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ECM CONTROLLED BOOST, HOW MANY POUNDS DO YOU GET ?

MrMarty51

MrMarty51

Well-Known Member
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Location
Miles City, Montana
The 2000 K3500 Chevrolet with automatic trans. and no. 5 resistor.
When cruising at about 70 mph and on the flats, the boost gauge does not move at all, just hangs on zero.
On the steepest hill, truck empty, at the same speed, the boost gauge will get about 3-1/2 pounds.
is anyone still running the ECM boost control and what boost levels does Your truck run.
 
From the description (and presuming the truck is running normally), it seems that there is something out of whack with the gauge. Maybe the gauge, possibly a clog (or leak) in the line feeding the gauge. If the gauge's sending unit is electronic, it may have died from the heat (and the reason I moved my sending units to over the wheel well).

To answer the question, from what I remember of when the Burb had the vacuum controlled wastegate, at 65 - 70 mph the PSI was in the 5 - 7 range on flat road while empty. Even had 1 - 2 psi on deceleration while the TCC was locked.
 
JayTheCPA said:
From the description (and presuming the truck is running normally), it seems that there is something out of whack with the gauge. Maybe the gauge, possibly a clog (or leak) in the line feeding the gauge. If the gauge's sending unit is electronic, it may have died from the heat (and the reason I moved my sending units to over the wheel well).

To answer the question, from what I remember of when the Burb had the vacuum controlled wastegate, at 65 - 70 mph the PSI was in the 5 - 7 range on flat road while empty. Even had 1 - 2 psi on deceleration while the TCC was locked.
Click to expand...
Guess next step will be to attach the vac pump to the boost gauge and see how closely they match, and see if it does hold vacuum.
 
I was in the zone of 2 -8 psi boost with my stock PCM and vac wastegate until about z week ago. Turbo stopped whistling, guage showed 3psi max under load on a hill. I run an electric vac pump and today found it was running about 80% of the time
Pinching off lines until it built vac and stopped running I found it was the wastegate solenoid thats leaking. Im never getting full vac on my wastegate diaphram. Ill try to get a new one tomorrow and see if its the only issue.
 
Sand said:
I was in the zone of 2 -8 psi boost with my stock PCM and vac wastegate until about z week ago. Turbo stopped whistling, guage showed 3psi max under load on a hill. I run an electric vac pump and today found it was running about 80% of the time
Pinching off lines until it built vac and stopped running I found it was the wastegate solenoid thats leaking. Im never getting full vac on my wastegate diaphram. Ill try to get a new one tomorrow and see if its the only issue.
Click to expand...
I do have the original waste gate solenoid that came on the truck, maybe I will install thst and see if anything changes.
Made up some air fittings to compression fitting and hooked the gauge to the airhose through the pressure regulator.
I need to get a new gauge on the regulator, this one no longer returns to zero so i know it is off.
I have a 1/4 turn valve on the air fitting at the compressor. I turned the valve to closed position and so far the boost gauge is holding pressure.
More to come tomorrow after I get a new gauge on the pressure regulator.
I have tested the waste gate actuator and it does hold vacuum and the actuator works nice and easy, along with the waste gate.
 
New gauge on the air pressure regulator.
The Banks gauge seems to be close, even a pound or two over what the regulated air gauge reads.
Cleaned the terminals at the boost solenoid.
A few more terminals that`ll get a scrubbing, around the IP, then see what it does on the road.
 
Okay, thank You Will. I`ll geter out of the garage and do a test run. if it fails to pass, I`ll install the new solenoid back onto it then give it another run.
I just crawled under and took a peek at the lift pump. It is a Facet pump and had been replaced just prior to Me purchasing the truck.
I`m thinking I will run it through the engine running test just for the peace of mind.
 
