Cold start tuning for big injectors without glow plugs

[kidturbo]

Need some advice with cold starts / no glow plug setup tuning tips.

Getting these puppies to fire up in a 50-60 deg shop first time is a real pain. With the 200% over sticks, I've finally got them firing up and holding a good idle on first try once they have a little heat in em. But when they're cold, first start of the day, it's a 10x plus crank and smoke marathon. Only way they will start is kick in some throttle soon as they fire off, and after two or three attempts, they will take off. About to break out the ether can...

Yet to have any coolant in em, and no MAF sensors, so only values ECM has go off of is IAT2, ECT, and MAP. So far I've tried bumping {B1127} Cranking Torque Reference up to around 900Nm below 40c range, with little success. But they rattle pretty good on upon firing with that higher.. Also set {B1181} ECT Torque Multiplier to 0.0, which helped out once warm. Brought idle up to 800+ cold, and cut the P1 fuel rate in half. Now they clean up within about 10 seconds of stating warm.

I was going to try adding some timing below 500R next and see how they react. But figured I'd ask around to see what others have found that helps first. We have the main PW cut back and FP is 60Mpa on bottom end to help atomize and cleaned up the idle. But I kinda think they need more fuel when cranking cold.

Suggestions?

 

[Bdsankey]

Any reason not to have glow plugs? Are you concerned that they will fail in the cylinder and break causing catastrophic damage? Maybe add an inline grid heater if you can't get it cleaned up?

 

[Chevy1925]

Add more fuel when cranking (can’t remember if that ecm has that parameter though) and see what happens.

Is rail coming right up when cranking? Is it white smoking once it starts?

 

[NC-smokinlmm]

I too was thinking grid or block heater, they are almost on all marine diesels.

 

[2004LB7]

I would try more fuel pressure. Maybe 80 mpa. What do you have on cranking timing. I thought there was a separate table for crank timing.

 

[kidturbo]

Add more fuel when cranking (can’t remember if that ecm has that parameter though) and see what happens.

Is rail coming right up when cranking? Is it white smoking once it starts?

No cranking fuel table in LMM, just torque and timing. But I can possibly bring it up in another table, or add the second pilot back below X rpm.

FP is making about 30MPa at 140Rpm, then it jumps to or past desired soon as it starts to fire off. Lift pump is on by starter relay and oil pres safety switch. So once it make some oil press, it stays on.

It's got plenty white smoke when first fires off..

 

[kidturbo]

Any reason not to have glow plugs? Are you concerned that they will fail in the cylinder and break causing catastrophic damage? Maybe add an inline grid heater if you can't get it cleaned up?

Yeah basically, They can be added, but it will be spending majority of life in +80F environment. Grid heater would have been good idea....

Sent from a russian troll farm using Tapatalk

 

[2004LB7]

140 cranking RPMs seem just a tad slow

 

[2004LB7]

Does it still have the block heaters?

 

[DPC]

What is the compression ratio? Sounds just like my race truck, ALWAYS have to use glow plugs until truck is warm.

 

[kidturbo]

Does it still have the block heaters?

Nope. Currently no coolant either..

Sent from a russian troll farm using Tapatalk

 

[kidturbo]

What is the compression ratio? Sounds just like my race truck, ALWAYS have to use glow plugs until truck is warm.

16.0cr.

Sent from a russian troll farm using Tapatalk

 

[DAVe3283]

This may seem counterintuitive, but it really helped my motor start nicely in the cold. Pull a TON of cranking fuel. Or reduce desired torque or whatever has the net result of reducing pulse width while cranking. You may be hosing so much fuel in that it's cooling the cylinder a bunch. I ended up reducing cranking fuel from 70mm³ to 40mm³ with my larger injectors, and it starts way better now.

I still have glow plugs, but the principle is the same. And it's free to try, so might as well, IMO.

I'd also look at regulator current tables and see if you can't get it to make more rail quicker. I'll have to pull we of my logs, but 35 MPa and 140 RPM do seem quite low. If you can get cranking RPM up that'll help a ton too. Are these used starters?

