88 5.0 Swap

51F100 · 06-30-2005

After installing a 88 5.0 into a 1951 Ford truck I am having some trouble trying to get it started. I have spark at the plugs, fuel pressure at the rail but I am sure the injectors are not firing (I pulled one of the spark plugs and it is dry), and the tach needle wants to turn the opposite way it is supposed to. I pulled the codes and the only one present is a continuous memory Code 15. I have checked and rechecked and checked again the static timing and ground connections, all joints are soldered and main ground is attached to negative battery terminal. The ECM has been changed the distributor is new and I am using a Ron Francis wiring panel for power distribution. I have also metered the ECM plug connections for power and ground and they all check out. I am not using the oil level sensor or the smog system, is there a circuit or switch that could be preventing my injectors from firing. Getting pretty frustrated but I keep telling myself that I will eventually get this beast running. Thanks for your time.

51F100 · 06-30-2005

I was doing some reading and wondering if there is a major difference between a 5 speed harness and a harness for an automatic. The engine and harness were from the autowrecker and I am not sure if the all parts were from the same donor car. I have an AOD trans and the ECM is for an automatic.

tmoss · 07-01-2005

If the TPS circuit is open (full resistance/full throttle), the EEC interprets that as a signal to not fire the injectors on cranking, which is a feature of the EEC IV. Check your TPS voltage.

51F100 · 07-01-2005

Thanks for your help when you say full resistance what would the reading be on the meter(an open circuit)? I should have mentioned that I am not using the stock throttle body - I have a new BBK 65mm and I will check the installation instructions that came with it. Also my system is a speed density and I have full length headers and a BBK cold air kit. I did attempt to adjust the TPS but the readings were way off even after I made the mount holes bigger - I will read through the adjustment process and try it again.

tmoss · 07-02-2005

I don't know how familiar you are with electrinics but I'll try to explain this as best I can. The stock TPS is about 4.5k ohms to 5k ohms. What more importnat is that the EEC "vref" (voltage reference) is 5v and it gets "dropped" across the 5k resistor. Then, the "wiper" wire that wipes across the resistor will pick up that "dropped" varying voltage across the resistor (.97v to ~4.5v) and send it back to the EEC as an indicator of throttle position. So, worry less about the ohm value and more about the voltage going back to the EEC. If the voltage is over ~4v, the EEC will not fire the injectors.

Sounds like there is a decent chance this is your problem.

51F100 · 07-02-2005

I followed the instructions in the post about setting the TPS and I set it to .975 - the initial reading was 1.180. There must be a signal or circuit that the computer is either not reading or reading in error. This is from the Fordfuelinjection site, which wire sends the fuel pump signal to the EEC?

Start / Crank
The EEC needs to senses several things to start an engine:

* Power to EEC and fuel pump(s)
* Slow and irregular PIP signal from the distributor
* MAF/MAP low and irregular
* TPS is closed
* HEGO shows lean

GhostDog 5.0 · 07-02-2005

I've ran my car for two days with a bad TPS ground. The green (signal) voltage was reading the same 5v that the red (reference) wire was.

Doesnt that sort of contradict that injectors wont fire ?

I ran into the problem of the computer dumping way too much fuel like if it was at WOT and evenutally the spark plugs were overfueled. I couldnt start the car. I replaced the plugs and it started right up. I finally figured out what the problem was and fixed the ground wire.