phone book or do some research on the NET.. I found a guy down here in Fairfield that will dyno your car.. 3 pulls for 125.. And he can also do some tunning..

**brantsz** · 03-23-2007, 02:26 AM

Well in most cases I would say yes you would be ok with no tune. Seeing how you have changed your MAF I would be on the look out. I personally would leave the MAF stock unless I was making serious HP and then I would remove it from the car completely. If it were me I would have a tune done so that corrections can be made for the MAF and the headers, etc. What I found after doing my headers was the obvious "rich" and also found that I was getting o2 switch codes due to the o2 sensors being moved back and running cooler. This code showed up about a week after my install and was using new 02 sensors. With this code the car was dropping out of closed loop operation making it run a little richer. If I had no tune and I tripped this code that shuts off the LTFT learn I would be running on the factory VE and MAF settings. Where in your case you have changed your maf ! Do a search on the o2 switching errors with LT headers. Not trying to be negative here, just so you are aware of all of the possibilities

**bigtyme** · 03-16-2008, 09:58 AM

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?

i have the same prob i got my cats gutted out an my engine light came on my code is 02 sensor heater circuit malfunction bank 2 sensor 2 if i switch them from side 2 side will this make the light go off

**00z28bubba** · 03-16-2008, 11:41 AM

i strongly suggest a tune just based on my experience with lt's it makes a world of difference and i would never ever suggest running a car rich or lean but also on my car my afr was way off to my knowledge.before tune my afr was 14.7-15.0 and after was 12.4-12.6 and my car was completely different after as well. if want to know my basic mods click my profile and click about me. nothin special mostly intake and exhaust.