mustang 5.0 hesitating and popping under wot

Double check your timing and firing order. This past spring I made some changes to my combo and had the same problem you have. Turned out I had accidently put the timing at 10 degress ATDC instead of BTDC. Its a little hard to see down there! I felt dumb as hell but shyte happens

Did you really only use one period in that whole post? Or are my eyes hurting from reading it and can only see one?

I would re check timing and pull plugs. I had a cracked plug that had 300 miles on it and it would backfire a full WOT and be fine the rest of the time.

Did this happen and you just started throwing parts at it?

302mustanglx said:

ive check the fireing order twice same with the timing the wires are fine also oh yeah about the period this aint english class lol

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But it is a communications forum, and if you want people to help, that means they have to read it, and if you want them to read it, don't make it so damned hard to do.

That said, I wish I had the answer, because I've been chasing a similar problem for years. It could be the PIP in the distributor. It could be the MAF. It could be the TPS. It could be any number of sensors causing the EEC to give improper output. It could be a cracked plug insulator, it could be plug wires arcing, it could be your fuel filter.

Did you pull the SPOUT plug out when you set the timing and when you checked it? Did you put it back in when you were done?

302mustanglx said:

ive check the fireing order twice same with the timing the wires are fine also oh yeah about the period this aint english class lol

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A negative attitude will discourage people from taking time to help you. Since you are asking for help, you should do the best you can to effectively communicate your problem.

A polite bit of advice: check your spelling and grammar if you want consistent good advice. There are some very smart people here who can be a great help when you have a problem. However, if your spelling and grammar are poor or you don't care, those same people will write you off as not being worth their time to help you.

302mustanglx said:

hi there i recentyly put a 255 fuel pump on my 88 mustang 5.0 after the install whent 4 a ride and the car stared sputering and poping at full trottle if i only go half way the car runs just fine its only when i flor it all the way down it does its thing i have my fuel presure set at 39psi without vacum also the timing is set at 12 degres the distributor is new the ignition module got tested at autozone like 15 times till it got hot and it past all the time i also replase the wires coil and cap with msd ones i set my tps at 96.also put a new fuel filter swaped out the map sensor and the tps 4 new ones and nothing i dont know what it could be it im tire of replacing things and not working i ask u guys for some help also look 4 kink lines and nothing everything looks right the fuel pump got install just like the stock one was it was runing just fine until the fuel pump swaped

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then go back and drop the tank and find the pinched fuel line.

Step 1. Attitude is everything. The right attitude will get people involved in helping you. It will also help you succeed in life and in getting your car fixed.

Step 2. Please take off the caps lock when you type. It is the same as yelling at someone.

Step 3. Please express one idea at a time. Use a capital letter to start a sentence and a period to end it.

Step 4. Please do not use numbers in place of words: 4 is not for, 2 is not to or too. The ABC with the checkmark under it in the top right hand corner of the message box is a spell checker. It would be to your advantage to use it before you post a reply.

Step 5. The better we understand you, the better your chances are to get your problems fixed.

Step 6. 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.