01 cutting out when coasting

[RiVerBum01]

I'm going to try to explain the best I can. When and only when I am coasting in gear my truck sounds like it cuts in an out very quickly. Kinds like its skipping combustion. It doesn't do this all the time, it's random, and doesn't do this for long periods of time(just a few seconds). This has never caused any problems and everything functions as it should. I'm just courious as to why this happens. Thanks in advance!

 

[ghohouston]

Cps, idm, tps could all be giving issues. Any codes?

 

[GreenMachine]

My past 2000 did it with 236k on it. It was usually getting off the highway, coasting onto a off ramp. It would sound as if it were misfiring/skipping but as soon as you hit the brake or throttle it would straighten right out.

My 96 PSD dump does the same and it only has 100k on it. I've never even attempted to figure out why.

 

[RiVerBum01]

Mine only has 115k but sounds as if we have the same problem. I'll have the codes read later in today an see what comes up.

 

[Rideracelivemx7]

has it ever hiccupped while on the throttle? usually light throttle

 

[RiVerBum01]

has it ever hiccupped while on the throttle? usually light throttle

Never had that happen, she has always ran perfect.

 

[GreenMachine]

I even replaced the IDM in my 2000 for other reasons and it still did it.

 

[RiVerBum01]

Only code that I got was an over boost code LOL oh well I guess

 

[Powerstroke Man 6.4]

Only code that I got was an over boost code LOL oh well I guess

I throwing the out there but doesn't the PCM command the injectors to turn on and off when coasting to slow the truck down? If I know the sound you hearing when coasting My truck usually does it when I am coasting down a hill when I let the throttle out.

 

[backwoodsboy]

Edit: Treed


Every 7.3 I've ever driven has done the same thing.
Its due to the transmission driving the engine, so to speak. Throttle position sensor is at 0%, and rpm's are being maintained by the vehicles momentum. As a result the pcm skips injection events, or stops injecting all together. No injection = no combustion, just the pistons moving up and down compressing air.
Similar to if you've ever heard a truck with large injectors (400/400) trying to idle when the tuning is a little off. Fuel from one cylinder creates enough angular velocity that the injection event in the next cylinder(s) are skipped until angular velocity drops below the desired level at which point injection resumes....and so on and so forth.

 

[mustube]

Yeah. If I get a big enough hill my injectors will cut out for 20 seconds while I coast down the hill. This is normal. It should only happen with the torque converter locked. But it sounds like what your truck is doing is normal.

 

[RiVerBum01]

I throwing the out there but doesn't the PCM command the injectors to turn on and off when coasting to slow the truck down?

Im not sure. But It doesn't slow it down much of any at all. It's done this since I bought the truck with around 95k. This is my first psd just trying to read up and learn as much as I can. Posting questions when I can't find answers else where.

 

[RiVerBum01]

Awesome! Thanks for the info guys. Liking this place more and more everyday!

 

[ghohouston]

Now that I think of it, I remember my 7.3 did the same thing when I had her, I guess i just got used to it after a while and never thought about it again

 

[Idiesel]

I love the way they sound when they cut out then slowly start firing back up again. Definitely a powerstroke thing

 

[GreenMachine]

Great info guys!

 

[Southmike]

on mild trucks with no reg return I wonder if you are hearing fuel cackle.

 

[alradco]

Sounds like mine too.

 

[mandkole]

mine and my FILs OBS sound similar and Ive never given it a thought.. if you were to drop it in neutral, it would clean right up and go to idle.