Intake install done. But...

I think you're in the right ballpark with it being a timing issue of vac leak. Did you take the distributor out for the install? If so you may have it off a tooth. so

Idea 1: I'd try to advance and retard the timing a little and see if it runs any be
tter or worse.

Idea 2: Listen for a whistle or air sound when you give it gas and make sure all the vacuum connections are where they are supposed to be. Also if you have the brittle lines, they crack really easily so could be one of those.

Idea 3: Check all your electric connections to everything you had to take off, such as the injector wiring, egr sensor, tps, etc.

Oh and did you pull the codes? that could give you an idea whats goin on too

Did you check the timing? If you cannot see the timing marks then you are prob off a tooth or your distributer needs adjusted depending on where it is.. It always helps to put a paint mark on the timing mark that you want that way it is easier to see when you set the timing..

There is no such thing as "one tooth off" with a 5.0 Mustang. If you get one tooth off, you just have to twist the distributor housing until the timing marks line up when using a timing light. If you get too far off you may not be able to twist the distributor enough to get the marks to line up.

Using a timing light is the only way to properly time an engine. If you can afford to swap the manifold on a deciently running car you can afford to buy or rent a timing light.

Paint the mark on the harmonic balancer with paint -choose 10* or 14* or something else if You have NO2 or other power adder.

Remove the SPOUT connector (do a search if you want a picture of the SPOUT connector) It is the 2 pin rectangular plug on the distributor wiring harness. Only the EFI Mustang engines have a SPOUT. If yours is not EFI, check for a SPOUT: if you don’t find one, skip any instructions regarding the SPOUT
Warning: there are only two places the SPOUT should be when you time the engine. The first place is in your pocket while you are setting the timing and the second is back in the harness when you finish. The little bugger is too easy to lose and too hard to find a replacement.

Connect timing light up to battery & #1 spark plug.

Start engine, loosen distributor hold down with a 1/2" universal socket. Shine the timing light on the marks and turn the distributor until the mark lines up with the edge of the timing pointer. Tighten down the distributor hold down bolt, Replace the SPOUT connector and you are done.

The HO firing order is 1-3-7-2-6-5-4-8.
Non HO firing order is 1-5-4-2-6-3-7-8




Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 19-May-2009 to update drawing for dumping the codes on 86-88 Mustangs with no check engine light.

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

See Troublcodes.net Trouble Codes OBD & OBD2 Trouble Codes and Technical info & Tool Store. By BAT Auto Technical





If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

what injectors are u using and is your mass air calibrated for them? I have personally installed an intake any torqued everyhting to spec and had a failure in the lower intake gaskets. jst something to think about

Dump the codes... it is simple, cheap and the engine does not need to be running to do it.

There is no such thing as "one tooth off" with a 5.0 Mustang. If you get one tooth off, you just have to twist the distributor housing until the timing marks line up when using a timing light. If you get too far off you may not be able to twist the distributor enough to get the marks to line up.

Click to expand...

I guess I shoulda clarified in more detail. What you said is basically what I meant. I've marked the distributor position, the rotor position and everything and put the distributor in slightly off due to the twisting of the gears.

I agree completely about checking the codes, I've used jrichker's code checking method every since I learned about these cars. If anyone knows what he's talking about, listen to that guy!

And I believe to advance the timing you turn the distributor clockwise and to retard it is to turn it counterclockwise. And isn't the timing supposed to be 10 degrees BTDC?

Post the codes you get and I will give you the fixes. The code list I have is 5.0 Mustang specific, and is an ongoing project. I revise the code information as new details and fixes come to light.

jrichker said:

There is no such thing as "one tooth off" with a 5.0 Mustang. If you get one tooth off, you just have to twist the distributor housing until the timing marks line up when using a timing light. If you get too far off you may not be able to twist the distributor enough to get the marks to line up.

Click to expand...

yes your right if you could turn the distributor the whole way around you wouldnt have to pull it out and move it one tooth to get the adjustment necessary. its just easier to say its one tooth off.

No info about your car's model year or other mods make it difficult to troubleshoot when we don't know what you've got. That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing.

The Code 23 will shut off the injectors on cranking. Fix it first

Code 23 - Throttle sensor out of range or throttle set too high –

Revised 02-Jul-2009 to update TPS setting procedure.

TPS needs to be reset to below 1.2 volts at idle.

Setting the TPS voltage

You'll need a Digital Voltmeter (DVM) to do the job.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

Always use the Dark Green/lt green & Black/white wires to set the TPS base voltage.

Do the test with the ignition switch in the Run position without the engine running.

Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.
Setting the TPS: you'll need a good Digital Voltmeter (DVM) to do the job. Set the TPS voltage at .5- 1.1 range. Because of the variables involved with the tolerances of both computer and DVM, I would shoot for somewhere between .6 and 1.0 volts. Unless you have a Fluke or other high grade DVM, the second digit past the decimal point on cheap DVM’s is probably fantasy.

Since the computer zeros out the TPS voltage every time it powers up, playing with the settings isn't an effective aid to performance or drivability. The main purpose of checking the TPS is to make sure it isn't way out of range and causing problems.

