OK, I've read about the boost fooler system used by many on this forum...I got a 10K fixed resistor and put it on the B wire on the MAP sensor, and am getting over 15PSI boost at full throttle. It seems to me that putting a POT on the BARO sensor is pointless with this resistor in place...I'm already at the max rated boost for this turbo. Should I put a smaller resistor in the place of the 10K, and run the POT at the BARO?? QM?? I see you are running 5.6K on MAP.


Thanks

im still kinda confused with the whole boost fooling thing. everybody said to run 10k ohms on the green wire, but then everybody said to run something on the green wire and then something from the green to the orange i think. then everybody started using pot's.


im probably just going to go ahead and use the 10k on the green wire and be done with it. i have read enough posts about doing this from people saying that it did make a difference.

What they were saying to wire to the orange wire is the ground for the POT...the resistance is added into the green wire. It made a very noticeable difference. The boost used to max out at about 11 or 12 psi, and immediately drop off. I added a 10K resistor to the green wire on the MAP, and was going to put a POT in place below the BARO sensor, until I installed the fixed at the map. NOW, I have put a new downpipe on, and am exceeding my guages' boost level (15 PSI) at max boost with only the fixed 10K...It's my understanding that with anything over 15 PSI out of the GM-X series, you are losing the benefit of more boost to the added backpressure in the turbo.


My question is should I place a smaller resistor in the wire at the MAP, and install the POT to fine tune the boost to my liking?? Also, being that I am exceeding the guages' rating, should I get a bigger guage?

a fixed 10k resistor will still allow normal operation of the WG. You should see a spike near 15lbs and ride at 8-12lbs under load. The resistor on the baro fools the PCM into thinking you are in a high altitude location, which I myself am unclear as to whether this does change anything at all. 15lbs of boost is 15lbs of boost whether your in death valley or colorado.

So in all actuality, the POT should be on the MAP...not on the BARO...


I just saw that it's the way you have yours, TEXAS...is there really any reason to change the fixed 10K to a POT?? Where do you adjust yours...

If you were racing on pike's peak would it matter? The higher the elevation the less oxygen per volume. Perhaps the ECM is programmed to allow more boost when at higher elavations to compensate and resisting the baro simulates this.


I'm still unclear on the baro resistor myself but I noticed the WG duty cycle increased with it's addition. I had added fixed resistors 'til WGDC was 99.7%. I switched to the potential from resisters to gain a broader understanding of "fooling"


Orange wires are power wires. black wires are grounds.

What's WGDC...as long as the boost is up, the duty cycle shouldn't matter, right??? Or are you saying that by fooling the BARO, you can sustain a higher boost for longer?? Now, I'm getting confused...all I know is that with a 10K resistor on the MAP, I have higher boost, and rather than falling to 0 as soon as I peak out, it stays there and follows the power curve--high sustained boost untill the load on the engine begins to fall off. Then the boost gradually decreases to it's cruising level.


Without the resistor, the boost would peak out at 12 and immediately drop to 0...now, it exceeds 15, stays there for a few seconds, and gradually drops down to about 11 or 12 until my foot leaves the floor

15 psi at high alt is not the same as 15psi at low alt, because the reading is relative to the ambient pressure which is lower at high alt and higher at lower alt. At sea level the barometric press is 14.7 psi at 1 mile above sea level the barometric press is 12.2. So essentiatlly if your guage showed 15 psi at sea level your engine would feel the effect of 2.5psi more pressure than a guage showing 15psi at 1 mile high. I might not be the best at explaining this, but there are many web sites explaining the relationship between altitude and pressure. Edited by: mattsparacio

WGDC is waste gate duty cycle. It is a ratio of how much exhaust you waste through the gate instead of using to push the turbine. Adding a resistor increases wgdc from 65% at idle to 79%. I run mine at 99.7% wgdc Edited by: quantum mechanic

people get confused when they use pothttp://www.dieselplace.com/forum/smileys/smiley5.gif

Quantum...but what effect does increasing the WGDC have as far as performance go?? If I'm getting over 15 PSI of boost at 65% WGDC, then what benefit of bumping it up to 99%?? Quicker spooling? More Constant boost?? More boost at lower RPM?? I'm obviously missing something, because the way I see it is if I'm getting the boost, and quickly, then there's not much more I can do....or is there??

