superstreeter

Does anyone know if GM actually makes a real 2 bar map sensor ? or is it just the 2.5 one that everyone has ?

sssalah

Check this out

https://ls1tech.com/forums/forced-in...ap-gen-iv.html

superstreeter

So, I guess they dont make a 2 bar, all I see is part # 12615136, which is a 2.5. the holley efi only has maps for a 2 or 3 bar. and I dont need a 3 bar. half of the 3 bar scale would never get used !

sssalah

Why do you think it's a 2.5 bar sensor? it reads to 210 kpa so thats 2 bar.

superstreeter

where are you reading it ? I can plug it into my engine and run my 2 bar map, and it will go to 210 also...but is your sensor calibrated to your map correctly ?

superstreeter

everywhere you read people are thinking its a 2.5, but I havent done the real testing to show me otherwise. why would everyone else think it was a 2.5 if it wasnt ?

superstreeter

and a 2.5 cant run effectively on a 2 or 3 bar map without being recalibrated.

Ferocity02

iTrader: (60)

What do you mean a real 2 bar MAP sensor? I use a Cobalt 2 bar sensor.

superstreeter

OK I might have some clarification here. I talked to a turner at a shop not far from here. he tells me that a 12615136 map sensor is indeed a 2 bar sensor ! from a cobalt, he also says that GM also makes a 2.5 bar # 12614973. one thing he says make me wonder a bit ! he says that cobalts have 2 sensors, one will overide the other!

So, Im going to Dyno and log some runs tonite and see if what I have is a 2 bar. Mike the tuner may be right !

(Ive been doing a bunch of reading online, and most call this 12615136 sensor a 2.5 bar )

Slowhawk

iTrader: (12)

A lot of people call the Cobalt a 2.5bar sensor. Doesn't read 2.5bar for me.

stevieturbo

Surely you can calibrate any map sensor into the holley ? After that point everything else becomes irrelevant.

I would be very surprised if the system was so restrictive that you were forced to use 2 particular map sensors.

Mike@Diablosport

iTrader: (2)

Yeah, you'd think the MAP slope and offset were editable.

OP, can't you confirm the MAP is correct by checking Baro at key on?

stevieturbo

Just looked, you can just select custom x bar sensor and fill in the linearisation manually.

In short, you can use whatever sensor you want.

Although it is silly the way when you change the MAP sensor, it automatically changes the load sites on the main tables.
IMO that is actually a stupid and dangerous thing for it to do automatically.

allout06

iTrader: (11)

speaking of a map sensor. My friend just had his 99 Camaro SS tuned with a D1 procharger, 12psi, made 644rwhp. He bought the kit off me, and i ran that same 12615136 map sensor and i gave it to him with the kit. He went to the same guy who tuned my car with the D1, Hes pretty well known, Mike Norris @ Norris Motorsports, and he didnt even use that map sensor i gave my buddy. He tuned it with the stock sensor. How? I thought you HAVE to have a Map sensor that can read the boost pressure. Am i missing something?

superstreeter

I was running a 2.5 sensor on a 3 bar map, the big problem was the fuel map. it ran so lean after 5000 rpm the it actually shut the car down, the map showed spikes from 8 - 25 in the AFR,

so I could recalibrate the whole thing....but Id rather not.

I shud just buy the 2 bar holley sensor, but Im dynoing tonite, and It takes a week to get a sensor.

stevieturbo

A bad map has nothing to do with the sensor used.

Calibrating the map sensor is a 5 minute task. If you already have the voltage scaling for that sensor, it is a 2 minute task simply filling in the values on the ecu software.

Although as said, the way the Holley automatically changes the MAP values on the load tables is incredibly stupid and dangerous as this will affect tuning.
These should be left alone for a manual change if required so that tuning is not affected after a sensor change.

vwdave

iTrader: (3)

He probably just tuned it rich in the WOT cells.

superstreeter

Ok we dyno'd lastnite, the car ran like **** for a couple passes (it kept breaking up, due to I think bad fuel map) so we made about 12 passes, only getting about 9.5 # of boost and peaking out in HP and Torque around 5200 - 5300. it seems the more we ran the cleaner the map was looking. we didnt do a voltage check on the sensor, cause I believed it was a 2 bar sensor, and its a pain to get out ! with the 9.5 # boost we were 2/3s the way up on the 210 scale. so Im not sure if thats right or not.
Either way,we picked up about 60 hp from start to finish, and Im sure this stock little LS will get me in the 9s with an unknown mph.
One issue I still have with this Holley system is the rev limiter. Ive never ran a limiter on a boosted car before. Just my msd on the BBC, and it worked flawlessly ! but anyway this holley limiter sure breaks up the rpm badly when the boost starts coming on ! and does a real number on the AFR, we did a couple on pulls on the transbreak to 4000. We were getting boost within 1.5 secs. and the Afr was just going crazy !
Im not sure if this is how all rev limiters work with boosted cars, but I sure dont like the Holley version !

vwdave

iTrader: (3)

Of course the AFR goes crazy, youre basically inducing a controlled misfire to keep the engine RPM down. Pull a plug wire off and see how it reacts.

superstreeter

So, what your saying is, that it doesnt matter which rev limiter you use,,,Its always going to be erratic ?. wow! ..how do these guys get out of the hole with a decent 60' ?

I tried leaving at 4000 (on the limiter). I got a 1.51 - 60'

then , on the convertor (no rev limiter) 1.44 - 60'

thats a huge difference !!!