I am only getting 5 lbs of boost on full throttle for dead stop. Now what?

Kinda vague,more info please

Is this a new problem or something you just discovered after intalling 3 bar map & gage, or just the MAP, or is all of it new WG sol included too much new stuff to consider at once

You still have Vac WG system,so start troubleshooting for loss of vacum to WG ststem, main vac off the pump and vac out of the wg sol, maybe a stuck WG, scan for IAT may have a problem there with high IAT clipping fuel

Where did u get a 3 Bar MAP and why? Are you now in the state? We need to get together and sort this out. Let me know if you are free wednesday this comming week, OK. We will make you have boost, don't worry, Bagalac and I can make it work;) .

Now, at full throttle do you mean:
(A): foot to the floor and engine screaming
or
(B): engine loaded up and foot as far in it as possible before downshift?

If answer is (A) then that would be about right. If you answered (B) then there is an issue. Could be a leaking vaccume line or faulty map sensor or vaccume solonoid.

You will always make more boost with the engine "loaded up" rather than free revving.

I have had many recent posts, and all ultimately stated I needed to install a boost gauge to go any further.

1. My foot is to the floor engine screaming before upshift

2. 3 bar MAP is the one Brian told me to get for GNX 6 cyl Turbo

3. Still in TX, as Suburban is not trailer pulling ready

Okay maybe a little better, but still I'm still missing something, we now have a gauge to see actual boost levels, also a MAP sensor that has been fooled for 3 BAR constant so PCM isn't cutting back on overboost control and a new waste gate solenoid is that a correct statement?

Did you get a gauge reading before changing anything else, you may have posted this before but ist's hard to keep up with multiple threads of who's truck is doing what so help us out some more please.

I suspect from description of problem we are looking at problem with vac, or WG flapper, or WG actuator can, do vac readings and post them or repost them if taken before, actually since changing things up with other new stuff take readings again to see if they stay the same as before.

Can you accesss a scan tool that gives out engine run data, IAT, codes, fuel rate, rpm etc. which will assist with this troubleshooting.

All I have is vacuum gauge that you stick into a vacuum line, don't have any accessories if they are needed. Not really sure where the lines are located that I need to check.

Check the line going to the wastegate actuator, should be 15 PSI at idle, afair. Also check the tube coming from the vacuum pump, should be 25 PSI afair.

Lessening the vacuum on the WG actuator is for opening the wastegate to reduce boost. WG lever must be pulled thightly up at idle.

Check the wires going to the WG solenoid, they can invisibly break inside and result in low/intermittant/no boost, with and without setting the SES light.

At the wastegate its 17 PSI. Not sure where you access the vacuum pump, but I would imagine it's working properly if I am getting 17 PSI at the WG.

First, suspect every piece of the stock vac system, from the pump to wg actuator every time there's a problem. very failure prone stuff. Leaks in the intake or exhaust crossover gaskets will reduce WOT boost as well usually limiting it to 5-6 psi max where 18-20 is physically possible.

I did notice that one of the 2 factory hose clamps doesn't wont to tighten up, is there a trick?. Are these special type clamps they dont look like the others? Can you get them at autozone/pepboys? Also it looks like some sort of gasket sealer was used around the openings is that supposed to be used there?

Your talking about the two spring loaded clamps right? How tight is the one that won't tighten up? threads stripped?

You can use a regular hose clamp like the 92-93 6.5TDs came with.

And yes there is grey silicone on the hose from the factory, but its more to keep oil from leaking out than air.

Got the clamp tightened. I took it for a run on the highway, and per the boost gauge I am not able to break 5 psi under any condition.


Also, here's a pic of where I installed the gauge.

Can anyone explain, or have pictures of the tube off the vac pump that I need to check with the vac gauge and how to access it properly? Thx

It's a thick black rubber hose that the hard line plugs into. It should come stight up off the vac pump in front of the engine, then plug into the hardline under the crossover.

see pics of pump: http://dieselplace.com/forum/showthread.php?t=39400&page=2

Um, I think that maybe the line is orange. I am not positive, I know it is hidden in the black convoluted covering, but I am pretty sure that the stuff is orange, about 3/16 in diameter.