 

[Chevy1925]

This may seem counterintuitive, but it really helped my motor start nicely in the cold. Pull a TON of cranking fuel. Or reduce desired torque or whatever has the net result of reducing pulse width while cranking. You may be hosing so much fuel in that it's cooling the cylinder a bunch. I ended up reducing cranking fuel from 70mm³ to 40mm³ with my larger injectors, and it starts way better now.

I still have glow plugs, but the principle is the same. And it's free to try, so might as well, IMO.

I agree as well.

 

[kidturbo]

That sounds reasonable. Removing the ECT multiple did seem to make it happier on cold restarts.

What I observed is it starts fueling with a big PW in that 150-250rpm range, and adjusts downward as RPM and FP increase. About the time FP hits commanded (60) it will fire off but,, FP will overshoot desired, and then it pulls mm3 out to zero for a sec. Then cant recover. By adding a little TP% it doesn't cut the fuel on the overshoot and will start hitting on 3-4 cyl before taking off.

We didn't have much issue with em firing on the dyno, but room temp was better and sticks were on +100s.

Sent from a russian troll farm using Tapatalk

 

[DAVe3283]

We didn't have much issue with em firing on the dyno, but room temp was better and sticks were on +100s.

Something else I remembered I did is cut the PW table way down in the low fuel pressure + high mm³ range. You shouldn't have a big mm³ demand at low rail pressure except during starting, so that may be a way to cheese the PW down without affecting the rest of the tuning.

Especially with the larger sticks, a stock PW of 2000+ μs is absurd, even at a low rail pressure. Most tunes I've seen leave that area of the PW table alone, which doesn't make much sense with larger sticks. Even my +75% sticks needed a bunch pulled out there.

 

[Chevy1925]

Twins with Twins, Anyone?

Something else I remembered I did is cut the PW table way down in the low fuel pressure + high mm³ range. You shouldn't have a big mm³ demand at low rail pressure except during starting, so that may be a way to cheese the PW down without affecting the rest of the tuning.

Especially with the larger sticks, a stock PW of 2000+ μs is absurd, even at a low rail pressure. Most tunes I've seen leave that area of the PW table alone, which doesn't make much sense with larger sticks. Even my +75% sticks needed a bunch pulled out there.

Same here, my truck would crank maybe 1-2 sec longer due to that area wanting to spike to 4000uS till rail came up but even by time rail was around 2500psi to start firing them, I was at 2k uS. I pulled about 1/2 of that out and she fires right off much sooner. It’s about 40* outside in the mornings and I have no glow plugs or grid heater, it will fire right off but I’m on 100% overs. 200% will probably take much more tweaking than what I have done.

Adding more rail pressure didn’t make any change for me. Playing with timing made a little difference but not much. I have not tried pulling timing, that might help some as well. I made so many little tweaks it’s hard to remember them all though and your tables ain’t the same as mine, kidturbo

 

[kidturbo]

Ok thanks guys.

I slashed the PW below 30 MPa, and I now see the direct correlation between cranking torque and our final injection amounts. By raising FP, your lowering PW automatically, but not by same factor as if you lower base mm3, or the requested Nm values.

Cranking Tq / Nm = ECT @ RPM
Tq Based Fuel / mm3 = Nm @ RPM
Main Inj PW / us = mm3 @ FP_C

Lets try a short pulse at high pressure vs dumping the fuel in it...

 

[buick455]

Isn't Mark from Danville tuning it, I'm sure he can dial it in? What are his suggestions?

 

[kidturbo]

Yeah Mark had em running sweet, with 100 overs. Then sent me update based on flow rate of our new sticks to get things fired up. Along with plenty of helpful suggestions that's got em idling smooth. Soon as I get in the water he's going to seat of the pants rest if it.

However this cold weather presents an issue we hadn't anticipated. And I need to fire em up daily to test other crap. But think I'm onto the key.. Gonna load latest config and report back in a few.

Sent from a russian troll farm using Tapatalk