18 intake manifold tune problem

[Racerx009]

I had a 18 manifold installed on my 17 mustang gt non pp with stock throttle body..I had it Dyno tuned it made 423whp so I wasn't thrilled and decided to try Lund racing tune. I loaded the tune and my car started to back fire threw the intake. It does it every few minutes. I did the Kam reset and crank and nothing. It only happens at idle it drives great with no hesitation.
I load my Dyno tune and it goes away !! I spent all day going back and forth with Brandon at lunds. He sent me another tune and same thing. I do data log with him and I cleaned my MAF and checked for vacuum leaks. No problems found no codes
Any ideas ? ??
My mods are bbk long tubes 1 3 /4
BBK high flow cats
18 intake manifold stock throttle body
JLT CAI
H pipe
3.73 gears
Jms pedal max
160 thermostat

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[Nuked]

Mine did the exact same thing when I was messing with the tune. Ended up being a vacuum leak where the Evap solenoid connects to the manifold. That is the connection you have to "make work" with a short piece of tubing to go from the bottom of the evap to the manifold. My Lund tune never did it, so I assumed I screwed something up in the tune when I was messing around. I ended up deleting the Evap which I believe Lund disables by default as I have not thrown a code for it in over 3k miles. Try unhooking the evap solenoid and plugging the port on the manifold and see what that does,

 

[beefcake]

Yep. Check for leaks and make sure vacuum hoses are routed correctly

 

[Racerx009]

Yep. Check for leaks and make sure vacuum hoses are routed correctly

I spent hours spraying carb cleaner around the manifold and checking vacuum lines. I have no idea how the vacuum lines should be installed???
I told Brandon at lunds that I was going to disconnect my pedal max. Just for piece of mind.
I may be rusty on all the new technologies for car computers. I was out of the game for 20 years. I did go to automotive technical school and before I joined NYPD. I was the head tech for the FBI and still worked on my own cars. But this issue got me at a loss since it does it with one tune and not the other. I went back in my garage at 10pm because it was eating at me. I have the Dyno tune loaded and I let it warm and nothing not one pop. I resprayed around the manifold tugged at the vacuum lines.
I don't like part swapping but after checking the Evap sensor. I will try another throttle body. If it still does it then I will just leave the Dyno tune.

 

[Jay-rod427]

Carb cleaner is not what it used to be. Much harder to find leaks that way. And in today's computer engine world a very small leak can make a difference. The dyno tune may have something turned off or on, or different parameters than the lund tune.

 

[Racerx009]

Mine did the exact same thing when I was messing with the tune. Ended up being a vacuum leak where the Evap solenoid connects to the manifold. That is the connection you have to "make work" with a short piece of tubing to go from the bottom of the evap to the manifold. My Lund tune never did it, so I assumed I screwed something up in the tune when I was messing around. I ended up deleting the Evap which I believe Lund disables by default as I have not thrown a code for it in over 3k miles. Try unhooking the evap solenoid and plugging the port on the manifold and see what that does,

Will try that and I am going to disconnect my pedal max just for the hell of it. I am actually right now sitting outside with my car running with the Dyno tune to see if it pops at least one time. So far it's 20 minutes and nothing lol. I am retired so I have all the time in the world to figure this out.

 

[Racerx009]

I might crazy I deleted the Evap sensor completely .The popping only happens when the fan comes on and when it turns off it will pop again and no popping at all till the fan turns on again.

 

[Tommy V]

Do a log at idle and see what long term and short term fuel trims are,tell us what u see.If u delete the evap solenoid it has to be turned off in the tune also.

 

[Racerx009]

Do a log at idle and see what long term and short term fuel trims are,tell us what u see.If u delete the evap solenoid it has to be turned off in the tune also.

Okay will do

 

[Lennon1313]

Okay will do

I have the exact same thing going on as described in your original post. Have been searching for a vacuum leak to no avail but am gonna try closing off the Evap port. Any update on yours?

 

[Bluemustang]

Please please get rid of the pedalmax. It is not doing anything good for you.

Sounds like a mechanical issue. The stock TB shouldn't be causing any issues. Going to a different TB probably WILL cause you issues.

Are your IMRCs turned off and locked out? No issues with my Lund tune, runs better than stock.

 

[Nuked]

I might crazy I deleted the Evap sensor completely .The popping only happens when the fan comes on and when it turns off it will pop again and no popping at all till the fan turns on again.

When the fan comes on it changes the load on the engine. The ECU looks for a specific TQ number based on rpm/load. If it is making more/less TQ than it should it will adjust spark and throttle to achieve what it wants. The fan coming on changes the load of the engine which changes the TQ number it looks for. Log spark and load and you will notice they change when the throttle pops. Lund does a lot of these so odds of it being off in the tune are slim, but it is always possible to make a mistake. I still lean towards a vacuum leak somewhere.

 

[Bluemustang]

When the fan comes on it changes the load on the engine. The ECU looks for a specific TQ number based on rpm/load. If it is making more/less TQ than it should it will adjust spark and throttle to achieve what it wants. The fan coming on changes the load of the engine which changes the TQ number it looks for. Log spark and load and you will notice they change when the throttle pops. Lund does a lot of these so odds of it being off in the tune are slim, but it is always possible to make a mistake. I still lean towards a vacuum leak somewhere.

When my fans come on, the RPMs drop a little bit but then come back. No popping sounds.

 

[Joe 5.0]

Mine did the exact same thing when I was messing with the tune. Ended up being a vacuum leak where the Evap solenoid connects to the manifold. That is the connection you have to "make work" with a short piece of tubing to go from the bottom of the evap to the manifold. My Lund tune never did it, so I assumed I screwed something up in the tune when I was messing around. I ended up deleting the Evap which I believe Lund disables by default as I have not thrown a code for it in over 3k miles. Try unhooking the evap solenoid and plugging the port on the manifold and see what that does,

What would happen if I capped off the EVAP solenoid, but it's turned on in the tune? Would the car run like ass?

 

[Nuked]

What would happen if I capped off the EVAP solenoid, but it's turned on in the tune? Would the car run like ass?

No, just get a CEL.

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