Threaded Mode | Linear Mode

Titan313 · 10-17-2023, **(Subject: Another low power isx870 )**

Short story. Bought an older Volvo with a bad cm870. Had a good donor engine. 10 speed manual , as soon as you switch into high gear (5th) it only catches low rpm and takes forever to pickup. Pulling 40k is miserable , and going up a grade is a struggle. It is a 400hp but from what I hear they should pull 40k no problem. This was 2 years ago , I was not very informed about these engines. So I welded the egr valve shut and unplugged it. Still not much power. Not sure if the previous owner had the ecm flashed.

** only get a little black smoke when she bogs on a lower rpm going up.

- changed turbo
- changed actuator
- replaced exhaust pressure sensor
- replaced manifold pressure sensor
- I plugged in the egr valve and unplugged the egr temp sensor today just to see what it would do. Same performance.
- Onboard diagnostic shows not codes for sensors.
( or do I need a scanner to read codes?)

It’s still a healthy engine with some life , I just really want to get it purring.

•• I have yet to clean out the exhaust pressure sensor tubes

Any suggestions are appreciated.

Rawze · 10-17-2023, **(Subject: Another low power isx870 )**

What kind of boost numbers are you seeing?.

Does the program in the ecm match the engine ser#?.

Have you had the ecm flashed back to the latest factory version?.

How old is the muffler?

How old is the turbo controller?.

Has anyone bothered to find out what system of manager in the ecm is holding thr fuel back when it acts up?.

===========

It should be spiking about 36 psi in a pull, then falling abck to about 32 psi or so in a hard pull due to derate from egr being defeated. It also should have a check engine light on.

If the program in the ecm does not match the engine ser#, this can be a cause for it to act up. Also, replacing the engine warrants a re-flash to clear out the ecm of the old engine's collected data and lets the ecm re-balance itself to the replacement engine properly.

Muffler/exhaust can get really restrictive on one of those older trucks and make for a lot of power loss and turbo lag.

Turbo controller is also known to go bad on those CM870 engines and make for weak boost and therefore weak response.

To see what is holding the fuel back, a person can use this screen in calterm to see what is causing it to be weak...
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

Titan313 · 10-17-2023, **(Subject: Another low power isx870 )**

(10-17-2023 )Rawze Wrote: What kind of boost numbers are you seeing?.

Does the program in the ecm match the engine ser#?.

Have you had the ecm flashed back to the latest factory version?.

How old is the muffler?

How old is the turbo controller?.

Has anyone bothered to find out what system of manager in the ecm is holding thr fuel back when it acts up?.

===========

It should be spiking about 36 psi in a pull, then falling abck to about 32 psi or so in a hard pull due to derate from egr being defeated. It also should have a check engine light on.

If the program in the ecm does not match the engine ser#, this can be a cause for it to act up. Also, replacing the engine warrants a re-flash to clear out the ecm of the old engine's collected data and lets the ecm re-balance itself to the replacement engine properly.

Muffler/exhaust can get really restrictive on one of those older trucks and make for a lot of power loss and turbo lag.

Turbo controller is also known to go bad on those CM870 engines and make for weak boost and therefore weak response.

To see what is holding the fuel back, a person can use this screen in calterm to see what is causing it to be weak...
ref: http://rawze.com/forums/showthread.php?t...3#pid58693

I’m in the Detroit area and don’t know anybody that tunes these trucks.

- Air boost controller is most likely original with engine
- Muffler is a couple years old. Muffler delete likely soon.
- The ECM from this engine was automatic so we could not use it.
- Recent tune up and injectors done last year , I’m really leaning towards a ECM issue
- Check engine has always been on.

Rawze · 10-17-2023, **(Subject: Another low power isx870 )**

(10-17-2023 )Titan313 Wrote: ...
I’m in the Detroit area and don’t know anybody that tunes these trucks.

- Air boost controller is most likely original with engine
- Muffler is a couple years old. Muffler delete likely soon.
- The ECM from this engine was automatic so we could not use it.
- Recent tune up and injectors done last year , I’m really leaning towards a ECM issue
- Check engine has always been on.

If you need someone to help you with CM870 programming specifically, then forum member 'running rough' is the recommended person on here for that kind of thing.

He owns his own trucks, helps others remotely, and has been well trained with all things that are CM870 related, including their particular quirks, etc.

You did not mention the boost levels, so I can only assume you don't have a boost gauge installed. - If so, then that is something else that you need to cure right away, especially for that CM870, as they are known to have a bit of a wonky turbo to begin with.

Titan313 · 11-01-2023, **(Subject: Another low power isx870 )**

Did some digging and found the original ECM from my motor that we pulled out of another truck! Turns out it’s been tuned before ! We shall see results this coming week when I swap ECM’s

Rawze · 11-02-2023, **(Subject: Another low power isx870 )**

(11-01-2023 )Titan313 Wrote: Did some digging and found the original ECM from my motor that we pulled out of another truck! Turns out it’s been tuned before ! We shall see results this coming week when I swap ECM’s

Running unknown quality programming in your engine is the same thing as pouring sand in your oil. - Must be nice to be so rich and not to care about such things.