any suggestions?

[87WhiteStang1]

so i am still dealing with a horrible missfire like a ihave been for the past couple of weeks and i can't figure it out. it spits and sputter under load and when cruising it cuts out slightly. at WOT it feels very underpowered and will sputter alot. iidle will sometimes sit right around 700 and the needle will shake alot. then sometime the idle will go back and forth from about 700 to 1500 and sometimes even around 2 grand. all ctlinders get spark from what ive seen. fuel pressure sits at 32psi at idle and goes up to about 38-40 when on throttle. fuel pressure at about 44psi when vacuum line unhooked. i'm not sure whether this is fuel or spark related but heres what ive done so far:

-fuel pump replaced with walbro 255lph
-dist replaced not long ago, tested it today with dist out of another car.
-timing set at about 12 where it has seemed to run good in the past.
-msd blaster ign. coil
-plugs ,wires, cap & rotor replaced/plugs gapped
-new fuel pres. regulator
-checked for vecuum leaks in engine area
-egr tested
-headers tight
-o2 sensors replaced
........any other suggestions please! i want to get this fixed but i may just bring it to a shop because i have been dealing with it for too long, thanks

 

[2000xp8]

Did you try swapping out the msd coil for a stock one? They are notorious for being poor quality.

 

[87WhiteStang1]

yes i have a brand new stock replacement that i swapped out. i guess i should have said that.

 

[jrichker]

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.