870 loss of power and bad fuel mileage

[Redland1]

I have a 2003 International 9900i with an 04’ 870.It feels sluggish compared to how it used to run.It would pull 103-115k easily.But now 80k feels like it’s struggling.In the low end it’s really sluggish to get going and I have a good puff of black smile from the exhaust when climbing hills from a dead stop which it did not do before.At best it was a slight haze.I pressure tested the CAC in December and sprayed with soap.Found a couple of leaks at the boots but sealed them.Truck has always had an intake manifold pressure sensor circuit voltage below normal and or shorter to low source.Have changed the sensor and still the same.Even with that I was able to get 6.5mpg pulling a step deck.When I switched to frac sand pulling 103k it dropped to 5.5MPG but it was to be expected with the difference in weight.After a few months I got a code for EGR circuit short and a derate so instead of figuring out why it shorted I deleted it and the derate went away.Fuel mileage dropped to 4-4.5 pulling the same loads.

With the different voltage below normal or shorted to low source I’m wondering if I have a bad harness.Also wondering if the turbo or controller is bad with the extra smoke I’m getting.

[Rawze]

what is the boost going down the road? .. and under maximum engine load?

who did the de-mandate program? .. because almost nobody can do an 870 correctly.

Also,.. if it cannot read the correct boost levels into the intake, then it will act a fool too. - That error is not normal and you need to solve it.

[Redland1]

I keep it under 20.Under 10 is impossible on this truck so far.34-38 psi.

Running Rough.

I agree.Just haven’t found anyone capable of figuring out the issue.The last guy just replaced the sensor that I had replaced a month prior.Bunch of parts changers.

[SquareOne]

Redland1, be sure to only replace those sensors with genuine Cummins stuff. Be careful as there are excellent 'fakes' out there which are extremely close physically to the OEM stuff. (Hell, my dealer even had a batch of either fakes, or shitty ones which required me to replace my IMAP and EBP sensor multiple times before getting a good ones.) Make no mistake, they aren't worth a shi#t..... They'll give random readings and be anything but reliable.

[Redland1]

(08-22-2023 )SquareOne Wrote:  Redland1, be sure to only replace those sensors with genuine Cummins stuff. Be careful as there are excellent 'fakes' out there which are extremely close physically to the OEM stuff. (Hell, my dealer even had a batch of either fakes, or shitty ones which required me to replace my IMAP and EBP sensor multiple times before getting a good ones.) Make no mistake, they aren't worth a shi#t... will give random readings and be anything but reliable.

I did get them from my international dealer,but it’s worth a shot to replace them.I don’t know about the second intake manifold pressure sensor that was replaced by a mechanic shop.I don’t remember all the sensors that need to be replaced on a demandated 870 but am I missing any manifold pressure sensor,manifold air temp sensor,and exhaust gas pressure sensor?

[Redland1]

(08-22-2023 )SquareOne Wrote:  Redland1, be sure to only replace those sensors with genuine Cummins stuff. Be careful as there are excellent 'fakes' out there which are extremely close physically to the OEM stuff. (Hell, my dealer even had a batch of either fakes, or shitty ones which required me to replace my IMAP and EBP sensor multiple times before getting a good ones.) Make no mistake, they aren't worth a shi#t... will give random readings and be anything but reliable.

I did get them from my international dealer,but it’s worth a shot to replace them.I don’t know about the second intake manifold pressure sensor that was replaced by a mechanic shop.I don’t remember all the sensors that need to be replaced on a demandated 870 but am I missing any manifold pressure sensor,manifold air temp sensor,and exhaust gas pressure sensor?

[Rawze]

(08-24-2023 )Redland1 Wrote:  I did get them from my international dealer,but it’s worth a shot to replace them.I don’t know about the second intake manifold pressure sensor that was replaced by a mechanic shop.I don’t remember all the sensors that need to be replaced on a demandated 870 but am I missing any manifold pressure sensor,manifold air temp sensor,and exhaust gas pressure sensor?

yup... engine still uses the ...
Intake Pressure sensor.
Intake Temp Sensor.
Exhaust Manifold Sensor.
and several others, like the turbo inlet temps sensor, crack & cam position sensors, fuel pressure, fuel temp, etc. and others.

[Redland1]

Would a lagging turbo,more smoke than usual,and loss of power be a turbo,or VGT air box issue or can it be something else?
I’ve had the VGT air box go bad before but that was prior to me having a boost gauge and I could tell because I couldn’t hear the turbo spooling going down the road.Now I can’t hear at idle like I used to but have boost going down the road.

[Rawze]

Maybe installing a boost gauge for the dash would help to always see whats going on + you can use it to help you save fuel?.