video of my lovely power loss

I'd be fixin those vac leaks first. Then go for basic tuneup items and pullin codes.

Have you tried doing all the usual tune up stuff?

Where is your timing set ?

Any idea what your fuel pressure is?

But first and foremost I fix those vacuum leaks.

5pointohmustang said:

believe me i want to fix the vac leaks im just highly confused with those diagrams so i just capped everything but it didint seem to make a difference, my tune up is only 4 months old and msd stuff i dont know my timing or my fuel pressure and i dont know how to check either one lol

Click to expand...

If you have all those vacuum line capped off then you have more than just a vacuum leak.

I've had my fair share of vacuum leaks and I can tell you that a vacuum leak will not cause what you have. A typical vacuum leak will make your car start and then die almost instantly. If you try to rev the engine when it's cold to keep it running with a vacuum leak you'll usually hear it pop/backfire in the intake. Once you can get it to idle it will sound like you have a big cam in it, and once the engine has warmed up there isn't that big of a noticeable different that how it would run normally.

Are you sure your cats are clear or that your mufflers aren't plugged?

So you only have the 2 cats not the 4 cats that came originally with the car from the factory,and NO mufflers?

If your timing chain has gotten real sloppy it might change the timing.
Have you done anything recently that required you to loosen the bolt and turn the distributor?

I'm sure jrichker will chime in and direct you on now to check your timing and the fuel pressure.
Or you could always do a search on here about timing and fuel pressure and add jrichker name.

5pointohmustang said:

when i got the car it only had two front wielded cats bolted on hpipe two mufflers and the tips i unbolted the hpipe because it sounds good

Click to expand...

So you're saying your running just 2 cats and NO mufflers then?

I think 4G might be on to something. If you still have your original cats they might very well be clogged (especially if someone has used leaded fuel or additives in your car). If so, they will have to be replaced or an off-road H-Pipe used (don't get in trouble with the eco police!).

It's pretty easy to check the fuel pressure from the test port on the fuel rail (right behind the alternator). I think the local parts stores will even lend out a tester. Just make sure you don't get fuel on the hot headers and don't create any sparks.

Make sure your distributor hold down bolt hasn't loosened up, if it has it will spin in the "retard" position.

Might want to replace your fuel filter if it's been a while. Also have someone sit in the car with the gas pedal floored (with the car off) and make sure your throttle body is fully opened (the blade will be flat to the flow of air flow). Sometimes the cable will stretch and it won't fully open.

Step 1 - Dump the codes
Step 2 - Do a cylinder balance test.
Step 3 - Check fuel pressure
Step 4 - Check timing.

Dump the codes: may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

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.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

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





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. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some 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.

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 clutch (if present) is pressed to the floor, 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.

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 Equus - 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.


Cylinder balance test:

Revised 30-July-2011. Added need to make sure the clutch is pressed when dumping codes.

The computer has a cylinder balance test that helps locate cylinder with low power output. You’ll need to dump the codes out of the computer and make sure that you have the A/C off, clutch depressed to the floor and the transmission in neutral. Fail to do this and you can’t do the engine running dump codes test that allows you to do the cylinder balance test.

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 clutch depressed to the floor, 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.


Here's how 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.





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. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and drivability problems

Some 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.

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, clutch depressed to the floor 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.

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

Cylinder balance test
Warm the car's engine up to normal operating temperature. Use a jumper wire or paper clip to put the computer into test mode. Start the engine and let it go through the normal diagnostic tests, then quickly press the throttle to the floor. Remember to keep the clutch pedal (5 speed) depressed to the floor during the test.The engine RPM should exceed 2500 RPM's for a brief second. The engine RPM's will increase to about 1450-1600 RPM and hold steady. The engine will shut off power to each injector, one at a time. When it has sequenced through all 8 injectors, it will flash 9 for everything OK, or the number of the failing cylinder such as 2 for cylinder #2. Quickly pressing the throttle again up to 2500 RPM’s will cause the test to re-run with smaller qualifying figures.
Do it a third time, and if the same cylinder shows up, the cylinder is weak and isn’t putting out power like it should. See the Chilton’s Shop manual for the complete test procedure


Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder balance test. Low compression on one of these cylinders rules out the injectors as being the most likely cause of the problem. Look at cylinders that fail the cylinder balance test but have good compression. These cylinders either have a bad injector, bad spark plug or spark plug wire. Move the wire and then the spark plug to another cylinder and run the cylinder balance test again. If it follows the moved wire or spark plug, you have found the problem. If the same cylinder fails the test again, the injector is bad. If different cylinders fail the cylinder balance test, you have ignition problems or wiring problems in the 10 pin black & white electrical connectors located by the EGR.

Compression test
Only use a compression tester with a screw in adapter for the spark plug hole. The other type leaks too much to get an accurate reading. Your local auto parts store may have a compression tester to rent. If you do mechanic work on your own car on a regular basis, it would be a good tool to add to your collection.

With the engine warmed up, remove all spark plugs and prop the throttle wide open, crank the engine until it the gage reading stops increasing. On a cold engine, it will be hard to tell what's good & what's not. Some of the recent posts have numbers ranging from 140-170 PSI. If the compression is low, squirt some oil in the cylinder and do it again – if it comes up, the rings are worn. There should be no more than 10% difference between cylinders. Use a blow down leak test (puts compressed air inside cylinders) on cylinders that have more than 10% difference.

I generally use a big screwdriver handle stuck in the TB between the butterfly and the TB to prop the throttle open. The plastic is soft enough that it won't damage anything and won't get sucked down the intake either.

A battery charger (not the trickle type) is a good thing to have if you haven't driven the car lately or if you have any doubts about the battery's health. Connect it up while you are cranking the engine and it will help keep the starter cranking at a consistent speed from the first cylinder tested to the last cylinder.



Check fuel pressure:
The local auto parts store may rent or loan a fuel pressure test gauge if you don't have one.
Disconnect vacuum line and check it for evidence of fuel present on the line. If you find fuel, the fuel pressure regulator has failed. Cap the vacuum line and stow it out of the way.
Connect fuel pressure test gauge to Schrader port located just behind the alternator.
Turn the ignition switch on & start the engine. Observe the pressure : you should see 37-41 PSI at idle.
Turn the ignition off, reconnect the vacuum line and disconnect the fuel pressure test gauge. Watch out for squirting gas when you do this.



Set ignition timing
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





Your success is going to be a function of how well you can follow directions and then post the results. What I have given you is the exact same thing you would pay a professional mechanic big $$$ to do. None of it is all that difficult, but it is all time consuming and and requires thought...

5pointohmustang said:

where is the distributor hold down bolt?

Click to expand...

Open the hood and face the engine look, now look at the base of the distributor where it enters the block.
On the right side at the bottom of the distributor you'll see that bolt with a hold down.

is your smog pump intact and pushing air through the cats?

from the 44-94 id say no.

you need air from the smog pump if you run cats. might be why?

well with the 44 and 94 i dont think the valves are opening and doing what they are supposed to do. the air from the smog pump goes through them

5pointohmustang said:

i just changed the pump two weeks ago because the bearings went out so its brand new, how do I check if its pushin air to the cats?

Click to expand...

Take the rubber hose off the backside of the pump and put your finger near the hole, if it's working you'll be able to feel it pushing the air.