Somthing Is Holding My Car Back Under Acceleration

[john c]

94 mustang gt 5.0HO 5speed. Somthing is holding my car back when under hard acceleration. I was getting on a free way so i had to run it pretty hard.as i accelerated i noticed somthing holding me back just alittle and out of know where it would break free and kick me back to my seat.it repeated its self after every time i switched gears wich was about 4,000 rpms .what is your oppinioun on this? what would be the first thing you would check?

it worries me that its gonna snap my crank.my crank has broke once before but i dont recall it holding back like this..the mechanic that replaced my crank told me the cause of it breaking was my tail shaft.what it done was wallard out on the end causing my drive shaft to wobble a bit and that it put stress on the crank (so he says) so after the crank and all that was replaced i replaced the tail shaft and put up a aluminum driveshaft along with it.will a wallard out tail shaft cause a crank to break? or could it be somthing else that he just didnt wanna tell me?...i mean i dont see the guy lieing to me his name is larry rowe. he builds race cars and is in alot of magazines

 

[madspeed]

Need more info. What mods are done to the car? How many miles? Have you run the computer codes?

 

[john c]

as of mods im not sure.i believe it is mostly stock. the guy that replaced the crank said the motor has been rebuilt and that whoever did it did a real good job so if the pistons are forged i couldnt say he did say it was cammed tho. other then that has a high performance coil and ford racing spark plug wires and cold air intake.also has a off road h pipe with no cats and flow master exhaust i believe its geard as well but id have to go check the gearing if you need it...as of miles there currently unknown my speedometer quit working at 180,xxx that was before i bought it so the miles on the crank are very low it was roughly 6-7 months ago when ot was replaced along with new rod bearings..as of codes ill have to retrive them around 6pm or so...thats when ill have the scanner

 

[madspeed]

First thing to do is run those codes. It could be many things, this will help sort it out. Post up your findings and we'll help you out

 

[john c]

ok heres the deal. i ended up needing to to do a koeo/koer test. i have never had to do that, i was haveing trouble trying to read my codes so i recorded it to try to study them on my phone but i was wondering is there a way i can upload the video and get help? i mean im not stupid when it comes to cars i just dont know a whole lot about fords

 

[madspeed]

upload to you tube and then link it here

 

[toyman]

While we're waiting for you to upload the codes to get a clearer picture I suggest you clean the MAF sensor element and check the battery to engine and engine to chassis grounds. Physically unbolt the connections clean the terminals and check for corrosion in the cables.

 

[john c]

im going to upload the codes in alittle while.i just got home from work so im going to rest up a bit first.but as of grounds and terminals and maf,i already did that a few weeks ago...i check that stuff periodicly

but i believe i have my problem narrowd down.i have always had a slight noise in my tranny but not real noticeable but today on my way home i ran the rpms up a bit again to see if it would act up and every time i squeezed in my clutch what ever gear im in would just chatter and hum kinda like they where trying to grind then after id change gears i tried to down shift and it wouldnt go in gear it would just grind unless i slowd down.my whole clutch is new so i can only assume its my tranny (i do have a spare that i might put in it if i do im going to inspect my clutch again as well)

 

[madspeed]

Or the person that installed the clutch didnt do it correctly...

 

[jrichker]

Some help in the dump the codes department...

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

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.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.

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. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some 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.

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 clutch (if present) is pressed to the floor, 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.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10

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 www.midwayautosupply.com/Equus-Digital-Ford-Code-Reader/dp/B000EW0KHW Equus - Digital Ford Code Reader (3145It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.