new guy with 4.6

[BK_CAULEY]

hey guys, first thing i guess is im new to the 4.6 tech but not new to mustangs. been running 5.0's forever and im finally got me a 4.6
and here is my issue. its a 1996 and has some modifications (i will list them at the end) and off the line through about third it will run strong but when i get up in speed it starts to kinda bog. and it is real noticeable. It ws like this uppon purchase and the guy i bought it from told me it needed a good tune to be right and that was all. and i would like to know is this the case or could there be something wrong with it i need to fix first.

Here is a list of what has been done to it.
and a picture of it and picture of the engine(might help)


2001 PI Heads W/BBK valve covers(heads have 20,000 miles on them)
PI intake
Pacesetter long tube headers W/ X-Pipe
Flowmaster mufflers with 2 1/2" tailpipes
Prof. Products upper intake
Splitfire Plugs
70mm MAC throttle body
24# injectors
80mm Mass Air Flow
Cold air intake
Strut tower brace
BBK underdrive pulleys
Steeda Tri-Ax short shifter
3:73 rear gears
Mileage is 85,000

 

[Mike97gt]

Try going up a hill at low rpm's in 3rd or 4th gear and see if it bucks/ jerks.. If it does then it is probably a plug and or wires problem

 

[BK_CAULEY]

going to do it right now. and why would it need a dyno tune with such minimal amount off mods?

 

[COramprat]

The head swap isn't too minimal. The swap lowers the compression and could be the problem where a tune would help. Someone with experience with a headswap may be able to confirm.

I ran my car without a tune for several months after my cam swap. I was running 14.5's and after my tune it dropped to 14 flats. I could tell that before it felt like it was falling off a bit in the upper range. I'm betting that will be your issue also.

 

[BK_CAULEY]

Try going up a hill at low rpm's in 3rd or 4th gear and see if it bucks/ jerks.. If it does then it is probably a plug and or wires problem

ok ijust drove it up a hill in third, fourth and fifth at a fairly low rpm and didnt feel anything. but as soon as i cresed the hill an dgot into it and got some speed it it started to slack off BADLY.

The head swap isn't too minimal. The swap lowers the compression and could be the problem where a tune would help. Someone with experience with a headswap may be able to confirm.

I ran my car without a tune for several months after my cam swap. I was running 14.5's and after my tune it dropped to 14 flats. I could tell that before it felt like it was falling off a bit in the upper range. I'm betting that will be your issue also.

so getting a tune with a P.I. swap and all the other stuff thats done is pretty much required?

 

[COramprat]

It helps a good bit but I'm not sure that is what your problem is. Sounds like it is more than a tune to me.

Is it flooding like too much fuel or not enough?

 

[BK_CAULEY]

It helps a good bit but I'm not sure that is what your problem is. Sounds like it is more than a tune to me.

Is it flooding like too much fuel or not enough?

im not smelling gas, but i will check my pressure later on today. and it might help to check the filter huh? is there a possiblity that my pump isnt keeping up? how much fuel is to much and how much is not enough? how could it be getting either? only way i see it getting to much is if an injector is stuck open or my pressure regulator is bad. am i right in these assumptions?

 

[COramprat]

I think you are headed in the right direction. I think it is fuel related. Start with the easy stuff like the filter and work that way.

I think if it wasn't getting enough it would be cutting out. Too much and you bog. I'm just guessing though but it sounds like the logical way to go. Bouncing ideas around usually gets to the root of the problem.

 

[BK_CAULEY]

I think you are headed in the right direction. I think it is fuel related. Start with the easy stuff like the filter and work that way.

I think if it wasn't getting enough it would be cutting out. Too much and you bog. I'm just guessing though but it sounds like the logical way to go. Bouncing ideas around usually gets to the root of the problem.

yea i wasnt even thinking about the fuel system till you mentioned it.
at first i was thinking it was some of thesen new fangled electronics. it took me forever to understand the 5.0's. im going to go get a new filter and check idle pressure now. i will let you know what i got.

 

[reddrgn01gt]

This may be a stupid question but I didn't see pi cams listed. does the car have those also? You definitely need to have the car tuned after the pi swap.

 

[BK_CAULEY]

This may be a stupid question but I didn't see pi cams listed. does the car have those also? You definitely need to have the car tuned after the pi swap.

im not sure if they are stock or pi cams. im going to try and call him in a few and find out.

COramprat-pressure was around 38,39,40ish.

 

[blown4_6]

if you need PI cams let me know, I have comps in my car (2002) now. Ill sell them cheep you pay shipping. Name a fair price and there yours. Only 15,000 miles on car.

 

[Mel96GT]

going to do it right now. and why would it need a dyno tune with such minimal amount off mods?

You have A LOT of mods. FWIW, the PI headswap raises the compression ratio. Are you running 91+ octane? It must be fuel related since I noticed you were running 24# with an 80 mm MAF, therefore your current tune is WAY OFF. You definitely need a tune since the computer still thinks you are running 19#'s and a stock (65 mm) MAF so it's dying at higher rpm's.

Check your compression, they should be within 5% on both banks. If not, one cam may be off by a tooth.

This is not a 5.0 so you don't need to upgrade your injectors and MAF so quickly. For a cheap fix, try some 19#'s and a stock MAF with the stock tune. You only need bigger injectors and bigger MAF if you go FI or radical NA.

Also, try some stock Motorcraft sparkplugs. According to my mechanic friend those Splitfires are not very good (shattered pistons, burnt valves, etc.) if your car isn't designed for them since they raise the combustion temps.

It appears to me whoever was modifying your car thought it was a 5.0! Good luck.

 

[BK_CAULEY]

If i get a tune can would that put everything in order without having to remove stuff? and the guysaid it had pi cams but how hard would it be to upgrade to comp cams? If my cams are off by a tooth how hard is that to fix?

 

[BK_CAULEY]

One more delima while im at it. he never hooked the heater hoses back up and i was wondering why and how can i reattach them to the heater core inlet and outlet tubes.

 

[COramprat]

Could be the heater core has a leak. That would be the only reason I wouldn't reattach. The cam swap isn't too hard if you are mechanically inclined but depending on how aggressive you go you will want to time and degree them.

There is a how-to on the MD on how to degree and swap the cams. Check it out and see if you want to tackle it. There is also a timing article there.

 

[BK_CAULEY]

ive read around about the swap and isnt there some kind off tube that has to be replaced for the coolant? how hard would it be to hook it up if i want to put it back. that is if the heater core isnt messed up and leaking. are the lines as easy to locate and reattach as a 5.0's

 

[Mel96GT]

ive read around about the swap and isnt there some kind off tube that has to be replaced for the coolant? how hard would it be to hook it up if i want to put it back. that is if the heater core isnt messed up and leaking. are the lines as easy to locate and reattach as a 5.0's

Yes a tune will usually cure your ills on the car.

No, the coolant tube change over is when you go from NPI to PI. The cams are not too bad if you use the cam-changing tool and you don't have to degree them. Otherwise you will have to remove the whole front cover of the engine. I would just get the thing running right first then think of additional mods.

 

[BK_CAULEY]

Yes a tune will usually cure your ills on the car.

No, the coolant tube change over is when you go from NPI to PI. The cams are not too bad if you use the cam-changing tool and you don't have to degree them. Otherwise you will have to remove the whole front cover of the engine. I would just get the thing running right first then think of additional mods.

tune is on order.
and my last question was reffering to replacing the cross over tube it was switched from npi to pi and the heater core lines are not attached and i was wondering what coolant lines from where needed to be attached.