Boost pressure............

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

Well I finally got around to installing a boost gauge today after finally getting my Jeep back. I took it out and it seems to me that the boost is coming in really late and doesnt seem to go as high as I thought it would. At WOT I get 12psi and spikes to around 14 when it shifts..................is this normal or should I be getting more.

The gauge is a brand new Autometer GS 0-35psi so I know it isnt wrong.

geordi · **Posted:** Thu Sep 29, 2011 12:12 pm

Where did you install the probe?

That does seem low, is it possible your CRD is in limp mode and you didn't know it? What about your boost hoses / clamps? All solid?

How many miles on the turbo?

Radman · **Posted:** Thu Sep 29, 2011 12:20 pm

Here is what Keith at GDE replied to me when I asked question...:

Peak boost is at 2200rpm and fairly constant to about 3200rpm, then is tapers off a bit as you approach 4000rpm.

Stock peak boost is 19.3 psi
ECO peak boost is 19.6 psi
HOT tune is also 19.6 psi

These are the set points for closed loop control, there typically spikes above these values that will taper back down to the set point as the turbo governor kicks in.

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

I placed the probe in the intake manifold, right before that valve thing. The turbo has maybe 50km on it, I just had it replaced under warranty last week. I dont think it is in limp mode, it still runs fine and everything. I have the MAF unplugged so the CEL light is on, ill go scan it and see if any other codes show up.

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

Checked the codes and had a few but they were all basically related to me placing the key in the on position with a few things unplugged to check gauge opperation inside the Jeep. I erased them all and took it for a drive and it still drives the same and there is no longer a CEL........................

Kgeisler2010 · **Joined:** Sun Sep 04, 2011 9:56 pm **Posts:** 66

Mine was doing the same thing except i had the codes p0229 low boost, and p1250 vacuum resevoir control circuit. After changing out cac hoses it was still the same. It turned out to be the boost solenoid was bad.

papaindigo · **Posted:** Thu Sep 29, 2011 5:03 pm

There is a boost solenoid bypass procedure that you can try, if your boost goes up the solenoid is bad. Email me if you need the procedure with pictures.

warp2diesel · **Posted:** Fri Sep 30, 2011 7:03 am

The intercoler drops the boost pressure by cooling the air down to make it more dense (PV=NRT). The closer the probe is to the turbo with out drilling into the housing, the higher the boost pressure it will be. In the past, GDE published their figures that agree with the Laws of Physics, if you want to hunt and dig to get to them.
Open up the exhaust by replacing the crappy stock muffler, and open up the 2 1/8" choke point behind the CAT. Then your boost should get as high as 20PSI going up a steep hill or hard acceleration.

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

warp2diesel wrote:

The intercoler drops the boost pressure by cooling the air down to make it more dense. The closer the probe is to the turbo with out drilling into the housing, the higher the boost pressure it will be. In the past, GDE published their figures that agree if you want to dig to get them.
Open up the exhaust by replacing the crappy stock muffler, and open up the 2 1/8" choke point behind the CAT. Then your boost should get as high as 20PSI going up a steep hill or hard acceleration.

Yeah exhaust is the next thing I am tackling. I despise the stock muffler, its a friggin exhaust brake, lol.

I can live with where the boost is I just want the most out of the Jeep and if its not up to snuff ill do everything I can to get it there.

CATCRD · **Posted:** Fri Sep 30, 2011 1:10 pm

My CRD with the hot tune shows about 19psi peak continuous boost, and that's at 5000ft elevation, measured in the manifold. I see spikes as high as 23 when flooring it to get a downshift into 1st or 2nd.

DynoPax · **Posted:** Fri Sep 30, 2011 2:21 pm

Is it possible the variable vanes get less efficient over time, like coked up with carbon? If the case, what is the alternative?

warp2diesel · **Posted:** Fri Sep 30, 2011 4:51 pm

DynoPax wrote:

Is it possible the variable vanes get less efficient over time, like coked up with carbon? If the case, what is the alternative?

Some of the TDI owners with high mileage have had to free up and/or un-stick the vanes, but as long as the actuator moves the vanes and the turbo does not have any other problems, I would not mess with it. Use a good synthetic oil that meets the specs and don't settle for some newer EPA regulation lawyer (who even makes the tree hugger bang his/her head against a rock wall) approved oil that is short changing the additives the CRD needs. I consider Rotella T-6 to be the minimal quality oil to save both the engine and the turbo. Some of Mobil's oils are cutting out some of the additives like zinc to keep the EPA Lawyers happy.
I said EF the EPA regs and now use Amsoil.

yrkcrd · **Posted:** Sat Oct 22, 2011 11:45 pm

What are you guys seeing for boost around 1600, 1800, and 2000 RPM's?

Glend · **Posted:** Sun Oct 23, 2011 2:17 am

I would dispute that 19psi peak boost. Based on my experience and the memory recall on my Prosport Boost Electronic Gauge I am getting 23psi peak boost (with GDE Eco Tune, Airflow Snorkel, additional airbox mod, Samco hoses). The boost sensor is tapped into the top of the intake body. The electronic boost gauge has a relatively short hose from the intake body fitting into the pressure sensor and then wires running to the gauge from there. I noticed a slight increase in peak boost when moving from the stock tune to the GDE ECO tune (maybe 2psi at peak).

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

I believe my problem of getting no more than 15psi is related to air in the fuel. I have a brand new turbo, have bypassed the solenoid and still nothing has changed. The Jeep is also alittle laggier than I would like off of the line, again pointing towards air in the fuel. I have bled the system several times but it really doesnt make a difference, I think a lift pump would make a world of difference and plan on doing so in the future.

MrMopar64 · **Posted:** Sun Oct 23, 2011 11:36 am

Are you near sea-level, or somewhere with some mild to moderate altitude? The boost setpoint decreases as elevation increases to prevent overspeeding of the turbocharger rotating assembly.

yrkcrd · **Posted:** Sun Oct 23, 2011 12:33 pm

dieseldak wrote:

I believe my problem of getting no more than 15psi is related to air in the fuel. I have a brand new turbo, have bypassed the solenoid and still nothing has changed. The Jeep is also alittle laggier than I would like off of the line, again pointing towards air in the fuel. I have bled the system several times but it really doesnt make a difference, I think a lift pump would make a world of difference and plan on doing so in the future.

A little off topic but how is the dieseldak doing?

Your in PA too aren't you?

dieseldak · **Joined:** Thu Aug 25, 2011 2:53 pm **Posts:** 32

Im in Windsor, Ontario Canada........how far above sea level that is I have no idea, lol.

The truck is coming along great, just have exhaust and intercooler piping left to do. But winter is coming fast and my snowmobile takes importance over the truck right now. Based on your PA comment though im assuming someone else you know is building one????

EAB · **Joined:** Tue Sep 06, 2011 9:39 pm **Posts:** 141

Windsor Elevation, 190 m (623 ft) (according to wikipedia)

yrkcrd · **Posted:** Sun Oct 23, 2011 10:54 pm

dieseldak wrote:

Im in Windsor, Ontario Canada........how far above sea level that is I have no idea, lol.

The truck is coming along great, just have exhaust and intercooler piping left to do. But winter is coming fast and my snowmobile takes importance over the truck right now. Based on your PA comment though im assuming someone else you know is building one????

Ah yes someone in PA did one w a 6bt swap.

Snowmobiling is awesome. I'm hoping to go more this year.

Boost pressure............

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