Big T said:
Check the boot from turbo to intake for leaks. It capping off suggests you’ve got a leak.
Click to expand...
The boot appears to be in good shape. Ha it off a couple of months ago and it did not appear to be breaking down on the inside.
Might pull it off and take another gander at it. LOL
IMG_3398.jpg
 
Boot is okay. While I had the upper intake off I unclipped the connectors under there and scrubbed the terminals real good.
I did scrub the solenoids connectors, then installed the old Delco boost solenoid.
I did take it for a test drive, wind is a howling out there, driving into the wind on the flats it was bootsing about a 1/2 to 3/4 of a pound, that is more than it was before, tail wind coming back and the boost set right on 0 until I was climbing the big hill before town, it then went about a 1/2 a pound.
Too much wind for any good testing today, looks like it`ll be not much better tomorrow too, I have a nice drive to church in the morning so I will know more about it then.
For now though, I put back on the new solenoid and We shall see how that works out.
 
Driving, regardless of wind, you should see more boost than that. While hard acceleration you should see 8-9 psi.

Any smoke under acceleration?

Is this how it has been since you had it or a new thing and noticed power loss?
 
Will L. said:
Driving, regardless of wind, you should see more boost than that. While hard acceleration you should see 8-9 psi.

Any smoke under acceleration?

Is this how it has been since you had it or a new thing and noticed power loss?
Click to expand...
It just started happening.
I had previously checked the vacuum pump so I was thinking it was okay. I had two vacuum gauges Td into the in and out hoses at the solenoid and it was pulling good vacuum and the solenoid seemed to be properly functioning..
After I just got back from another road test, while the truck was idling, hung the vacuum gauge to it, a little under 5" of vacuum with the engine at idle and the needle was bouncing like crazy.
Just extended the vac hoses and revved to about 2500 RPmz, 7" of vacuum was all She`d pull.
Guess I had better get a vacuum pump a coming.
In the meantime, I`m thinking I`ll reinstall the home made Turbo master.
 
One good thing come out of all of this, every engine control terminal under the hood is cleaned to bright and shiny and has corrosion preventive dabbed on them.
Vacuum pump will be here Tuesday.
 
The cleaning of the terminals really helped.
Now when driving about 70 mph it is showing just under 2 pounds of boost.
When pulling the steepest hill it was showing next to 5 pounds of boost, still too much black smoke out the pipe, in My opinion.
Still not what it should be, when I get the vacuum pump replaced I`m sure that all will change.
 
Stock calibrations should run roughly 1.5 atmospheres, or 7.5 lbs of boost at sea level(boost should increase as altitude increases) max, but late 2000 calibrations can run upwards of 10. Cruising steady should be 1-4 lbs of boost, but most I've seen at 70 run 1.5-3. The vacuum pump must supply at leadt 15" vacuum at idle, but 20"+ is better(my worn out 150k mile pump made 23 inches of vacuum). It's also a good idea to connect a scanner as the boost pressure sensors can fail, read high, and cause low boost without coding.
 
THEFERMANATOR said:
Stock calibrations should run roughly 1.5 atmospheres, or 7.5 lbs of boost at sea level(boost should increase as altitude increases) max, but late 2000 calibrations can run upwards of 10. Cruising steady should be 1-4 lbs of boost, but most I've seen at 70 run 1.5-3. The vacuum pump must supply at leadt 15" vacuum at idle, but 20"+ is better(my worn out 150k mile pump made 23 inches of vacuum). It's also a good idea to connect a scanner as the boost pressure sensors can fail, read high, and cause low boost without coding.
Click to expand...
I`m sure the vacuum pump is original to the truck, truck has 245,000 miles on it.
When I had the vac. gauge hooked to it, the pump was pulling only 5" of vacuum with the engine revved to about 2500 rpmz.
I checked the tubes and hoses as far towards the vac pump as I can see and there is no rub throughs or kinks in any of them.
Might be the connector hose at the pump may have split or broken, I did replace it when I had the front of the engine off when replacing coolant pump and timing cover gaskets due to a prestone leak. That was about February of this year.
When I had the manual waste gate control set up on the turbo, it would kick the SES lamp if it got over about 10 pounds of boost and also under a heavy pull and the boost pressure was real low.
 
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