I have a Question? does anyone know if there is a spring in the vac motor on the side of my 6.5 turbo diesel. I am wondering why I get No boost reading while I have scanner on truck.it seems to do something. I am wondering why I don't hear the whirling sound anymore. I checked it spins freely and seems to be making Power. i replaced the Boost Map sensor(which is not easily found dealer Only) the voltage never goes below 2.11V. Has anyone Incountered this problem. David

are you sitting still? boost will not build if there is no load. i don't know why.

Hello I am driving down the road while this is happening. With the scan tool attached

WG solenoid still working? I'd ditch the vac pump and put a spring on the WG arm.
Also summit sells a MAP with the resistance in it for 15+ psi without the SES light for less than the dealer's stock MAP.

Volt signal of 2.11v seems high but that amy be an OBDII thing. My OBDI base reading here at 200' above sea= is 1.49v.

TFI, start all over man. Are you saying your getting boost and then it drops, or your never getting boost at all? What year model truck are we talking about here?

It is a 1995 C3500 truck. I setup the scan tool and drive the truck, around and watch the boost Volts they never go below 2.11 Volts. Boost Pressure is 0. and i watch the wastegate go form 89% to 23% is the lowest i have ever seen it go. if i take the boost Pressure map sensor out and Rev the truck I get air blowing out of the hole very hard and fast. I think it is doing something But How much is the real story. I have a Utility bed on the truck and it weights about 8600 Pounds. It Moves along good. I have replaced the Injection pump in the last 2 weeks. Because the Goofy PMD. I plan to Move this off the pump but could not find a nice Heat sink for cheap. 70 buck is a lot for a piece of heat sink. let me Know what you think Thanks David

First, I have a heat sink for you cheaper than you quoted. PM Me if interested.
Second, Sounds like wastegate actuator or soleniod is bad. They are cheap 25.00 or so and that fixed my problem like this.

QM You got a summit part number for that MAP?

NO, It has been a topic on http://gm-diesel.com and several members have bought them ~$50.

TFiKnight -

Idle vacuum at the pump should be ~25", check at pump AND WG solenoid.

Idle vacuum at WG should be ~15", check at WG solenoid AND WG servo.

PCM regulates WG solenoid.

Boost is required for work - idle is.......idle - revving is.....play.

NO, It has been a topic on http://gm-diesel.com (http://gm-diesel.com/) and several members have bought them ~$50.
OK GREAT JUST ASKING THANKS

I get a snap to 5 psi boost when sitting when i just give it some quick revs to 3000 to clean it out from idling for so long.

Check your sig for a brief understanding of why..............

You trying to confuse me again gmctd.... its not hard to do you know... lol

CR - Am I reading that right? Going for 26psi?

Locate QM's post(awhile back) about IAT's at different Boost pressures of 10,15,20psi...

You'll melt the Intake Manifold.

How long do you think you can hold 20-26psi for without Charge-Air cooling?

Once you're Charge-Air cooled, how long do you think you can hold those pressures?

Billman
I just changed the sig today, sure didn't take long for it to get noticed...lol. I do plan to get some cooling of some sort, as to after its installed dunno how long i can keep it at that. I'm not saying sustained at 26, just max, maybe sustain around 18-20. Will have to see what happens...

Reflash .....hi-pops.....WG unsupervised...........all the sanity checks, gone!

I setup the scan tool and drive the truck, around and watch the boost Volts they never go below 2.11 Volts. Boost Pressure is 0. and i watch the wastegate go form 89% to 23%
The drop you noticed in the Wastegate Duty Cycle from 89->23% indicates the the PCM is trying to open the wastegate to drop boost pressure, which means it has to be getting a reading from the MAP sensor. Why your not seeing this on the scanner I don't understand. My guess, is the Wastegate Solenoid needs to be replaced. You must be building boost pressure, or you would have black smoke and low power. Solenoid is probably hung OPEN, full vacuum to the actuator all the time.

CR,
A bigger turbo (a PS garret or Cummins holset) will make 26 psi without as much heat.
I found them as low as $100 used.
I've never held either one up to a 6.5L exhaust manifold but if it doesn't fit cut the flange off the exhaust and machine and weld one on that works.

Unlike most farmers i don't have any machining tools or a welder, would have to hire that stuff out, bolt on would work best for me.

CR,

You have enormous frac pumps and work all around that well gear and don't know a welder and machinst that would help ya for a bottle of "antifreeze"?

http://www.dieselplace.com/forum/images/smilies/joke.gif

Unlike most farmers i don't have any machining tools or a welder, would have to hire that stuff out, bolt on would work best for me.

Most of the guy's i do know are probably 2 hours from me when i'm at home, as i never know when i'm going back to work being self employed and need my truck i can't afford to have it down for a day or two in case the phone rings to go to work. When it rings, i'm off to work. I do not get weekends off, i work 7days/week and push over 300 days/year.

But if the need arises antifreeze is a great bartering tool.

Yeah I hate it when work gets in the way of the fun stuff. http://www.dieselplace.com/forum/images/smilies/censored.gif

The drop you noticed in the Wastegate Duty Cycle from 89->23% indicates the the PCM is trying to open the wastegate to drop boost pressure, which means it has to be getting a reading from the MAP sensor. Why your not seeing this on the scanner I don't understand. My guess, is the Wastegate Solenoid needs to be replaced. You must be building boost pressure, or you would have black smoke and low power. Solenoid is probably hung OPEN, full vacuum to the actuator all the time.

I will Install a Vac Gauge and take the Truck for a Ride It has been rainning for 2 days and don"t like Getting wet when it is 38 Degrees out today looks better. LOL. I will Let you Know I want to Thank you For all the Imput. I was wondering if there is a spring that helps the waste Gate to close? maybe inside the Vac Motor? the vac Pump is New. about 2 yrs ago. I had to replace it because the other was doing nothing. it seems silly to me to put a vac pump on this truck for the turbo alone. what helps the wastegate close? just the exaust? I will look at it again today. Thanks again David

You should check to see if the lines that go from the vacuum pump arent broken. same thing happened to mine, the turbo would work for awhile then die out. I found one of the lines had snapped when I changed the pump

I was wondering if there is a spring that helps the waste Gate to close? maybe inside the Vac Motor? the vac Pump is New. about 2 yrs ago. I had to replace it because the other was doing nothing. it seems silly to me to put a vac pump on this truck for the turbo alone. what helps the wastegate close? just the exaust? I will look at it again today. Thanks again David
No spring there stock but I posted pictures no long back of the spring I had added on my '94 and '96 K3500's. They're good for 15-20 psi steady wot, not that you should push it that far.