Another low power isx870

[Titan313]

(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?.

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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.