I'd say the metal outlet on the pump is about 4/16 and the 'runaround tube' on the pump is about 7/16. But I couldn't find my ruler to measure it.

The rubber tube on the outlet is secured with a hose clamp. The hose clamp is of the type with no screw; it holds together by its elastic force.

Are the pumps all the same on different years?

Ok, I am seeing the orange line the runs up next to the block and then over to the WG Solenoid. Now is it this orange line that I disconnect from the piece of rubber-like hose? I dont see what clamps it on, does it just pull out?

Hm, if the orange line is a thin plastic line sticking in the black rubber tube which is on the outlet on the pump, you can pull the plastic line out of the tube.

The rubber tube is closed on one end except for a small bore. The plastic line sticks in the bore; it is thickened on its end so that it won´t come out easily. If you can, hold the end of the rubber tube while you try to pull the plastic line.

Make sure that you later can stick the plastic line back into the tube before you take it out! You _must_ hold the end of the tube to get it back in. Otherwise, the rubber tube will just bend aside when you try and you´ll have quite some fun with it.

Thus, it´s easier to take off the hose clamp and the rubber tube, if you can get at it. If you can, I´d suggest that you get some tube and put it on the outlet of the pump, where the rubber tube was. Secure it with the hose clamp and start the engine. If you get vacuum on your tube then, the pump is probably working and you have a leak somewhere in the plastic line(s). --- Car shops should have vacuum gauges, maybe you can drive there and ask them to measure on your tube, should be about 25 psi of vacuum.

If you don´t get vacuum from the pump, you need to replace it or go for mechanical control.


PS: Ooops, I´m confusing the threads! There´s another one going on about the vacuum pump ... You can start to measure vacuum at the plastic line going to the WG solenoid. Maybe we should draw the layout of the system to show how the tubes run and where to check/measure and put it into the FAQs ...

Thanks Lee, that helped, I am going to check the line tomorrow just for grins, as broke down and ordered a Turbo Master yesterday. I can only hope and pray this will solve this problem.

Speaking of vacuum pumps, what sort of noise do they make when they are about to crater? I wonder if this can be the "whomph whomph" noise I am hearing and maybe causing the vibration I feel.

Turbo Master Installed....I got as much boost as I could possibly want now.

Do I need to remove the vacuum pump? And if so does that mean the pully has to be removed and a new belt installed?

Take the whole pump off and use a belt one size smaller :grd:

Now I am very confused. While driving on the freeway @ 65 mph. Turbo @ about 5 PSI. The SES light comes on and my diagnostic system says its the dang 236 again. How can that be with a turbo master and a 3bar MAP?

very easy if you exceed rpm vs boost vs map curve in stock PCM even with 3 bar map may code which is where reflash or chip comes in.

How much boost you trying to stuff in there, & what is PCM seeing for MAP, also you could be bumping hi IAT, which PCM controls by dumping boost 1st, it can't since you no longer have vac control, PCM doesn't see reduction in boost and codes because it thinks WG is stuck shut, next if it can't control boost it pulls fuel, need to watch real time with a scanner to see what is happnin, maybe back off boost a little if you are running 7+ boost by gage on a hot day or hard pull

On edit you say 5 psi gage, could be faulty MAP sensor gone high, need to see if MAP input to PCM matches what gage says, don't fergit PCM is looking at kPa, need to do your "gazintahs" and convert it rite.

Being from Dallas he knows what gazintahs are; for you yankees and others that don't speak Suthern, translated it means it's higher math than toe and finger countin can handle like multiplaction wher it is that 4 goes into 12, 3 timeses

Thanks, I will make an adjustment tomorrow and see if that will keep the SES light off.

This might seem dumb but did you unhook the electrical wires from the waste gate synoild??

Not dumb and actually better to leave connected to reduce chance of stray trons going back to the PCM from unterminated devices, PCM does not monitor WG position only sends voltage to move it, monitors results of that movement via MAP sensor(changes in boost pressure) only a vac actuator opend or closed, no feed back circuit in the WG solenoid itself