Hi, thanks again for reccomending the fordfuelinjection page, lots of great info, I need to ask someone who is VERY familiar with my specific setup which is an 86 F-250 302. I was told by the guy (who really does seem to be an expert ) that spent 10 minutes here one day showing me how to get my system plugged in that I could cut the wire that read the temp sensor on top of my intake and install an aftermarket temp sensor. I seem to be having issues now that I have never had with motor and am wondering if this motor requires that sensor to be read. When I say motor I mean computer. Thanks

I sent this as a private message to a member but figured I would post it here also and see others opinions. I transferred the motor which is an 86 F-250 302 into my 52 F-7 ford and did all work except the actual wiring in of the ECM. Any help would be appreciated.

 

Can you splice the original wires back together and see if it runs any better?

 

Yes I could I am sure but first I would have to find out which wire out of the many that I cut is the one. I could do this but I would like to know if not having the temp. read by this comp. makes any difference to it. Will it run poorly if it reads no temp.
I should also add that after running a few minutes if I shut it off and go to restart it acts like its overheated, you know those noises you get when a motors hot!!! The starter acts like its straining and it does not want to spin over quickly, but it is not hot, the aftermarket temp gauge never goes over 180 or so.

 

My '85 F150 has a black wire, and a black with yellow stripe wire tucked behind the upper hose on the passenger side.

 

This sounds like something which would make a great article in the spec section. When trans planting a newer motor with a computer what exactly needs to be connected to make the computer function correctly. I plan to use a 302 out of a 89 in my 56. Good chance I will run into similar problems myself down the road.

 

Yes, the computer needs to know the operating temperature of the engine so that it can go into closed loop mode. It also uses the information to help determine the amount of fuel to inject. I'd say that your issue may well be related to the cut wire.

 

Hey 30dodge sent you a PM.
But just in case anyone wants to know my opinion here is the PM I sent:

Ok...... if it is the sensor I am thinking about, ECT engine coolant temperature, then yes the computer needs that sensor. The computer needs to know what temperature the engine is at for fuel mixture ratio, also it affects timing plus probably many other things I can't think of off the top of my head.
If the stock ECT was replaced with an aftermarket sensor and it still just feeds the computer on the original wire I can't see a problem, as long as it is a direct replacement version for your particular engine/computer.
But if you cut the wire that fed the computer and didn't have anything feeding the computer temp signals then I could see a problem.
What issues are you having and can you read the codes?
I would think without ECT signals the engine would run rich, black smoke, bad mileage, hard starting when warm to name a few.

 

Do a searchfor "ford efi"
there is a link to the ford efi sys manual free

wiring - schmatics - faq

it was posted about I-----------------------I that long ago.

 

I am learning as I go along here, I called the guy that came over to help me wire up my F.I. module and he informed me that the motor in 86 truck has two coolant temp sensors, on is a double wire and is mounted just off the water neck which I just looked and is still there intact and there is the single wire that is on intake manifold just toward the front drivers side that I did remove and cut wire but that only is for the gauge. I installed an aftermarket thermal gauge so I guess I have not done any damage. Thanks for the replys, I am still trying to correct a few issues but I need to look in a different direction possibly.

 

Here's my .02$ to further Sparky's explaination..
Yes indeed your engine has "2 " sensors,the two wire sensor "should" be the sensor "dedicated" to the EFI...it probably has a negative temp co-effient reading..that would mean(don't quote me here..or make me get out my book LOL!!)..as the coolant temp rises=the resistance drops..quite different from your normal "temp gauge" sensor in which as the coolant temp rises=so does the resistance.
So,..if you put a "new" aftermarket temp sender for your new gauge set,and wired it into your fuel injection..you can expect some strange things to happen,Black sooty smoke,rough or no idle,no accell etc...
This sensor should should be a "TWO" wire sensor(for the injection)...the one for your temp "gauge" should be a "single" wire sensor...
The bottom line is, find the correct ETM for the engine your using...find the ECT sensor,it's wire colors(remember..there are two !!..)...find it's location on the engine,re-wire/repair and give it another shot.Good Luck!

 

Thanks I will be posting what I come up with in the next couple of weeks