r/DieselTechs • u/AdGlittering7842 • 4d ago

Diagnostic assistance Maxxforce dt9,10. Acceleration not consistent.

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Hey, fellas how you doin. My buddy working on a 2009 international 4000. With maxforce dt9,10. I believe its deleted, egr as well. Got a inconsistent acceleration. Replaced it with the test turbo and actuator we salvage from another similar truck. But still got this inconsistent acceleration.
Did cylinder cut out test- its pass.
Icp pressures is good ,
Got a little doubt in Fuel pressure- it reads above - 55 psi. Idle . And 6-70 at 1500 rpm.
Oil pressure is 50 psi at 1500 . 30 plus psi at idle.

3 Upvotes

72% Upvoted

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5

u/MonteFox89 Mod, Verified Tech, Navistar, Volvo/Mack 4d ago

have you confirmed the pedal resistance is steady through actuation? Have you checked for air in the fuel yet?

When it gets up to temp, after a drive, is it a hard start after shutoff and restart after 1 minute?

5

u/HHSOCCER28 4d ago

The pedal assemblies go bad pretty often. They start developing sloppy side to side and takes out the sensors.

3

u/conyers117 4d ago

I can't even count how many TPSs and entire pedal assemblies I've replaced in those trucks. 

3

u/Single_Ad_5294 4d ago

Don’t expect it to be a race car. A running maxxforce from that year is a blessing and a curse.

You can keep it running but once you solve one problem there will be another. It’s the only engine I’ve seen with a hole in the block multiple times. Clean filters, clean gaskets, send it.

1

u/AdGlittering7842 2d ago

This one seems like a curse. 😬😬

1

u/gnashingspirit 4d ago

Oil leak at an injector in the high pressure oil rail? Consistently inconsistent? Pull out the IPR and check to see if the screen is still there or been blown out. IPRs get tired too, so it’s the original on a high hour engine the solenoid could be weak.
When was the last oil filter and fuel filter change? I’ve seen the strainer screen pretty gross in the fuel system too.

Are you just increasing rpm or actually driving it for this complaints of inconsistent acceleration? If it is an auto transmission, check the fluid level, and look at the clutch health. Might be some slippage.

1

u/Cbnbshwacker101 2d ago

6-70 or 60-70?

1

u/AdGlittering7842 2d ago

My bad , its 60-70

1

u/Cbnbshwacker101 2d ago

Have you checked for air in the fuel system?