Cold start PW tuning

[mandkole]

Theres been more cold start smoke threads again, but Ive wanted to ask the question on what others are seeing with cold start PW tuning. I see between 1.5 and 1.8ms when cold and Ive always had a hazer until it gets a little heat in it.

What parameters drive the PW in a cold start? I still have 1.4ms when hot. Ive often wondered if I have too much that that is a big contributor to the smoking issue.

 

[mandkole]

Wanted to bump this back up--

Yesterday, I started the truck after it had been sitting the shop for a couple weeks and at temps that often went below 30F. The truck started fine, but was a smoker until the oil temp got up to 75-80F.

During the time when the oil was real cold, the idle PW was 2-2.2ms. At that level of PW, thats a lot of fuel for a motor to want thats idling. Although it dropped as the oil warmed up, Ive never recalled the OBS being that high when it was real cold. It gets down to 1.3 at idle out of gear when at operating temp.

Can any guys familiar with tuning detail explain why the PW is so high when its that cold?

 

[IHPowerstroke7.3]

Drove a friends innovative tuned 6.0 a few weeks back, had the truck overnight. Noticed on cold start, below freezing temps, pw was around 2.1 2.2 which I thought was really high as well. Two different trucks, but maybe its normal? As oil/ coolant temps came up it went down to a normal 1.2-1.4 range. Maybe the oil being thick when cold and tuning is adjusted to compensate? As far as smoke on his truck when cold, yes it does have a bit of grey smoke for the first minute or so.

 

[cleatus12r]

Can any guys familiar with tuning detail explain why the PW is so high when its that cold?

How fast does cold, thick oil respond? Nothing would happen inside the injector if the commanded pulse width wasn't increased due to oil viscosity. It's the same reason that the PCM is able to command a calculated start of injection event that seems extremely stupid when dealing with a cold engine (unless some brainiac put a "clamp" on the maximum advance limit ).

 

[mandkole]

thanks -- I thought it was related, but I'd ask the question anyway.

Seems to be a temp vs. PW line as Id never noticed it that high before at slightly higher temps. I didn't know that viscosity really kept changing between, say 50F to 25F, to warrant that much more PW.

 

[cleatus12r]

Also, think of the additional parasitic load on the engine when it's cold.

 

[mandkole]

^^ that is a good point. Load will pull extra PW too. At the end of the day, I think the injectors just get a little crankier when its cold.

Again, thanks--

 

[Tom S]

Also, think of the additional parasitic load on the engine when it's cold.

HPOP does not sound too happy when they are cold for sure. Good to see you posting Cody!

 

[cjfarm111]

Cody! Your alive!