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2002 f250 lariat 7.3 4r100 4x4
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Discussion Starter · #1 ·
Hello all, I’ve been hunting down an answer to an issue I’ve been having for a month or two now and tried asking on other forums with no one replying. This is my dads old truck that he passed down to me and it’s my work truck/ hauler and would love to keep it going.

2002 f250 lariat 7.3 auto with 240k miles
Cold air and ts performance chip are only mods to this truck.

ive done a lot of research across multiple forums and threads with nothing quite like what I’m experiencing. The truck is hard to start, idles perfectly fine with good throttle response, good vitals, etc. I’ve let it idle for a good 45 mins with no hiccups. Then I go to blip the throttle to about 2500 rpm and it will dead miss. And throw the engine light. Turn it off and Let it sit for 5-10 minutes and it’ll start and idle fine again, but once you give it throttle, it’ll miss and blow all kinds of black smoke. I pulled the valve cover on the passenger side and when it’s missing, the whole passenger side injector bank isn’t firing. I pulled all injectors, all shared the same 3.0 ohms. I replaced all the o-rings and threw them back in with no luck. I read somewhere that the idm could be at fault so I cracked it open and there wasn’t any water in it or anything so I sealed it and put it back in. The cps sensor is only 2 months old (dark blue, purple, dark gray, whatever color you wanna call it), but for giggles, I stuck the old one back in (light gray, still fairly new, only changed because it was recommended to switch to a blue/purple) and the thing fired right up, had excellent throttle response and bellowed our a healthy amount of black smoke (not thick enough to where you couldn’t see through it). I haven’t had enough time/chance to test drive it to see if the cps is at fault or if it’s the idm.. So my question is.. could the cps very well be what’s causing it to dead mis and have no power? Like the sensor is getting too hot or it’s faulty? Because the truck now runs like brand new and then some with the old one. I just don’t want to tear anything up by running on 4 cylinders all the time trying to diagnose something. I’ll any questions to the best of my knowledge, Thank you in advance!
 

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One question.. Is the replacement CPS a Ford OEM unit? Lots of folks have had problems with aftermarket units.

Cj
 

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2002 f250 lariat 7.3 4r100 4x4
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Discussion Starter · #3 ·
One question.. Is the replacement CPS a Ford OEM unit? Lots of folks have had problems with aftermarket units.

Cj
Theyre both fairly new so if you mean The replacement as in the dark blue/purple, It’s an international part number replacement that was suggested in multiple forums and websites. I got it from Riffraffdiesel.com. The light gray one that I swapped BACK in is motorcraft.
 

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2002 f250 lariat 7.3 4r100 4x4
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Discussion Starter · #4 ·
Update: it was in fact the cps. I let it warm up and drove it easy and hard for about an hour this morning running errands in town with no hiccups or any signs of issues. I couldn’t even make it 2 minutes down the road before. Needless to say, I’m ordering a couple of extra sensors to throw in the glovebox with a 10mm and ratchet in case I get stranded from home. Hope this helps someone with these symptoms, since I haven’t seen this combination of them anywhere. So try the cps before dumping $$$ into an idm or injectors!
 

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Muddy,

Nice to hear you solved it. I have heard that there are slight differences in spacing on these. As such it messes with the sensor's ability to "read" the tone ring.

Cj
 
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