Ok, I installed a boost gauge.
Readings are interesting.
Any under strong acceleration in 1/2/3 gear it never pegs ove 7 or 8 lbs
If I stay in Overdrive and floor pedal at approx 2200rpms (ca. 60mph), the pressure raises up to 14 and 15lbs and stays at that until I let throttle off.
If from OD under strong acceleration (14lbs) truck shifts into 3rd, then pressure drops to 7lbs again.

I have stock vac pump and solenoid.

I am going to install a Turbomaster kit as soon as UPS delivers it here.

Any consideration or difference after upgrade ?
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not sure? i just installed mine a couple of weeks ago and still have not understood it. alot of times the the pressure goes upto 14-15 and under normal acceleration it drops to 5-7? i have not yet figured it out???

Makes it for an interesting entertainment doesn't it ??? That's exactly what I need when driving, I am already loosing attention with cell phone.... :eek:


After I install the Turbomaster I will post difference results.

I am hoping to achieve a more constant pressure during acceleration, even if it's just stock 7lbs.
I think all the different pressures are caused by vacuum switch that opens wastegate under ECM control, that's why it keeps going up and down.

You should check out "boost fooling" and other ways to make more boost whether using the vac pump or the TM. It's the computer that cuts the boost levels. only a chip or a resisted MAP signal will let you do it.

My truck WOULD NOT pull with the Turbo-Master alone. I had to wire in a boost fooler. Listen to the guys on this board. They know their stuff.

That was my plan B....but now looks like it will have to become plan A..


Thanks

Id really add a pyro if I were ya before winding the boost up. Also be aware that anything abouve 15psi for longer than a period of time (30 seconds?) will trip an overboost code and the ECU will jump into a limp mode and cut fuel. Thats were fooling the MAP and BARO comes in, BUT you need to cool the intake air as well.

10 psi sustained 12 peak is max I'd go for without post turbo cooling, will have to use fooling as PCM will request for WG to retard, with a TM & no control of WG PCM will defuel. Really though ANYTHING done that alters boost or fuel delivery should only be done AFTER gauges are installed, more gauges the better IMO, boost & EGT at minimum, if you can afford only 1 go with EGT 1st PCM will take care of boost, don't fool before adding boost gage & EGT both

Nothing in your sig to indicate why PCM is allowing sustained 15psig Boost, Val.

Normal oem operation would be a spike to 12 or so on a coold (that's cool or cold) morning, with immediate pull back to 6-8psig depending on instrument gage accuracy, with PCM holding that level until throttle is released.

Stock PCM conforms\performs to stock oem specs.............

Ok, got TM installed.

Prior to this, I was pulling a 3,000lbs trailer with a 7,000lbs Dodge truck.
I noticed the boost cutout from ECM is mainly in first 3 gears. If I let truck stay in OD and accelerate hard, but not to shift down, I could keep a pressure of 12/13lbs constantly . As soon as truck shifts to 3rd, pressure drops to stock 7 or 8lbs.
It was kinda interesting, but now I am at step 2, Turbomaster installed and set at 8lbs at 2500rpm.
I definitely can see difference in pressure, more constant and different than stock.
Eg. at 65mph 2200rpm with trailer only stock pressure was 2lbs maybe 3lbs on flat interstate.
With TM pressure stays at 4 to 5lbs.

I will try to tweak a little more, and I am getting pyro gauge and a tranny temp, so I will be set for a while.
My main reason for Turbomaster is removing vac pump, which it's the 2nd one 6 months and going downhill.

Thanks again everybody, you've been a great help, I will keep posting further results of my trials.

Aren't the '98 & newer 6.5 trucks rated at more torque than the earlier ones? Maybe the PCM programming was changed to allow more boost to create this higher peak torque rating, and this is what Val is seeing with his guages.

Good question, but the answer is no - PCM controls Boost to ~7psig to maintain Intake Air Temps below 200deg, because of no factory-installed charge-air cooler.

7psig Boost keeps Exhaust Gas Temperatures within safe limits, long as Intake Air Temperatures and Engine Coolant Temperatures are within spec'ed limits.

Requires at least one of several upgrades\modifications to achieve higher Boost levels, some of which are required to prevent PCM from logging DTC, reducing Boost, then reducing fuel to control and reduce over-Boost condition.

He's chipped, or wired, or sprung, or bypassed, and something is preventing over-Boost DTC, which will occur within 15-20secs of sustained over-Boost condition.

I guess one way to find out is to crank spring more to get a higher boost pressure and see if ECM will throw a code.

