Timing retarded

[jerry598]

Am pretty sure my timing is a bit retarded after completing my rebuild. With engine cold and in neutral, I run up the rpms to about 2k and it breaks up just a bit. I also get no black smoke whatsoever under full throttle pulling a 3 horse trailer loaded with one horse or a ton of hay in the bed.

If I turn the pump slightly to the passenger side to advance the timing, how far should I go? 1/8 inch? 1/16 inch? Or what? Would 1/4 inch be too much?

[ronniejoe]

If it's the 95 in your signature and you're still using the DS4 pump, moving the pump alone won't change anything. You need to set the timing electronically through the PCM. You need a bi-directional scan tool to do this.

Moving the pump changes the mechanical window that the pump has to work within to adjust the timing electronically. If you move it just a little, the computer will compensate and injection timing will not change at all until you do a TDC Offset Learn. If you move the pump too far one way or the other, the computer might not be able to achieve the timing that it wants and you will end up with a code.

To get it right, you need to do TDC Offset Learn on a scan tool and see what you can get. The factory spec calls for 0 to -.5 for the TDC Learn value. Lot's of folks here (including me) like to run at -1.94 for improved performance. You may need to move the pump to get to the number that you want, but you must have a scan tool to properly time the pump.

[john8662]

DS4, from the description.

Timing isn't altered on the fly by rotating the pump. You have to have the computer learn the pump's position in order to change the timing.

This requires a scan tool to initiate TDC learn.

If the pump's getting choppy, suggest looking for an airleak, I wouldn't suspect timing right off.

No smoke at full throttle with a load is a good thing, means that the turbo is doing it's joba nd the engine is running efficiently.

[jerry598]

Thanks for the replies, guys. Yes, it is the latest DS4 pump. I do have clear yellow Tygon line on the fuel exit port from the pump. No bubbles visible. One small one does form in the line when the truck is shut off. My guess is that air is not the problem but I'll have the wife run the rpms up and look for any air running through next time she's around. Then I'll get a scan tool next month when the budget allows.

[rameye]

Jerry...

If its stone cold and you give it the juice its not uncommon to get a little subtle break-up on giving it some pedal....my timing is set to -.25 and this happens...maybe for the first minute. My set up is solid. Idle is very smooth.

Any break up after the first minute is not so good..

Your timing may be a little behind still however..

On the 95 DS$ there are 2 seperate processes to get it right correct base timing @ -3.5 and then TDC offset...you need to find somebody with a scanner as mentioned to get you spot on.

Come to CT I'll set it up for you!

[rameye]

PS 1 MM of pump rotation =1 degree of timing...Morepower taught me that trick

However without a scanner ...it means nada.

[jerry598]

Jerry...

If its stone cold and you give it the juice its not uncommon to get a little subtle break-up on giving it some pedal....my timing is set to -.25 and this happens...maybe for the first minute. My set up is solid. Idle is very smooth.

Any break up after the first minute is not so good..

Come to CT I'll set it up for you!

Thanks for the offer to set it up for me! But CT is a little far from Idaho and I really don't ever want to go east of the Mississippi again. That's a different country, isn't it?

I may not be as far off on the timing as I think then. The breakup is very subtle when cold, no breakup when warm. Under full throttle at about 50-75 when empty I seem to notice a slight hesitation occasionally, but its not much. When loaded with the horse trailer or a ton of hay at the same speeds I don't feel any hesitation under full throttle. But, it just slowly and gradually increases in speed and I guess I'm just expecting more power out of it - but of course everything is stock. 1100 miles on it now. Maybe it really won't fly to pieces after all.

[rameye]

Dont mistake a break-up for the computer trying to decide if it wants the torque converter locked up or not....

It happens right around the area you are talking about....it's a little unnerving till you understand whats happening.

Anyway...yeah Idaho is a bit of a truck.....go find a good local guy and have him set the base timing and move the TDC to the -1.50 area...you'll like it...bout as good as it gets.