Electrical Possible C3w1 Ecu Problem?

[Krisverde]

Hey guys. New guy here. While I don't own a fox body. I do own an 89 f150 with an f4te and maf swap. So because of this I dont know if this is allowed if not, I apologize, if so well cool... the truck forums really aren't any help. Ok anyways I have an f4te 5.8 w/ HO cam, 2400 stall, Pacesetter longtubes and a maf conversion kit from ford racing. m9000t51.

I bought this kit used a couple of years ago and installed on truck a couple months ago. Got the truck running and had issues. Idle and full throttle issues. Found out that I had a c&l maf with a 24# sample tube. Bought a 94/95 gt maf, swapped in and truck idled great.

Now onto the other issue, had truck running decent but once I went full throttle the truck would fall on it's face, So I checked tps, fuel psi (did replace the intank and frame rail pump along with the FPR), timing, and vac leaks and all came back in spec and no vac leaks to be found. I even got frustrated and threw a new tps at it. Which was dumb but I was fed up lol. Still no change. I pulled codes and had and EGR code (expected since that's not hooked up) and o2 not switching codes (I guess also to be expected since the o2 was close to collector on header and I have no exhaust currently)


Long story short before I got mad and threw parts at the truck I decided to swap back to the factory SD system and the truck ran great and didn't fall on it's face at WOT.


So what are your guy's opinions? Maybe ecu got shorted out in the past? Wasn't adding timing when needing too?


Here is a vid
View: https://youtu.be/AZHC3kmwo2o


Don't listen to my stupid comments as I don't know what I was thinking....ECU goes to open loop under WOT correct? I was being dumb LOL.

 

[jrichker]

F4te 351 Windsor roller block? How many cubic inches if not stock?
The engine goes into closed loop once it warms up, the possible exception to that condition is WOT.

The 94/95 GT MAF is only good for a 5.0 with stock 19 lb. injectors and computer. It isn't a proper match for your setup.

Check the chart out below and give a HP estimate. it sounds like the WOT problem is because it runs out of fuel.


Your first step is to get the right size injectors and a Pro-M MAF matched to injector size.

Fuel injector sizing & injector photos

Revised 11-Dec-2011 to add larger injector sizes to injector table

Injector HP ratings: divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines at the flywheel.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP
36/.5 = 72, 72 x 8 = 576 HP
42/.5 = 84, 84 x 8 = 672 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

19/.5 = 38, 38 x 8 = 304 HP x .85 = 258 HP
24/.5 = 48, 48 x 8 = 384 HP x .85 = 326 HP
30/.5 = 60, 60 x 8 = 480 HP x .85 = 408 HP
36/.5 = 72, 72 x 8 = 576 HP x .85 = 490 HP
42/.5 = 84, 84 x 8 = 672 HP x .85 = 571 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See Stan Weiss' - Automotive Performance Software / Interactive JavaScript to Calculate Change in Fuel Injector Flow from change in Fuel Pressure to get the calculators used in these examples.

Here's the duty cycle explanation. Duty cycle is how much of the time the intake is open the injectors are turned on. The 85% figure means that for 85% of the time the intake valve is open, the injectors are spraying. The idea is that you want some percentage of the duty cycle left over so that you have some room to grow the process.

If you are at 100% and you need more fuel, all you can do is turn up the fuel pressure. That means the whole fuel curve from idle to WOT is affected. Maybe you are already too rich at idle, and turning up the fuel pressure makes it worse. If you had some injector duty cycle left to play with, a custom tune could use that where it is needed. That would not over richen the whole range from idle to WOT.

If you did turn up the fuel pressure, you might be able to change the injector duty cycle to get the air/fuel mixture ratio you want since the injectors will have extra fuel delivery capability.

With larger than stock injectors or higher that stock fuel pressure, you will need an aftermarket MAF that matches the injector size. The MAF “lies” to the computer to get a fuel delivery schedule that meets the engine’s needs and isn’t too rich or too lean. The best strategy is an aftermarket MAF and a custom tune to insure the best air/fuel ratio over all the RPM range.

Don't forget to increase the fuel pump size when you increase injector size or significantly increase the fuel pressure



Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

 

[Krisverde]

Yes f4te roller windsor. 5.8. It's basically stock besides the HO cam and long tubes. Here is where I am confused.....stock 5.8's came with 19# injectors. I can't imagine I am making enough power to even warrant the use of 24's. Also please correct me if I am wrong but I swear I read somewhere that the 94/95 maf could also be used for 24's too. I could be imagining it. I was just thrown for a loop as I went back to the stock ECU for the truck and had more power at WOT with no cutting out. Obviously the SD vs maf computer differs. I do appreciate the info you have posted. Thank you.

 

[addermk2]

The 94/95 MAF is close to being compatible with your current computer, just not with 24# injectors.

All is not lost, I have the capability to fix your issue. (PM ME IF INTERESTED)

Moving on



In this thumbnail, you will see a comparison between the T4M0 (94-95 GT) MAF curve (green line, orange values) VS the C3W1 maf curve (blue line, yellow values).
The curves are very close to each other throughout the voltage range. While it is not an ideal swap, it can work well enough to drive the car.

Your issue lies in the fact that you are still calibrated for 19lb injectors, as well as still being calibrated for a 302, not 351w.