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Help needed please, sudden loss then regaining of power

4K views 5 replies 2 participants last post by  Macon 
#1 ·
To start with I have a 2001, F-250, 4x4, 6 speed manual, fairly stock truck. It does have a chip however as the 2nd owner of the truck and not the one who chipped it I honestly have no idea what kind it has. I purchased the truck 9 years ago and the previous owner just told me it had a 95hp chip in it. I added a 4 inch, turbo back, silverline dual exhaust on it after I purchased it and other than a K&N air filter in the air box the truck is stock. It has been fairly trouble free. I recently had to replace an oil pressure sensor to fix a lope it developed. The problem I am having started before the lope and has continued since the lope was fixed.

That being said the problem in which I am having is an intermittent problem that never seems to happen when it's been to a shop and the 3 different shops it has been at has been clueless as to the cause. There is no specific time or place that it happens however the same thing occurs when it does happen. Whether on the highway, on a back road at slower speeds or on 2 occasions even at idle the motor experiences what I can best describe as a hiccup. It is a sudden and at most lasting for a period of 2 seconds complete loss of power. The rpm gauge drops to 0 and the motor sounds as if you turn it off and turn it right back on. When it occurs there is a puff of smoke from the exhaust and it goes right back to running like normal. The biggest thing of all is that it does NOT throw a trouble code, there is NO check engine light activation when it happens. Does anyone have any ideas or experienced this same problem? Looking for any help I can possibly get please.
 
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#2 ·
Kind of odd for no ses light, but it sounds like a cps. You have a manual, and you're reading 0 rpm while going down the road. That is impossible unless the rpm sensor is broken. Cps is that sensor.
 
#3 ·
What is the cps sensor? If it would help with diagnosis this typically occurs within the first 5-10 miles that it is driven typically from a cold start but not limited only to cold starts it does occur after it reaches normal operating temp. It doesn't change with weather conditions either. When it occurs it usually only happens once then runs perfectly fine the rest of the trip whether it be a 20 minute ride or a 5 hour trip. At most it has happened 3 times in a single trip and that was while pulling a trailer with a tractor on it however it doesn't seem to occur any differently if hauling or empty.
 
#4 ·
Crankshaft Position Sensor. You can be driving along just fine, loving life, ready for the party, and then the truck will die. It might restart, it might not. It might start again after it's cooled down and run just fine for a while and die again. You could experience nothing more than a hiccup that makes you scratch your head. But, the CPS tells the engine it's running.

If it goes out, indicated RPM's go away as well, which is why I'm thinking it may be your culprit.
 
#5 ·
Ok I have already had to replace it once shortly after buying the truck (around 90k miles)it along with the Oxygen sensor both went out at the same time and it would run but barely. The truck now has 173k on it but I have heard those are a common problem with the 7.3 and some even carry around spares. Definately sounds like a good place to start, I will call the local parts shop and have one ordered and give it a try, thanks for the assistance.
 
#6 ·
Yeah, I've been lucky on mine so far, but my buddy bought one about a year before me and he's gone through a couple already. Easy fix, and cheap to prepare for.
 
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