Going lean

[Karlos]

Hi
Last year in October before i parked the Cobra in my garage for the winter, is was running 11:7 a/r
Running with these options.
Custum tune.
Home port blower
Dragon inlet and throttle body
K&N air filter
SCT BA2600 MAF
60lb injectors
2,76 upper pulley
Kenne Bell BAP
2,5" magnaflow cat back

This winter i added a few things to the Cobra.
ARH longtubes 1" 3/4 with 3" catted X-pipes
JLT CAI, with same BA2600 as used last year
4lb lower pulley
PPRV delete.

And now it is running lean WOT 16:5 and also giving codes p0171 and p0174, lean bank 1 and 2
Only going WOT very shortly.
And that is the only codes i gets
In idle it very steady at 14:7 a/r around 1000rpm, and cruising 5 gear 2000rpm it is the same
I know from the start i had to get a new tune, but can it be true i should see this much difference?
With the new things mounted on the car, i thought maybe it would run about 12:5 a/r
Or do i have another problem?

Hope somebody can help me.

Thanks

 

[bigmoose]

You added 4# of boost. Yes your A/F will be off that much. Get it returned and check again. Hope you didn't melt anything.

 

[s351]

You better hope you didn't make a full pull, and let out quickly. Those are some big changes to make without re-tuning before making a pull. Like the guy said above I hope you didn't hurt your motor.

 

[cj428mach]

The extra boost as no effect on the AFR unless the tuner didn't bother to try to dial in the upper part of the MAF curve. For example I can change from 17 to 21 psi and my AFR doesn't change.

The big issue comes from whether or not timing was adjusted for the extra increase in load.

More than likely the upper part of your MAF curve wasn't dialed in or the new CAI is throwing things off that much or both. It also seems odd that you're getting a lean code as I'd think that should only be something you'd see in closed loop driving situations. I'd lean towards a vacuum leak or the CAI really is throwing it off that far. You're probably really lean at idle/low load but you don't notice it because of closed loop covering it up.

Don't get me wrong you need a tune before you go WOT again, but people always think that since you up boost AFR changes because of the extra airflow. Thats not true though if your car has been tuned correctly.

 

[RichM1983]

I"m not an expert but how is that even possible? If you add around 4lbs more air the afr has to be effected. Fuel to air ratio. Your adding air and not fuel it has to go lean. OR am I just an idiot? Everything I've ever read contradicts what your saying.

The extra boost as no effect on the AFR unless the tuner didn't bother to try to dial in the upper part of the MAF curve. For example I can change from 17 to 21 psi and my AFR doesn't change.

 

[cj428mach]

I"m not an expert but how is that even possible? If you add around 4lbs more air the afr has to be effected. Fuel to air ratio. Your adding air and not fuel it has to go lean. OR am I just an idiot? Everything I've ever read contradicts what your saying.

I'm sorry but apparently everything you've read is wrong.

Why wouldn't you be adding fuel? You have a Mass Air Flow Sensor that would see the increase in air flow and add the corresponding amount of fuel.

You've heard of pegging your MAF right? thats just running out of MAF range. Lets say under your current setup the max reading you get at the MAF is 50lb/min. Just because you change pulleys and are now seeing 57lb/min max at the MAF that doesn't mean your lean. The hard limit for the MAF is 63.9lb/min so if your tuner set up the tune correctly you'd have some head room above your original 50lb/min on the MAF meaning that until you saw 63.9lb you'd be fine.

Now the tuner could have just quit tuning the MAF transfer after the original setup maxed out at 50lb/min but that would be a bad tuner. Since its impossible to tune over what the setup is maxing out the MAF at, you have to guess where fueling should be above the max out point.

Now this only matters in regards to fuel, load which affects timing would change with the extra air flow and if the tune isn't setup correctly would cause issues. I hope this makes sense.

 

[stang910]

Your issue is coming from your JLT intake. Anytime you change the diameter of the maf you need a retune, doesn't matter if your using the same sensor or not. The reason your seeing 14.7 while cruising is cause the O2 sensors are correcting in closed loop. Your throwing the lean codes because the O2's are correcting over 25% or whatever it's set at in the tune to throw the code.

Put your old intake back on and like cj428mach said as long as the maf was dialed in correctly the car will compensate for the extra boost. Timing does become an issue with 4lbs of extra boost. This could have also been dialed in to compensate for the extra boost as long as your not seeing over 2.00 load. Your best bet is to get the car tuned before going WOT.

 

[RichM1983]

Damn you guys just totally turned my understanding upside down. So your saying if he puts his old intake back on that the car was tuned with the only thing he should be worrying about is the timing because of the extra boost? His old tune intake and maf can compensate for the 4lb lower?

I can't believe I'm just now figuring this out. I thought I knew a thing or two about these cars and how things work.

 

[stang910]

No he needs to worry about the AFR also because his maf counts are gonna be higher. If his tuner has that specific maf combo dialed in all the way to 1023 maf counts then yes his AFR will be pretty close to where it needs to be with any amount of boost increase. The other issue he could run into is maxing out the maf which will cause the car to go lean. These are a couple reasons you need to have your tuner check the car.

Now if you understand how everything works and you can read datalogs you can easily check to see if the car will be safe to run with the new mods. My guess is if you do understand tuning you wouldn't be paying someone to tune the car in the first place. The best advice I can give is if you don't know what your doing have someone that does check it over for you. Paying someone a few hundred dollars to check the car is a lot cheaper than replacing a melted piston.

 

[Karlos]

Thanks for a very good response.
It all makes sense to me.
This coming weekend i will put back on old filter and intake, and will take it from there.

I could imagine that there is a lot more air running through now, with JLT, 4lb lower and also a lot lees back pressure with the longtubes.

I also replaces fuel filter to a K&N when i did the PPRV, and thought maybe the filter was collapsed. But it that was the reason it should also have giving a code for fuel pressure. The FRPS sensor.

I will keep you updated on this one

 

[bigmoose]

Is your JLT intake the high boost or the other one that uses the stock BA2600 housing. If you moved the sensor to a high boost JLT then that would be your issue.

Not thinking before the extra boose likely shouldn't case our issue assuming your original tuner wasn't dumb.

 

[MalcolmV8]

There are so many "but ifs" you should get the car checked by your tuner and data logged. Yes true swapping pulleys doesn't always need a re-tune if there's head room on the MAF and it was previously tuned correctly. But if the MAF now pegs you'll go lean. Also timing is a huge concern based on load. If load is clipping at max then the ECU can't "see" the additional boost and adjust timing accordingly.
If your new intake adjusts the diameter around the MAF then all bets off, you need a new tune. The fact that you have lean codes suggest something like that has happened.
Don't blow it up, get the tune fixed.

 

[Karlos]

Hi

So now I have mounted the old intake again, and you are all completely right.
The issue is the big air JLT intake.
My afr reading is now back to normal.
So now i just need too get it tuned in again.

Thanks guys, you are the greatest

Anyone know a good tuner for a handhold?

 

[cj428mach]

Hi

So now I have mounted the old intake again, and you are all completely right.
The issue is the big air JLT intake.
My afr reading is now back to normal.
So now i just need too get it tuned in again.

Thanks guys, you are the greatest

Anyone know a good tuner for a handhold?

Malcolmv8 remote tunes

 

[Bdubbs]

And 04sleeper!