Hi guys. Long time no post. I hope someone can help me. I have a CAI from Modular Depot with a custom tune. It looks like they do not exist anymore. Hopefully that won't be a problem. I recently took my mustang in for service and before I did, I reverted back to the stock tune along with the stock intake. It was body work, but I did it because I was paranoid. When I got the car back, I reinstalled the CAI and the tune. I have multiple tunes on my SCT Xcal2 tuner and I noticed I installed an old one the first time. Instead of reverting back to stock and installing the new one, I just installed the new one. The next morning when I left for work, the car stalled about a half mile from my house and will no longer start. Have I really screwed up by not reverting back to stock before installing the new tune? Does anyone have any idea how to fix this? I did call the dealership to make sure they did not re-flash the computer while they had it and they have assured me they did not.

 

I have switched tunes multiple times, at least a dozen, without reverting it back to the stock tune. I don't think that is your issue. Try reloading the tune and then go through an idle relearn procedure if you can get it started.

If you can't get it to start, double check all of your intake connections. Especially the underside of the TB where you can't see. Then verify you are getting fuel and spark. Try and start it with the MAF unhooked. Then report back.

 

Currently I have the stock intake on the car and have reloaded the stock tune. I get the same problem as with the CAI and performance tune. I was able to get the car home without the MAF sensor hooked up, so I know it is getting spark and fuel. But once I hook up the MAF sensor, the car dies. It will not idle. As soon as the engine starts, it immediately dies. I guess this is pointing to the MAF sensor being the problem. I just didn't think about it going out just because I switched it from one intake to another. I have never had a problem with that before. I have tried cleaning the MAF sensor, but that did not make any difference.

 

Before replacing the MAF maybe try and datalog the MAF counts and see if you see anything funky. I guess that's not that important if you have narrowed it down to that but I always hate replacing parts that don't need it.

 

I don't like replacing anything I don't have to as well. Especially something as expensive as a MAF sensor. Is there anything specifically I need to pay attention to or be on the lookout for?

 

Look for weird **** like the count jumping around when idling or if the count does not go up in ratio with the throttle position. I mean it's going to jump around a bit but should stay within a certain range. Maf count will determine how much fuel should be going in through the injectors. if it's off it will mess up your A/F ratio. Also check out your fuel trims and see if they are jumping around trying to compensate for a bad A/F mix.

 

Well since I cannot get the car to start, watching for the numbers at idle is kinda hard. I did log the numbers as I tried to start it, and they never got above 1 volt. Based on that, I ordered a new MAF sensor. Once I installed it, the car started right up. Problem solved. Thanks for your help.