Ford Mustang Forums banner

1 - 20 of 38 Posts

·
Registered
Joined
·
248 Posts
Discussion Starter #1
I will try to make this as short as possible. but PLEASE BEAR WITH ME! My buddy just got a turbo fox body. This is as much of the specs as we got: not sure on turbo make or size.
Forged internals 347
single intercooled turbo with methanol
Aeromotive fuel pump
sheetmetal intake
not sure on injector size but I know its not a ford injector. possibly fast because it has the early style fast computer system.
trick flow heads
Looks like an adapter plate between upper and lower that has p51 on it. seems like there is tons of money into the motor and turbo setup.

Now for the problem. The motor has about 100 miles on it and it ran great. owner is claiming 800 rwhp. I drove the car and in 4th gear when it hits spool it destroys the back tires. Very fast car. Just recently, it started really breaking up anywhere over 3800 rpms and the boost guage jumps all over the place. When the car is running right, it boosts at 28 psi. I logged some data with the fast and the a/f is anywhere between 14/1 up to 17/1 when it broke up and injector duty cycle was like 98 %. It will run great for the first 3 miles then start acting up. let it sit for 15 minutes then you will get another 3 miles. could the fuel pump be getting hot. and not flowing enough volume. the car sat for 2 years after it was finished. ANY HELP WILL BE GREATLY APPRECIATED. I am a full time mechanic but this is my first dealing with a turbo mustang. thanks Sorry for the length :confused:
 

·
Registered
Joined
·
2,722 Posts
Definitely lean if it's breaking up and spitting out those A/F numbers.

If it's happening not long after start up, only thing I can think of is possibly the O2's are acting finicky, that is unless you don't have them.

Has it thrown any codes?
 

·
Registered
Joined
·
4,744 Posts
What size fuel lines ?
Could be vapor lock if too small or getting too hot.

Really this could be any number of the things.

What do the plugs look like ?
 

·
Registered
Joined
·
248 Posts
Discussion Starter #4
I do understand that there is many things it could be. Im just not sure where to start looking. Im trying to remember any details I can. It has one 02 sensor for the fast. the car ran great when it was first used then he tried the stereo (it has a big stereo in the back with 2 dry cells. They both were dead so when he switched the breaker you could hear the sound of the pump change. It is a very loud pump. So we disconnected the main stereo wire and pump sounded normal again and it ran great. Next, the clutch melted fast to the flywheel and the car sat for about 6 weeks. We put in a twin disk spec setup and now the car is acting up again. I thought maybe the stereo was hooked back up but that was not the case. When the car is at idle it seems very rich. Last night, I cleaned the 2 aeromotive filters thinking maybe they were dirty and wasnt producing the volume but that didnt help. it started acting up again in second gear but when put in fourth, it pulled strong all the way to 6000 rpms. It seems like its worse in the lower gears. I dont want to drive it any more to see so I am looking for any suggestions. Like I said before this is my first problem with a turbo car that has the full functionality of tuning the car. Thanks so far guys. Im sorry if I have been repeating myself, I just want to give any information I can about the car as I find out more about it!!! Thanks again
 

·
Registered
Joined
·
3,209 Posts
Possibly the TFI or PIP acting up as well. If it’s dropping spark it can cause the wideband to read lean from excess fuel thrown into the exhaust.
 

·
Registered
Joined
·
248 Posts
Discussion Starter #6
whats the easiest way to tell if its dropping spark? I can look back at the data to see what timing was at when it was happening if that helps. When the car is running good, injector duty cycle is right around 70% then when it runs bad Its well into the 90s. Its not a fast breaking up it jerks around and the boost gauge is very jumpy. Very odd !!!
 

·
Registered
Joined
·
4,744 Posts
Vac leak messing with wastegate control and air metering?

Running MAF or SD ?

What do the plugs look like ? are they all the same ? color ? tip condition ?
 

·
Registered
Joined
·
248 Posts
Discussion Starter #8
The plugs are a dark gray color. when the car is idling or at low rpm it seems rich, it pushes some black smoke. I dont really know what to think about it. Im a little puzzled. Is there anything else i can look at on the logs to lead me in the right direction. My buddy is ready to dump the car and the car is to much fun to do that.
 

·
Registered
Joined
·
4,744 Posts
with the injector duty cycle fluctuating like you are describing
the computer must be seeing some air inflow errors.

only reason computer would start dumping fuel in, out of nowhere
is a vac leak, bad injectors, or bad MAF or MAP.

but if you're a/r's are going super lean with duty cycles going thru
the roof, that is weird and opposite of what you would think would happen.

Sounds like you really need a FAST "expert" to take a look at whats
going on.

I'm betting he fried some sensor somewhere when he hooked the mega-boom
stereo system.

take a look at the MAF or MAP voltage data log, see if you see any strange errors.
 

