Good Afternoon everyone,
I have a 2009 mustang bullitt im trying to diagnose and having a little trouble. It has 39545 miles on it with a cold air intake, long tube headers with a catback exhaust. The vehicle will not accelerate past 3k RPM's with a CE light for random and cyl. 1-3 misfire. I have replaced the spark plugs, and swapped coils to different cylinders to see if it follows but no change. There has been a major exhaust leak where the header and midpipe meet on bank 1 (psngr side). I don't know if that has anything to do with it but it whistles like nobody's business. I've also removed the fuel rail with injectors and did not find any build up on the ends of the injector. I've cleared the DTC's multiple times and comes right back. I don't know if this is a common issue with these motors and if i need to go more into depth with it like fuel filter even though the faults are only on one bank. The MAF sensor, but no faults for lean or rich. Or the EGR. I'm hoping some of this will help and somebody at least has an idea as to where to start. Thank you all for your time.

 

First, welcome to the forums. IMHO, a major exhaust leak would most definitely be a contributing factor towards misfiring issues along with the CE light. Therefore, I would start by fixing the exhaust leak which should correct the acceleration/misfire issues and CE lights. I would also change the fuel filter as well, depending on how long it was last changed?

 

Howdy! Welcome to the forums!

I agree with m05 there. Exhaust leak needs fixing before you move on. May fix it all up. The scavenging might not be working correctly on the exhaust stroke so the air/fuel is messed up and it misfires. Ditto the fuel filter needing replacing maybe (which reminds me...) And one can hope that yeppers, that's that, car's great, good to go!

BUT... it might not, and so, if it does not:
I need clarification on this. You swapped plugs and coils and 1-3 didn't change? Still misfire on 1-3?

If that's correct, then (beyond the exhaust thing) the coils and plugs are good, supposedly, and therefore the items left: Injectors, cam followers, lash adjusters, camshaft itself, phasers for the TiVCT, wiring, ecu, timing, head/head gasket, and finally, the motor's toast. One hopes it's not that bad...

I noticed you looked at the injectors to see if they were gunked up... but at this point I'd move those from 1-3 to 5-7 and see what happens. It may be that no visible gunk is there, but they're still stuck/broken. The low miles vs higher years... that's my guess actually

You said you reset the codes... don't reset them, post them here. All of them are important for helping us know what's up. So get them up again and let's see what all ya got.

I'm gonna stop there. That'll be enough for now, you got a little work to do, methinks, to see if any of this advice so far works or not. If it doesn't, we can go further, yes? Attack the exhaust leak first, definitely.

Hope that helps, let us know!

 

yep, I'd start with the exhaust leak (that could be messing up the O2 sensor readings) before "chasing my tail" with the other things

also, I assume it was running correctly in the past with the same modifications . . . if the problem started after a modification, then that modification is probably the cause . . . for your mods you do need a custom tune, you did not mention that but I assume you have a custom tune and it was running right with that tune . . . if not, that would be another place to start

 

Excellent points, Bert. Mods are fun, but mods can make a car cranky too.

 

Well obviously the OP must be running a custom tune, otherwise his car wouldn't run properly whatsoever with LT headers lol. Therefore, IMHO, it's an exhaust leak as originally posted..

 

yeah but ya never know, he never actually said whether it ever ran right or not with those mods

 

He most definitely needs to clarify whether the car ever ran right or not with his mods and which ones specifically, otherwise, all we're really doing is spinning our wheels guessing, no pun intended lol.