I bought a 1997 f350 in April. It is the third obs 7.3 I have owned. This one is sluggish until about 2250 rpms but will then will build boost and hit 14 psi. The other two I have owned ran much stronger at low rpms and one of them had 3.55 gears. I have replaced the manifolds and up pipes which brought my ebp back to spec. The truck pulled a little better since then but still is an absolute dog until around 2250 rpms. I can put the pedal to the floor and it just won't go until it is ready. Sometimes I can't even accelerate uphill. So I bought a Snap On MT2500 and the only thing that seems to be wrong is that the IPR duty cycle % is low at idle, WOT in neutral, and under hard acceleration. The ICP readings are within range. IPR bad? Any suggestions would be greatly appreciated.

 

What's the readings you're getting ?

 

9% at idle
16% wot in neutral
high 20's (28 or 29%) under hard acceleration

 

Make sure the tin but is on the IPR solenoid properly.

 

If it is a Cali emissions truck then 9% at idle is normal.

Diesel Diagnostic information for Powerstroke 6.0, 7.3, IDI 7.3 and 6.9 L, by Oregon Fuel Injection

 

Is it chipped ? Any other mods ?

 

IPR nut is tight. No chip. Tymar intake, downpipe, and cat delete are the only mods. Did a buzz test and it passed. Truck is warming up now for cylinder contribution test. Had both of those tests done by a mechanic this summer and they were fine but I thought I'd check myself now that I have a scanner.

 

Unplug the ICP and go for a spin. A biased ICP sensor can cause the IPR to hold things back because it thinks the pressure is too high.

 

Passed the cylinder contribution test. I'll unplug the ICP and check the numbers again.

 

Don't bother checking the ICP numbers. They will be fictitious based on the PCM programming. IPR will reflect the PCM ICP pressures, but that might tell you something if the duty cycle is up.

Check the seat of the pants meter. ICP unplugged won't run with as much pep as when everything is working properly, but see if you get some power back.

 

Runs much stronger with the ICP unplugged. Much more like the other two that I have owned. It even seemed to shift firmer and not bog down as much. I don't know if the readings mean anything, but it read 14% at idle and 35% under hard acceleration. Does this mean I need a new ICP sensor?

 

No, it doesn't. Put a gauge on it to verify if your ICP is accurate or not, and go from there.

A low duty cycle with ICP in range could mean that your truck is just fine, and doesn't need the extra duty cycle to get the pressure it wants.

The plugs in the head for high pressure oil are #5 ORB.

 

Sounds like you might need an ICP sensor, but as stated above... You should put together a mechanical gauge to compare to the ICP readings you're getting on the scan tool.

What were the ICP readings you were getting with the ICP sensor plugged in at WOT and what was the duty cycle at that specific moment?

 

Its always good to verify, but it seems like a slam dunk to me. If it were me I'd take the gamble and just replace the ICP sensor.

 

I sold my cousin my 1997 f250 which runs great. He lives only two miles from my house. I'll borrow his sensor and take my truck for a test drive. That should let me know if the sensor is bad or something else.