Dan_Soprano
15 Year Member
CCRM is fords devil.... spawned by Satan himself. That's why I went with after market fuel injection....
1994 Mustang Gt Rough Idle, Major Power Loss
- Thread starter PaulG22
- Start date
Dan_Soprano
15 Year Member
Limp Mode means reduced power and economy. The computer uses a set of tables that contain preset values that insure safe operation of the engine without engine damage. This Limp Mode enables you to drive the car until you can get the problem fixed that caused the computer to go into Limp Mode.
You can use O2 sensors on a car that doesn't have catalytic converters. All that is required is that the H or X pipe have the bungs for the O2 sensors to screw into. If the O2 sensors are missing or malfunctioning, that could account for the problems you are having. The only way you will ever know is to get a correct code dump and fix what caused the codes.
On the 94-95 cars, the codes are all 3 digits. The fact that you posted some 2 digit codes tells me that you missed something. That may be the crucial bit of information needed to find and fix your problem.
To remedy that, I recommend that you spend $25 or so and buy one of these.
You can order it online at Walmart if you like. See https://www.walmart.com/search/?query=Code Reader 3145
Or 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.
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I also recommend that you stay away from any repair shop that doesn't have a bunch of older Mustangs in the parking lot and a good reputation in the community for good work. Many of the new auto techs have no idea of how to troubleshoot and fix 5.0 pushrod Mustangs. You have already been bitten with some expensive work that didn't fix your problem.
Last edited:
jozsefsz
15 Year Member
Your computer might be in open-loop ('limp mode') but that shouldn't run any worse than it does before it's warmed up. Yours sounds worse. The CCRM has nothing to do with being in open-loop, it's just a set of relays that send power to the computer, fan, fuel pump, and so on. O2 sensors are suspect, but with how much gas you're using, it may also be a fuel pressure regulator or an injector stuck open.
Fuel pressure should be easy to check, borrow a gauge from AutoZone (need the thread-on adapter) and check at idle with the vacuum line off of the regulator. If it's around 39psi, you're good there.
A stuck fuel injector will cause all sorts of mayhem, and it rarely shows up on a scan. Puling codes is great, but often it tells you what you already know (you're running rich!) You'll want to run a cylinder balance test (this is done after you pull the codes by kicking the throttle). The tester will announce any cylinders that are running out-of-pace with the rest and help you locate a stuck injector. The other way (the old fashioned way) is to pull the plugs and see how they look. If one's all sooty and the rest aren't you have your answer.
The final easy-to-overlook thing towards driveability is a major vacuum leak. That hose under the manifold is a pain, and so is the evap-system hose which often rots away. Good luck!
Fuel pressure should be easy to check, borrow a gauge from AutoZone (need the thread-on adapter) and check at idle with the vacuum line off of the regulator. If it's around 39psi, you're good there.
A stuck fuel injector will cause all sorts of mayhem, and it rarely shows up on a scan. Puling codes is great, but often it tells you what you already know (you're running rich!) You'll want to run a cylinder balance test (this is done after you pull the codes by kicking the throttle). The tester will announce any cylinders that are running out-of-pace with the rest and help you locate a stuck injector. The other way (the old fashioned way) is to pull the plugs and see how they look. If one's all sooty and the rest aren't you have your answer.
The final easy-to-overlook thing towards driveability is a major vacuum leak. That hose under the manifold is a pain, and so is the evap-system hose which often rots away. Good luck!
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.[/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. 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, 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.
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.
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, 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.
