Timing a 1994 turbo diesel

miked

Registered User
Joined
Dec 9, 2005
Posts
14
Reaction score
11
Location
ontario
Hello All
I bought a 1994 2wd extended cab turbo diesel a little over a month ago. And after having it safetied, I have been driving it for the last couple of weeks to get a feel for how it runs.
This truck came with stock size exhaust and no other modes that I can see.

Today I decided to check the timing on the engine. As I was having more smoke at cold start then I thought it should have and even though it has more power than my naturally aspirated truck had, it just did not seem quite right to me.
I have a Chinese made diesel timing light I picked up from princess auto here in Canada and had never used it before. It seems to be working well. Other than, the advance wheel is touchy to use, but once you get it set it worked well.

My first reading, at 2000 rpm and 0 advance, showed the timing mark 3/4 of the way to the top hole in the bracket.
After a number of adjustments, I ended up at around 4 to 5 degrees advanced, using the centre of the bottom hole as my guide.
This rotated the injection pump about .200 thou. As per my vernier.

I am struggling to move it more, as the injector lines are binding. I loosened the line nuts that I could reach, and that got me to where it is now.

Are there any more tricks to gain the last few degrees needed????
If you see any errors in the way I timed it also let me know.

The différance in drivability even at that setting is very noticeable. Where before if I was a 50 mph if I tried to increase to 60 mph it would always kick down the transmission. It had me cursing the tranny as being the problem. But on my test drive tonight, it would smoothly accelerate from 50 to 60 mph with ease and no downshifting unless I punched it. Tomorrow morning I will see if the cold start smoke will be less also.

Thanks
 

IDIBRONCO

IDIBRONCO
Joined
Feb 5, 2010
Posts
12,827
Reaction score
11,759
Location
edmond, ks
You can remove the line that comes into the back of the pump from the filter and then use a crowfoot to loosen the lower lines that you can't reach otherwise.
 

Black dawg

Registered User
Joined
Jan 9, 2006
Posts
4,018
Reaction score
723
Location
sw mt
You wont gain much if anything if you are at 5 now. I time all turbo motors to between 4 and 6 degrees.
 

miked

Registered User
Joined
Dec 9, 2005
Posts
14
Reaction score
11
Location
ontario
Thanks idi bronco and Black Dawg,
I will have to pick up a set of crowsfoot wrenches for the future.
I was trying to go to 8 Degrees as per the manual but sounds like it is not needed.
 

IDIBRONCO

IDIBRONCO
Joined
Feb 5, 2010
Posts
12,827
Reaction score
11,759
Location
edmond, ks
Engines with a turbo seem to like slower timing for some reason. Of course that's also not chiseled in stone. If you're happy with how it runs right now, I'd say to leave it. You can always mess with it later if you want to.
 

miked

Registered User
Joined
Dec 9, 2005
Posts
14
Reaction score
11
Location
ontario
I will leave it for now. This truck ran noticeable better after I finished timing it. Shows that having the timing checked on an old pump can be worthwhile.
I am interested in the possible reasons turbo motors might like slower timing though.
 

KansasIDI

I hate printers
Supporting Member
Joined
Jan 21, 2023
Posts
1,442
Reaction score
1,229
Location
Wilsey, KS
I can't even make a guess on that part.

My guess is because retarding the timing moves the combustion heat back, putting more heat into the exhaust and less into the piston itself. This is why some say ‘EGTs are just a number’

Moving that heat into the exhaust will spool up the turbo better, more heat moving is more energy moving. And with more exhaust force, the turbo will in turn push more air into the engine, an ingredient for better power.
 

KansasIDI

I hate printers
Supporting Member
Joined
Jan 21, 2023
Posts
1,442
Reaction score
1,229
Location
Wilsey, KS
I'm willing to bet it was something emissions based during cold starts.
That is definitely a factor as to why they might be set back from the factory, but the reason they would run a little better with less timing would pertain to where the heat peaks at…
 
Top