Boost related to temp/humidity?

DCsleeper · Oct 19, 2006, 05:20 AM

I am running closed loop boost control and on a cool dry day a value of 350 will hold ~21 psi, then on a warm humid day the same 350 value will only hold around 19-20 psi. Has anyone else experienced this? Does everyone typically have two sets of maps, one for cool days and another for warm?

I noticed this the other day when I was logging on my way into work and then again on the return trip home. No changes were made to the maps in between.

AndyBandy · Oct 19, 2006, 06:18 AM

do you have an MBC? If you do, you shouldn’t see fluctuation in boost levels.

DCsleeper · Oct 20, 2006, 05:41 AM

Andy,

No manual boost controller and no desire to use one. I am looking to utilize the boost map functions of the UTEC using CLB control. I am interested in responses with those familiar with this tuning device.

dubbleugly01 · Oct 20, 2006, 09:25 AM

I don't have personal experience wtih the Utec boost control, but any solenoid/duty cycle type boost control setup should respond about the same. In cooler weather, the charge air is more dense and makes more power, giving you more exhaust energy to drive the turbo. The turbo makes boost easier in cooler weather for this reason, and you'll need to change your duty cycles to compensate.

DCsleeper · Oct 20, 2006, 03:00 PM

What you are saying is true. The thing is that CLB (closed loop boost) control is exactly that closed loop. Basically the UTEC reads the manifold pressure and adjusts the bleed rate on the turbo output to hold the target boost pressure in the manifold. At least that is the theory behind it. In practice I have seen some variation. I have spoken with others more familiar with the system than I and have learned that the possible reason for the deviation is due to the stock BCS. The stock BCS does not react quick enough nor can it accurately control the duty cycle.

I will be changing this out soon since it has been pointed out to be the root cause of many of my current issues. I will update my posts once I replace the stocker with either the GM or Perrin upgrade, and will confirm whether or not the issues were fixed. I bet they will be.

Of course I could just fix it the easy way with a manual boost controller, but then I would have to make several adjustment between maps rather than just one switch.

dubbleugly01 · Oct 20, 2006, 04:18 PM

Quote:

Originally Posted by DCsleeper

What you are saying is true. The thing is that CLB (closed loop boost) control is exactly that closed loop. Basically the UTEC reads the manifold pressure and adjusts the bleed rate on the turbo output to hold the target boost pressure in the manifold. At least that is the theory behind it. In practice I have seen some variation. I have spoken with others more familiar with the system than I and have learned that the possible reason for the deviation is due to the stock BCS. The stock BCS does not react quick enough nor can it accurately control the duty cycle.

I will be changing this out soon since it has been pointed out to be the root cause of many of my current issues. I will update my posts once I replace the stocker with either the GM or Perrin upgrade, and will confirm whether or not the issues were fixed. I bet they will be.

Of course I could just fix it the easy way with a manual boost controller, but then I would have to make several adjustment between maps rather than just one switch.

ahhh, I'm with you now, it's not a simple duty cycle, but actual feedback control.

But don't jump to the manual boost controller to solve your issues too soon. That's what I'm using, and my settings have to change with weather, as well as it won't hold steady boost from peak torque to redline. I gain about 1 to 1.5 #'s as rpm's rise (this is on a 50 trim turbo though).

Please post up your results. If it works for you, I'll probably follow in your footsteps.

DCsleeper · Oct 20, 2006, 06:01 PM

I will, but I am by far not the first to use either. I believe that MalibuJack was the pioneer of the GM and there are a few others that have either or and all have said the results are much better than the stocker.

nirvevo · Oct 21, 2006, 08:23 AM

I also had trouble getting the CLB feature to work right.

From what I've read you are on the right track. I used a MBC to temporarily get around the situation, but now that I have some time to install the EBCS and play with things,

I'm putting in a Perrin EBCS -but the GM is cheaper - I just happened to get a pretty good deal on the Perrin.

I'll be watching your results so keep us posted, it nice to see something other than "I selling my UTEC" posted in this forum again.

DCsleeper · Dec 4, 2006, 11:03 AM

Update:

Well I finally upgraded the boost control solenoid to the GM. The new solenoid did in fact reduce the boost spikes that I was experiencing previously. Now I am only seeing a .5 to 1 psi spike were on the stocker I was seeing 2 to 3 psi. Also, I seem to be able to hold boost to redline better. Currently I am hitting 22-22.5 psi and tapering to ~ 21 at 7500. I think that with a little more tuning I should be capable of holding 22 psi constant with my setup. Overall the GM is much better than the stocker.

Couple things to note that I found out along the way.

1) using the GM you have to use open loop boost control (duty cycle)
2) it is extremely difficult to find a plug and play connector for the stock harness, currently I have a modified Molex plug and pins being used with electrical tape (did not want to cut my stock harness)
3) I used a 10 ohm 1 watt resistor in series to keep the GM from overheating as per MalibuJacks advise

If anyone knows what the correct plug is for the stock connector I would really appreciate it if you would let me know.