Timing issue??

[jrichker]

You have been connecting and disconnecting the MAF and didn't get a Code 66. That mean you either have a defective computer or it is a Speed Density computer. Remove the computer and post a picture of the sticker on the side of the computer opposite the wiring connector.

Computer & interchange information for 5.0 Mustang

Revised 16-Oct-2011 to add O2 sensor harness warnings

The Mass Air computers from 89-93 are interchangeable with a few exceptions. Just be sure you use the MAF & MAF sensor from the same series computer. The auto transmission computers use a different start circuit than the manual computers. You can use an auto trans computer in a 5 speed car with no problems or changes. I have done it in my original 89 Mustang GT, and I know it works OK. I would recommend avoiding using a 5 speed computer in an auto trans car due to the possibility of damaging the computer’ internal signal ground circuitry.

The odd duck is the 93 Cobra computer, labeled X3Z which is internally calibrated for 24 lb injectors. Use the MAF & MAF sensor from the X3Z computer to avoid problems with the computer's internal calibration. Try and avoid the 93 Cobra computer if you can.

Some cautions about O2 Sensor harnesses need to be observed to avoid damage to the computer.
Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
See http://forums.corral.net/forums/general-mustang-tech/1094179-oxygen-sensor- harnesses-manual-auto-differences-year-differences.html for more O2 sensor wiring harness info
If you have a damaged computer with signal ground problems, See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the computer internal signal ground.

All the following are mass air unless they say Speed Density
8LD - MANUAL 88 5.0L Mustang Mass Air - California
8LF - Auto 88 5.0L Mustang Mass Air- California
8LG - Auto 88 5.0L Mustang Mass Air- California
A9L - 89-93 5.0L Mustang 5-spd Mass Air
A3M - 93 5.0L Mustang 5-spd Mass Air
A3M1 - 93 5.0L Mustang 5-spd Mass Air
X3Z - 93 5.0L Cobra 5-spd Mass Air internally calibrated for 24 lb injector
A9P - 89-93 5.0L Mustang Auto Mass Air
A9S - 88 5.0L Mustang California Mass Air
C3W - 89-93 5.0L Mustang Auto
DA1 - 87 5.0L Mustang 5-spd Speed Density
J4J1 - 94-95 5.0L SVT Cobra 5-spd
T4M0 - 94-95 5.0L GT Vert 5-spd
U4P0 - 94-95 5.0L GT Auto
W4H0 - 94-95 5.0L GT
ZA0 - 95 Cobra R
D9S - 88 Lincoln LSC Speed Density

 

[General karthief]

Oohhh k! The more I see of this car the more questions I have
what amp is that alternator? Is the fuel pump switch run through inertia switch? Electric water pump on a street car?
Are all the grounds present? There are several that are very important, one from the back of the drivers head to the firewall, one in the injector harness that bolts to the intake (or back of passenger head) there should be a ground wire from the battery cable to the fender panel between the battery and the solenoid, that ground should also have a wire from there to a black cylindrical connector that travels to the wire harness, and the battery ground that is bolted to the block by the oil pressure .
Also what size injectors?
I know this is a lot but I'm thinking you have more than one issue

 

[General karthief]

Let me add something here. Get a quality repair manual, not a chilton or haynes, they are ok for changing a water pump but for wiring and technical stuff you need a ford assembly manual for your year, year to year changes can make things confusing.

 

[Busaboy]

You have been connecting and disconnecting the MAF and didn't get a Code 66. That mean you either have a defective computer or it is a Speed Density computer. Remove the computer and post a picture of the sticker on the side of the computer opposite the wiring connector.

Computer & interchange information for 5.0 Mustang

Revised 16-Oct-2011 to add O2 sensor harness warnings

The Mass Air computers from 89-93 are interchangeable with a few exceptions. Just be sure you use the MAF & MAF sensor from the same series computer. The auto transmission computers use a different start circuit than the manual computers. You can use an auto trans computer in a 5 speed car with no problems or changes. I have done it in my original 89 Mustang GT, and I know it works OK. I would recommend avoiding using a 5 speed computer in an auto trans car due to the possibility of damaging the computer’ internal signal ground circuitry.

