Every now, and then my 4.6L wants to show it's ***. When starting off under load the engine will buck, or jump. That's the only way I can describe what happens. It will do it once, and then go on as nothing has happened. It has new plugs, throttle/MAF has been cleaned, and has a new gas filter. It's been doing this on, and off for awhile. I actually though it had quite this craziness until today when it did it twice. Any suggestions, or help will be greatly appreciated.

Jim

 

Is this completely random or are there any common factors you've noticed? Like when the car is cold, or certain weather or after its been sitting a while, anything like that?

 

mine bucks and farts sometimes when it is cold too . . . usually when I am just taking off slow and easy in 1st gear . . . never figured out why it does it, or why it only does it sometimes, but I have read that others do it too

 

Any CEL or stored codes? I am thinking a COP is going bad...

 

It's random RB, and when it's warmed up.

 

That could be the problem my friend. I didn't change the coil packs, and didn't think of that possibly being a problem as the things runs smooth as silk all other times. It hasn't thrown any codes.

 

Yep, that's when it does it Bert, but the car is fully warmed up. When I be starting off, and it's under some load. Feels like someone hit me in the buttocks, and then it will jump.

 

Sounds like your open loop tuning could use some adjusting. Who is your tuner?

Are you running boost?

 

No tune my friend. She's stock. In my searching I found that there was a fuel pump TSB 06-9-9. It describes exactly whats happening to mine. However, I'm not sure if ford will honor a TSB that old, and I'm not even sure that is the fix.

 

Ahh, that's just your wife's new Mustang kicking it, showing it who's the new boss in the stable.

 

You know how it is bud, the boss drives the boss. And, we must listen.

 

When was the last time you cleaned the TB and intake? I'm assuming you have the stock pcv system. Don;t forget your charge motion plates also. and give your MAF a spray with some cleaner. When was the fuel filter last changed?

 

Other than for cleaning the CAI and charge motion plates, the OP has previously stated that he cleaned his MAF, added new plugs and also replaced his fuel filter. As for cleaning charge motion plates, how exactly would you go about cleaning them other than by uninstalling them first

 

Well that's the only way I know how also. It's not that hard to take them off and that is what I did when I saw how oily they got. Also deleted the pcv system so that I wouldn't have to clean them again.

OP, are we talking stick or auto?

 

Thanks for the help Boss, it's a manual. As Rocky stated all has been cleaned, or changed. It doesn't do it around town, or on short drives. It seems to happen after a long drive at highway speeds. And even then it doesn't do it every time. I may just chalk it to "one of those things" until it gets worse. IDK

 

After a long hwy cruise....hmmm. I remember a while back, pre 07 cars had an issue with the fuel pump after long sustained drives. Something to do with cavitation around the filter sock on the bottom of the pump. There was another guy back then that was having this issue and I sent him my old fuel pump and it fixed his issue.

It is a PIA to pull the pump because of the way the access hole is lined up with the tank, but I might check it and see what it looks like or try and find the TSB on it and see if it might be your issue. I will browse around and see if I can find it.

 

http://cdn.lrsstatic.com/downloads/t...sb06-09-09.pdf

 

Guess this is something I should look into, especially that my car is FI lol. Although I still run the active pcv system, I hope that by running an oil separator along with the c-f-m billet oil cap breather will also prevent the plates from becoming oily as well

Correction: I forgot that since upgrading to FI, my car no longer has the charge motion plates, as the Saleen PD setup doesn't require re-using them anyhow.

 

Yeah, I don't have mine any more either, whipple manifold.

The catch can should catch a good amount of the oil. I just eliminated it as I have done on so many of my previous cars.

 

After 2+ years, the UPR 4 chamber catch can including one-way inline check valve along with the c-f-m billet oil cap breather also with built-in one-way check valve appears to be doing its job, as I haven't noticed any crankcase oil getting past the barb connectors at the intake manifold at all. So anyhow at least, for the time being, I'm still able to keep the factory pcv system fully intact