blue smoke at warm/cold idle

[magnethead494]

Just picked up a new to us 2001 Dmax 3500. Has a banks wastegate and no telling what else. May be chipped for all we know???

Exhaust has blue smoke at idle regardless of temps. No white smoke or black smoke, and clears up just off idle. Has good power, boost gauge goes to 20psi and egt gauge (goes to pass side manifold) stays under 800, idle around 250. Injectors were changed at 40,000 and 90,000 and it has 126,000 now. Water pump was changed with injectors at 90,000.

What should I be looking for?

 

[magnethead494]

Also, even on a 20 minute trip in traffic, the temps never get above est 180 or so on the gauge. I know the engine was designed with a 210 rear and 180 front. I'm wondering if the rear was deleted and if the front is a 160 or 180.

I have an ultragauge in the dakota, i just need to plug it in and see the water temp and see if gauge is correct.

 

[Kappa9012]

sounds like the thermostat could be stuck depending on how warm the truck actually gets, I would expect in texas the truck would be warm in 20 minutes even this time of year.

The blue smoke is a sign of poor combustion, it could be a variety of things. is it idling smooth, start ok? I'd probably start with something simple, make sure the fuel filter is new, then move to looking at the injectors. What do the balance rates look like at idle, and then in gear with your foot on the brake.

 

[magnethead494]

it starts, idles, and runs fine.

What's the easiest wat to check balance rates? Not sure if my ultragage can show those or not. I know on gas engines it lets me view short and long term fuel trims. Same thing, but per cylinder? This is our first diesel so alot of things are foreign.

 

[TheBac]

Temps sound about right for an LB7. They are very coldblooded and take a while to get up to temp in cooler ambient temps. Mine up here in MI rarely gets up to full operating temp in the fall/winter unless on a long drive, even with the winter front on.

Just curious, but the second set of injectors...were they stock remans or could the original owner have installed larger % tips?

 

[magnethead494]

Temps sound about right for an LB7. They are very coldblooded and take a while to get up to temp in cooler ambient temps. Mine up here in MI rarely gets up to full operating temp in the fall/winter unless on a long drive, even with the winter front on.

Just curious, but the second set of injectors...were they stock remans or could the original owner have installed larger % tips?

The truck was owned by a dealer employee's parents as a ranch truck, and all service was at said dealer, so no telling. It could be chipped for all I know, I wouldn't know where to look. Could have been traded in with a super chips/ect tune for all I know.

 

[THEFERMANATOR]

Also, even on a 20 minute trip in traffic, the temps never get above est 180 or so on the gauge. I know the engine was designed with a 210 rear and 180 front. I'm wondering if the rear was deleted and if the front is a 160 or 180.

I have an ultragauge in the dakota, i just need to plug it in and see the water temp and see if gauge is correct.

It's a 180 rear stat and 185 front stat. Blue smoke at idle sounds like bad nozzles to me. If it has a tune or pressure box it could be a low injection pressure problem as well.

 

[magnethead494]

What is a pressure box and where would I look for it at?

What boost/EGT readings are normal? The EGT probe is in the pass side exhaust manifold.
What does the banks wastegate do and where would I find it on the motor?

 

[magnethead494]

The blue smoke is a sign of poor combustion, it could be a variety of things. is it idling smooth, start ok? I'd probably start with something simple, make sure the fuel filter is new, then move to looking at the injectors. What do the balance rates look like at idle, and then in gear with your foot on the brake.

Just curious, but the second set of injectors...were they stock remans or could the original owner have installed larger % tips?

Blue smoke at idle sounds like bad nozzles to me. If it has a tune or pressure box it could be a low injection pressure problem as well.

What is the easiest way to check balance rates?

where would I find a pressure box if it had one?

When you say tips/nozzles, from my reading, they are separate from the injectors themselves?

 

[Muff]

Balance rates- grab somebodys edge cts insight, or the dealer can check them (dunno what they charge for something that simple).

Nozzles are on the end of the body of the injector, where the fuel sprays out of.

The pressure box is foreign to me.

 

[THEFERMANATOR]

A pressure box is one of the plug in boxes that fools the ECM into giving more rail pressure. basically it goes inline with the rail pressure sensor and manipulates the sensors output. So if the ECM thinks it's sending 160 MPA of pressure, a pressure box will send the 160 signal when the sensor is reading 180 or something like that. Pressure boxes can fail and do the reverse, and if rail pressure drops much below 35MPA on a LB7 without a cat, it will smoke(CALI emissions trucks ran 30 MPA, but if you do it without a cat you can get smoke at idle).

 

[magnethead494]

I don't know if ours has a cat or not. I will look on the fuel rail and see if I see anything astray.

26,000 PSI fuel rail.......I can't even begin to fathom that amount. The MFI on our race motor is only 150 PSI spike/100PSI average.

What boost/EGT readings are normal? The EGT probe is in the pass side exhaust manifold.
What does the banks wastegate do and where would I find it on the motor?

 

[magnethead494]

found the big head wastegate, Banks # 24323. What does it do that the stock doesn't?

there is no cat. It's straight pipe from the turbo to the muffler.

I couldn't find the fuel rail pressure sensor or any astray 'pressure boxes', but I did not remove the plastic engine cover, either.

 

[Muff]

Banks waste gate = Moarrr boost pretty much

 

[magnethead494]

Banks waste gate = Moarrr boost pretty much

what boost and EGT levels are safe? The EGT probe is in the passenger side manifold between #'s 6 and 8.

Highest we've seen boost was 25psi and EGT's around 850.

 

[Muff]

what boost and EGT levels are safe? The EGT probe is in the passenger side manifold between #'s 6 and 8.

Highest we've seen boost was 25psi and EGT's around 850.

30-32 is as high as you wanna be on a stock charger "safely"

You wanna try and stay under 1200 egts towing.

 

[magnethead494]

30-32 is as high as you wanna be on a stock charger "safely"

You wanna try and stay under 1200 egts towing.

those numbers were around town driving. We won't know towing numbers for a bit.

Where would I find the fuel pressure sensor and any associated pressure boxes at?

 

[magnethead494]

A pressure box is one of the plug in boxes that fools the ECM into giving more rail pressure. basically it goes inline with the rail pressure sensor and manipulates the sensors output. So if the ECM thinks it's sending 160 MPA of pressure, a pressure box will send the 160 signal when the sensor is reading 180 or something like that.

Ok, i'm familiar with the principle. Normally on the TPS on a gasser.

Pressure boxes can fail and do the reverse, and if rail pressure drops much below 35MPA on a LB7 without a cat, it will smoke(CALI emissions trucks ran 30 MPA, but if you do it without a cat you can get smoke at idle).

It's straight pipe, no cat. So I need to find the fuel pressure sensor, and find out if it had the pressure box.

If it was chipped, where would I find it? One of our friends said it just wired in somewhere on his cummins. If it's tuned through the computer, then I know we're SOL and stuck with what we've got, seeing as there's no tuner laying around or a manual for one.

Would blue smoke also indicate being lean? I would presume black would be rich (unburnt fuel) and blue would be lean (poor combustion/too much heat)?

 

[magnethead494]

30-32 is as high as you wanna be on a stock charger "safely"

You wanna try and stay under 1200 egts towing.

Would lengthening or shortening the rod put closer to the safe zone? Could this be related to the smoke at idle, or is the wastegate passive at idle?

 

[TheBac]

Just buy a boost valve (PPE, Kennedy) and leave it alone. Cheap and easy.