The odd duck is the 93 Cobra computer, labeled X3Z which is internally calibrated for 24 lb injectors. Use the MAF & MAF sensor from the X3Z computer to avoid problems with the computer's internal calibration. Try and avoid the 93 Cobra computer if you can.

Some cautions about O2 Sensor harnesses need to be observed to avoid damage to the computer.
Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
See http://forums.corral.net/forums/general-mustang-tech/1094179-oxygen-sensor- harnesses-manual-auto-differences-year-differences.html for more O2 sensor wiring harness info
If you have a damaged computer with signal ground problems, See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the computer internal signal ground.

All the following are mass air unless they say Speed Density
8LD - MANUAL 88 5.0L Mustang Mass Air - California
8LF - Auto 88 5.0L Mustang Mass Air- California
8LG - Auto 88 5.0L Mustang Mass Air- California
A9L - 89-93 5.0L Mustang 5-spd Mass Air
A3M - 93 5.0L Mustang 5-spd Mass Air
A3M1 - 93 5.0L Mustang 5-spd Mass Air
X3Z - 93 5.0L Cobra 5-spd Mass Air internally calibrated for 24 lb injector
A9P - 89-93 5.0L Mustang Auto Mass Air
A9S - 88 5.0L Mustang California Mass Air
C3W - 89-93 5.0L Mustang Auto
DA1 - 87 5.0L Mustang 5-spd Speed Density
J4J1 - 94-95 5.0L SVT Cobra 5-spd
T4M0 - 94-95 5.0L GT Vert 5-spd
U4P0 - 94-95 5.0L GT Auto
W4H0 - 94-95 5.0L GT
ZA0 - 95 Cobra R
D9S - 88 Lincoln LSC Speed Density

I’m not sure of the alternator, it came with the car. It has no stickers or anything.
Attached are photos of the computer. As you see it’s out of a 93 convertible. Also a book that’s beat up but all there. I’ll check the grounds

 

[Busaboy]

Ok, so I’m not seeing any ground wires behind drivers head or passengers head. There is a ground from battery to fender. It’s a mess!!! 24# injectors. And I got the egr delete spacer with the plug to “trick the computer”.

 

[Busaboy]

Also, I wanted the race car feel so I used the switches to control fuel, air and water. I used electric fans and water pump to free up horsepower.
my biggest problem here is that pre Windsor heads the car ran great!!!! No issues. I changed the heads, that’s it. Well to be honest, I attached the heads to the block, but before I could adjust the lash on the push rods, my wife passed away and so she sat for 6 years. One would think, you pick up where you left off, reassemble and it should run just as good if not better than before. I may have forgotten the grounds though I don’t see any unhooked dangling wires anywhere. I’ve changed the gas, fuel filter, injectors, distributor, spark plugs and oil.
I guess maybe moisture could have rotted the connections in the computer‍ I did take the rest of the egr stuff out but did it the right way with the right parts. I did cob the sensor and will redo that but I don’t think that is my real problem right now.
I used to have a couple of friends that knew EVERYTHING about these old foxes. Wish they were still around.
the only thing I can see that’s not hooked up is in the picture. Not sure where it goes either.
My vacuum lines are what’s shown in picture as well. Brake booster to intake, intake to pcv, fuel rail to intake. That’s it.

 

[General karthief]

That one pic with the sender in the oil pan and cut wire is the oil level sender, ignore it.
Now take a look at that evtm stuff to make sure your 02 sensors are pinned right for your transmission.
there are so many things going on here it's hard to keep up. What rockers you using? Was there any issues setting the lash?
Sort out your grounds first.
where is your coil?

 

[Busaboy]

I have no o2 sensors, they’re plugged on the pipes. Sorry, what is evtm?

 

[Busaboy]

That one pic with the sender in the oil pan and cut wire is the oil level sender, ignore it.
Now take a look at that evtm stuff to make sure your 02 sensors are pinned right for your transmission.
there are so many things going on here it's hard to keep up. What rockers you using? Was there any issues setting the lash?
Sort out your grounds first.
where is your coil?

