If an engine has a P0308 cyl 8 missfire will it derate that injector?

444getsitdone · Dec 29, 2014

I have been driving the truck for probably 8 years with that code (p0308) is came from the CPS so I knew the injector and cps were good so I just ignored it. but after 2010 when smog came out I had to get that light off. Took it to a repair shop and after replacing the CPS and injector no. 8, which did no good the tech replaced the CPS with a on old style "black" IIRC and that took care off the check engine light. got it smogged and everything was cool then the CPS went out, they replaced with a used black one again and it went out again so they just put in a regular Ford one in and it was fine with the check engine light. next smog I had to get that light off so I personally just to see put in a napa CPS and the light went out and I smogged it, then the CPS went out again. so now I keep the a new napa one for smogging then run the ford (or international one its the same result of P0308) CPS. Now I have no problem switching CPS's every two years but I was wondering the other day if the PCM thinks that Cyl 8 is not doing well will it derate or totally kill that injector? I think it runs fine for a truck with 376k miles, but then again sometimes I think it may have a slight miss. What are your guys thoughts?

golfer · Dec 30, 2014

The PCM does not control individual injectors differently from the others.

silverpsd_06 · Dec 30, 2014

I think common rail is the only system that can balance like that... 7.3's are too old to do it

444getsitdone · Dec 30, 2014

OK this is good to know, thanks guys. Do you guys think my injector harnesses will go out anytime soon? They have never been changed, the injectors are "only" 125000 miles old so if there is any running issues would they probably not be the injectors but something else?

Arisley · Dec 31, 2014

If you can come up with a wiring diagram, you can ohm out the wires from the IDM to the injector, that will tell you if everything is OK. If not isolate it down to the bad section of wire. Repair or replace as needed.

lincolnlocker · Dec 31, 2014

by the sounds of it. the wires are ok and it its just a cps issue. do you have any of the old style fat end cps's that went bad? if so, are there contact marks on them from the cam gear? the old style black cps's are a hair longer than the new skinny ends.. are the napa cps's that cleared the code skinny or fat on the end?

live life full throttle

444getsitdone · Dec 31, 2014

lincolnlocker said:
by the sounds of it. the wires are ok and it its just a cps issue. do you have any of the old style fat end cps's that went bad? if so, are there contact marks on them from the cam gear? the old style black cps's are a hair longer than the new skinny ends.. are the napa cps's that cleared the code skinny or fat on the end?

live life full throttle

I do not have one of the old dead CPSs (just the ones from International, Ford and Napa that are in "circulation") but yes the Napa one is fat, verses the two skinny ones from Ford and Inter', I do not think that the old ones had marks on them, not 100% sure either way. I do know that the three, including the Napa one, do not have marks from the Cam gear. I would always use the Napa just to get the stupid CEL from coming on but I had a bad deal when I bought one from Napa, installed it and had the truck doing the death lurches of a bad CPS. That was not that fun so I put a Ford one in and it had the CEL and I just ran with it. BUt when smog time came I needed that CEL off so I tried a new Napa one and it worked fine, but right after smogging it I took it out and saved it for two years. I have done that for the past two smoggings and its been ok, I do not remember the engine running any differently with any of the three CPSs compared to another.

lincolnlocker · Dec 31, 2014

444getsitdone said:
I do not have one of the old dead CPSs (just the ones from International, Ford and Napa that are in "circulation") but yes the Napa one is fat, verses the two skinny ones from Ford and Inter', I do not think that the old ones had marks on them, not 100% sure either way. I do know that the three, including the Napa one, do not have marks from the Cam gear. I would always use the Napa just to get the stupid CEL from coming on but I had a bad deal when I bought one from Napa, installed it and had the truck doing the death lurches of a bad CPS. That was not that fun so I put a Ford one in and it had the CEL and I just ran with it. BUt when smog time came I needed that CEL off so I tried a new Napa one and it worked fine, but right after smogging it I took it out and saved it for two years. I have done that for the past two smoggings and its been ok, I do not remember the engine running any differently with any of the three CPSs compared to another.

ok. thats just crazy! might he able to put a spacer in with the napa one just in case its closeer to the cam gear.. its possible that it can be too close to the cam gear. but its also possible that the quality is crap on the napa ones..

live life full throttle