This will be my first post to Mustang Forums I'm a noob here. Anyways I have a 1996 Ford Mustang Coupe with a 2000 year model 3.8l v6 crate engine in it. When I first got the Mustang it had a few problems idling and surging a bit. I put in new plugs, plug wires, air filter, changed oil, removed air filter silencer, and put a gt mustang tune on it with my trusty SCT SF3 3015. The car doesn't have cats and the evap system hoses are rotted so its all plugged off with vacuum caps. Egr and Rear cats are disabled with the tune. Running on 87 octane gas. After all that it ran significantly better for a while until Yesterday. Yesterday my check engine light came on with a code for evap no flow and p1151 for H02 fault/lean condition. I checked all the vacuum lines and I don't think there should be a reason for it to be running lean. Now its surging a little bit again and acceleration isn't what it used to be. Any ideas guys?? I've posted many details so you get the whole picture. Sorry if that bothers you. I have also attached a SCT Datalog Screenshot of the H02 sensors data. Some sensors flat line which i believe isn't normal. It appears to me that I have one or more H02 sensors going out. Idk. I just want my power back. Oh and btw does anyone know where the charcoal canister of the evap system is? I'm planning to repair it sometime. Any help, ideas, comments, or possible solutions are much appreciated. Thanks

 

Curious as to how you loaded a GT tune. Shouldn't work at all with that. If you have the EVP capped off, you'll need to account for that in the tune as well.

 

I'm thinking the gt tune is probably just a name. When I connected my SCT SF3 3015 to the car the car showed up as Ford Mustang GT and the only tune available was the GT tune. I can verify it is a 3.8l v6 though and it does operate on the tune. I had no problem tuning it. None of the egr stuff is altered just disabled in the vehicle computer. The evap line to the intake is capped off the rest of the system is there but the hoses are rotted though. So it doesn't surprise me to pull a code for evap no flow because i capped the vapor hose to the intake off. I guess the H02 sensors are going bad and screwing with my mixture. Idk. Thanks for the reply though.

 

Why did you shut off the EGR system in the tune? IIRC you need to actually remove the system if you have it off in the tune. It's been awhile since I've done something like that.

 

You don't have to remove it. Turning it off in a tune basically closes all the valves and stops it from working.

 

I would return everything back to stock tune wise and see if that fixes the problem. And like Matt stated, the GT tune could be causing issues in it's own right. The V6 and GTs opperate on two totally different ECU programs, if that's the case and it really did upload GT settings I'm amazed that the car would run at all.

 

I have a lot of knowledge about computers and electronics. I own an IT business. I do understand that the computers have two completely different computer programs but i also know that the guys at SCT Flash know their stuff. Their tuner grabs the vin number and computer code to match the tune so its either their screw up or the gt tune is just a name. Also the guys at AmericanMuscle.com have used it before many times. I am gonna take you guy's advice and remove the tune and just leave the evap system capped off because I really don't wanna mess with fixing it right now. Just a couple questions though. Could it be the IAT or MAF sensor causing it to run lean?? I know it peaks to 120F here!! Their probably pretty dirty too. The car has been starting to overheat lately with ac on so I really need to figure out whats causing it all. If problems are there without the tune I'm convinced it's a sensor. I've done plenty of vehicle electronic diagnostics before.

 

Having EVAP just capped off and not accounted for in the tune will be part of the issue.

The overheating thing could be many factors. Dirty radiator (inside and out), water pump going out or thermostat getting stuck. I'd check the thermostat first, and give the radiator a good flush.