Is the stock sensor set at 2.7 BAR?
I also read this somewhere else too. The implication is that all this stuff about 24-25 lbs not being *read* is WRONG.

Found this at *LNF PERFORMANCE.COM*...won't let me post link for some reason.

The stock MAP and TMAP are good for 2.7 bar, IIRC. 2 BAR is about 29 psi boost at sea level. 1.7 BAR is about 25 psi boost at sea level. That's as much or more boost than even the highly tuned cars are making . I would say that failing MAP sensors (if that is indeed what's happening) are due to a defective production run from Bosch (less likely) or some other, as yet undetermined issue on the car itself (more likely).


Here's another reference to the stock sensor being 2.7BAR

http://www.solsticeforum.com/forum/785899-post26.html

I have someone looking into the tune side of things, I already have more power than the GM tune without the new parts. I want the sensors to get the 3 bar MAP, instead of the 2.7 we have now. I have no overboost issues, that was solved long ago.


OK, looks like we have answer. The stock sensor WILL READ 2.7 bar..24.65 lbs.
According this post, they need the 3bar to push the higher readings out of the *dead band* in order to diagnose a FAILED sensor (always reads high). This is to satisfy emission requirements in the diagnostics. So the stock sensors ARE READING boost levels up to 24.65. Sure, for those running higher....GM 3 bar is required.

http://gmtunersource.com/index.php/b...5-%E2%80%93-qa

GM HPVO: The 3.0 bar map sensor is required because the added boost for the stage kit uses up the diagnostic "dead band" of the production 2.7 bar sensors. Now stay with me here and I’ll explain: Any sensor that is used in controlling the engine must be able to be diagnosed for problems and reported to the drive via the "service Engine Soon" light and reported to the repairing technician via the stored trouble code. With any sensor the top, say for this example, 5%, is reserved to be able to tell if the sensor has "failed high", constantly reading high. If the sensor was not changed and we boost into the dead band we cannot fully diagnose all the sensor's possible failure modes. Therefore the sensors were required to be changed to meet the diagnostic requirements of the emission certification regulations. Hopefully that helps everyone better understand the situation with the sensors

 

good read..

 

interesting read indeed! Good post.

 

That info is not wrong. if that were the case, then gm wouldn't have wasted the resources to developed a 3.0 bar map sensor for their kits. the sensor may be good for 29 psi by itself but other information is stored on the sensor and therefore lowers its threshold of readable pressure. check the gm tune source website about the stage kit sensors.

 

Yeah, this was known by some. That's why when people were popping the stock MAPs, we knew that it was the MAP itself, not the fact that people were pushing too much boost on them or something.

On that note though, sounds like the extra overhead is still needed for legit purposes though.

Ironically, the GMS1 MAPs are cheaper than the stock MAPs.

 

" If the sensor was not changed and we boost into the dead band we cannot fully diagnose all the sensor's possible failure modes. Therefore the sensors were required to be changed to meet the diagnostic requirements of the emission certification regulations "

He doesn't imply that it won't FUNCTION in that upper range..the range was exteneded for DIAGNOSTICS ONLY.
What they're saying is that GM needed to extend the range to comply with emission standards which require diagnostics for dead sensor and a dead sensor constantly reads high. I'm not so sure that the sensor range for functionality is LOWERED by the *dead zone* itself. It's only there to define a *dead sensor* should it constantly read in that range. Even if that range limits the functionality, they said 5% (but that was an *example*..we don't really know)..so you would have 23.4 lbs as the limit for reads. Still plenty high for most tunes except the most aggressive which breach 24lbs (threatens turbo life). I really don't think that's the case though.

 

That information is correct

The stock turbo can go to at the utmost 30psi. 26-27psi is doable 20-24psi is fine if the tune is good.

 

Yeah, and people are having *issues* with them too. Probably install glitches. Looking back, glad I didn't go with GM and went with HTP tune.. I'll never go above the boost I now have (holds 20..spikes 22) so it's stock sensors baby. *Let sleeping dogs lie*.

 

why would you not want the 3.0bar sensors and a hpt? car is beastly then

 

First, those sensors won't do jack unless I want more boost and I don't. Like we have shown on this thread..they will work fine up to 24 lbs.
Second, installation of those sensors is causing *problems* for people with GM1. Don't know if it has to do with mounting or fit, but there are problems. Why *go there* if I don't need to?

 

incorrect, as with any sensor by changing the range, more accurate values can be had

this includes having a tune that can adjust to changing manifold pressures more responsively.

 

incorrect, you cannot gain the benefits of the changed tables the gm stage 1 has that cannot be changed in hpt. Also what JapEatr said.

As for people having issues with sensors....see who installed theirs. All my personal friends, 6 people, did it themselves and have not had an issue.. Those people know how to splice wires though. Not sure why you think theres so many issues...its a GM part they wouldnt sell it if it was meant to break your car.

