fuel injection problem. Need help?
 

I have been having this reoccuring problem with my 1988 5.0 LX Convertible. It is pretty much stock besides exhaust system and cold air intake. It is a Mass Air Flow car. The car is has no chech engine light on. It was orginally a AOD. New plugs, cap, eec IV and Map sensor. When driving the car in warm conditions for two hours. It has a loss of power and serges. I am only able to drive it by reving it up to 4 and a half grand untill it totally wouldn't work. It doesn't like high altitude driving. Does any one know what the heck is wrong.

I am having the same problem with my '89 bronco, and I think I got it down to one thing. The fuel pump relay. When my bronco did this, I took the relay off, and found that the conections were very much junked up. I cleaned them off, and haven't had the same thing since. Also u might need a new relay, if it does it when the motor gets warm, this would most likely be it.

Fuel Pump Relay
 

Relay ways all nasty, but it was replaced and and cleaned up and is still doing it. Any other ideas are much appreciated. Thanks

Are there any stored codes? Are you holding fuel pressure? Any vacuum leaks?

Help PKRWUD
 

I wondered if PKRWUD would help me. I have put some series money in to this car.

Exactly.

grant66-

I will try and help you, but you still need to answer those questions.

I don't see a vacuum leak being the problem, but I need to know what codes came up during KOEO, and if you have verified your fuel pressure, and whether or not it holds after the key is turned off.

Take care,
~Chris

Testing completed
 

So today I did the tests you asked me to. The Key On Engine Off stored codes were 29 and 66. Very weird because their wasn't a check engine light on. I tested the fuel pressure on the shreider valve and I came up around 220 KPA, which should be enough pressure.

Okay, you have a few things you need to do, and you need to do them EXACTLY like I tell you to, and in this exact order:

First, buy a can of electric contact cleaner, and unplug the MAF at the harness and thoroughly clean the contacts, then reconnect it.

Second, disconnect the negative battery cable, and then turn on your headlight switch. After ten minutes, turn the switch off, and reconnect the battery.

Third, Start the engine, and warm it up for 10 minutes. Drive the car to the end of your block, and turn so you're facing home. Put the tranny in low gear, and accelerate HARD to 25 mph, and then coast the rest of the way home. Shut off the engine, and run the KOEO codes again, and post your results.

Take care,
~Chris

Okay, after reading your PM, I still want you to follow my instructions in my last post, exept for #3, when you are at the end of your street facing home, shift to 2nd quickly, then drive it hard to 40 mph, and coast home. The rest is the same. If you can't hook up your speedo, estimate the speed.

Take care,
~Chris

Grant, sounds like a fuel pump or a weak coil. how many miles aree on your beast?

5.0 LX Vert
 

I have under 90,000 miles on the car. I hardly drive it. I lost the AOD in the car at 63,000 miles that was the second AOD in the car. So I put a t-5 in the car with a manual EEC IV. Can you believe it. I have under a hundred thousand miles on the car and three transmissions have gone into it. All my mods are a cold air intake and a header and x pipe. When I changed the car from a AOD to a t-5 I didn't hook up Clutch safety switch with to much power 12 volts instead of 5 volts. I smoked the brand new computer and a map sensor.

Any ways I have tested the fuel pressure it was 120 kpa. I believe the conversion is 40 psi. I would like to test the fuel presure when the car is acting like poo. That means hooking the fuel pressure into the car.

Followed your directions
 

So I did what you said to do PKRWUD and I came up with the code 29 (VSS). What do you think?

Unplug the VSS and test it's resistance with a DMM set to ohms on the 2k ohm scale. If the reading isbelow 190, or above 250, replace the VSS, reset the ECM again (disconnect neg bat cable & turn on light sw. again), and test drive it, then run KOEO again.

Post the results.

Take care,
~Chris

VSS
 

I don't know what the VSS is. May be I call it something else.

What year is your car, what year is the tranny, and what did your ECM come out of (year and model)

VSS=Vehicle Speed Sensor

Information about my car.
 

My ECM was just bought from Ford dealership it is an 5.0 1989 LX EEC IV. I have a t5 transmission I pulled it out of an 1985 GT. But the guy I bought it from said it probably was a later year t5. I don't know how to read the ID tag now that the transmission is in the vehicle. My car is an 1988 5.0 LX Convertable. It was made in September so it is a late model car. The car is a mass airflow car. Stock except for March cold air intake, Mac equal length headers and Mac off road X pipe.

Computer
 

My computer is also a convertable

Check and see if you have a VSS. It should be installed on the pass side of the tranny tail, and will have an electrical connector.

VSS probably was never installed.
 

My ECM was just bought from a Ford dealership it is an 1989 5.0 LX Convertable EEC IV. I have a 1985 t5 transmission I pulled from an 1985 GT. But the guy I bought the transmission from doesn't know what year car it came from. I don't know how to read the ID now that the transmission was installed into my vehicle. My car is a 1988 5.0 LX Convertable. It was made in September. So it is a late model year car. The car is mass airflow car. The car is stock for the most part except for the March Cold Air Intake, Mac equal length headers and a Mac Off road x-pipe. I would like how to buy and install an VSS. I thought manual transmission cars didn't have them on it. I know my AOD did.