JBT4,





You have to block off the egr with a shim that's why psi is out of sight with only 10K ohms, wgdc at 79%. EGR is pulling in heat(exhaust) into the intake and it's not good for the heads at that level. Look at how TD did his.

If I disconnect and plug the vacuum to the EGR Valve, that will bypass it for the time being, right?? In time, I'll do it right, but I don't have the time to right now...getting ready to head to the big sandbox.

A threaded bolt or machine screw of just the right size will suffice as a plug in the end of the egr hose.

thanks QM,


Once I disable the EGR system, you are saying that my boost will drop slightly...then I add the POT to the BARO circuit to get it back?? I still dont understand the WGDC...I assume by fooling the MAP, I am increasing the DC, in turn, increasing the boost...

At sea level the barometric press is 14.7 psi at 1 mile above sea level the barometric press is 12.2. So essentiatlly if your guage showed 15 psi at sea level your engine would feel the effect of 2.5psi more pressure than a guage showing 15psi at 1 mile high.


I know the point your trying to make Matt, but the PCM doesn't read boost the way a boost gauge does, MAP and BARO pressures are interpreted as absolute pressure, where a boost gauge reads relative pressure. The PCM will control the Turbo Wastegate to achieve the same absolute pressure in the manifold, in a high altutude location, a gauge will read a higher relative boost level but the ECM will see the same absolute pressure.


WGDC is simply the PCMs electrical command to the WG solenoid to regulate the WG actuator. 100% Duty cycle means the full vacuum available from the vacuum pump is being supplied to the actuator to hold the WG shut, at 50% the solenoid only allows half the vacuum. As long as MAP pressure is less than what the computer wants, the WGDC will be high to hold the wastegate closed further, when the desired pressure is exceeded the DC is lowered to allow the WG to open partially until the desired boost level is achieved. Edited by: Texas Diesel Guy

ok i got the 10k on the green wire. and i got my turbomaster tightened down to 1 1/4".


how far can i tighten this down? can i use the aftermarket pcm spring that comes with the kit? its a lot stiffer spring.

Put on the reflash spring and see what boost you can make and if it throws a code.

ok, i guess ill put the other spring on in the morning and tighten down to 2" or so and see what happens.


http://www.dieselplace.com/forum/smileys/smiley32.gif 300th post!!! http://www.dieselplace.com/forum/smileys/smiley32.gifEdited by: steiner43511

well i got the reflash spring in and tightened down to 2". can tell sop difference. no codes yet, but i havent gone full throttle with it and i probably wont.

Okay, I think I proved my point today...I broke down and cut the wire coming from the center of the BARO...on mine, it's a grey/black wire...and wired in a POT. With the 10K fixed resistor on the map, there was ABSOLUTELY no difference in 0-60 times. I ran a 11.2 and a 11.1, one at one extreme, and one at the other. The 10 K on the MAP woke the truck up from a dead sleep, but the POT added onto the BARO sensor made no difference at all. I checked the POT with a volt meter and got 4.9V all the way down, and 4.18 turned up...no SES lights at either extreme.

Well I finally wired my POT using the ground wire on the third terminal
and my boost shot up to over 15 so I removed the 10K fixed and now I
can vary the boost from normal 7-8 to 16. The problem is that anything
over half sweep of the POT results in SES light and overboost, and a
loss of all boost. At half the sweep I hit 16-17 boost but anything
more cuts all boost, with a SES light.



I'm wondering if I should drop to a 5K POT, so that if anyone else drives my vehicle they won't twist it too far.



I've dialed it back to about 14 lbs boost but the best benefit other
than increased boost is that the boost is not dropping back to 8 like
it was before. It used to bounce to 12 then drop to 9-10, now it goes
to 14-15 and stays there until just before it shifts it drops to about
12.



I think a 5-6K would be just perfect since the 10K only allows me to use 50% of the dial anyway.

JTB4,


I thought you changed that Baro.

Quantum,


No, I didn't change the BARO...I found a vacuum leak in the line going to it, and fixed the code...I will, as soon as I find some extra $$.