Need help troubleshooting a possible EEC startup problem

JohnW63 · Feb 6, 2022

"ECT sensor that monitors coolant temp, that is on the passenger side lower intake behind the thermostat,"

I have that one figured out.

"The air temp sensor is located on the drivers side lower intake #5 cylinder intake tract behind the injector."

Then that is straight across the engine from the ECT, right? #5 is opposite #1 cylinder,

General karthief · Feb 7, 2022

Yeah kind sorta like, it sits a little farther back where the intake track starts to go vertical, I'll try to get you a pic later.

General karthief · Feb 7, 2022

It's the bigger threaded hole in the vertical part of the intake track

JohnW63 · Feb 7, 2022

Makes sense. I check for it, on Tues.

JohnW63 · Feb 8, 2022

OK, I checked and there is a sensor in that location. It does make me wonder what sensor could go in the plug right next to the engine coolant temp sensor.

I also confirmed there is no EGR valve or the spacer for it to attach to. The throttle body bolts right to the intake manifold.

I sprayed around the base of the intake, where I could reach, which is only about half of it and the throttle body with carb cleaner and did not find a spot that changed the engine rpm.

General karthief · Feb 8, 2022

The second connector by the ECT sensor is for the purge valve, you don't have a charcoal canister so don't worry about that one right now,
is that IAT plugged in?

JohnW63 · Feb 8, 2022

General karthief · Feb 9, 2022

Ok, time for a computer check, pull the computer and get it checked out, they are 30+- years old and things can get outta wack, contact the ECUExchange, you can find them on Ebay, it's less than $150 bucks shipped, it's well worth the piece of mind.
While the computer is getting checked out you can make sure all the computer grounds are there and properly attached. There are several that can get lost in the suffel from one year car body to another, let me know if you need more info

JohnW63 · Feb 9, 2022

I figured it might come to that.

I'll have to check the pinouts and see if all the grounds are grounded before I send the unit off. Thanks for the referral.

CAMTWO1070 · Mar 6, 2022

Like the General suggested is one thing Id definately do and heres why...

I saw codes for a 2.3 engine and your dads car is a V8 which means to me that the ECU maybe your culprit as I found out that BlueStreak uses 2.3 computers and turns them into ones that will run a V8...I had so many problems too ...

So many problems I finally broke down and bought an actual A9L from Ebay then I sent it direct to ECU exchange to be diagnosed and beefed up..In the end I spent $600.00 for peace of mind...

Im glad I did as the guy told me the fuel pump circuit was toast and some injector caps were blown...........He also said the computer was heavily bombarded by flyback..

For the flyback issues I put a diode protected starter solenoid and I also put diode protected relays for the fuelpump and the EEC...............

First pic is the ECU I bought and then had refurbed. Second pic is of a diode protected starter solenoid and Third pic is of a diode protected relay....They started putting diode protection on the EEC and fuelpump relays starting in 1995..........

Last picture is of the Blue Streak Computer I had issues with....Even though it was burnt as an A9L it wouldnt work with my tuning chip...............

Another tip I can give is to make sure all sensors are grounded, engine block is properly grounded and ECU is grounded directly to the cylinder head....

Good Luck

JohnW63 · Mar 31, 2022

I got the eec back and they did find some issues with the power supply and upgraded some capacitors, etc. I tested for 12 volts on the always on power pin, the two grounds and the power from the EEC relay before plugging it back in. Grounds and always on power were good. Relay power was 11.80 volts, which I hope is close enough to 12v. Plugged it back in and it was the same as before. It may idle more steady, but I didn't have a timing light on it to check the RPM.

It still fired up on the first go and shortly after that shut off, just like before. It started on the second try and kept running but pressing on the gas still made it stumble badly. Once it ran for a few minutes I could then apply the throttle.

Dad and I started thinking the bad running while cool felt like it was not running on all 8 cylinders. I don't know if an injector could be leaking into the cylinder and fouling things.

JohnW63 · Apr 15, 2022

I've lost the thread, I guess.

General karthief · Apr 15, 2022

Without going back through the thread to see what has been done/replaced/fiddled with, the only advice I can give is to do the 'surging idle checlist'. This will identify what could be the problem(s), do the complete list step by step, don't skip around.

Help me create the "Surging Idle Checklist"

Updated 26-Oct-2019 to clarify creeping idle RPM increase as the car is being driven. Many of you are familiar with the "Cranks OK, but No Start Checklist for Fuel Injected Mustangs" checklist and the No Crank Checklist. They are very effective in finding and eliminating the problems by use of...

forums.stangnet.com

JohnW63 · Apr 16, 2022

I can do that. May I assume I can skip the " manual way to clear the codes " section, since we have a reader that does that? However, " surging idle " is not really the problem I'm trying to attack first.

I did see the " No no " picture with the cone air filter. This is exactly what my Dad has, but it hadn't caused the main issue I am most concerned about. Just look at post 91.

General karthief · Apr 16, 2022

If you read the checklist through and do the list step by step, not skipping around it will help resolve issues that can cause stalling, surging and other issues.
The cone filter attached to the maf can be a contributor to idle/stall issues, you likely have more than one issue to fix. That's why it says to do the list step by step, the next step may depend on the results of the one before.
Example: a car with a high idle may need the 'base idle reset', and the TPS checked, now the surging idle may start as the maf now has trouble reading the slower incoming airflow accurately and the computer trying to keep up with the erratic maf readings make the engine surge. Installing the original airbox or a pipe that puts the filter outside the engine compartment gives the air the distance it needs to straighten out and a steady maf reading at idle and low rpm shlepping around.

JohnW63 · Apr 17, 2022

"Installing the original airbox"

No room for that in a 65 Mustang engine bay. I don't think we would have the room to put some tube out into the right fender area either. The tire does a good job of filling the space. I'd hate to cut a hole for it in a 65 Convertible anyway.

That being said, the car has run well enough for years, with the cone. It was when my Dad got tired of the "start->die->restart->runs OK now." situation and we put in a tank that was fitted with the proper internal fuel pump that the "runs OK" part had to wait for the car to warmup. I had to do a lot of wire tracing to get that working because it wasn't sending power to the fuel pump. Then it started doing so. It makes me think I knocked a wire or a plug loose.

General karthief · Apr 17, 2022

I keep forgetting it's a early body.

JohnW63 · Apr 24, 2022

I may have found something. I was checking for loose connections in the areas I was testing at the beginning, when the fuel tank install didn't work. I found one of the three wires on the distributor that my Dad or one of his helpers made when they relocated the electronic module to the driver's side fender was loose. That made me recall that it had come off, back at the start and I just reached in a plugged it back in by feel. Well, today I pulled it loose and found it was really easy to plug the small male solderless connector in to the wrong place. it was real easy to stick it into the gap between the brown insulator and the distributor case and not where it should go. I had to use a mirror and a flashlight and it took multiple tries to get the little spade go into the female connector in the distributor. I had the engine warming up, prior to this, to run the diags again, so I can't say for sure it made an big change, since the big symptoms happened when it was cold. It did fire up and let me rev it, when it was plugged in, I'm going to see if I can come up with a better way to plug into the bottom of the distributor. Something where all three get plugged in together and stay spaced apart and snug.

I'm hopeful about this, since it ran better before I started wire tracing way back when. I'll look up what the far left of the three pin, as looking at the distributor from the front does and see if it would cause my issues.

I'll still run the above mentioned troubleshooting, since the RPMs were not consistent.

JohnW63 · Apr 24, 2022

View attachment 695666

JohnW63 · Apr 24, 2022

Need help troubleshooting a possible EEC startup problem

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