If I switch to a Mustang GT cam (from a 1992 in this case), does the firing order change? Do I also have to switch the crankshaft in this case?
EDIT: I just noticed that this section is for non-technical posts. Mods, would you be able to move this to the appropriate section?
Yes, the cam dictates firing order...and the SO 5.0 found in Tbirds/Cougars shares the truck 5.0 firing order.
The HO and 351w are the same.
Once the HO cam is in, re-route the plug wires accordingly. Depending on what year your engine is, you may need to swap the distributor. Some of the older cams require an iron dist driven gear, newer ones require steel.
If your engine is an '87, '88...you'll be fine with your stock dist an the HO cam. Otherwise, switch the plug wires around and go like hell.
I have an '87, so I'm guessing my distributor is fine? Question is, since the firing order changes, does the crankshaft also need to change?
Thanks. The reason for these questions is because I've had the changes in my sig yet my engine sometimes runs very rich. I wonder if it's either from bad O2 sensors or because I'm still using my stock computer. I just double-checked my firing order for kicks and it's got the HO firing order, and with a Mustang GT cam it should be getting plenty of air. Has me scratching my head.
Are you running the stock Tbird EEC with an HO cam?
At best you'll need a Speed Density EEC from a Mustang....make sure to NOT get one for Mass Air. Or you could switch to mass air in which case an A9L would be what you'd need. IIRC, the SD (speed density) EEC is a DA-1.
The crank is the same between an HO and an SO engine, block too.
But yeah, if you've got an HO cam, you'll definitely need the corresponding EEC to run the show...
Did you start off with the SO 5.0 and upgrade it to HO specs?
I'd almost say you're going to want to go to Mass Air since you have the P heads and an Exploder intake on there...it'll run a good deal better with it.
That's exactly what I'm running, the T-Bird SO EEC, as I started with an SO 5.0 and upgraded it to HO specs. I had my mechanic friend try a mass-air conversion but he couldn't make it work; he said it ran better with the stock computer. I don't know if the pinout differences tripped him up or if it was something else. I wonder if I need to go to a speed shop. I think I need an expert, and I'm not it.
Question: will an A9L work for an auto trans? The one I'm seeing on ebay says it's for a manual trans.
EDIT: I found the answer. Looks like I need an A9P since I have an AOD.
Yeah, the A9P would be the one for AOD
I ordered a 1989 Mustang A9P and EVTM book so I can see what has to be done for a MAF swap. Hopefully comparing the Mustang EVTM with my T-Bird one will show all of the differences. I already have the Mustang split tube, but no mass air meter or barometric pressure sensor yet, but I'll get all my ducks in a row before attempting anything.
https://www.coolcats.net/modifying/
Scroll down to Mass air conversion for the HO engine (which you've converted to) for an in-depth guide to what you need to do
:)
Yup, I've been over that section. I got my 1989 Mustang EVTM today and it confirms that computer pins 3 and 6 go to the speed sensor and pin 19 goes to the fuel pump relay. Pin 6 is really just a ground though and can be grounded right at the computer. I can connect pin 3 to a wire coming off the speed control module. That only leaves the fuel pump relay; I have no idea where that is. The T-Bird EVTM says its above the right rear wheel well -- I guess I take out the back seat to get to it? I've never seen that relay.
It's in the trunk, attached to the rear seat bracing, passenger side. Might have to remove the trunk liner to get to it, but it's there, should be green in color.
Thanks. I went through both EVTM's and built an Excel spreadsheet with the differences in EEC pin allocations. It looks like I'll also have to connect pin 30 to the neutral safety switch. It looks like there's a spot near the fuse panel where I can tap it. I'd attach the spreadsheet here if I knew how.
I've made a harness that will simplify the wiring for the MAF conversion, but I have a simple question: how on earth do you get the computer out of there? Is there a way to do it without pulling the dash?
EDIT: I did some Googling and I found a video that shows pulling the blower motor box to get to it.
For what it's worth, here is a link to the spreadsheet I built based on the 1987 and 1989 EVTM's:
https://www.mediafire.com/file/cjuiieuvrxnp4n9/EEC_Differences.xls/file
I thought the EEC on Foxes was down behind the passenger side kick panel?
EEC processor is indeed behind the passenger side kick panel. Remove panel, remove insulation. There is a white-colored plastic bracket holding the processor in at an upward angle; one bolt (10mm?) needs removed and the bracket can swing out of the way-ish, allowing the processor to drop down. The wiring harness is held in by one 10mm bolt.
They are, but it's nigh impossible to get the box out. It's really wedged in there. You can't just slide it down and out because the car's frame is in the way. Nonetheless, I'll take a second look at it. I'd hate to have to remove the entire blower motor box just to remove the processor.