I’m sorry, I know there is ALOT going on here haha. It would be nice having someone close to just come look at it like my buddy jay but he’s gone now just like Matt. Two guys that could listen to a motor going down the road and tell you what was wrong with it. Where I live if they aren’t building Honda’s or Mitsubishi’s they aren’t interested. I think it’s time to move lol.
Anyway, my coil is on the fender next to solenoid, the rockers are the ones that came with the jr Windsor heads1.6 I believe. They are rollers. I wish I could send a video of when the car was running good. I think it may be the computer gone bad because it’s the only thing that makes sense at this point with the maf not working and the car running when it’s unplugged. Idk. Thankfully it’s a project car to fill my boring days and I’m not in a hurry to have it perfect now that winter is approaching. Not to mention there are a lot of other things I can work on while I wait for parts or that moment of clarity when the problem reveals itself in a dream haha. I really do appreciate your time, help and patience in all this.
I was looking at the harness by the heads and I don’t see any ground wires at all. I know I pulled the old harness out of the car way back when because the guy before me butchered it. I remember bitching about it, but then I went and butchered this one. Plugs were broken so I just soldiered and or crimped the wires together and being it was so long ago, I forgot.
you can see the blaster coil in this photo.

 

[Busaboy]

Boy I wish you could call me lol all this typing...... anyway while looking for grounds, I stumbled on something‍ How much of an effect would having at least a .025 gap between the upper and lower intake have? Well, I have it lol. My valve covers are too high. I did replace those when putting it together this time around, now I know why I didn’t use them the first time.

 

[96pushrod]

I feel like you’re trying out way too many different things at once. If you change 5 different things then you’ll probably fix one thing while screwing up another.

The car will indeed run with the maf disconnected. As stated above: if there are no codes displayed when the maf is unplugged, you have other issues.

You need to start with the basics. Unplug your battery for 30 mins, Do a base idle reset, and set timing (with spout out). Your car will almost certainly have the H.O. firing order so stick with that.

There is a gasket between the upper and lower intake so there will be a small gap between them.

 

[Busaboy]

I feel like you’re trying out way too many different things at once. If you change 5 different things then you’ll probably fix one thing while screwing up another.

The car will indeed run with the maf disconnected. As stated above: if there are no codes displayed when the maf is unplugged, you have other issues.

You need to start with the basics. Unplug your battery for 30 mins, Do a base idle reset, and set timing (with spout out). Your car will almost certainly have the H.O. firing order so stick with that.

There is a gasket between the upper and lower intake so there will be a small gap between them.

I hear you and you’re right, fixing all kinds of stuff at once will just get confusing. As for the gap, yes with the gasket it should look like a gap but it should be sealed, no? I can slide a the biggest feeler gauge I have to the hilt. Is there a way to test the maf sensor with an ohm meter? I’m thinking it’s the computer. The maf sensor while purchased 6 years ago, was sitting on a shelf since tear down. I only had it on the vehicle for a week maybe and only driven twice so it should be good.
I am going to tear the upper and change the valve covers, and while apart search for the ground wires. It’ll be easier that way and I’ll know at least the gap is gone.

 

[General karthief]

Yeah, that gap would be a problem if the gasket can't seal, surprised it even ran.
Wait, it didn't really run did it
When you take the upper intake off look for a orange wire with a round terminal end, thats a ground, needs to be bolted to the head or intake bolt. It's usually under the fuel pump regulator area coming from the injector harness.
Oh, and the evtm is the 'electrical vacuum technical manual.intake
you also need to find the 02 harness and get them put back. The computer depends on them.

 

[Busaboy]

Man I can not find any ground wires. In the book it shows 109 on the location views but it doesn’t show them on the grounds pages. I have 100, 102, 103 and 104. I’m missing 105 and 109

 

[Busaboy]

Yeah, that gap would be a problem if the gasket can't seal, surprised it even ran.
Wait, it didn't really run did it
When you take the upper intake off look for a orange wire with a round terminal end, thats a ground, needs to be bolted to the head or intake bolt. It's usually under the fuel pump regulator area coming from the injector harness.
Oh, and the evtm is the 'electrical vacuum technical manual.intake
you also need to find the 02 harness and get them put back. The computer depends on them.

