Car wont start after warm not TFI

[jrichker]

Use an ohmmeter to measure th resistance between pins 46 and pins 60 & 40. It should read less than 1 ohm. Most of the time when it burns up it reads an open circuit. That would account for the 5 volts on the TPS green wire all the time.

 

[Blown88GT]

...But the more obvious was a blue capacitor that was blown in half that read 16V 47hf 16V and 105 degree. I went to circuit city to try and find one but the closes i found was a 35wv 47HF 35wv at 85+ degrees. I soldered that one but didnt change anything and said screw it spent the 85$ on a remaned from autozone. It will be in tuesday. Cant wait!

If the cap is blown out, the TO-220 transistor in the driver circuit is blown, too. When that cap fails, it takes the transistor with it.

That value cap is about the most common one available.

Hope your reman one works out, I just got one from AZ, too, but am unable to try it out yet until the new dizzy arrives.

 

[jrichker]

All the electronic parts you could ever need are available at Electronic Components Distributor | DigiKey Corp. | US Home Page. Good prices and delivery via the good old US Post Office, which makes it inexpensive to order parts online.

P/N 399-6098-ND, 47 ufd, 35 volts, radial leads, 40°C ~ 105°C, cost 19 cents each. plus shipping.
Digi-Key - 399-6098-ND (Manufacturer - ESH476M035AE3AA) unfortunately they are currently out of stock.

The 35 wV is not a problem That just means the cap will safely operate at 0-35 volts instead of 0-16 volts.

However, I can assure you that there are more problems than just a single capacitor that died...

 

[mr2gq]

Damn thats really good info. Yeah I know there was more than just that capacitor too but I was just hoping that was it lol but obviously it wasn't. Oh well 85$ isnt that much to not have to deal with the headache of wondering if I put the parts in right or the right part ect ect. I'll get my ecu after work today and hopefully I don't have anymore problems. I got on the waiting list to get a stinger p.i.m.p EMS. Cant wait to get that!! bye bye MAFlol

 

[mr2gq]

k well a liiiiiittle bit of good news. I got the ecu in. got the new tps adjusted so thats working correctly now. Started it and let it run for about 10-15mins idling. It wasnt really up to norm operating temp cause its so damn cold out side right now. But it didnt have to be up to norm temp before when it would not start back up. I cut it off after running tho and started it up 3 times. I was thinking it was fixed after I shut it off. I put something in my other car and remembered it started right back up a few times right after I shut it off. So I decided to check it one more time and the damn thing wouldnt start! Grrr! However after running teh battery a little low I put the jumpers. tried some more and thought about holding my foot to the floor and it finally started. It didnt want to tho. I had to keep turning it over while it was sounding like it was trying to start. So....now im at a quandary. WTF is causing it to do that? I have changed to a new coolant temp new tfi new tps new ecu. Idle air control isnt working, but if it was that like the check list say it could be why would it start by cutting fuel to the injectors? The car does have 24# injectors on it though with a stock airmeter.

 

[jrichker]

The car does have 24# injectors on it though with a stock airmeter.

That's a small but important deal that either you left out or I missed.

The 24 lb injectors and stock MAF are a mismatch unless you have a custom burned chip to match the injectors to the computer. Ford does not use MAF size or type to accommodate larger injectors. They do it right by modifying the computer operating program to get the correct fuel flow with whatever combination of MAF and injectors are the best match for the engine.

Until you get stock 19 lb injectors, or an aftermarket MAF designed to use 24 lb injectors or a custom dyno tune & chip, you are going to have problems.

Unless you have different heads, cam and intake manifold the stock 19 lb injectors are sufficient for a 5.0 engine with minimal modifications.

Fuel injector sizing & injector photos

Revised 20-May-2011 to add MAF and custom tune requirements for use with larger injectors

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

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

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 Automotive Performance Software / Interactive Calculators 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.

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

 

[Blown88GT]

... The car does have 24# injectors on it though with a stock airmeter.

As jrichker has noted, that's never going to work. 24# injectors must have 24# calibrated meter. Stock 55mm meter is calibrated for 19# injectors.

Lots of good info here: C&L Performance

 

[mr2gq]

Thanks guys. Yes i have read alot about injectors and increasing fuel pressure ect ect. However I guess not having the tps work correctly was exacerbating my problem by not allowing me to start the car when holding the gas to the floor. But no my car is not totally stock. Has a E cam headers exhaust GT40P heads and intake. Have a turbo kit for it but its not on now since I got a bad turbo and it blew the head gasket and I replaced with FMS ones and ARP bolts. But with the injectors there no drive ability issues or performance, that i can tell. Do you think it will perform better with correct injector size?

 

[jrichker]

With a basically stock engine and no custom tune or aftermarket calibrated MAF, it will run better with stock 19 lb injectors.

 

[mr2gq]

Ok I'll go get some at the yard. No got to fix these damn dim headlights lol

 

[Stangz_87]

Ayeee I'm having the same problem did u find out what it was??? I have an 87 foxbody and I can't figure it out PLEASE TELL ME YOU DID

 

[General karthief]

Thats is a 5 year old thread, start a new thread with the problem and any mods already done to the car in the 50 tech section, you'll get some help then.