when i let off the gas when im driving and get back on it, it starts bucking and i have to downshift to stop it. it does it at any gear and at any speed. what is wrong? its driving me crazy
I am going to make a dangerous assumption that you have an aftermarket MAF matched to the 24 lb injectors.
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.
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.
i dont think its the engine doing it, it feels like something in the drivetrain is loose. its kinda hard to describe what its doing. it started doing it when i put the engine back in after i rebuilt it.
how bad is it? mine did it a little bit like only a few slight bucks...this is after changing to a 5.0
it seemed like the drivetrain going front to back a little
...then it somehow got better and never did it again after a while...I also re-did my engine again recently and I don't have the problem again this time either
...I always wondered why it did it in the first place...don't think it'll go away through...because I did have the tranny rebuilt around that time, so the symptom I think got better after the tranny was put back in a second time...I beleive the issue was still there..but after it settled a week later it went away????.
mine is pretty bad, i have to downshift and then accelerate to get it to stop.
it just feels like something in the driveline is loose.
could it be the transmission?
its a 3550 i got off ebay.
it never did this with my t5
I would get under there and see if you can check for movement...maybe with a buddy
that's what I personnally would be trying...not sure if it's possible to tell this way or not...???
I think the chiltons/hayes book explains how to check the crossmember for excessive play...If there's play there...I could easily see how it could cause problems like that; but I am guessing.