I went to a speed shop this morning to investigate the possibility of having an expert make the switch. I got the impression that they could do it but they didn't really want to. It was an interesting conversation, though. One question they raised was whether I had repinned or otherwise changed the injector wiring to match the Mustang firing order. I don't think this was done, which raises some interesting issues with using my stock T-Bird computer.
Don't go back to that shop. They don't know what the F they're talking about.
The injector pulses are controlled by the EEC. The firing order is controlled by the cam, via the distributor.
The EEC is easy enough to get out. I'm not following how the blower motor is seeming to be in the way...?
I guess the easiest, Beau-podunk way to explain is like this LOL: sit in the passenger seat. The little triangular panel to the right of your right foot....you take that out. The EEC is behind it. 2 smallish bolts and a little wiggle and she's free. Sticl the DA1 or A9L in there (assuming you've went ahead with the Mass Air) and installation is the reverse. Except you won't have to sit in the pass. seat again
Blower motor shouldn't be anywhere in the way at all I think..? Been some time since I was into a Tbird but I think a Fox Stang is identical in layout...
When the cam changed the firing order it also changed the sequence of the intake valves opening.
Your stock EEC is firing the injectors in the wrong sequence. The injector should fire when the intake valve close to it is open.
If your EEC has a Brown/White wire on pin 30 you're OK there. The 88 EVTM shows it wired. They may have made the change in 87 but the EVTM didn't catch-up untill 88.
I've devised a way to make it easy to switch back and forth between the computers in case it doesn't work out. It involves two eight-pin connectors that go to the computer and one that goes to the rest of the car. Basically you choose either the "Mustang ONLY" eight-pin connector or the "T-Bird ONLY" eight-pin connector. Those two connectors are on the EEC side and the connector at the bottom is connected to the rest of the car. This scheme requires cutting the TAB and TAD solenoid wires and splicing the "T-Bird ONLY" and "T-Bird or Mustang" connectors in between, but it means that no wires have to be moved on the EEC connector: only added.
(https://i.postimg.cc/65dynB2D/EEC-Switching-Connectors.jpg)
When I look at the ignition switch terminals in the '87 EVTM, it shows a circuit 376 connected to the start terminal, but the wire color is listed as Y/R instead of BR/W. So maybe it's wired with a Y/R wire instead? I'll have a look tomorrow.
I'm glad you posted those '88 diagrams. I almost connected to the wrong end of the neutral safety switch. I've updated my Excel spreadsheet accordingly.
I couldn't resist a look. The 87 does indeed have a BR/W wire connected to pin 30. So that's something I don't have to worry about. And I took the opportunity to plug in the "Mustang only" harness. So the easiest part is done.
Good news.
The 87 EVTM shows the circuit connected for the 3.8L and 2.3L engines.
I decided to do all the wiring myself, and just finished it this morning. Tip: once the wiring is done, start the car and check your power and ground wires at the mass air meter connector. I discovered a bad ground this way.
Now I only have to wait for the mass air meter to show up, then I can make the switch. Fingers crossed...
Hmm. I did the switch and I've got a surging idle and a check engine light. The surging idle got a little better after 10 minutes but didn't completely go away. The computer is throwing a code 66 (MAF voltage low), even though the MAF meter is new. I'm not sure what to do here. I did notice that the mesh screen on the MAF was dented when I opened the box.
For now I switched it back to the T-Bird computer. I'm glad I made the changes so easy to reverse!
From the 93 Shop Manual, Mustang 5.0L:
With the engine running, you should have between pin 50 and pin 9, 0.36-1.50 volts
You have a SFI engine.
Code 66 is a memory code.
Did you pull the engine running codes? You should get a code 26 if the sensor completely broke.
According to the manual with the code reader I bought, 66 (continuous memory code) is MAF voltage too low. I didn't pull any engine running codes.
Just a question...did you by chance ever replace the IAC or TPS?
If one of those are faulty, you'll have idle issues. I had a TPS out of range on a 94 truck and while it affected idle and throttle response, there wasn't a code.
Also, disco the battery cable for a few and let it sit, maybe tap the brake pedal and cycle the ignition off/on 4 or 5 times.
Start from clean slate, as it were, in regards to stored codes, etc.
Maybe it'll clean up, and run right..
Continuous memory codes are generated while you are driving. They are stored in the KAM (Keep Alive Memory). When these are the only codes you get, you have an intermittent problem. As Beau stated, they can be reset by disconnecting the battery.
You should first clean-up any "hard codes" found by KOEO (Key On Engine Off) and KOER (Key On Engine Running) self tests.
Warm up the engine before the self tests.
KOEO:
Runs self test and post fault codes or code 11 for no faults.
Code 10, a Seperator, then posts memory codes.
KOER:
Posts a 4 indicating the ECU is for a 8cyl engine.
Runs self tests and posts fault codes or code 11 for no faults.
Run self tests and post all the codes here.