Good afternoon I am new to this forum. I need some help. I have a 94 mustang gt 5.0 auto that is having some engine problems. It has a rough idle, bad gas mileage, and major power loss. The parts I have changed recently to try and fix this problem are the TPS, IAC, MAF, EGR, distributor cap, rotor, coil pack, spark plug wires, spark plugs, and fuel filter. None of these parts have fixed the problem. the car does idle better but it shakes when I'm in gear at a stop light and when I accelerate there is very little power. It sounds like the engine is dogging down until I get to about 50-70 mph. I filled the gas tank and 70 miles later I've already used half a tank. I took it to a shop the other day and they ran a diagnostic of some sort and told me that the engine was running lean but the code they gave me was for an obd2 car and if I'm not mistaken mine is an obd1 since it's a '94 so I don't know how they came up with that code. They refused to do a vacuum leak test or a trickle down test until I paid them $400 to change the fuel pump because they said the pump was only making 26psi and needed to make 32 minimum. I have spent a good bit of money trying to get this car to run right and I'm a little frustrated. Can anyone give me some advice? It would be greatly appreciated and thank you for reading.
1994 Mustang Gt Rough Idle, Major Power Loss
- Thread starter PaulG22
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Sorry to hear your have'n a hard time with it, but welcome to stangnet where some of the finest minds hide from society but will give you some good advice on to turn that dog into a stallion.
I think I'll move this over to the 5.0 tech forums and see if we can get you some good advice.
I think I'll move this over to the 5.0 tech forums and see if we can get you some good advice.
Dan_Soprano
Mod Dude
No sir I haven't. I took it to the shop to do the vacuum test but they refused to do it until I paid them $400 to change the fuel pump.
Two good ideas there dan, might I add to run the codes, there is a sticky in the 5.0 tech forums, I'll try to post it for ya, it's easy, is the car stock?
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 orvoltmeter 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.[/B]
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. Itcomes 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, seeActron® 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 3145.
It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.
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 orvoltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
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. Itcomes 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, seeActron® 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 3145.
It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $22-$36.
Don't thank me, jrichker is to blame er, thank for that little splash of wisdom, amongst others, I'm just a boob with a mod button.
Dan_Soprano
Mod Dude
Great post! I'd also like to add, if you have the ability, pull a couple spark plugs (one from each side) take a picture and post it up if you can. I'd like to see how rich it is running. From what you are describing the car is running pig rich for some reason, which will cause the issues you are having. Bad O2 sensors will cause the motor to run a bit rich, but shouldn't be that bad. I can almost guarantee your fuel pump is fine.
I see your in doubt about the findings from your trip to a repair shop, what codes did they get?
When I hookup the shop scanner to my 89gt it tells me what I have, V8 stick check digit names my first born, kinda hard to fool that thing.
When I hookup the shop scanner to my 89gt it tells me what I have, V8 stick check digit names my first born, kinda hard to fool that thing.
Dan_Soprano
Mod Dude
Ok burnt white is a lean condition, which makes no sense with your horrible fuel mileage. I was expecting black wet.....
Your computer is likely in limp mode, hence poor fuel mileage and poor performance, no 02's and whatever else is missing from the imputs the computer needs to function properly. I think you need to determine what sensors are missing/malfunctioning and I also suspect wiring problems.
Do you have any background on the car?
Do you have any background on the car?
Unfortunately I don't have any background history on this car I got it as a trade but it seemed to run fine at first and then things started popping up one after the other. The more I dig the more I find that this car was a major hack job. I would like to go ahead and put the cats back on so I can run o2's so the computer reads what it needs to. I honestly didn't know that cars can go into limp mode. How would I get it out of limp mode?
Dan_Soprano
Mod Dude
Limp mode is just open loop mode. Nothing major should change besides that. Something else is up.
Fix the codes.
Honestly, 94-5's are a little different than my fox. There is ccrm, I think thats what its called, and I'm not sure what all it controls.
I think you need to do a vin check to see how your car was equipped, pm me your vin and I'll see what I can find.
Honestly, 94-5's are a little different than my fox. There is ccrm, I think thats what its called, and I'm not sure what all it controls.
I think you need to do a vin check to see how your car was equipped, pm me your vin and I'll see what I can find.
Dan_Soprano
Mod Dude
Open loop is still open loop.... it's the basics of fuel injection. There is something else going on....