The Orange/White wire is the VREF 5 volts from the computer. You use the Dark Green/Lt green wire (TPS signal) and the Black/White wire (TPS ground) to set the TPS. Use a pair of safety pins to probe the TPS connector from the rear of the connector. You may find it a little difficult to make a good connection, but keep trying. Put the safety pins in the Dark Green/Lt green wire and Black/White wire. Make sure the ignition switch is in the Run position but the engine isn't running.

Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

The TPS is a variable resistor, must like the volume control knob on a cheap radio. We have all heard them crackle and pop when the volume is adjusted. The TPS sensor has the same problem: wear on the resistor element makes places that create electrical noise. This electrical noise confuses the computer, because it expects to see a smooth increase or decrease as the throttle is opened or closed.

TPS testing: most of the time a failed TPS will set code 23 or 63, but not always. Use either an analog meter or a DVM with an analog bar graph and connect the leads as instructed above. Turn the ignition switch to the Run position, but do not start the engine. Note the voltage with the throttle closed. Slowly open the throttle and watch the voltage increase smoothly, slowly close the throttle and watch the voltage decrease smoothly. If the voltage jumps around and isn’t smooth, the TPS has some worn places in the resistor element. When the throttle is closed, make sure that the voltage is the same as what it was when you started. If it varies more than 10%, the TPS is suspect of being worn in the idle range of its travel.

See Ford Fuel Injection Wiring Harnesses for more wiring help & 10 pin connector diagrams


Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral or the clutch depressed (T5, T56, Tremec 3550 & TKO). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear and jumper the safety pin to the ground near the computer.

Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

With the with the ignition on, look for 12 volts on the red wire on the solenoid connector. No 12 volts and you have wiring problems.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Putting the computer into self test mode will cause the solenoid valve to toggle. If you listen carefully, you may hear it change states.

If you have catalytic converters, you need to fix this code. If not you can use a TAB and TAD eliminator.


Code 63 - Throttle Position Sensor (TPS) signal too low.

Revised 02-Jul-2009 to update TPS setting procedure & add 10 pin connector layout.

Vref missing (5 volt reference voltage supplied by the computer), bad connections or damaged wiring, TPS sensor failed, TPS sensor way out of adjustment. Use a DVM to check for 5 volts on the Orange wire. If it is missing, look for +5 volts at the Orange wire on the EGR or MAP/Baro sensor located on the firewall near the center of the car. If there is +5 volts on the MAP/Baro sensor, but not on the EGR, clean the #2 & #5 pin on the white 10 pin connector. If there is +5 volts on the EGR but not on the TPS, look for bad wiring inside the engine fuel injector harness.



Setting the TPS voltage
You'll need a Digital Voltmeter (DVM) to do the job.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

Always use the Dark Green/lt green & Black/white wires to set the TPS base voltage.

Do the test with the ignition switch in the Run position without the engine running.

Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.
Setting the TPS: you'll need a good Digital Voltmeter (DVM) to do the job. Set the TPS voltage at .5- 1.1 range. Because of the variables involved with the tolerances of both computer and DVM, I would shoot for somewhere between .6 and 1.0 volts. Unless you have a Fluke or other high grade DVM, the second digit past the decimal point on cheap DVM’s is probably fantasy.

Since the computer zeros out the TPS voltage every time it powers up, playing with the settings isn't an effective aid to performance or drivability. The main purpose of checking the TPS is to make sure it isn't way out of range and causing problems.

The Orange/White wire is the VREF 5 volts from the computer. You use the Dark Green/Lt green wire (TPS signal) and the Black/White wire (TPS ground) to set the TPS. Use a pair of safety pins to probe the TPS connector from the rear of the connector. You may find it a little difficult to make a good connection, but keep trying. Put the safety pins in the Dark Green/Lt green wire and Black/White wire. Make sure the ignition switch is in the Run position but the engine isn't running.

Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

The TPS is a variable resistor, must like the volume control knob on a cheap radio. We have all heard them crackle and pop when the volume is adjusted. The TPS sensor has the same problem: wear on the resistor element makes places that create electrical noise. This electrical noise confuses the computer, because it expects to see a smooth increase or decrease as the throttle is opened or closed.

TPS testing: most of the time a failed TPS will set code 23 or 63, but not always. Use either an analog meter or a DVM with an analog bar graph and connect the leads as instructed above. Turn the ignition switch to the Run position, but do not start the engine. Note the voltage with the throttle closed. Slowly open the throttle and watch the voltage increase smoothly, slowly close the throttle and watch the voltage decrease smoothly. If the voltage jumps around and isn’t smooth, the TPS has some worn places in the resistor element. When the throttle is closed, make sure that the voltage is the same as what it was when you started. If it varies more than 10%, the TPS is suspect of being worn in the idle range of its travel.

Your TPS or the wiring associated with it is definitely flaky - both a code 23 and 63 point to really weird things going on...

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Sensor removed or disconnected, Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.
Measuring the voltage at the computer helps you spot broken wiring and intermittent connections.


I would look closely at the EFI wiring harness and especially the 10 pin connectors.

See the graphic for the 10 pin connector circuit layout.