93 Mustang LX Rough Start

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  #1  
Old 06-06-13, 06:03 PM
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93 Mustang LX Rough Start

OK guys I need some help.

93' Mustang LX
2.3l 4 CYL
5 Speed

Occasionally upon starting after sitting it runs really rough for a minute or two and then smooths out and runs like a new car. It don't seem to matter if it's 50 degrees or 80 degrees outside and it doesn't do it every time.

I pulled codes using a jumper wire and test light and got the following.

223: Dual plug (DPI), spout or IDM circuit fault

224: Failure in ignition coil primary circuit

334: EVP sensor is/was high

On the run test it put out 224 again and a 998? Couldn't find a discription for 998?

When it's running rough I seem to smell gas.

This car was wrecked and sat for a few years until it was given to me. Mechanically I replaced the fuel pump, plugs, timing belt, and changed the oil.
 
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  #2  
Old 06-06-13, 06:35 PM
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mattison,

DTC 998 is the code for a failed computer. It means “FMEM”, which abbreviated means “Failure Mode Effects Management”. In keeping it simple it means that the computer is using backup software to run the car. The only repair for this is to replace the computer.

Thank You
Amy
 
  #3  
Old 06-06-13, 06:39 PM
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Would that cause the rough start issue? Runs great other than that. Computer sound costly.
 
  #4  
Old 06-07-13, 03:08 AM
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mattison,

The computer in your Mustang is operating in failure mode. It went into failure mode, because it saw a signal from one or more sensors that indicated that the sensor (or sensors) have failed and are operating completely out of their original design specifications. At that point the computer substituted a fixed signal value for the failed sensor (or sensors) to keep the car running. That explains the rough start, and why the engine smoothes out after the rough start. Any code (or codes) that accompany DTC 998 must be resolved immediately, because your Mustang is operating at minimal level. DTC 224 (for example) is an erratic IDM input to processor, and indicates a crankshaft position sensor issue.

Thank You
Amy
 
  #5  
Old 06-08-13, 06:17 AM
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So it's not saying the computer has failed. That's good. Any advice on what needs replaced going off of the other 2 codes? Knock on wood it's been giving me no problems starting lately.
 
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