Idle smoke?

[wolf_walker]

Getting my truck back on the road, put in a pretty good running motor from an 86 Jetta
with new reman injectors.  It runs well enough, smooth starts though it hasn't been cold here really
yet.  Idle is steady and all, cold start handle seems to have little effect cold or hot.
I've played with the pump timing from .90 to 1mm and while it's I think quieter at .90,
there is what I consider unburned fuel smoke kinda wafting out at idle and steady no-load rpm.
White-ish, rich diesel smelling.  I haven't had one of these running in a few years but I don't seem to remember
that being normal.  Why would have I unburned fuel at idle, and more of it the less pump
timing I give it?  This pump sat up a long time but it isn't leaking (yet) and seems to work alright.
My limited test driving feels alright far as I remember.
Thoughts?

[maxfax]

How old is the fuel??  Has it been sitting around a while???  Maybe some diesel purge and an Italian tune-up..  Mine will get to doing that from time to time..  A good cleaning and beating usually straightens it up...

[wolf_walker]

drained the tank at the line in back, put in 5 fresh gallons, might be.

I just bumped it back to 1mm from .95 and I swear there is less smoke.
Course I have a shop light laying at teh rear of the truck on the floor to
be able to see it, but it's there.

It don't sound any different to me really.  How much is too much?
It's a little marbly at idle, but they always were far as I remember.

[maxfax]

They are a tad rattly at idle..    1mm is probably about as far as you wanna go with a NA engine..  Your fuel *should* be good (although anymore what comes outta the pump is a gamble too).. If it's starting and running okay I would guess that the filter is fine, and you have no air leaks, never hurts to check forair leaks though...

If that's all the more smoke you are getting at idle it's probably fine.. Even on the best days I've noticed ever so slight wofts form time to time..   Give it the italian tune-up and see how she does...

[Baron VonZeppelin]

You probably wouldn't even see it outside in the daytime.
The 81 i'm working with does about the same thing as you describe.

But its inj timing is still lower than spec right now.
It improved the more i advanced it - until went as far as it would travel. It must be a tooth out somewhere.

Putting off the whole routine and pulling off of valve cover until after it gets its first good engine bath.... soon now.

My 89 NA is timed a weebit over 1.0 (think 1.02) and has done just fine past 18 months. But 1.05 would be pushing on the ceiling probably. Give it what it wants up to that though.

Good to hear its gaining ground again. :thumbup:

[Baron VonZeppelin]

And these days you need to keep a fuel lubricant in the tank too.
If you really really care about it.
Max runs more fuel ubricant than most of us put together. lol

[MizpahPAH]

Ok so I have to ask?

Italian tune up?

When I was first starting out working on cars a little old lady brought her 60's mopar in and said it was running rough

My boss pulled it around back sent me in for a cup of water.

He rev'ed the engine and poured the water in without stalling it then took it out and beat the piss out of it.

and called it an Italian tune up? Said thats how his uncle used to clean the grill after making philly cheese steaks all day.

[maxfax]

then took it out and beat the piss out of it.

Right there!!   Less the water....  I've heard of the water thing, but I wouldn't do it with a diesel....

[wolf_walker]

cool, I'll leave it be till I get it on the road and observe some more.

How do you know when you have the pump advanced too far?
It starts fine and runs smooth, holding any steady rpm over idle
the rettley-ness is gone.  It sounds pretty normal to me overall, maybe
a little more quiet at idle with the timing back some.

Back when I drove these critters regularly I never messed with
the pump timing much other than to set it to whatever the book
listed.  Always wanted to muck around with it some.

[Baron VonZeppelin]

. ...How do you know when you have the pump advanced too far?

Probably not the living breathing answer you're looking for -

but have read many times that 1.00 - 1.05 is the ceiling on basically stock NA with stock injectors.

[wolf_walker]

Still got the little idle smoke, it's also there holding a steady unloaded rpm, just sorta wafts out, smells like unburned fuel.  Pump is back at 1mm, still there.  Starts instantly and smoothly in the low 30's over the weekend, seems to run well.  Pump is old but not leaking, injectors are rebuilds.  Peculiar, eh?

[jtanguay]

i have a theory on the smoke situation... cold coolant being pumped through the engine actually cools the swirl chamber, and you don't get a proper burn. other things like outside temp and moisture level also affect smoke.

its situations like these in which i like to ponder for solutions... a wacky idea would be to remove the WP impellar and pulley, and have a 3 phase a/c motor (super efficient & long lasting) running a coolant pump elsewhere. it could be temperature controlled to really smooth out the engine when cold. it would also last about 10 times longer due to the lack of belt tension on the bushing... if i had it my way, i'd have a large alternator powering all the accessories electrically. and maybe an electric thermostat too??? hmmm

i'd say just live with the smoke. use the cold start to increase the idle timing to reduce it as much as you can, and thats about all you can do, other than plugging the car in for a few hours...

[maxfax]

A PMA would handle that nicely...   

[jtanguay]

A PMA would handle that nicely...   

yea  imagine 100% of the mechanical energy being transmitted electically back into mechanical energy... ahh thank you Tesla!!!

[wolf_walker]

I'm likely being over-concerned.  Or it's this tired pump that's been sitting for three years.  I'll find out in another week or so when I finally get i ton the road.  It's amazing how much work it is to replace, um, everything.  But it's cheap.