I finally got my gauges installed today and went for a test drive and I had it in 5th gear and turning 2250 2300 rpms and the boost gauge said that I had 20psi. That sounds high to me or I may be wrong but I don't know. I haven't done anything to make it boost more or anything like that. Is it possible that I have my gauge in the wrong spot?

sounds wrong.. at 2250.. I am running over 75.. and I still only ever run 8 psi uphill unless I want to get faster.. :D

I was wide open when I was reading the gauge if that makes any difference

Where is it installed?

Mark

on the upper intake near between 2 of the screws on the drivers side

So explain this a bit more.

It is at zero and goes up with acceleration all the way to 20psi and drops when you let off, etc?


What kind of gauge is it? No kink in the line?

on the upper intake near between 2 of the screws on the drivers side
Closer to the center of the intake?
Do you have a pic. I want to make sure it is the same set-up I'm thinking of and you are not getting some sort of mis-reading.

Mark

Do you have an EGR?

So explain this a bit more.

It is at zero and goes up with acceleration all the way to 20psi and drops when you let off, etc?


What kind of gauge is it? No kink in the line?

David,
Not to be a smart a$$(just curious) but I would think a kink would lessen the pressure. Should the boost pressure hod steady until the truck shifts while giving it throttle, and what would it mean if it started to drop a bit while accelerating?

Mark

I don't have a picture or an egr I think its perpendicular to the screws on the drivers side edge I don't have any kinks in the line

That would be normal for a manual transmission, if you've got the wg tied down - the normal failure for that, without a charge-air cooler, would be broke 6.5.

Be more than careful doing that in winter temps -

so your saying that my waste gate is the culprit

Yeah.. being floored would definitely change it up.. but if I floor mine I can get it up to 24-25...

I'm not clear on which truck you're driving... that would be normal for the Dmax, but not the 6.5

Are there any imediate problems I should check just to be sure

Holy cow! She's gonna blow captain.

The only thing about a kink in the line is maybe a buildup of pressure that won't go down between the gauge and the kink. Pressure might build up by slight bursts of high pressure.

Will the turbo-master work on his truck?

Mark

Holy cow! She's gonna blow captain.

The only thing about a kink in the line is maybe a buildup of pressure that won't go down between the gauge and the kink. Pressure might build up by slight bursts of high pressure.
Noted!!!!!:D ;)

Mark

DMax stuff is not even relevant to the 6.5, porterz...................

If your wastegate is sticking, stuck, tied shut, or over-sprung, exhaust back pressure cannot 'blow' the 'gate open, resulting in high Boost levels - 20psi is way high for a new 6.5, and can be sudden death for an old hi-mileage hoss.

Got your pump turned up, any?

FYI - 20psi is 20psi, no matter how many kinks or how many times the turbo spools up - it ain't additive.

I'm not clear on which truck you're driving... that would be normal for the Dmax, but not the 6.5
I would hope he's talking about the 01. If the 93 is pushing 20 psi with whats in his sig, then I want to know what I'm doing wrong?:D

Mark;)

This is the 6.5 forum, guys - leave your Dmax'es out in the parking lot...........

Your truck will never see the Boost levels attainable with a manual trans truck, Mark - Diesels work best under constant loading, which the 4L80E defeats with it's constant shifting.

Higher rpm is in the horspower band, so less Boost is needed because rpm is making the power.

At lower rpm, which is closer to the torque band, the turbine makes more Boost to get the power up.

The constant loading of the manual box keeps Boost up.

My GMC had a T400 and an auxiliary overdrive transmission, which gave 3.00:1 effective final gearing - by holding the T400 in third and the aux in o\d, I could easily make 20psi from 30mph up to any point I backed out of it.

The newly-installed 4L80E doesn't allow 20psi, except as peaks - it likes 12-15psi at the same settings with the 4.10 final.

so Should I be worried about anything or just go with it and drive careful

Thanks for the info. So it's the shifting that lowers the pressure while accelerating on the 4l80e even when it does not seem to shift?

Mark


This is the 6.5 forum, guys - leave your Dmax'es out in the parking lot...........

Your truck will never see the Boost levels attainable with a manual trans truck, Mark - Diesels work best under constant loading, which the 4L80E defeats with it's constant shifting.

Higher rpm is in the horspower band, so less Boost is needed because rpm is making the power.

At lower rpm, which is closer to the torque band, the turbine makes more Boost to get the power up.

The constant loading of the manual box keeps Boost up.

Like I said, if it's the Dmax, no problem. If it's your 93 6.5, assume the position:

put your head between your knees, pucker up, and kiss your crank webbing goodbye.

Aside from the boost, think about the amount of force being applied without a torque converter.

PCM demands less Boost pressure because it can keep the engine in a more suitable power range by shifting the auto trans or unlocking the TCC, based on demand from the APP.

App demand with the NV4500 results in more fuel only.

Your truck can easily make 20psi Boost, if system conditions demand it - not even safe, so PCM is programmed to limit that.

App demand with the NV4500 results in more fuel only.

Your truck can easily make 20psi Boost, if system conditions demand it - not even safe, so PCM is programmed to limit that.

... which means EGT climbs, which means the PCM de-fuels until fuel rate is matched by available boost. Which keeps the EGTs reasonable.

All things being stock, that is...

He's driving a 93...is that not one of the years that has manual boost control......someone must have turned her up a notch if that is the case....

my 93 only hits about 7 psi in 5th with a load of red oak pullin' a hill......

Sorry guys I was referring to my dmax as I never put gauges in either of my 6.5s

I asked that question already...You do know there's a Duramax forum, right?

'93's have oem manual Boost control - but, it's not adjustable.

My 93 stock would only make 4psi before the wastegate would open, I would suspect a stuck waste gate or linkage or perhaps a piece of wire preventing it from opening. You should be able to open the manual wastegate by hand (not real easy but doable) If not try to soak with penetrating oil for awhile then gently try to wigle the shaft with pair of vise grips. the wastegate will open in a clockwise direction and the closed position or boost position is counter clockwise.

My waste gate on my 95 truck stuck for a bit.. wd40 worked it a bit and it worked fine.. before that.. it would stick open or closed.. talk about black smoke.. try flooring that thing and no turbo air.. yikes.. and then talk about a whine when you run the truck with the turbo always spooling!

I don't know hopefully it won't explode on me because it sounds fine and runs fine so I am not complaining but I think maybe the gauge is wrong