1996 f350 psd 237k miles.

Bad gas mileage has decent power but there are problems

Has a knock can't tell if its a fuel knock or injector knock

Seems like it misses rpm drop.

When I put it in reverse sometimes it chugs

No excessive black smoke. Fuel water seperator has been changed. Tranny fluid and filter have been changed.

Cps changed no different
Unplugged map sensor no change
Air filter good.
Unplugged injectors one at the time each of them changed the idling

All the problems happen when the truck is at operating temp

 

Also has pretty damn firm shift.

Only code that came up was p0236

Didn't throw a check engine light

 

I don't know much about these trucks but looking in the manual this is where i would start to look

0236 code turbo boost sensor A circuit performance restricted inlet exhaust hose

 

Mine has always had a P0236 code from the day it came from the factory. Replaced the MAP sensor and still got the code. I just ignore it.

Have you looked at the ICP sensor or replaced it in the last 237,000 miles? Mine went at 245,000 miles. Had oil in the sensor prior to that. Truck stumbled occasionally and missed. Replaced the sensor and haven't had any problems. Mileage back up to 19 mpg on average.

 

Maybe its the IPR O rings that are bad.

 

Where is the ipr located on my truck?

 

IPR is located on the lower right rear of the HPOP. You will need to pull the fuel filter/water separator to access it. First check the ICP on the left side oil rail towards the front of the engine. It has a wiring harness with 3 wires connected to it. Pull it and see if there is any oil residue where the wiring harness plugs in. If so it is going bad. Even if there is no oil present the ICP sensor seems to typically have a lifespan of around 200,000 to 240,000 before they need replacing.

If it doesn't seem like it is an ICP sensor I would have a set of IPR o-ring on hand before pulling it. Once you go to that effort you might as well just replace the o-rings anyway.

Another problem area producing poor performance could be sludge build up in the HPOP. If the oil hasn't been changed regularly (3000 miles or so) for the life of the truck the HPOP tends to get gunked up. No one changes that oil and it seems to cycle back to the lower oil pan slowly. The injectors like clean oil that flows well to work properly. There is a plug on the left side top of the HPOP that you can remove and stick a tube down to the bottom of the HPOP and pump out about a quart of oil and replace it with new clean oil thru the same hole you pumped it out of. A vacuum pump or oil transfer hand pump will work. Run the truck for about 10 minutes at idle and then remove another quart and replace it. This will help clean out any sludge and keep clean oil firing the injectors. Remember to put the plug back in the hole before starting the truck as the HPOP can produce a lot of psi and with out the plug in you will have one heck of a mess.

 

Checked the Icp sensor no oil in it and pulled it while engine was running and it had a big miss then idled again smoothly but threw a CEL. I think I'll still replace it since I'm about where the life span of them are.

No next is the ipr. I've pulled the fuel/water seperator off before but I don't know where the hpop is let alone the ipr. Can someone please maybe post a picture of all that or maybe describe where it is after pulling the water sep out. Thanks

 

on the hpop...back side of upper timing cover...hoses come out of it to each head..
there is a two wire connector.that is the ipr.remove the tin nut,then the coil will slide off.THen you will need a very deep socket to unscrew the ipr valve part.when you get it out it will have two segments where o-rings go.the smaller has a backer along with the actual ring.check the rings,mine were damaged in the smaller size one and had deterirated the backer. I did it mearley because I had the hpop off for another issue.I got lucky and caught a real problem before it stranded me.I had 317000mi.
my icp was full of oil also.The truck ran just fine bellieve it or not.THOSE were the least of my worries.

 

[QUOTE=fordman67;12692115]on the hpop...back side of upper timing cover...hoses come out of it to each head..
there is a two wire connector.that is the ipr.remove the tin nut,then the coil will slide off.THen you will need a very deep socket to unscrew the ipr valve part.when you get it out it will have two segments where o-rings go.the smaller has a backer along with the actual ring.check the rings,mine were damaged in the smaller size one and had deterirated the backer. I did it mearley because I had the hpop off for another issue.I got lucky and caught a real problem before it stranded me.I had 317000mi.
my icp was full of oil also.The truck ran just fine bellieve it or not.THOSE were the least of my worries.[/

Do I have to remove the turbo? To get access to the hpop? Is it behind the turbo and down pipe?
Also am I replacing the ipr? Or just the orings

 

Ok for the hpop removing sludge since I have to remove the water seperator to get to the ipr which is on or near the hpop so I pull the sludge out then replace it with fresh oil then run it. Do I have to remove my fuel/water seperator to get access to that plug on the hpop? Mean I'd have to install everything run it for 10 min then take everything off again and pump fluid out of the hpop?

 

The inspection hole on the HPOP is located on the top left side. You do not need to remove anything other than the flip up plastic protective cover over the fuel filter housing (if you still have it) to access it. The HPOP is the rectangular aluminum object on the very top front center of the engine located between the alternator and the A/C compressor. The IPR is located on the lower right back side of the HPOP, to remove that the fuel bowl has to go to get access to it. If you are going to pull the IPR you will end up draining the HPOP anyway - less messy to pump as much oil out thru the inspection hole first.

I do not have any photos of it handy but if you search this forum for ICP, HPOP, GPR, IPR you will come up with a labeled photo fast.

 

Not under the turbo, it's in front of the turbo by several inches.
The fuel filter housing is under the plastic engine cover at the tep front of the engine, dead center. It has a 4 inch dia. black plastic / nylon fiber cap on it. The unit directly under the fuel filter housing is the HPOP.

 

Dang icp sensor is 260$ at dealer.
Can I order one online for cheaper?

 

I got one on Ebay.