14 GT with Long tube headers Tuned?

[Jacob Nolen]

Hey all,
A while back I bought a 14 mustang gt with kooks long tube headers and HFC. I’ve been driving it for about 6 months now and noticed that when I fill up with 91+ my Mpg skyrockets. Before on 83 I would get 16mpg, maybe 17mpg but now it’s about 20mpg. I have also noticed a bit more power when using 91.

With the car having Long Tube Headers being installed by previous owner, would that warrant a tune? Is there a good way to tell if it is tuned aside from trying to see if some of the factory limiters (rpm/mph) are removed like most tune do?

I know I probably should have asked the dealer if it has been tuned before I bought the car, but here we are!

Thanks!

 

[86GT351]

Hey all,
A while back I bought a 14 mustang gt with kooks long tube headers and HFC. I’ve been driving it for about 6 months now and noticed that when I fill up with 91+ my Mpg skyrockets. Before on 83 I would get 16mpg, maybe 17mpg but now it’s about 20mpg. I have also noticed a bit more power when using 91.

With the car having Long Tube Headers being installed by previous owner, would that warrant a tune? Is there a good way to tell if it is tuned aside from trying to see if some of the factory limiters (rpm/mph) are removed like most tune do?

I know I probably should have asked the dealer if it has been tuned before I bought the car, but here we are!

Thanks!

It most likely has a tune currently. Is there a check engine light on?

 

[UpAllNight91]

Stock rev limiter is 7k. I would start by trying to see if it runs up to 7.5k. Headers alone won't really require a tune. But a cold air intake in most cases does. Mainly due to the larger area around the mass air flow which reads less with more flow. If its just headers you should be good on a stock tune. I know there are some that say anything and everything needs a tune but I'm coming from the angle that it will run fine and fuel trims won't be effected greatly with headers alone

 

[Dino Dino Bambino]

Hey all,
A while back I bought a 14 mustang gt with kooks long tube headers and HFC. I’ve been driving it for about 6 months now and noticed that when I fill up with 91+ my Mpg skyrockets. Before on 83 I would get 16mpg, maybe 17mpg but now it’s about 20mpg. I have also noticed a bit more power when using 91.

With the car having Long Tube Headers being installed by previous owner, would that warrant a tune? Is there a good way to tell if it is tuned aside from trying to see if some of the factory limiters (rpm/mph) are removed like most tune do?

I know I probably should have asked the dealer if it has been tuned before I bought the car, but here we are!

Thanks!

The answer as to whether you need a tune after installing long tube headers is it depends on two factors:

1. The length of the primary pipes and how much further downstream the B1S1 and B2S1 O2 sensors have to be placed. If their warm up after a cold start is delayed appreciably (especially in cold winters), it can cause the engine to run lean and hesitate for a few minutes because the ECU transitions from open to closed loop before the O2 sensors have properly warmed up. The tune may need to be modified to delay the ECU going into closed loop after a cold start to account for the longer O2 sensor warm up time.
A tune is definitely necessary if you install full length headers such as BBK, JBA, Stainless Works, and American Racing. The Kooks are actually 3/4 length with shorter primaries that place the upstream O2 sensors closer to the engine and may thus not need a tune.

2. If you have cats downstream of the LT headers. Deleting the cats necessitates disabling the downstream O2 sensors B1S2 and B2S2 in the tune unless you fool the ECU by installing O2 sensor extension spacers.

With Kooks headers and high flow cats, there's a fair chance the ECU might still have the stock tune since it can command the injectors to add more fuel to compensate for the increase in airflow by simply reading the MAF sensor signal. Therefore the short term fuel trims will slightly increase but as long as your stock fuel pump and injectors can supply enough fuel, there's no problem.

 

[Juice]

Get Forscan.
Read mode 6 data and look at O2 response time. Its the first 2 lines of the report. It is in ms, miliseconds.
LTs without a tune will be mid 100-200ms.
I got mine to 80 ms tuning transport delay. Could not get it any lower.

 

[gbstang]

Hey all,
A while back I bought a 14 mustang gt with kooks long tube headers and HFC. I’ve been driving it for about 6 months now and noticed that when I fill up with 91+ my Mpg skyrockets. Before on 83 I would get 16mpg, maybe 17mpg but now it’s about 20mpg. I have also noticed a bit more power when using 91.

With the car having Long Tube Headers being installed by previous owner, would that warrant a tune? Is there a good way to tell if it is tuned aside from trying to see if some of the factory limiters (rpm/mph) are removed like most tune do?

I know I probably should have asked the dealer if it has been tuned before I bought the car, but here we are!

Thanks!

I would think that if you are seeing a mileage change from one octane 83, to using 91-93 octane that would indicate that a "tune" optimized for a specific octane range... Aside from what Dino has said, most performance cars are optimized from the factory to run on "pump gas" most certainly 83-85. Most supercharged cars need 93 octane or better.. I am thinking when you run that crappy 81 octane you get alot of pre detonation at WOT, aka rattle in the valve train...

We are constantly being forced to "Settle for what we can get" 20 or so years ago you would never see 81 octane.. in the 70's it was in the 90's. Still overseas you will see octane higher than 93. All for the illusion of saving the climate...BS!

 

[JC SSP]

Pretty much it has been 87, 89 and 93 here in south FL for many years.

I do recall Sunoco had an unleaded 95 or 96 octane back in the late 70's & early 80's that my Brother ran in his 455 HO T/A. Not to mention the aviation fuel he would occasionally use... LOL

I have stated this before, but I run 93 in everything (Mustang's, Taurus, Audi and Durango), from generators, to lawn mowers, just easier for storage and refueling...