mirandaandjimmy

I have a 06 Mustang Gt I have sunk a lot of time and money and have gotten no closer to a solution, any help would be greatly appreciated. The car will idle perfectly, throttle up to 2000+ car starts making a miss noise out the exhaust. I have replaced the plugs with champion plugs, put on a new set of msd coil packs, put on 24 lb. injectors. I have cleaned the throttle body. Rechecked the plugs and gaps 4 times. Checked the compression perfect. Pulled the intake cleaned and replaced the gaskets. Even cleaned the butterflies on the back. I have pulled the valve covers and check the cam shaft no visible marks anywhere, Put new valve gasket on. I have replaced both cam sensors, crank sensor, maf sensor, tps sensor, 2 upstream o2 sensors, and 2 down stream 02 sensors. Checked battery and the alternator. I put on new exhaust gasket checked for leaks. I have also replaced the mufflers with flowmaster 40s. I have replaced the fuel pump and filter. I have even tried setting the tune back to stock then back on nothing helps. About to just take to dealership just wanting to know if there is anything someone else might know of before I take that step.

bl817

is it throwing any codes while its acting up? I would say go back to stock plugs and coil packs and see what happens. why the higher flow injectors? stocks are 19 lbs. any other mods like LT, after market TB, OR X/H pipe? could be as simple as vacuum leak.

mirandaandjimmy

No it is not throwing any codes and have put everything on the car after the problem started. I have checked for leaks not found any yet. there might be a slight one in the intake that i havent noticed.

JCON

Can you explain exactly what you mean by hesitation and give as much detail about the scenario as possible?

mirandaandjimmy

Get in the car fire it up and take off letting the car pull itself or barely pressing the throttle and the car will move fine engine sounds good. Press the throttle harder or even all the way to the floor and the car will buck and jerk making a popping noise which sounds like it's coming from the passenger side of the car almost sounds like i can hear it from the exhaust. I ran a Bosch code reader on it last night. No CEL on but it came back song u1900 u2011.

JCON

Those aren't Ford diagnostic codes as far as I know. I believe they relate to the CANBUS system in the car. Does your engine, ABS, or traction light(s) flash when it hesitates?

mirandaandjimmy

No there are no engine, abs, or traction control lights flashing. nothing at all is illuminated.

jpplaw

For sh*ts and giggles, clean every ground connection you can find and replace fuse #47 in the underhood fuse box and see what happens. MSD coils are good but they do crap out and get rid of the champion plugs, try NGK's instead. Why did you change injectors? Put the stock ones back on unless your tune has been changed for the new ones. You CANNOT just add bigger injectors in these engines without tweaking the tune for them.

mirandaandjimmy

I will try cleaning the grounds and replacing the fuse. The coils only have maybe 10 miles on them, I have only replaced these things since the problem first arised. The injectors state that the do not need a tune and are fine to run on the engine. But with the tune I have on it I have an adjustment for the injectors. I have also wondered if the CMCV could be an issue. When I pulled it off the butterflies were packed with carbon and barely able to move. As far as the plugs I just dont want to go back with the stock 2 piece plugs. Not fun when 6 of them brake off.

bl817

alright, well we are throwing possible answers to help your situation and your not wanting to try any of them. go back to motorcraft plugs, use nickel anti-seize on the snouts only and they will come out like butter next time. but the oem coilpacks and injectors back in. if you still have the stock air box, put it back on and put car back to stock tune. start it up and try to drive it. the alternators on these cars are prone to failure and will bench test good. im leaning towards alt as problem. if that's the case, get one for a 10' GT and throw it in. you also haven't mentioned mileage or what tune/tuner your using.