Why does my truck have a huge sputter/misfire in Neutral (?) at like 2800 rpms?
 

If I floor the truck in gear, it pulls great and sounds great. If I floor the truck in neutral, half the time it will sputter/misfire (??) real bad for a second, then it will clear up and floor fine til it hits governor. Sometimes it spits some oil-smoke out too. But the other half the time it does this, there is nothing. So what the heck is going on?

Matt

I honestly am not sure. I would have to hear it myself.

I have never held the truck to the floor out of gear anyway. Why would you be doing this?

I'll try to take a video of it.

I just did it once to hear the exhaust, and ever since hearing it fumble like that, it's become an obsession to hear it and try to figure it out. Like I said, it's only sometimes.

More then likely its a ICP or fuel issue. Doubt its a mechanical issue.

Alright so heres another update.


So recently the truck was ran VERY low on fuel. So low that while I was sitting on an inclined ramp, it was sputtering trying to accelerate up it from a stop. So I parked it at home and filled up a 2gal jug and put 2 gals worth of diesel in.

Since that day, when I've cold-started my truck twice, it POURED out smoke. It looks whitish from the cab, but by time I ran out there it looked bluish. It cleared up after a minute.

Also, now I have a damn oil leak coming from somewhere!! I've never had ANY leaks on this truck, and now all of a sudden my newly sealed driveway is getting trashed.

BTW, this truck is not driven very often at all.. few times a month maybe. I'm working on uploading the video.

---AutoMerged DoublePost---

Heres the actual cold-start (60*f).

It's NEVER cranked that long, and it's never had that horrible stumble on start-up either.\

Part 2: the stumble at 2800rpms

EDIT: Also, when I ran the fuel tank super low, the water in fuel light came on non-stop. I drained that and it hasn't come on since.

If you watch your volts gauge on the first video, your GPR is still active. This tells me your glow plugs are getting tired. The white smoke is just a motor that was cold that didnt have all the glow plugs working.

The other video could be an ICP issue. Could be a fuel issue. Need to do more digging.

Throw a can of diesel clean in the tank and fill it up. Change the fuel filter and drive it a bit.

NEVER park it at low fuel levels, when you do that its a breeding ground for algae to grow in the tank, water to build up and rust to flake off.

I see nothing to be overly concerned about right there. The white smoke was just cold motor, the blue smoke is just incomplete combustion. Drive the truck for a while and I bet 99% of that will go away.

man your a beast.

The thing is, I can almost believe it's GP's because it's been cool lately... 50's... and thats when it started acting funky on start-up. But the thing is, the gp's are all brand new!! The previous owner had them installed, not sure when, but they are newer! And just last winter I didn't have ONE issue with my gp's.

You are right, it's a fuel issue though. I stuck my face in the smoke upon cold-start today, and it was raw fuel... NOT oily smelling like I was thinking.

I generally always run diesel kleen in my tanks, but it's been a minute since I've totally filled them up, so I haven't been adding diesel-kleen. I'll give that a try though.

if you are confident that the glow plugs are good. put a test light on the relay. if that checks out good, check the VC harness. OBS like to short out right at the plug. it could take some trouble shooting.

i think you should drive the truck and clean the engine out might have and injector o-ring problem to.

Thanks for the input brother... I'll look into these things.

I was wondering this too, since the truck hasn't been driven much at ALL lately (past few mos). But when I *do* drive it, I like to open it up a lot to keep it clean and running good.


I also noticed that yesterday if I would romp on the throttle to about 2500 rpms or so, it would puff a good puff of black smoke.. all stock 'cept intake/exhaust.

when you romp on it are you driving or are you parked?

I romp on it every single time I drive it to clean it out and keep it running good

ok. when you romp on it i'm guessing it down shifts. my 96 would do it and it was almost stock. just intake and exhaust. if it's black i wouldn't be to concerned about it.

Oh shoot let me re-write that! When I romp on the truck and it puffs black smoke, it's in neutral! NOT in drive! Sorry I messed that one up

either way, it opens up the injectors and it can't burn all the fuel so it puts out black smoke. it's just unburnt fuel.

My 96 does the exact same thing and even started leeking oil from some were really bad since. like thew hole bottom of my truck is oiled from driving with the leek

89 7.3idi- check this. on the passenger side of the engine oil pan there is a big brass nut where the dipstick tube goes into the pan. those love to loosen up on the OBS. my 94 & 96, and moms 97 would leak there all the time. if that's not it, check your VC bolts. sometimes those get loose and leak a little bit. or the o- rings on your turbo pedistol could be leaking. but VC and pedistol o- rings shouldn't leak the much unless they're shot. i'd say your best bet is the dip stick tube.

Icic so dont worry about it? because I dont remember the truck ever doing this previously, but if you say it's ok I'll stop worrying about it.

Ya thats odd because I've noticed a small oil leak forming on my driveway too... it's very irritating because the truck never leaked anything prior to this.

well it's probably not good wrapping your engine out when you're in nuetral. but i wouldn't worry about it to much. but i'd check you dip stick tube on the pan.

There's nothing wrong with revving in neutral; gotta love a governor ;)

But I appreciate the input and help man :tu:

true. the 7.3 has been known as a high winder. when i decided i hated my 94 it seen 3400 alot. LOL

There's nothing wrong with riding the governor on these (or any diesel for that matter...) thats why they are put there :choochoo:

yeah i just don't like to. i will in certain cases...