·
Registered
Joined
·
203 Posts
maybe the wide band got screwed up also. the aeromotive pump could have taken a dump, but this is all just speculation
 

·
Registered
Joined
·
248 Posts
Discussion Starter #11
I can look at the MAP readings when I get home from work. I could also hook up my snap on fuel pressure guage to the aeromotive regulator and monitor pressure when this is happening but like I said before, I hate to keep driving it like this!!! Is it possible that when the pump heats up, it gets weaker. I have only known pumps to either work, or not work. I know this has me a little puzzled. The best thing to do is probably have it retuned on a dyno but I hate to send it to a dyno just to find out that there is a fuel pump or some other mechanical problem and then have to take it back? Would a tune act like that. If I go get in the car now, I will get 3 good miles out of it, it doesnt matter how I drive it, it will run great then just like that it jerks around on the top end. you can even hear the wastegate slamming shut when it is doing this. It just sounds ugly. thanks so far guys for all the help
 

·
Registered
Joined
·
4,744 Posts
Def. hook up mechincal fuel press. gauge and watch while driving.
Aeromotive pumps while good are known for failing too.

and yes they are loud as hell normally.
 

·
Registered
Joined
·
248 Posts
Discussion Starter #13
What is the best setting for the fuel pressure at wot. Im just not quite sure where to begin with the car. My brother had an 86 gt with a 306 that acted similiar but that ended up being the ecm was bad. That had the a9l ecm not a fast setup though like this turbo car. Im not used to using fast and a wideband. Im just trying to learn as much as I possibly can about the car. I appreciate all the input so far. Any idea on where anyone would start. Am I in the right direction with the fuel pump. Thanks again guys much appreciated
 

·
Registered
Joined
·
4,744 Posts
40psi at WOT on an N/A car

then usually +1psi per 1psi of boost with a 1:1 boost ref. fuel press. regulator.
So you would see 68psi at 28psi boost.
 

·
Registered
Joined
·
248 Posts
Discussion Starter #15
Ok guys I got some info from the logs that hopefully helps a little bit I will post it frame by frame

RPM MAP(KPA) MAP(PSIA) A/F
2850 127 4.6 12.75
2950 131 5.4 12.5
3000 139 5.4 12.5
3050 145 6.3 11.94
3100 154 7.4 11.00
3100 159 8.8 10.31
3200 168 10.1 9.56
3300 176 11.0 9.44
3450 192 13.1 9.75
3400 207 16.1 10.25
3550 220 17.4 10.63
3650 237 19.9 11.63
3500 266 20.6 12.63
4000 248 21.7 11.5
3700 274 24.5 12.5
3800 226 17.6 14.6
3950 250 21.1 11.13
3750 205 14.5 14.38
4450 204 15.1 11.0
3750 279 22.2 12.75
4250 204 15.1 15.19
6100 200 14.7 11.0
6250 226 19.9 15.9
6250 263 23.5 14.0

that was all wot at 92% tps I hope this helps. Any ideas?? anyone need any more info??? please help if you see anything. Thanks again guys
 

·
Registered
Joined
·
248 Posts
Discussion Starter #16
Hey guys. Does anyone notice anything wrong with this data. Any idea at all. Im just hoping to learn as much as I possible can about this car. I would love to find out the problem. If anyone sees anything out of the ordinary there please let me know. I know this forum is the place to ask these ?s. If anyone knows, it will be you guys. thanks again
 

·
Registered
Joined
·
3,209 Posts
Wow...no a single reading in the 5000 rpm range? That looks like it's seriously breaking up at higher rpms...and going by the 11.0 readings at 4450 and 6100 it would appear that you have the ability for proper fuel flow (this is pure speculation).

What does your igniton system consist of? What is your plug gap?

Do you have the stock dizzy or an aftermarket?

Regardless, I would pull the TFI module and have it checked at a parts store. Just make sure they cycle it good 10-15 times to get it nice and hot...which is usually when they'll fail.
 

·
Registered
Joined
·
248 Posts
Discussion Starter #18
It has an msd billet dist. thats adapted to a small style cap to clear the sheetmetal intake. Im lost, its hit or miss. sometimes when you pull out it will do it in second gear and then a little in third, and none in fourth then the next run it will be opposite. At first I thought it was running out of fuel but now im starting to question if its dropping spark. Any other ideas. why does the a/f vary so much. thanks again everyone for your imput
 

·
Registered
Joined
·
3,209 Posts
It has an msd billet dist. thats adapted to a small style cap to clear the sheetmetal intake. Im lost, its hit or miss. sometimes when you pull out it will do it in second gear and then a little in third, and none in fourth then the next run it will be opposite. At first I thought it was running out of fuel but now im starting to question if its dropping spark. Any other ideas. why does the a/f vary so much. thanks again everyone for your imput
MSD dizz's are NOTORIOUS for failing! It wouldn't at all surprise me if that was atleast part of your problem. If you have access to a stock dizzy, throw it in and see if it helps. The afr's can vary so much from spark issues...so it can be very misleanding.
 

·
Registered
Joined
·
4,744 Posts
Whole reason I went to Distributorless Coil Pack ignition was because
my MSD billet distributor was giving soooo many problems.

There is something strange about their shuttle wheel or something
and the TFI module and pick-up were crap.

When I had a bad coil pack wire, it would drop that cylinder every now and then
and A/F's would bounce all over the place.
 
1 - 20 of 38 Posts
Top