Tachometer / engine issues

[Bill Jones]

Hello.
I am having an issue with my 93 LX that I cannot diagnose. Several months ago my engine tachometer started reading half speed. This was accompanied by the check engine light being illuminated. I retrieved the codes, 223 and 224. This led me to believe that the Ignition control module had gone bad. I replaced the module with a used piece from a salvage yard and all was well, until about a week ago.

Now the tachometer will jump to 6K if you are descending a grade, or coasting up to a red light, basically anytime that you do not have your foot in the gas. When it does this it will usually die when you finally do stop, or push in the clutch.

I assumed it was an electrical issue so I checked all the grounds, the battery and the alternator. The trouble codes stored were 327 and 328, so I pulled the EGR and cleaned it out and checked to make sure it was still functioning.

Does anybody have a clue what to check for next?
Thanks,
Bill

 

[bonestock87]

Being that your current ICM was pulled from a junk yard, I'd say it has now gone bad. I had the same tach problems you have. My tach just sat at 6k all the time. New ICM ($89 at rockauto.com, btw) and life is good.

 

[glowstang93]

I had similar problems. I replaced the ICM and then found out I had a bad coil pack too. Won't tell you to replace all, but start with a new, lifetime warranty one, then go from there.

 

[Bill Jones]

I had similar problems. I replaced the ICM and then found out I had a bad coil pack too. Won't tell you to replace all, but start with a new, lifetime warranty one, then go from there.

I started switching parts last night from my 92LX. I am fortunate enough to have several LX's that I use for parts cars. I switched the ICM and the car ran worse. I switched it back and now the car runs pretty good. I am unsure what the isssue is.

Bill

 

[93stangnow2.3t]

try your crank sensor that was my problem.