I am thinking this is a vacuum leak somewhere. I have good power under normal driving conditions but at a light at WOT the car bogs down (I would think that I could do a burnout with the mods on my car). When the car hits about 3K the car wakes up and takes off but driving on the highway at cruising speeds it is fine. The other issue, could be related, when the engine is hot the car cranks but wont start unless the throttle is down. ECT was replaced about 6 months ago. Also fuel is about 40 psi at idle with the vac line on and off which makes me ask another question, should that be different with the line on. I can't see the gauge when driving though. Thanks for any help.
Vacuum Leak?
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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 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.
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 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.
Should get three 11's
One for KOEO
One for CM
and one with engine running for KOER codes
After the three 11's, run the cylinder balance test and confirm all 8 cylinders are contributing equally. WIll rule out a weak injectors
I'm sure that Hissin or Joe will chime in again with more test info for you. You said the fuel psi is the same with or without vacuum. With vacuum at idle, the psi should drop. Without vacuum is your max psi setting for WOT. If you have no change in the fuel psi, you may have a bad regulator, gauge, or a vacuum problem. You're going to have to hookup a vac gauge to the manifold and test from there.
Do you have a repair manual? It's a great $20 investment for reference.
Do you have a repair manual? It's a great $20 investment for reference.
Did all three test, I got 11 on the three and on cylinder balance test the code kept giving different numbers. 8,6 the first run and the 2,1 the second run, and 5,3 the third one. Going to buy a manual had one but its falling apart from being used a lot. Also noticed fuel pressure was at 35 psi (down from 40 psi) and rpms at 1500 during the balance test.
Went and checked the lower intake after looking up some posts. The lower was a little loose so torqued them to 18 ft/lbs. Also replaced the upper intake gaskets with thicker ones. Noticed that there was a fair amount of oil in the upper intake. Only give me the 11 codes and cylinder balance test is good. Still feels like it should be more power also after I let off the throttle after WOT there is some afterfire through the tailpipes.
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