What is this called when a diesel engine revs up and down?

[NTDaws]

Did a engine and tranny swap in my uncle's k2500 chevy. It's been doing this, what's it called? Btw that's just a example video of what happens.

[terrytek]

Pretty sure that's just idle. 

[ARikozuM]

Bad imitation of a cricket?

[Drak3]

For a Shitrolet, typical.

17 minutes ago, terrytek said:

Pretty sure that's just idle. 

Cummins, PowerStroke, and EcoBoost all are a consistent purr, or not nearly that pronounced.

[NTDaws]

1 hour ago, terrytek said:

Pretty sure that's just idle. 

I know theres a name when it idles like that though.

[LienusLateTips]

58 minutes ago, Drak3 said:

Shitrolet

People really like using the word "shit" for car/bus/truck nicknames, I like transit and I hear stuff like "fuckshitor", "Novashit", "DIEbrid" and "junkcelsior"

 

 

 

[Drak3]

Just now, JDE said:

People really like using the word "shit" for car/bus/truck nicknames, I like transit and I hear stuff like "fuckshitor", "Novashit", "DIEbrid" and "junkcelsior"

 

 

 

I use the name Shitrolet because shortened, it's just 'Shitty,' just like their vehicles.

[ARikozuM]

1 minute ago, JDE said:

 "junkcelsior"

I found my next build name, thanks.

[LienusLateTips]

1 minute ago, ARikozuM said:

I found my next build name, thanks.

That word describes these buses:

https://www.newflyer.com/buses/xcelsior-family/

 

They shake a lot, and are near universally hated except by some "weird" people like me

[Drak3]

After a very quick google, I found out two things:

1: It's called a Rough Idle

2: It can be caused by a few issues

1. Vacuum leak
2. Failed sensor
3. EGR malfunction
4. Throttle Positioner misalignment
5. Dirty idle air control valve

[dfsdfgfkjsefoiqzemnd]

It's often referred to as "loping".

[NTDaws]

2 hours ago, Captain Chaos said:

It's often referred to as "loping".

FINALLY SOMEONE WHO ISNT TROLLING. Appreciated thank you!

[FlatBrokeRacing]

14 hours ago, Drak3 said:

After a very quick google, I found out two things:

1: It's called a Rough Idle

2: It can be caused by a few issues

1. Vacuum leak
2. Failed sensor
3. EGR malfunction
4. Throttle Positioner misalignment
5. Dirty idle air control valve

actually in the diesel world its called a "hunting" idle. and has nothing to do with any of what you've listed, as diesel engines do not have throttle bodies or any vacuum and none of those things minus the egr/sensor are even apart of a diesel engine (generally a sensor will not cause hunting). Diesel engines are wide open to air, and when driving them you do not control how much air is entering the engine, you control how much fuel it is getting. Since a diesel is combustion ignition, they are noisy due to essentially the combustion process 'pre-igniting' which is why they rattle/make noise. Modern diesels are much quieter due to more modern injection systems like Common Rail with electronic injectors that have peizo electric crystals on them and can fire 3+ times per combustion event meaning that the oem can control the flame in the cylinder reducing noise/vibration.

 

What you are listening to is a 2 stroke Detroit diesel with the rack set to a higher fuel setting and not properly, so it overfuels the engine at idle causing hunting. These are mechanically injected engines that needed a positive displacement blower to run, if the rack setting and governor settings were not correct, they would hunt at idle, surge at speed, and generally run-away. Lots of guys used to set the fueling on the rack close to the edge, as you could essentially pickup "free power" for little to no money.

[jools]

ive heard it called hunting

[Drak3]

2 hours ago, FlatBrokeRacing said:

actually in the diesel world its called a "hunting" idle. and has nothing to do with any of what you've listed, as diesel engines do not have throttle bodies or any vacuum and none of those things minus the egr/sensor are even apart of a diesel engine (generally a sensor will not cause hunting). Diesel engines are wide open to air, and when driving them you do not control how much air is entering the engine, you control how much fuel it is getting. Since a diesel is combustion ignition, they are noisy due to essentially the combustion process 'pre-igniting' which is why they rattle/make noise. Modern diesels are much quieter due to more modern injection systems like Common Rail with electronic injectors that have peizo electric crystals on them and can fire 3+ times per combustion event meaning that the oem can control the flame in the cylinder reducing noise/vibration.

 

What you are listening to is a 2 stroke Detroit diesel with the rack set to a higher fuel setting and not properly, so it overfuels the engine at idle causing hunting. These are mechanically injected engines that needed a positive displacement blower to run, if the rack setting and governor settings were not correct, they would hunt at idle, surge at speed, and generally run-away. Lots of guys used to set the fueling on the rack close to the edge, as you could essentially pickup "free power" for little to no money.

Maybe I should preface it with the fact that I quickly looked it up. Something along the lines of 'after a very quick google.'

 

[FlatBrokeRacing]

5 hours ago, Drak3 said:

Maybe I should preface it with the fact that I quickly looked it up. Something along the lines of 'after a very quick google.'

 

its all good just figured i'd straighten some of it out, decent advice on a gas engine that wasnt modified just wrong for the diesel world! 

 

just like my response to the 'loping', loping and hunting are two different things with similar outcomes, diesels can lope but its a very uncommon thing and most loping engines do not hunt for RPM, they hold semi consistent rpm (within less than 100rpm) while the loping or surging noise you hear is exhaust resonance due to camshaft profile and 'overlap'. hunting is the engine actually revving up/down noticeably. its uncommon for a properly tuned gas engine to hunt (unless you think top fuel or blown alcohol).