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Discussion Starter · #1 ·
First of all, it's a pleasure to be a part of this site...I've enjoyed reading a number of threads on here! Quite informative!

Second, I'm truly at my wits end over here. I purchased a 2007 GT Mustang from the actual Ford Dealership that had been modified by the previous owner. I absolutely fell in love with it the second I test drove the car. I purchased it approximately 7 weeks ago and it's been in the Ford repair/service department for 6 weeks....yeeesh!

Forgive me that I don't fully understand all the Tech talk that you guys throw out in the forums, but I thought I'd try to convey what I know has been modified on the car (according to the Ford Dealership). The previous owner's modifications included 'Long' Headers, cold air intake, gear work, dual flow master exhaust, computer chip replacement, Hurst shifter, etc.

The first week I had it (and the minute I drove it off the lot) I noticed three significant problems. The check engine light came on/blinking and the car would slightly bog down every 5-10 minutes (ever so slightly) when I was in 3rd or 4th gear at about 2800 rpms. When this bogging down was noticed, the air conditioning would shut off and only blow room temperature air. This entire incident would only last 15-20 seconds (then the air conditioning would kick back on and 'unbog'). So I immediately took it back to Ford.

They immediately gave it an overhaul, changed the plugs, gave it a once around and thought it may be the Harmonizer/toner. They found that the previous owner had the wrong aftermarket harmonizer in there...so they replaced it. We thought the problem was fixed-Wrong! Car went back into the shop. I'm unsure of the exact codes, but they told me they thought it had something to do with the O2 sensors/the 8th cyclinder was getting a weird reading. They worked on it for another week and I ended up going on a ride along, with the service foreman, who said the problem was fixed (until I was able to recreate the %^$*#% problem on the freeway-twice in 8 miles). The check engine light came on, car bogged down ever so slightly, and the airconditioning compressor shut off...WTF?

After Ford decided to replace the entire computer/chip, they then decided to send it over to their professional Tuner/Dyno place where it has been on the Dyno for 7 days now. After tuning/reprogramming it for 5 days, they said it was running like a Swiss Army Watch...so we went on a test drive for 30 minutes. It DOES run like a champ, but after 20 minutes, BLAM, check engine light, bog down, air conditioning cuts out. Ford was P.O.ed that their Dyno place kept it for this long and didn't correct the original problem....and so it's been back at the Dyno place for the past 2 days.

I call Ford/Dyno place every single day for an update on what's going on. Again, I don't know the codes that are spewing out of this car, in regards to the check engine light, but what I do know is that they originally told me the codes were saying an O2 sensor problem that was messing with the 8 cyclinder...then the 3rd cyclinder...then their was a fuel/lean problem...blah, blah, blah. After reading all of your posts, and all of your suggestions on this site, it seems that the FORD/DYNO place has done all of this...and then redone it again to make sure they did it correctly the first time. (i.e. Tune,check all sensors,spark plugs,etc).

They informed me, yesterday, that they are opening the engine up today to check something with the Cams (I think). I've lost track of whats going on now. It concerns me that a Ford dealership and a profesional Dyno establishment can't diagnose such a problem. Did I buy a lemon? Give it to me straight, Doc?


~Any suggestions would be greatly appreciated...I'm just going to hand the 'responses' directly to the Service Manager.

~MaxSharp
 

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welcome to the site man, sorry you're having all this trouble with your car, hopefully they will get it straightened out, just remember they know how to work on factory stuff, not so much aftermarket seems like something was going on that's why the first owner traded it in, see if you can get the guys name and see if you can find out where the work was done at. Good Luck
 

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Sometimes these cars are a little twitchy when it comes all the sensors and the PCM. Anyways, with the limited mods that you have and only the intake and exhuast really being effected, it shouldn't be that difficult. As far as diagnosing the issue, it's a little hard over the net. Your A/C shutting down and bogging is part of your car going into limp mode. Basically when your engine senses something is wrong, it shuts down non-essential systems like your A/C and limits fuel and timing to the engine so you don't blow it up.

Things I would look for or try:

Check delay with the O2 sensors. Long tubes move the sensors farther down the exhuast and sometimes this distance causes a delay in the readings.

What kind of CAI is on there? Maybe try a stock airbox and intake tube to see if it helps.

Check for bad sensors, MAF, cam position, knock, O2.

Though I would think that these "dyno guys" could figure it out, but with your limited mods, would probably be able to get some sort basic e-mail tune from a tuner that has some reputation. Bama, or Brenseed, or Tillman, should have a standard type tune that we all know work well on many of our cars. At least if their tune does the same thing it rules out a tuning issue and makes it a little easier to diagnose as an actual engine issue.
 

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This is the main problem with purchasing an already modded car with no history attached to it.

That said, there's not much on the car that would through someone off and justify months of downtime like this.

A/c compressor makes this strange, no reason that should coincide with a CEL during loaded RPMS.

I'm wondering if the AC compressor isn't kicking over and causing some of that bog, pushing a load significant enough on the motor to generate a CEL ????

Any idea if they have looked there yet?
 

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I haven't experienced AC shut down on any of the cars that have passed by me like 07 mentions. However, it would make sense if that is the procedure to limp mode. My cars gone to limp mode after a hard pass on the highway and not killed A/C at all. So I'm torn on that explanation.
 

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If you could find out the codes that the car is throwing, and post them on here we may be able to help you better.
ya i was gonna suggest the same thing... if you have the handheld tuner they used to "chip it" you can use it to read the OBD-II codes your car is throwing.
 

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Discussion Starter · #8 ·
Just checked/talked with the Dyno guys and they said they might have found the problem...they didn't really elaborate on 'what' they found cause they have been driving it all morning and the problem 'apparently' hasn't shown its face....but I've seen this reoccur for the past 6-7 weeks...



Anyways, I asked for the actual DTC codes and all they said was it was a "Cylinder 3 misfire" and a "Random Cylinder Misfire" that keeps coming up. Suggestions?
 

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My car just had an electrical problem, went into limp mode and the A/C would not work. The tech told me that it will shut down the A/C so the car sees no unneeded stress until the problem is solved.
 

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The problem with having a Ford dealership "mod" a car is that the majority of techs are not too familiar with aftermarket stuff. If you take your car in for an oil change or warranty work its fine, but when you start having real issues its over their heads. Is this dyno shop a reputible place? It seems like the issue should have been diagnosed/resolved long ago. Did they datalog it? They must have if they told you its lean.IMO its a tune issue. Did the Ford dealer do the tuning? Good luck.
 

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like I said, I threw two coil failure codes and the car immediately went to limp mode, A/C kickin so good the nipples were standin.

Maybe it's tied to specific codes that bring on the limp mode condition?
Maybe, mine was a coil failure code also and the ac wouldn't work.
 

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Normally with OBDII systems though, when the CEL light flashes, it means it is "Catalyst damaging" meaning that if the problem continued, it would damage the catalytic converter. Could be tune related. It being too lean would cause major heat in the cylinder, valvetrain and catalyst.
 
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