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[t_cel_t]

first of all not my truck, but i have to drive it. i know some of you guys are truck mechs.

its a freightliner with a 8L cummins and 6spd. its got power and runs like a scalded dog, but it has something wrong with it that the shop refuses to fix/acknowledge exists.
 
its almost impossible to drive at any speed under 65, and this is why.

when in neutral, if you just touch the throttle(i mean just touch,like pushing down 1mm) it will start to rev all the way to redline( around 2600rpm). obviously you can see the problem this makes for driving at any speed other then all out 65.

i know this isnt right as all the other trucks have cat c7's and work 'right', when you push their throttles they rev up just a little bit 1%throttle=~800rpm and 50% throttle =1500rpm, ect. its linear like it should be.

the techs at ryder are fucking clueless.

my theory is the pedal assembly(fly by wire) is shorted or some shit which causes the on/off behavior. or cummins sucks nigger sack.

also in befor diesels dont have throttles.

[Joseph Davis]

In before someone else points out that diesels have "driver's wish" fuel maps based off of "TPS".

I'm no diesel expert, but it sounds pretty cut and dry.  Pedal sensor, wiring, or ECU.

[keelay]

Also no expert, but did a small amount of diesel work in the air force. Sounds like a pedal potentiometer issue. Basically I'm just agreeing with Jojo

[jabberwock]

Your diesel got Toyota'd

[t_cel_t]

In before someone else points out that diesels have "driver's wish" fuel maps based off of "TPS".

I'm no diesel expert, but it sounds pretty cut and dry.  Pedal sensor, wiring, or ECU.

what do you mean by drivers wish? you mean the 0% pedal=idle, 100%=2500rpm, 50%=1600rpm?

so im not crazy and this shouldnt work this way

[Joseph Davis]

In before someone else points out that diesels have "driver's wish" fuel maps based off of "TPS".

I'm no diesel expert, but it sounds pretty cut and dry.  Pedal sensor, wiring, or ECU.

what do you mean by drivers wish? you mean the 0% pedal=idle, 100%=2500rpm, 50%=1600rpm?

so im not crazy and this shouldnt work this way

Drivers wish is euro chip tuner slang for the map where throttle angle = requested torque @ rpm. 

[bob_barker]

Anyway you can hook it up to a laptop and check the TPS? sounds like its falty as they always go faulty also check the injection pump to see if theres a return spring im not sure if this truck has one. Third sell that fucker and buy a pete or Kw but stay away from the Accert cat engines there fucking junk

[t_cel_t]

its not my truck,its my works truck, its leased from ryder. i like having a job and money so i kinda have to drive it, 95% of the time we just do linehauls so you're running down the interstate.

second the c7 acert is probably the best engine we have had in any of our trucks. shit never breaks down, lots of power, and always starts in the winter. the cummins and the international 'smurf'/dt466 motor are fucking trash.

although i do like the cummins ISX thats in one of our tractors, 550hp i think. fucker screams.

[Towdogg]

My work truck does this also...    I have the cat motor...  M2 Frieghtliner...

[snm95ls]

If the 8 liter Cummins is anything like the 5.9 Cummins, then I would hazard to guess that it is the APPS(Accelerator Pedal Position Sensor).  That really is the only driver input to these things, and they can be calibrated.

This is of course ASSuming that it is an electronic injection model and not mechanical injection.  I really don't kneoe enough about the heavy(er) diesels to differentiate.

Don't know any diesel mechanics personally.

 

[Joseph Davis]

Given era and emissions, I'm pretty sure everything is electronic IP these days.

I need to learn more diesel theory.

[snm95ls]

Given era and emissions, I'm pretty sure everything is electronic IP these days.

I need to learn more diesel theory.

There was no mention as to how old this truck is, which is the only reason why mechanical injection was brought up.

[HiProfile]

I'm no diesel expert, but it sounds pretty cut and dry.  Pedal sensor, wiring, or ECU.

Erm, that's what Toyota said. 8 years ago, internally.

I need to learn more diesel theory.

Too bad BigWig is gone, he'd be able to learn ya after some surfing.

[t_cel_t]

yeah its a new truck, electronic injection. and i can see the pots right on the pedal assembly.

also it has that fucking afterburner shit on it, that fucker kicks in sometimes and i swear it steals like 200hp from the engine.

[Towdogg]

That afterburn shit is why my job when out and found a couple 07's that where leftovers...

Do you have an engine brake?   When mine does what yours does the engine brake will stop working too...

Mine is also an automatic...

[t_cel_t]

no engine brake but 6spd manual