 

No, very possible that you're spiking more than that. The scanner is limited to 255 KPA or 22.xx psi

Shhh, it's slower

No sir, that is not correct. GMS1 actually does quite a bit more. The sensors themselves do nothing but combining them with the GMS1 tune and then using HPT over that and it's well worth it. GM didn't mess with the DAL table to increase the boost... WG Duty Cycle.. More steady boost that doesn't just plummet off of a cliff. So essentially; mid-range/top end power increase, the ability to run much more boost and have it hold on a bit longer and some other features I can't remember at the moment but I do know we don't have access to them with HPT, yet..

The only installation issues were the people that took them to dealers who can barely recite their ABC's nor tie their shoes.... Splicing into two harnesses, soldering and making sure to follow the directions isn't too hard. Just time consuming when doing it the right way.


+1

+1 again


Not attacking you Ron, hope you don't take it as such.

 

ya not trying to attack, just trying to convince you the positives to buy the sensors

 

That what the forum is for...to get varying opinions and learn.
Thanks for the info.
I have HPT tune no GM1, so I'm going to stay with stock sensors. I have reached to performance levels I'm comfortable with, knowing I'm within the *safe* parameters for this car. For those who which to push into the *upper limits*..I wish them well. No doubt, there are cars here much more powerful or are so destined. The question is..and remains...will they escape the many pitfalls that come with the territory?
Stay *TUNED*!!

 

Yes sir, $100 well worth it

Good to hear man. Now, go buy the sensors!!

 

Double incorrect!... lol

The sensor runs on 5V. If you have a larger range of readings you're fitting in between 0-5V, then the resolution of your readings from the sensor goes down.

Exaggerated Example:
Sensor 1 reads between 0-1psi on a 5V system and Sensor 2 between 0-100psi on a 5V system...

A change of 0.5psi would result in a 2.5V change in Sensor 1, but only a 0.025V change in Sensor 2. The change of 0.5psi would be much easier for the ECU to catch with Sensor 1, and would allow for even more accurate readings and resolution, since the ECU has a sensitivity limit.

Alternative Example:
You once again have Sensor 1 and Sensor 2, with their respective ranges above, and the ECU can only detect changes of 0.1V.

This means that it can read boost pressure increments of 0.02psi on Sensor 1, while it can only read 2psi increments on Sensor 2.




If you're talking boost adjustments at levels above what the stock sensor reads though, I agree. MAPs are more responsive than MAFs.

 

AHHH..very interesting.
I still think that the only reason GM went from 2.7 to 3Bar was to satisfy the EMISSIONS requirement that a *dead sensor* be detected within the added range. I still see no benefit of using a 3BAR sensor if you're 24lbs or less. Does anyone here know if you can flash a GM1 WITHOUT the 3 bars installed? If so....I would like to know how the car would perform.

This bolsters your point:


From LNF Performance forum (won't let me post link)
3 Bar vs 2.7 Bar

--------------------------------------------------------------------------------

Quote:


the maixum volts out and the minimum volts out of the 3 bar is the same as 2.7 bar. The scaling is different as interpreted by the ECM. The analog out put is in volts. as an example (the volltages are changed to protect the inocent): the 2.7 bar had low reference in (ground) and 5 volts in. The out put would be 0 volts for zero absolute pressure and 5 volts for 2.7 Bar absolute pressure or 1.85 volts per bar pressure. The analog signal of the 3 bar sensor would 0 for zero absolute and 5 volts for 3.0 Bar or 1.67 volts per bar pressure. The computer interprets them based on the calibration. Now to get more boost you just can not change sensors because there is a rationality check at key up between 3 sensors. The MAP, TMAP and the baro sensor (which is located inside the ECM). if you change the sensors and the programing is not change the rationality check will fail and set a code and default to no boost.
__________________

 

ronn,

You can't run the GMPP tune on the stock sensors. Different OS in the ECU.

 

You are correct in your examples, however mind you that at 0V it shows an error and at 5 V is used to diagnose the analog input to the ECU

So you are effectively dealing with a transmitter that has been scaled to a larger analog range in order to effectively measure that upper limit LNF owners are capable of reaching

there is a great read on analog scaling of instruments at Rosemount.com, or emerson.com

both names manufactures the instruments i use in my industry

 

Yeah, GMS1 rescales the MAP readings for the new sensors so that 0-5V is properly translated to the correct boost levels. If it didn't rescale them, then the ECU would think 0-5V cooresponded with the boost that the voltages represented with the stock MAPs.

 

There are plenty of people running 24PSI Trifecta tunes on stock sensors with no issue. You don't need the 3 bars, apparently. The only people that will tell you that you NEED them are people that have already spent money on them.

 

maybe you didnt read what he used to tune...HPT, it does require the bar 3 to boost over that.