2004 poor throttle response

[Paladin]

I have added a cold air intake, replaced the tps and maf, and still the throttle response is way off, if I increase throttle gradually, it's fine, if I floor it, it's fine, but if I want to go from say 1/4 throttle to 1/2 throttle, it does not do so immediately, it either sneaks up on it, or it's like it has a discussion about what I mean, and then decides, (to put human qualities on a mechanical malfunction?) I can force a down shift by depressing the throttle further, but there in lies my problem, any ideas? Thank you.

This page contains affiliate links for which I may be compensated. As an eBay Partner, and Amazon Associate I may be compensated if you make a purchase at no cost to you.

 

[biddle]

Is it a transmission issue? Hook up a good OBO code reader that pulls all the codes and see if anything is logged.

 

[Paladin]

did, no codes, it just feels like it kinda bogs, unless I am expecting too much response out of a "fly by wire" set up? also, had the transmission fully serviced, but that wasn't it either?

it tries to respond, it's just not crisp? like a cable set up on a carb would be
are there possible suspects, as in sensors for the shifter on the trans, that would affect throttle response?

do you know of a throttle pedal control device that works with the tbird?

 

[Tnargrant]

did, no codes, it just feels like it kinda bogs, unless I am expecting too much response out of a "fly by wire" set up? also, had the transmission fully serviced, but that wasn't it either?

it tries to respond, it's just not crisp? like a cable set up on a carb would be
are there possible suspects, as in sensors for the shifter on the trans, that would affect throttle response?

do you know of a throttle pedal control device that works with the tbird?

It's perfectly fine. The powertrain is just garbage for response. The 3.9 is built to run at high speeds and very high RPM, and only performs well when it does. Get out of pump gas, as well. It'll eat cheap octane but you'll rattle and gum up your valvetrain, that's almost certainly choked to hell by 20 years of gunk. Seafoam/etc won't do it, either, btw. The only time I find the motor awake is at 120mph +. The rest of the time it's just asleep trying to lug around 4300lbs. The vehicle itself performs like a magic carpet at high speeds and handles exceptionally well. At about 100 the weight melts away and even the stock suspension performs pretty well. The rest of the time you're driving a cinderblock.

Highly suggest ditching the motor for something fresh, or stripping your 3.9 down and cleaning it out. There's not much to do with the 3.9, otherwise.

 

[Paladin]

It's perfectly fine. The powertrain is just garbage for response. The 3.9 is built to run at high speeds and very high RPM, and only performs well when it does. Get out of pump gas, as well. It'll eat cheap octane but you'll rattle and gum up your valvetrain, that's almost certainly choked to hell by 20 years of gunk. Seafoam/etc won't do it, either, btw. The only time I find the motor awake is at 120mph +. The rest of the time it's just asleep trying to lug around 4300lbs. The vehicle itself performs like a magic carpet at high speeds and handles exceptionally well. At about 100 the weight melts away and even the stock suspension performs pretty well. The rest of the time you're driving a cinderblock.

Highly suggest ditching the motor for something fresh, or stripping your 3.9 down and cleaning it out. There's not much to do with the 3.9, otherwise.

I agree, once I got the alignment dialed in to neutral, and lost the oversteer, it handles like a dream over a bill, what are you referencing when you say strip it down? I like the motor, and trans, just not the sloppy throttle response. I run 93 octanes, best I can get here.

 

[Tnargrant]

I agree, once I got the alignment dialed in to neutral, and lost the oversteer, it handles like a dream over a bill, what are you referencing when you say strip it down? I like the motor, and trans, just not the sloppy throttle response. I run 93 octanes, best I can get here.

Take the heads apart and clean it all out. The rockers, lifters, and valve springs get really gunked up from 20 years of Ford fudds crawling the Tbirds around. It's a real nightmare to get down into it, but once it's all sorted the motor is pretty sharp. If you've got a local track, I'd suggest running the hell out of it once a year or so, just to help keep the crap out of it. Also, you can fix faulty O2 sensors and some odd fuel related sensors if you just run it out for a while.

 

[TJJIM]

did, no codes, it just feels like it kinda bogs, unless I am expecting too much response out of a "fly by wire" set up? also, had the transmission fully serviced, but that wasn't it either?

it tries to respond, it's just not crisp? like a cable set up on a carb would be
are there possible suspects, as in sensors for the shifter on the trans, that would affect throttle response?

do you know of a throttle pedal control device that works with the tbird?

I’m afraid you are stuck with the electronic throttle body. Cable throttle on my 02 I bought new will jump an 03-05 off the line every time even though it is less horsepower. No issues like ETC response.
I’d suggest seeing if you can find another 03-05 and drive it. See what it feels like.

 

[Liquidlounge]

Take the heads apart and clean it all out. The rockers, lifters, and valve springs get really gunked up from 20 years of Ford fudds crawling the Tbirds around. It's a real nightmare to get down into it, but once it's all sorted the motor is pretty sharp. If you've got a local track, I'd suggest running the hell out of it once a year or so, just to help keep the crap out of it.

I would say that these are not a typical issues for the 3.9. As far as "running the hell out of it", the Tbird tachs at 2k @ just 60 mph, so no need to burn the cobbs out of it (similar to "running the hell out of it", but usually not at the local track haha!)

 

[Paladin]

I think I've traced it to the pcm module, it sounds like, now how to test it?

 

[jneuenburg]

Take the heads apart and clean it all out. The rockers, lifters, and valve springs get really gunked up from 20 years of Ford fudds crawling the Tbirds around. It's a real nightmare to get down into it, but once it's all sorted the motor is pretty sharp. If you've got a local track, I'd suggest running the hell out of it once a year or so, just to help keep the crap out of it. Also, you can fix faulty O2 sensors and some odd fuel related sensors if you just run it out for a while.

Gunk in that area is oil sludge, right? Not combustion chamber deposits, which "running the hell out of it" might attempt to correct. Doing a proper fuel injection system cleaning service with a high quality chemical is likely better than that, and/or a really good carbon dissolving tank additive.

But oil sludge is usually due to an oil drain interval that is too long for the average engine temperature. Oil oxidizes with heat over time. The additive in it that slows that gives up at some point, and the viscosity starts to rise. Soon it is too thick and too much of it is left behind during a drain. This builds up over time and eventually turns to sludge you can scoop out with a spoon. To prevent that, drain and fill more often, and use a high quality oil. Probably a synthetic or semi-synthetic and hope it has a great additive package due to its high price point. Synthetic oils usually last longer because the hydrocarbons that make up oil are the optimum size for an engine lube. Regular oil will contain a range of hydrocarbon sizes, with the smaller ones eventually evaporating and the large ones contributing to sludge sooner than you want.

There are engine flush chemicals for engine oil out there but one has to wonder what will happen as they break apart sludge. Will it liquify it so it can be drained out, or will it leave chunks floating around that cause wear before they are picked up by the filter?