Excessive EGTs and black smoke

[aloharovers]

I have a 98 K2500 w/6.5TD. I have a Heath manual waste gate control and my boost gauge shows I am getting 5-10lbs on hills, with no trailer behind.
I have the largest crossover I could find installed, 3" down pipe, and then a 4" cat convertor and exhaust.

The issue started suddenly. She has always smoked and I have to watch the EGTs when towing. But it's never been an issue commuting to work. Yes I could force it to smoke if I floored it at a light, and would smoke and the egts would climb up to 900. Now even on flat ground if I am heavy on the throttle it puts out tons of smoke (a cloud) and will hit 1200 quickly.

The fact that I still have boost pressure I dont know where to look.

[arveetek]

What is the boost pressure exactly when the smoke and high EGT symptoms occur?

Have you checked the air filter recently? Any restrictions in the intake system?

Casey

[aloharovers]

The smoke will start as soon as I get on the throttle. So if I am driving 55mph on a flat road, and it might be 1lb boost, and not even floor it, but start to give it more throttle the smoke starts, egts will start to climb. Boost might get up to 5lbs. I have to watch how quickly I try and accelerate, it hits 1000* quickly.

Since I dont have the trailer attached, have have to find a steep hill and floor it, and then will see the boost hit 1 amybe 11lbs. But I can't maintain it I have to start letting off the throttle because the egts are getting so high.

I have a K&N filter and I have cleaned it. I have a 'cold' air box that the filter is inside and it draws from the opening in the fender.

I picked up a blue tooth reader and an app on my phone. The air intake temp is 14-180* when this is happening.

Outside temps in the 70s.

I am wondering, never having rebuilt a turbo, is it at all possible that the exhaust is feeding back into the compressor side?

[aloharovers]

So, towing the trailer, on a gentle incline at about 6lbs boost I am at 1000* on the EGT. Engine and Trans gauges are at 180. Intake temp is 150*. If I give it any more throttle the EGT temp rise quickly and the black smoke starts.

From a stop going up hill I can get 10lbs of boost, but have to let off the throttle as the EGT hit 1200.

Going up Monarch Pass, I think it 6.5%, and is over 11,300' I was in second, able to maintain 30mph and the same EGT and boost. Engine temp hit 198, tranny was 201.
Intake air temp is around 200 with the water injection running. If I shut off the H20 intake air shot up to 300 and the EGTs went to 1150.

[Robyn]

Do you still have the cat in the system??

How many miles on the cat ???

This sounds like a plugged up exhaust.


I really don't think there is an issue with the turbo, and to answer your question ... the exhaust can't feed back into the inlet side of the turbo.


Those EGT's are too high.

A restriction in the exhaust will really foul things up


What has been done to the ECM programming ????

[arveetek]

This sounds like a plugged up exhaust.



Would a plugged cat/exhaust cause excessive smoke? That's what has me confused: excessive smoke, high EGT's, but normal boost.....

Casey

[DmaxMaverick]

Would a plugged cat/exhaust cause excessive smoke? That's what has me confused: excessive smoke, high EGT's, but normal boost.....

Casey

Simply, yes. All of the above.

[Robyn]

Gotta start some place.

High exhaust temps certainly result if the outflow is hampered

With a reasonably low load the EGT is being stated at 1000 F :eek:

I would expect 1000 if the rig was hauling a hefty trailer up a 10% grade.

With no codes showing or other symptoms I would drop the cat, stuff in a "Test" pipe and see wassssup.

Mention was made of having a sudden onset of the issue.

I'm still thinking the Cat has issues.

Rig has aftermarket intake filter so no worries there.


I have seen large RODENTS :eek: BUILD A HOME in the inner fender air channel on stock systems and plug off the air flow.


JUST REREAD THE OWNERS EXPLANATION ON THE COLD AIR BOX THAT DRAWS FROM THE INNER FENDER.


****NOTE****

CHECK COMPLETE AIR CHANNEL IN THE FENDER FOR BLOCKAGE BY ??????
LARGE RODENT/S
SQUIRREL/S

THING SUCKED UP THE TOWEL LEFT UNDER THE HOOD USED TO CHECK THE OIL WITH :eek:

Either a blocked intake or plugged outlet.

Gotta be one or the other.

I'm starting to get more into the idea that something is blocking the inner fender air inlet to the air box.

**** *****

OPEN THE AIR BOX AND REMOVE THE FILTER, LEAVE BOX OPEN AND DO A QUICK TEST DRIVE (ON NON DUSTY ROAD) That will test this theory

Very curious on this one.