CPS replacement

[Craigerz]

Throwing the CPS code. Clear it and its back in about 2 or 3 starts. I have one in my garage I took off the truck that was still good (the top part that plugs in). I replaced all of it when I did the tune up, the long gear driven distributor looking part. It came with the tool to line it up also, but I cannot seem to locate it at the moment. If I am just replacing the plastic top part do I have to do the whole TDC procedure all over? I only have about 7k miles on it since I replaced it about 18 months ago, is this going to be one of those parts like replacing the cap and rotor every so often or did I maybe just get a bad one?

 

[delexploder]

you're fine just swapping the cap/ sensor , what brand did you put in ? dorman?

 

[Craigerz]

I'm digging through my receipts because I was curious about that, but I'm sure it was an Oriellys brand one. Only thing I can remember buying Dorman was for the EATC and thats because its all I could find. Didn't realize what crap it was until I was reading on here about everyone not liking them.

 

[koda2000]

Keep in mind, often a bad alternator diode will cause the CPS TDC. There really isn't anything to the CPS sensor part, so unless it gets destroyed by the cam synchronizer there isn't much to go wrong with it.

 

[Craigerz]

I was afraid of that too, that's what the majority of the other post said also. I have the original alt that came off of it I will switch out next. Has a bad bearing but will be good for a test. I did the 3 wire ground/hot wire from the alt and it was reading 13.9 at idle a few months ago so I really really really hope that's not the case.

I don't know if it matters or not but I keep in on a battery tender when I'm not driving it.

 

[koda2000]

From what I understand, a bad diode in the alternator is not keeping it from charging the battery (at least to some extent) it's that it puts out a stray electrical signal that is interpreted as a CPS fault. If your battery isn't going flat I see no reason to charge it.

 

[Craigerz]

I just do it because sometimes its not driven for weeks at a time.

 

[Craigerz]

I might start with the alt first come to think of it. I’ve never been overly impressed by this alternator. I can’t really explain it but it’s never seem just right to me. I’ve change battery terminals, extra ground wires, ect.

 

[Craigerz]

Do I have the 3G or 4G alternator?

'97 5.0

 

[koda2000]

Do I have the 3G or 4G alternator?

'97 5.0

IDK, what's the part number on your old/original alternator? RockAuto's on-line catalog says your OE alternator was 130 Amp.

Alternate/OEM Part Number(s): 4G7U10300AA, 4G7UAA, 4G7Z10346AA, 4G7Z10346AARM2, 7787, F77U10300AB, F77U10300AC, F77UAB, F77UAC, F77Z10346AB, F77Z10346ABRM, XL2U10300AA, XL2UAA, XL2Z10346AA, XL2Z10346AARM

 

[Craigerz]

I will check. Just looking at replacing the rectifier if I swap them out and it turns out to be a diode like you were saying. Seems doable to me.

 

[Craigerz]

Swapped out the alternators and nada. Put a Motorcraft CPS on and codes gone. It appears I bought a cheap on. Still looked brand new when I took it off. Also went up to the factory 192 thermostat while I was in there and running outstanding.

After the new CPS, 192 thermostat vs 180 and the4406 swap I clocked 15.7 MPG I was getting 12.3 so the months of time it took was def worth it to me.

 

[CDW6212R]

Well done, glad that Ford part fixed it. I've only had to replace one so far, and I too went to a Ford cam synch, it was $100ish but it works.

Do I have the 3G or 4G alternator?

'97 5.0

BTW, you have a 4G alternator. The OHV 4.0 is the one that still had the 3G model, the SOHC and 302 both use the same 4G alternator.

 

[Craigerz]

Any idea what that part actually does? I've read about it timing injector pulses or something when cold but never really got a clear answer. I drove it for about 200 miles unitl the new one came in and I didn't really notice any difference in power/idling/ missing or anything.

 

[koda2000]

Any idea what that part actually does? I've read about it timing injector pulses or something when cold but never really got a clear answer. I drove it for about 200 miles unitl the new one came in and I didn't really notice any difference in power/idling/ missing or anything.

Yes it controls the timing of the fuel injectors.

BTW - It's not unheard of to have a bad alternator set the CEL for the cam position sensor.