86 mustang gt. AOD. when the car is cold it runs fine. when it warms up, different story. when accelerating the car has a bit of hesitation, unless i'm getting into the throttle. at steady speeds it also stutters but when you hit the gas a little it will take off like it should. also stalls sometimes when i'm stopped. it shifts fine. the tranny was just rebuilt (tremec). I dont know what to troubleshoot first. ignition or fuel. i have a new fuel filter (not on the car yet), msd street fire coil. I just put some sea foam in the gas and intake. i'm changing the oil tomarrow(royal purple). plug wires are good. theres a little burn build up on the dist.cap points. it almost feels like its not getting ENOUGH fuel when i'm not pressing the peddle much. any suggestions?
86 5.0 stutters while driving. HELP
- Thread starter jayuhl
- Start date
Spend time and money throwing parts at a problem...
OR
Diagnose it and get started in the right direction...
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 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.
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.
OR
Diagnose it and get started in the right direction...
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 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.
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.
stang&2Birds
Founding Member
VERY SIMPLE!
1) Read the codes, fix problem!
OR
2) Stupidly spend ~$30K in randomly replacing EVERY part in the car.
With the above said, it could be the MAP sensor. Then again, it could be anything!
BTW: Did I mention
Stupidly spend ~$30K in randomly replacing EVERY part in the car.
Hmm, jricker's post now seems to make the most sense, uh?
BTW: You could also have a bad valve, bad ring, bad pump, bad wiring, bad injector, bad EEC, and so on. Then again, spending $100 for a new MAP sensor to see if that's the problem makes a lot more sense than spending ~$40 on a code reader to get an idea of where to start - not!
With SD, at least you don't have the BS issues with the MAFs and all of the *****ed up ways that people have screwed up their MAF setups!
In short, get a code reader, read the codes, then proceed from there. Like I said, it could be a bad valve, bad piston, bad injector, and so on. You do realize that the car and engine are over 20 years old, don't you? Yup, in a few more years, my '86 with be 25+ years old, and that means no more smog testing in Conn! 
Opps, forgot to add:
Four Eyes Rule!
Mustang 86 - Mach1 Springs
1) Read the codes, fix problem!
OR
2) Stupidly spend ~$30K in randomly replacing EVERY part in the car.
With the above said, it could be the MAP sensor. Then again, it could be anything!
BTW: Did I mention
Stupidly spend ~$30K in randomly replacing EVERY part in the car.
Hmm, jricker's post now seems to make the most sense, uh?
BTW: You could also have a bad valve, bad ring, bad pump, bad wiring, bad injector, bad EEC, and so on. Then again, spending $100 for a new MAP sensor to see if that's the problem makes a lot more sense than spending ~$40 on a code reader to get an idea of where to start - not!
With SD, at least you don't have the BS issues with the MAFs and all of the *****ed up ways that people have screwed up their MAF setups!
In short, get a code reader, read the codes, then proceed from there. Like I said, it could be a bad valve, bad piston, bad injector, and so on. You do realize that the car and engine are over 20 years old, don't you?
Yup, in a few more years, my '86 with be 25+ years old, and that means no more smog testing in Conn! Opps, forgot to add:
Four Eyes Rule!
Mustang 86 - Mach1 Springs
be careful with putting a bigger cam in an 86.they run flat top pistons and you will run into piston to valve clearance problems if you aren't careful..i would say a 155 or 190 walbro pump would work great.
i just got a 190 lph walbro fuel pump. I changed the throttle position sensor, fixed a vaccuum line and ran some sea foam through it. also raplced the coil with a street fire msd and msd distributor cap and rotor. and replace the fuel filter. runs just fine . i'm putting the fuel pump in next week for the hell of it.. and for those who think im completely stupid, think again. i,ve worked on much more complex cars than this. working on a mustng is cake. not downgrading anyone , i just know what im talking about. i was just looking for suggestions. and thank you very much for any input. if anyone
has a question please feel free to ask and im sure i can come up with a damn good and accurate answer. i promise im not thinking im top dawg here but i have worked with some of the best mechanics in the world . sounds like a bunch of bs but take it for what its worth. this isnt my first rodeo, thank you everyonre who helped. even though some were more smartasses than anything. its all good
has a question please feel free to ask and im sure i can come up with a damn good and accurate answer. i promise im not thinking im top dawg here but i have worked with some of the best mechanics in the world . sounds like a bunch of bs but take it for what its worth. this isnt my first rodeo, thank you everyonre who helped. even though some were more smartasses than anything. its all good
now i have a ticking sound comming from the driver side header area where the header and h pipe meet. almost sounds like a plug is arcing. i know thats the problem because i tried tightening the two bolts and kinda made it worse. i'm replacing the frp shorties in a few monthe with BBK EQUAL SHORTIES and BBK CROSSOVER PIPE into SUPER 44's and dumping them at the axle. It will sound beautiful.
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