Eec-iv A9l = C3w1
 

I went to Ford parts and said that i wanted to get a replacement EEC-IV (A9L) for my 93 Mustang GT (manual transmission)

The replacement received was labeled (reman) C3W1.

I did some research and soon discovered that C3W1 is for Automatic Transmission.

I called Ford parts the parts person said that the C3W1 is an "updated part number". I asked him to double check and upon checking, he said that the C3W1 is good for both manual & automatic transmissions.

Is he correct? I'm going to have a custom chip burned because of a blower install.

Re: Eec-iv A9l = C3w1
 

Yes, it is interchangeable.

Re: Eec-iv A9l = C3w1
 

Are the air/fuel curves the same?

I installed it and now my Mustang pings at WOT.

Re: Eec-iv A9l = C3w1
 

There are some differences to the A/F and spark tables. In short, the C3W1 has richer base fuel values but a less WOT fuel fuel multiplier so it works out to almost the same. The C3W1 is commanding about 5.5-degrees more spark at WOT throttle than the A9L so that might be the cause of the pinging. You'd need a custom tune to change these things. Have you tried running premium fuel?

Re: Eec-iv A9l = C3w1
 

FWIW, I have the C3W1 in my car and it's been great