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Ok I have a 2014 gt500 I installed a JLT CAI a 65mm cobra jet throttle body and a 2.4” supercharged pulley and by everyone’s recommendation I got a $300 VMP level 2 performance tune all in the car I regaped the plugs to .028 like they told me but the check engine light still comes on my tuner sez there’s some misfires on some cylinders but I’m not to worried about that but it sez right and left bank running lean. What do i do ? What about colder plugs ?
 

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Ok I have a 2014 gt500 I installed a JLT CAI a 65mm cobra jet throttle body and a 2.4” supercharged pulley and by everyone’s recommendation I got a $300 VMP level 2 performance tune all in the car I regaped the plugs to .028 like they told me but the check engine light still comes on my tuner sez there’s some misfires on some cylinders but I’m not to worried about that but it sez right and left bank running lean. What do i do ? What about colder plugs ?
First off, stay out of boost until you get this figured out. Hammering on the engine with a lean condition can be a very expensive mistake.

You will need to work with your tuner (VMP) to find out WHY you have a lean condition.
 

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Ok I have a 2014 gt500 I installed a JLT CAI a 65mm cobra jet throttle body and a 2.4” supercharged pulley and by everyone’s recommendation I got a $300 VMP level 2 performance tune all in the car I regaped the plugs to .028 like they told me but the check engine light still comes on my tuner sez there’s some misfires on some cylinders but I’m not to worried about that but it sez right and left bank running lean. What do i do ? What about colder plugs ?
Like @Goose17 said, stay out of boost and you need to work with your tuner. However I am going to guess you need either bigger injectors, a boost-a-pump, or both.
 

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First off, stay out of boost until you get this figured out. Hammering on the engine with a lean condition can be a very expensive mistake.

You will need to work with your tuner (VMP) to find out WHY you have a lean condition.
Ok I already sent them a email about my problem the first time is when they told me to regap the plugs to .028 so I sent them another email this afternoon it’s probably to late to get a reply today
 

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Vmp have been around a long time & they know GT500's
I would go over everything and be sure you have not left anything loose or over tightened the intake so air can get in.
As mentioned above, work with your tuner to figure out the issues.
Do Data logging until that tune is dead nuts, then you will feel confident pounding on it.

There was recommendations on here someplace about plug gaps, having the misfire issue I would go back and just check things out there also.


Plug info


Colin
 

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What plugs did you get? Some plugs have been prone to misfire issues.

I cannot imagine a fuel issue. You are not at the level of needing fuel mods yet. I think the 13/14 guys usually see like 680-690 range before they start having issues that cause them to buy a bap.

What do your logs show for afr? This is stuff your tuner should be advising you on. That adults what you are paying them the big bucks for.
 

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Not sure where you're located but I would seek out a local tuner.
VMP has a good rep., but long distance tuning can be a crapshoot.
I understand " canned " tunes are sold everyday by many tuner shops, ( including my tuner ), there is nothing like having the tuner drive the car !!
 

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I would go over everything and be sure you have not left anything loose or over tightened the intake so air can get in.
It's either going to be this or the tune. If you overtighten the band clamps on the silicone adapters, it can buckle the tube and air will get into the engine that hasn't been metered by the MAF. If that checks out, get VMP to check the transfer function is for the correct JLT tube diameter. JLT has 3 tubes, stock, 123mm and 148mm. If you bought used, you may need to verify what you bought and what you told VMP you have.
 

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If that checks out, get VMP to check the transfer function is for the correct JLT tube diameter. JLT has 3 tubes, stock, 123mm and 148mm. If you bought used, you may need to verify what you bought and what you told VMP you have.
Very good point here & EASY thing to do.

As we all know,
VMP has tunes for pretty much every setup,the tunes have been tested and tweaked over years, that being said, once you get the issues sorted out,be sure to datalog and send to VMP to verify that she is good to go.

I do not use VMP for my tunes, but every time i got a tune, Lund racing would verify thing are good before proceeding, they tweaked my last tune a few times be giving me the go ahead.

Let us know how you make out.

Colin
 

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Discussion Starter #10
Very good point here & EASY thing to do.

As we all know,
VMP has tunes for pretty much every setup,the tunes have been tested and tweaked over years, that being said, once you get the issues sorted out,be sure to datalog and send to VMP to verify that she is good to go.

I do not use VMP for my tunes, but every time i got a tune, Lund racing would verify thing are good before proceeding, they tweaked my last tune a few times be giving me the go ahead.

Let us know how you make out.

Colin
I appreciate all the Advice and VMP said they wanted to see a data log on my car so I’m trying to get this figured out they have a YouTube video I’ve been studying. I’m 62 years old and trying to learn this stuff. Back in my day if my big block Chevelle ran lean we just put bigger jets in our Holley double pumper. Little different now.
 

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Not sure where you're located but I would seek out a local tuner.
VMP has a good rep., but long distance tuning can be a crapshoot.
I understand " canned " tunes are sold everyday by many tuner shops, ( including my tuner ), there is nothing like having the tuner drive the car !!
I’m located about 90 miles west of Fort Worth Texas I would like to take my car to a tuner. Friend of mine said there’s one in Arlington Tex called Gearhead performance anyone know much about them ?
 

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I’m located about 90 miles west of Fort Worth Texas I would like to take my car to a tuner. Friend of mine said there’s one in Arlington Tex called Gearhead performance anyone know much about them ?
Manny at HPP Racing in the DFW area runs a big Mustang tuning and performance shop. If you come towards DFW, give me a holler!

 

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I appreciate all the Advice and VMP said they wanted to see a data log on my car so I’m trying to get this figured out they have a YouTube video I’ve been studying. I’m 62 years old and trying to learn this stuff. Back in my day if my big block Chevelle ran lean we just put bigger jets in our Holley double pumper. Little different now.
i am not that far behind you, 67-69 Firebirds were my toys, rebuilt many over the years.

Did you get a chance to go over your car to be sure noting is out of whack? If not go over everything, you may find your issue.
like Cat says, check the size of the Intake if you used, be sure you gave VMP the correct info.

data-logging is not hard, just a pain in the ass.
There maybe a how2 on this site?

personally,
I would not drive my car if lean.
I would put back to stock and load the stock tune if planning on taking to a Dyno.

just my 2 cents worth.

Colin
 
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