Hey guys, i'm hoping one of you out there is a 4.6 expert! I'm having issues with my Cobra. It has an under fender cold air intake, going into an accufab single blade throttle body (had to do some cutting to get that in =P). Anyway. My check engine light started to flash on me. The car feels like it is losing power somewhere. When I first get on the gas it is very unresponsive up until about 3000-3500 RPM. When I slow down to a stop it idles VERY VERY rough before it smoothes back out. Also during acceleration i'm hearing what sounds like a backfire or perhaps a hole in my exhaust. I took it to a ford garage and they said my spark plug wire was bad going to cylinder 2. I changed those just recently and even changed the spark plugs to be on the safe side. It seems to run smoother with all 8 cylinders back. But I can't pinpoint this issue with the engine. The only thing extra i've done not mentioned before is put a T-56 in it. I'm totally lost at this point. I'm afraid that it's an inner component problem, like rods or somethin crazy, but that wouldn't really explain the rough idling that is making my whole car shake. Anyway, that's all I got. It goes back to the ford garage tomorrow but i'm in Germany and I don't have alot of faith in them being able to pinpoint the issue correctly.

 

2 things. has your computer been calibrated or tuned to the bigger throttle body. and is the throttle body bigger. it seems like you are having a detonation problem. that can be caused by improper calibration of your tune or a vacuum leak.

 

is ur check engine light still on?

 

yes my check engine light is blinking. Anotehr thing I noticed today. It is definately backfiring at around 4k rpm. If I turn the steering wheel as far as it will go to the right or left the engine acts like it wants to die. I'm guessing it's the strain from the power steering. I didn't get my computer tuned when I got the throttle body, but it was running very nicely. The throttle body and cold air intake has been on my car for over a year, with no issues what so ever. This whole problem started one day after me and my wife got back from a trip. I only drove the car about 45 miles, and the next time I started it, the idle sounded very rough, and it sort of spudders when I give it gas. I'm really hoping it's not a huge issue, something like a fuel pump or maybe injectors. Thanks for the help guys, any more info u can come up with i'll give it a shot.

 

hook that sucker up to a diagnostic tool! thats the first thing u gotta do. tell us what trouble codes come up, and then we'll be a lot more helpful. u can just go to ur local auto parts store so they can check it for free.

 

Hey guys, sorry took so long but I was a lil busy with the army, lol. I got the error codes from a local garage. The dealership isn't being much help. The only thing they specialize in over here is Ford Mondeos and Focus. They really don't know what to do with my car, lol. Anyway, here is a list of the codes, and I already know that one of them is a blocked valve in my manifold. That one has been around for a long time I believe, and I'm not sure what someone would charge me to take that apart and figure it out.

P0411
P0301
P0303
P0171
P1517
P302

I'm POSITIVE that the only fault I had before all that was the valve in the manifold. Just a quick note, i'm sure you guys already know. I have a 4.6 4V book from sean hyland motorsport. That valve opens up at about 3000-3500 rpm to let more air into the engine basically. I just don't know if it's stuck open, or stuck closed. I can't imagine it's stuck closed. If that's the case I feel like my car would have been running poorly at higher RPMs, but it does seem to be a bit slow off the line. My guess is stuck open. But yea... I appreciate all the help, you guys on this Forum are great!

 

Your talking about the IMRC , intake manifold runner controls, if they got stuck open they would cause absolutley no problems at all, in fact its a smart idea to have them delelted, they cause nothing but problems when they get carboned up and wont open. Just get the deletes

 

Wow, Thanks for that bit of information. I had seen in my book an area on removing those but the book said it would take a pretty decent machineist to get the job done. I had never heard of the deletes before. I'll definately have to look more into those. Thanks again!

 

Just a quick update. I've posted on alot of forums, and gotten alot of advice on this issue. I'm hearing mostly the same thing. Vaccum leak, or COP are bad. On the Vaccum leaks i'm being told to change my DPFE Sensor. I'm not exactly sure what this is or where to find it, but my best guess is the air pump. I'm just wondering if I get a whole new air pump if this will fix the sensor, or if it's something seperate ?

 

The DPFE sensor reads EGR operation....Check the little rubber hoses goin into it. The DPFE is a small black box (or sometimes metal) with an electrical connection and 2 rubber hoses going into it. When I get more time I'll check up on your other codes and help ya out, right now Im just a lil caught up.