Electrical Bad ECU?

OP ;- If you still have the car with the harness installed heres why your car runs like crap....

Its funny you mentioned the HEGO setting....How can the pulse regulated ground wire of the HEGO's be properly controlled if its wired into the clean ECU ground of pins #40&60 also #20 case ground....LOL...

Scott Bowers melded all of the grounds together and thats wrong...The dirty 02 sensor heater ground wires and the pulse regulated HEGO ground wire on pin #48 are not supposed to be wired into the clean #40/60 ECU ground and #20 the case ground either!!..O2 sensors go to the frame and pin #49 goes to the intake manifold..

A real Ford harness has 4 seperated grounds not 1 single ground wire for everything!!

Then another issue having the dirty 02 heater power wires melded with the MAF sensor on relay A isnt too ideal either aswell as the quality of the crappy fuse and relay block with inferior grip with terminals that are very loose with the terminals at the wires crimped like crap.........

Separating the circuits into 3 separate fuses w/ 3 general purpose non diode protected relays really chops up the voltage seen by pins #37 and #57 of the ECU which causes issues too...



Theres a ton more to note too so Check out the link below to the post I just posted about Scott Bowers wiring skills and his lack of knowledge in the EEC-IV inner workings and how they operate and after you make the changes to your harness your car will work as intended............


Good Luck

OMG Really! What was wrong with the stock harness again?
Clusters happen

manicmechanic007 said:

OMG Really! What was wrong with the stock harness again?
Clusters happen

Click to expand...

What stock harness are you referring to? The OP has a TDZ-75 harness from Ron Francis and made by The detail Zone/Scott Bowers.

I found out how bad he really is...

If you unwrap the harness you'll notice he takes the grounding wires from pins #20.40,49 and 60 aswell as the TFI shielding ground also the ground wires for the 02 sensors and melds them all together then has the people who buys his crap install the negative wire direct to a cylinder head...The noisiest place on a vehicle ...LOL

Heres how the grounds should be divided up and theres very good reason why it is that way too....



If you notice that on a stock EEC system pin #20 takes care of the ECU case and TFI shielding grounds and that wire grounds to the inner fender or the floor of the vehicle.

Pin #49 is a ground wire for the pulse regulated HEGO control that uses the negative to control the HEGOS....That ground wire goes to the intake manifold.

Pin #40 is a clean ECU ground that runs from the battery or the core support to the ECU & Pin #40 carries the ECU grounds,MAF grounds and 5v referrence signal return on pin #46....

Pin #60 is a dedicated ground with nothing else junctioned in on its path from the battery or core support to pin #60. This ground wire is used to help gauge the sensor ground differential coming into the ECU against pin #40 to rule out ghost readings from the sensors that are grounded into the engine block too........

The other issue is the manual states to use a Gray Non-CCD TFI module when utilizing a stickshift transmission but one thing Scott Bowers overlooked in his nonfinite wisdom was he forgot to add the 22k ohm 1/2watt resistor to pin #4...

The 22k ohm resistor is vital to have installed as it filters out the higher voltages that damage the circuitry in the TFI and ECU on the IDM circuit.....

Heres what one from Ford looks like so most know that its not some mythical unicorn...lol


I didnt want to spent $35.00 on a genuine Ford one so for $5.00 I got a pack of 100 and for another $5.00 I got a 650pc assortment pack of shrink tubing and made my own..I made mine so it could be easily changed if needed but well protected from the elements by shrink tubing over the spade connector connections.....


When tested after installing the 22kohm 1/2 watt 1% tolerance resistor the IDM circuit wire on pin #4 came out with-in specs....



And heres proof of a myth busted based on TFI module color...Look at this illustration thats going around the internet...



See what it says about the gray and the black modules?.........Pay attention to the next picture.....

If you notice both TFI modules are Gray but youll also notice the circuitry is very different.....The top one with the more intricate circuitry is a CCD [Computer Controlled Dwell] TFI module and messed badly with my F250 w/5 speed making me think the issues were elsewhere as I got no code or CEL until the day it quit working..............

If you take two 22k resistors and put them inline you double the resistance so my TFI module was obviously getting 44kohms of resistance having a 22kohm resistor already soldered inside a CCD type TFI module........If you put the resistors side by side doubling them up you get half of the rated resistance and will get 11kohms.......

If you have one module in each hand the weight difference is very noticeable too as the CCD module is alot heavier prompting me to crack it open to find out why.....and "why" I did....



Now we will get into the crappy wire crimps and awful relay block layout ....First off the 02 sensor isnt supposed to be powered by a clean power circuit. and grounded into a clean power circuit....02 sensors get keyswitch power and a cylinder head grounding.....

Second...Look at those crimps...Helen keller herself did those beauties...Also notice the lack of weatherproofing from moisture...1 year and the terminals are starting to tarnish/oxidize..





Heres the end result....I dry fired the harness in my basement on a 12v battery with all of the sensors except 02 sensors installed....

Yup, it looks like a giant cluster to me
Again, what was wrong with the original harness?
Wondering why you would ever go with an aftermarket harness
Especially when there are problems that you know? about
Maybe in another few weeks or years you will have it running correctly