Hello everyone. New guy here. I have a 99.5 F250. Been having an issue for about the last 2ish months. So the truck starts fine runs fine. But 6 times now has died while driving. It will start by complete loss of throttle response, followed by spitting and sputtering, then dead. It will not restart immediately after, but will after a short time. Which then it runs like poo til the following restart cycle. Its stranded me 4 times resulting in it getting towed to a shop. So far the icp, the idm, and cps have been replace based on codes. The cps has been changed twice. Batteries, starter, and water pump have also been changed recently but unrelated to this issue(i think).Everytime it dies it throws a p1670 and p0340 code. The shop i go to uses only motorcraft parts and the diesel mechanic was a ford master diesel mechanic for 25+ years before opening his own shop. Im starting to get frustrated with the truck... and the shop for that matter, and about ready to throw in the towel. Anyone ever run into this issue? Where do i even start? Ive read that a lot of issues can cause the p1670 code. But also why to i keep getting cps codes with 2 new sensors? I dont want to just throw more money at the truck with a hope that its the cure all. Thanks in advance

 

How about swapping the IDM relay with the blower relay under the hood, and see how it does? Check that CPS pigtail for broken insulation. You're using motorcraft parts, that's good.

 

Damn Gremlins, you didn't you feed them after midnight did you? It sounds like you've got an intermittent short in the harness. A common location is at the 42 pin connector where it crosses over the drivers valve cover. The underside often rubs on the cover and eventually shorts something/s out. Another common spot is the IPR connector harness will turn to goo inside the loom and short itself out. I'd probably give the section where the harness goes down the front of the engine and eventually hooks to the CPS a good inspection as well.

 

Well funny you mention that... all of that. I have a new fuse block on the way that im going to be swapping in with all new fuses and relays. I had the all too common windshield leak over the summer that caused havoc for awhile. And also, one of the guys on my shift last night brought up a good point. These issues didnt even start until my water pump started to leak, and given the close proximity of the cps to the pump, maybe it was soaking the pigtail and connector. I unplugged the cps and inspected the connector and pigtail. No noticeable damage as far as i could trace it while at work, but the connector itself was pretty disgusting. Soaked in coolant and had a bunch of carbonous build up in it. So i cleaned that out and put it back together. Only time will tell if it could have been causing issues. As far as data, i can hook up my tuner when i go out and about and screenshot the data for you, but like i previously mentioned, she runs great until she doesnt

 

Yeah, soon as i get a chance, whether while at work or a weekend i dont have my son, im going to start following the harness around looking for issues. But free time isnt something i get a lot of, and if the weather keeps above freezing, ill have even less when planting starts early. I gotta have a truck, and if someone or something are feeding them gremlins... it just might go to the dealer for LOF and magically come back as a 6.7😅😅😅😅

 

I'm chasing a similar issue on my 02. Replaced CPS and ICP w/ ford parts, issue persisted. I've got motorcraft IPR coming and hope that's the last weak point. I replaced w/ a NAPA brand years ago when I had a stall/no-restart(for about 30-45 min) issue, That seemed to fix the issue then. I did also play hopscotch between two CPS's every time it wouldn't restart, I had 30+m to kill anyhow and was worth a shot. I do intend to trace what I can of wiring harnesses when I replace the IPR, if is an additional hidden issue. When mine stalls, for the most part, its a dead stop like turning the key. I did start getting a lug in engine with some coming back and more often just dying after a chug or two.

If IPR and harness inspection doesn't bear fruit, my next step is to do ride along w/ mechanic hooked up to try to capture what's failing. When he was out last he did a software update and everything was running great, while idling. No codes and everything looked strong. Not much advice other then I'm in the same boat and sounds like were on similar troubleshooting paths.

If I find my gremlin I'll let you know, happy hunting.

 

So I just replace the IPR and she seems to have straightened out. In my experience the culprit has been the IPR.
I'm sure you may have seen my threads, being similar issue but here they are;

Recent issue: https://www.ford-trucks.com/forums/1...t-in-gear.html
Past issue: https://www.ford-trucks.com/forums/1...-ipr-help.html