Boosting 17 pounds at idle - HELP

[Witness]

Hey guys/gals

I've been lurking on this forum for a year now and you guys have helped me a lot with my 2007 speed3. Now I have a problem that I could not find the answer to anywhere.

At idle, my AP is displaying 17 pounds, and if i lightly tap the throt it goes to 22 pounds

Do I have a bad ebcs? is the wastegate stuck closed? what could be causing this?

Mods:
Stock Turbo (previously a GTX3071r)
Wiseco Pistons
Manley H-Beam connecting rods
Autotech high pressure fuel pump internals
ARP cap bolts
ARP main studs
Balance shaft delete kit
Corksport 3.5 BAR MAP sensor
JBR EGR delete kit
COBB front mount intercooler
COBB rear motormount
COBB electronic boost controller
COBB access port V3
COBB blow off valve
Catless downpipe

thanks!

[SaveMelMac]

I would verify the reading with some type of mechanical boost gauge first.

[Vansquish]

I would make sure that the units on the AP are displaying correctly, and if so, I would reflash the tune and see if the same symptoms persist. Logically speaking, you can't be at 17psi of boost at idle.

[Witness]

Originally Posted by SaveMelMac I would verify the reading with some type of mechanical boost gauge first.

The car accelerates faster then it normally would, and at the very beginning of boost, i hit boost or fuel cut immediately

[Witness]

Originally Posted by Vansquish I would make sure that the units on the AP are displaying correctly, and if so, I would reflash the tune and see if the same symptoms persist. Logically speaking, you can't be at 17psi of boost at idle.

The units for sure are PSI, I've tried a retune. Maybe ill try a third retune today and see if it wants to cooperate

[Vansquish]

Why don't you take a datalog at idle, a datalog under acceleration, and post both? That should help us troubleshoot what's going on.

[Vansquish]

@Witness;, OK. I've got a couple of questions about your hard parts.

You wrote that you used to have a GTX3071r and that you've got a CS 3.5 Bar MAP sensor. If you haven't swapped the 3.5Bar sensor out for a stock (2.5Bar) sensor, but you are using a tune designed for a stock turbo vehicle with a stock sensor, your MAP sensor will not read properly. You have to have the appropriate MAP scalars set in ATR for stock sensors (2.5 Bar), or for aftermarket sensors like yours.

So my questions are:

What tune are you running? Please be precise (i.e. don't just say "stage 1").

Are you trying to run a stock turbo tune with a 3.5 Bar map sensor?

[Witness]

Originally Posted by Vansquish @Witness;, OK. I've got a couple of questions about your hard parts. You wrote that you used to have a GTX3071r and that you've got a CS 3.5 Bar MAP sensor. If you haven't swapped the 3.5Bar sensor out for a stock (2.5Bar) sensor, but you are using a tune designed for a stock turbo vehicle with a stock sensor, your MAP sensor will not read properly. You have to have the appropriate MAP scalars set in ATR for stock sensors (2.5 Bar), or for aftermarket sensors like yours. So my questions are: What tune are you running? Please be precise (i.e. don't just say "stage 1"). Are you trying to run a stock turbo tune with a 3.5 Bar map sensor?

I do have a 3.5 bar map sensor, and I'm running the COBB OTS stage 3 93 v250 tune

I attached a log at idle

[Vansquish]

Originally Posted by Witness I do have a 3.5 bar map sensor, and I'm running the COBB OTS stage 3 tune I attached a log at idle

Well, that's your problem.

You cannot use an OTS map with an aftermarket MAP sensor. You have to modify the MAP scalar in order to safely run the 3.5 bar map sensor with the rest of the OTS stage 3 tune. The OTS tunes are only set up to use OEM MAP sensors which are 2.5 bar instead of 3.5 bar.

Using a 3.5 bar map sensor on an OTS tune will result in precisely the behavior you are experiencing. You will have uncontrolled boost, boost cut at inappropriate times, and false boost readings at idle (and everywhere else in the rev range).

You need a custom tune.

[Witness]

Originally Posted by Vansquish Well, that's your problem. You cannot use an OTS map with an aftermarket MAP sensor. You have to modify the MAP scalar in order to safely run the 3.5 bar map sensor with the rest of the OTS stage 3 tune. The OTS tunes are only set up to use OEM MAP sensors which are 2.5 bar instead of 3.5 bar. Using a 3.5 bar map sensor on an OTS tune will result in precisely the behavior you are experiencing. You will have uncontrolled boost, boost cut at inappropriate times, and false boost readings at idle (and everywhere else in the rev range). You need a custom tune.

sweet, that helps me out a lot. Whats weird is that the car was running okay, and yesterday out of nowhere, i started hitting boost cut and looked at the AP and saw the numbers. Could it be that the MAP sensor is not the only reason or this? If it were shouldn't the car have been like this since the day i put the stock turbo back on?

[Vansquish]

@Witness;, I don't know what else to tell you. Unless you were driving it differently before, I can't explain why the behavior would've just appeared seemingly out of the blue. The MAP sensor cannot read properly on the OTS tune, so that would never have changed.

If you have ATR and can modify your maps, you can set the appropriate scalar yourself. The information on what to do is on the site somewhere. If not, you can find it on CS's site.

Edit: I looked, and it appears that the scalars are:

A: 210
B: 0.35
OS: 4.26

[Witness]

Originally Posted by Vansquish @Witness;, I don't know what else to tell you. Unless you were driving it differently before, I can't explain why the behavior would've just appeared seemingly out of the blue. The MAP sensor cannot read properly on the OTS tune, so that would never have changed. If you have ATR and can modify your maps, you can set the appropriate scalar yourself. The information on what to do is on the site somewhere. If not, you can find it on CS's site. Edit: I looked, and it appears that the scalars are: A: 210 B: 0.35 OS: 4.26

So if I install a OEM 2.5 bar MAP sensor and run it on the stage 3 tune, it should be okay?

[ANS]

Originally Posted by Witness So if I install a OEM 2.5 bar MAP sensor and run it on the stage 3 tune, it should be okay?

Yes, it should be ok !

[Jeff23spl]

the changes could be related to colder temp. You were driving wrong beffore but maybe not enought to hit overboost level and now with more air density you reach it and start looking at why this happen...
As explain, ots are for oem map sensor but also for oem turbo and just give average results....you are always better with proper tune to your exact mods and engine wear..

[Witness]

Does anyone know what brand OEM MAP sensor i should get? I see a duralast brand that goes for $200 so i want to make sure its the right one. I see cheaper ones as well but they dont say what pressure they operate at.

[tegxsi]

Stock are all 2.5bar... if it's compatible with OEM then it should be fine.
I think $200 is way too much.

[Witness]

Originally Posted by tegxsi Stock are all 2.5bar... if it's compatible with OEM then it should be fine. I think $200 is way too much.

Do you have a website i can use to order? On the autozone website it shows map sensors that are compatible but operate at 1 bar

[SaveMelMac]

Just go on rock auto and look up your car. All the map sensors listed will be the 2.5 bar stock sensor. Or go to any parts store and ask for a map sensor. Don’t even bring up asking what bar it is they are all going to list the stock 2.5 bar

[SaveMelMac]

Or put the money towards a custom tune and you can keep your current map sensor

[Witness]

for anyone that comes in here with the same problem, it was the MAP sensor. Thanks everyone