What is a somehow safe max pressure I can try ?

Remember my truck has almost 200,000 miles and I would like to keep it running as long as I can....:D I would really hate to blow it up now.

Stock, sustained Boost over (iirc)10psi will set DTC within 20 seconds, with Intake Air Temperature of ~230deg.

See if it will do it in 3rd with TCC lockup, from 30mph to ?
50\4rth\lockup?

I do not have the 4L80E, am not familiar with that upshift\downshift operation.

Try to maintain steady Boost for 20 seconds.

OBDI used IAT - OBDII may be time-out, as 20deg ambient would hold IAT lower, longer.

Gmctd, I think we might have found something here. You mentione air at 20deg.

It's been in the single digites here (MInnesota), I don't have snorkel and my intake gets air directly from fender.
It might be the cooler air is allowing ECM for a little more boost, but today it's around 36deg..

I am going to take my skidsteer loader around, I will compress spring to max, and see what happens.
....stay tuned.....:D

Limit it to under 15psi for the test, but do not tow for any period at that level, if you do not have installed EGT gage, preferably also with Boost gage.

You can very quickly cause a siezed piston(s) at 1300deg EGT, pre-turbo.

I think he'll get fuel cutout as soon as it loads up or he has resistor or something in place.

Let's start betting here.....):h

Ok, now I am really puzzled.

Or I have a goofy (new) pressure gauge or my ECM has been modified.

John Deere 7775 Skidloader 6,000lbs + 24ft flatbed trailer 3,000 = 9,000lbs.
Pulled it for 10 miles, pressure varied from 10lbs to 14lbs on a constant pull.
Nasty fact I couldn't even let throttle down since I was uphill and I had to keep going, kept pressure for at least 2 minutes, then let off on level ground (speed approx 45mph).

Empty truck, more throttle pressure peaked at 16lbs and constant 12lbs for as long as I keep pedal down, but I had to let go since I was reaching 75mph on a 55mph busy highway.

Performance 0 to 60mph 13.2 seconds on average of 3 tries.

These are the facts, I will purchase EGT and trans gauge and be add to this later on, but I don't know what to say neither. I just have to remember to turn spring off a little, I was a little nervous when I was 16lbs for a while.

Here's pics of my motor:

http://www.kvesurplus.com/65a.jpg
http://www.kvesurplus.com/65b.jpg

Pics of the boost:

http://www.kvesurplus.com/boost3.jpg
http://www.kvesurplus.com/boost4.jpg
http://www.kvesurplus.com/boost5.jpg
http://www.kvesurplus.com/boost6.jpg

You purchased the truck, new?

No Sir, I bought it last fall at 160,000 miles. Previous owner was a trucking company, looks like they used it to haul flatbeds around, it has a back breaking rear suspension.

Truck was involved in a accident, I bought it, replaced some body parts and still have front frame slightly shorter (never have time to take it to frame shop).

I can guess they did something to ECM but I cannot say what, and how come.

That's where I was heading - and, btw, don't call me sir - I'm just a peon, with a passion.;)

You can pop the PCM from it's little nest, behind the glove box door - oem case will have oem scanner labels, aftermarket re-flash should have additional descriptive tag\name\color, etc.

Stock PCM regulates Boost to ~2 - 5psi cruise, ~7psi max, constant demand.
Spike to 8-10 is where PCM allows turbo to quickly spool-up.

For over-Boost or over-temp condition, stock PCM will first attempt to reduce Boost, via vacuum regulator system, after ~20 seconds.

If Boost does not reduce - stuck WG, wired shut, over-sprung - PCM will then reduce fuel, which will reduce Boost, fer sure.

OBDI systems go limp, require stop engine\restart routine to recover.
OBDII may recover after IAT\Boost drops sufficiently, but power will be reduced during DTC event.

So - even at those cold ambients, good for low IAT, PCM will still reduce Boost control and reduce fuel to correct the problem.

Reflashes usually defeat the function, requiring charge-air cooling, exhaust, and other upgrades.
EGT and Boost gages are an absolute must-have, since engine protection is now in your lap.

Check it out - mebbe you got a 'hidden' upgrade............:ro)

If you can pull a load up a hill for 2 minutes at 14 psi then you're set. OBDII is very noticable when it cuts fuel, like an intense shuttering above 2000 rpm, can't mistake it.
If not a sweet aftermarket reflash. It could be a summit 3bar map for turbo applications ~$50. That would be the same as sodering in the right fixed resister values on the MAP, something we call boost fooling or jacking.