Well the big problem with the o2 sensors is that the holes for them are welded shut with a bolt in themand I figured out what evtm was when I looked at the book hahaha. Yes I’m a dummy

 

[Busaboy]

Cut open the two harness’ at the back of the engine and no black/orange. There are two black/white wires and there is a light brown wire that’s cut going knowwhere coming from c118 or c119 plugs

 

[General karthief]

That light brown wire is likely the g109, I'm going from memory, it may be a different color on your year, I have a 89. That g105 is battery ground I think. They changed some wire colors in 91 and 92-3.
If that brown wire is in the injector harness then I bet that is the missing ground, that and you need a ground from the drivers side head to the firewall.
does your evtm show what the numbered grounds are? Maybe on another page.

 

[Busaboy]

On pages 10-1 thru 10-5 I think, it has all the grounds except for g109 for some reason. It definitely has it in the view but not in the grounds section where it shows where the grounds go.i just looked and I think you are right (again) the g105 is going over towards the battery. I’ll google g109 see what I find out. Thanks again

 

[General karthief]

Don't make me fly up there and fix this thing, I hate fly'n.

 

[jrichker]

On pages 10-1 thru 10-5 I think, it has all the grounds except for g109 for some reason. It definitely has it in the view but not in the grounds section where it shows where the grounds go.i just looked and I think you are right (again) the g105 is going over towards the battery. I’ll google g109 see what I find out. Thanks again

Some help with the crucial computer power ground...
Grounds

This checklist applies to all Mustangs , not just the EFI equipped cars. Some of the wiring will be different on carb cars and carb conversions

Revised 26 –Oct -2016 to add fuel pump ground to the list.

Grounds are important to any electrical system, and especially to computer controlled engines. In an automobile, the ground is the return path for power to get back to the alternator and battery.

Make sure that all the ground places are clean and shiny bare metal: no paint, no corrosion.

1.) The main power ground is from engine block down by the oil filter to battery: it is the power ground for the starter & alternator.


2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. The clue to a bad ground here is that the temp gauge goes up as you add electrical load such as heater, lights and A/C.

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery, computer, & extra 3G alternator ground wire as described above in paragraph 2. A screwdriver points to the bolt that is the common ground point.

The battery common ground is a 10 gauge pigtail with the computer ground attached to it.
Picture courtesy timewarped1972

Correct negative battery ground cable.

3.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally: it comes off the ground pigtail on the battery ground wire. Due to its proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness.

All the grounds listed in items 1,2 & 3 need to bolt to clean, shiny bare metal. A wire brush or some fine sandpaper is the best thing to use to clean the ground connections.


4.) All the sensors have a common separate signal ground. This includes the TPS, ACT, EGR, BAP, & VSS sensors. This ground is inside the computer and connects pin 46 to pins 40 & 60, which are the main computer grounds. If this internal computer ground gets damaged, you won't be able to dump codes and the car will have idle/stall/ performance problems

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is an orange wire with a ring terminal on it. It is located in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or bolt on back of the cylinder head.

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself. The TFI module ground terminates inside the computer.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) Fuel pump ground the fuel pump has a ground pigtail the connects to the body under the gas tank. You have to drop the gas tank to see where it bolts to the body.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help troubleshooting voltage drops across connections and components. Be sure to have the maximum load on a circuit when testing voltage drops across connections. As current across a defective or weak connection, increases so does the voltage drop. A circuit or connection may check out good with no load or minimal load, but show up bad under maximum load conditions. .

Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch
100 mV Ground
0 mV to <50 mV Sensor Connections
0.0V bolt together connections

]

Extra grounds are like the reserve parachute for a sky diver. If the main one fails, there is always your reserve.

The best plan is to have all the grounds meet at one central spot and connect together there. That eliminates any voltage drops from grounds connected at different places. A voltage drop between the computer ground and the alternator power ground will effectively reduce the voltage available to the computer by the amount of the drop.