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ILfarmer89 · 09-24-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

New member, please bear with me, looking to glean the knowledge found here and get some help with a few issues I'm having with my ISX. So I recently purchased my first truck, bought it on auction. As far as the truck itself goes, it seems to be a good, southern truck with very little rust and well taken care of inside and out and spec'd the way I wanted. My plan is to use it during the off season of farming to do some local custom hauling. The truck has '06 model year of the CM870 ISX rated at 475hp. It came with documented overhaul and has less than 50,000 miles since the overhaul was completed. The issue I'm having is the pyro is running high, on flat ground, pulling a load at 65mph, the pyro reads 1000-1100. Along with that, the boost never builds up beyond 25-27psi and the engine brake on stage 3 is basically useless. There's no CEL on, oil pressure runs steady at 35psi and coolant temp rarely gets above 200. It does have an adjustable fuel pressure harness on it but as far as I can tell, that's about it. EGR is still on the truck and as far as I can tell, it hasn't been De-Mandated. I intend on inspecting this further to see if it actually has been De-mandated but was left on the motor for appearances sake. My gut is telling that it actually HAS BEEN De-Mandated and has a hack-n-slash "tune" in it that is what is causing my problems. Any insights into what would be causing my problems? Could it be something else beyond a bad tune causing the problems? Thank you all in advance for taking the time to help with this problem.

tree98 · 09-24-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

Post a picture of the turbo side of the engine. Also unplug the EGR valve and see if the check engine light comes on, if it doesn't come on then the engine is likely demandated and probably quite badly.

Something else that can cause low boost and high pyro on the 870 is a stuck / sticky turbo VG ring or actuator. This will also cause weak jakes. You can apply shop air to the actuator and measure the travel, I can't remember off hand but I think it's supposed to move 10mm ?? You can look it up on quickserve.

Agentspd · 09-24-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

Pressure check cac system first.

Rawze · 09-24-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

(09-24-2022 )ILfarmer89 Wrote: ...
It does have an adjustable fuel pressure harness on it
...

You need to yank that fuel-pressure sensor fooling device off of it ASAP and throw it in the garbage can!!!!!.

The ISX CM570, CM870, CM871 model engine fuel pressure is 100% mechanical.. and the computer HAS ZERO CONTROL OF THE FUEL PRESSURES!!!.

THOSE FUEL FOOLING DEVICES ARE A SCAM.. And all they do if royally f#uck up the injection timing badly and fuel quantities into the cylinders, creating a ton of excessive internal engine friction, seriously shortening the engine life!!!.

They also destroy engine cylinder balancing and the ability for the engine to maintain a proper fuel-air-mix.

The engine computer can make whatever power/torque/efficiency trade-offs that someone desires ... PROPERLY and without shortening engine life.

===========

Unplug the egr valve and see if it gets a CEL light. If it does not, then take it to a dealers$ip and have the correct program flashed back into the engine. CM870 does not shut down if it has been de-mandated.. it will only have CEL light for whatever got unplugged. -= at least this way you can iron out all the problems and get it running right while the correct factory program is in it before moving onward.

ILfarmer89 · 09-25-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

(09-24-2022 )tree98 Wrote: Post a picture of the turbo side of the engine. Also unplug the EGR valve and see if the check engine light comes on, if it doesn't come on then the engine is likely demandated and probably quite badly.

Something else that can cause low boost and high pyro on the 870 is a stuck / sticky turbo VG ring or actuator. This will also cause weak jakes. You can apply shop air to the actuator and measure the travel, I can't remember off hand but I think it's supposed to move 10mm ?? You can look it up on quickserve.

Here are the pictures of the turbo side of the engine.

ILfarmer89 · 09-25-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

(09-24-2022 )Rawze Wrote:
(09-24-2022 )ILfarmer89 Wrote: ...
It does have an adjustable fuel pressure harness on it
...

You need to yank that fuel-pressure sensor fooling device off of it ASAP and throw it in the garbage can!!!!!.

The ISX CM570, CM870, CM871 model engine fuel pressure is 100% mechanical.. and the computer HAS ZERO CONTROL OF THE FUEL PRESSURES!!!.

THOSE FUEL FOOLING DEVICES ARE A SCAM.. And all they do if royally f#uck up the injection timing badly and fuel quantities into the cylinders, creating a ton of excessive internal engine friction, seriously shortening the engine life!!!.

They also destroy engine cylinder balancing and the ability for the engine to maintain a proper fuel-air-mix.

The engine computer can make whatever power/torque/efficiency trade-offs that someone desires ... PROPERLY and without shortening engine life.

===========

Unplug the egr valve and see if it gets a CEL light. If it does not, then take it to a dealers$ip and have the correct program flashed back into the engine. CM870 does not shut down if it has been de-mandated.. it will only have CEL light for whatever got unplugged. -= at least this way you can iron out all the problems and get it running right while the correct factory program is in it before moving onward.

I unplugged the egr valve and as I feared, the CEL light didn’t come on. Looks like it’s a trip to get correct program flashed into the ecm. Thanks for the help thus far and I’ll report back once that is done. Quick question tho, would it mess anything up in getting this lined out, if when I’m getting the ecm re-flashed, if I had them flash it to the 500hp program? I don’t want to cause anymore issues. Just a thought.

Rawze · 09-25-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

(09-25-2022 )ILfarmer89 Wrote: ... if when I’m getting the ecm re-flashed, if I had them flash it to the 500hp program? I don’t want to cause anymore issues. Just a thought.

do not try to up-rate it.. the power/torque can be adjusted later after you get it running correctly again.. that is fairly easy to do. Put the exact program that belongs in that truck/engine, so that all the internal and external hardware matches up perfectly, giving it the best engine and vehicle efficiency. That is more important that trying to change the power. -= it s a journey.. not a sprint.

ILfarmer89 · 09-25-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

(09-25-2022 )Rawze Wrote:
(09-25-2022 )ILfarmer89 Wrote: ... if when I’m getting the ecm re-flashed, if I had them flash it to the 500hp program? I don’t want to cause anymore issues. Just a thought.

do not try to up-rate it.. the power/torque can be adjusted later after you get it running correctly again.. that is fairly easy to do. Put the exact program that belongs in that truck/engine, so that all the internal and external hardware matches up perfectly, giving it the best engine and vehicle efficiency. That is more important that trying to change the power. -= it s a journey.. not a sprint.

Understood. Thank you again for all of your help. I really appreciate it.

ILfarmer89 · 09-26-2022, **(Subject: high pyro temp/low boost/weak engine brake )**

Update so far is I take the truck in the morning to get the ecm re-flashed. Best case is I’ll get it back end of the week-first of next week. In the meantime, is there anything I’ll need going further that I can get now while it’s in the shop? Cummins datalink adapter?