Need 2 bar map sensor for Vortec 4.2L

[jrw.1955]

I am running a 2005 Chevy 4.2L inline 6 from a Trailblazer in my 69 Camaro with a turbo. My tuner and I have done all tuning with the factory 2005 ecm, but am to the limit on on the fuel tables. This engine comes from the factory naturally aspirated and I am currently running 8lb of boost on an engine that has not been touched and is running as delivered in the Trailblazer. I need a 2 bar map sensor that will plug into the factory intake manifold and that I can wire into my factory harness to work with the factory ecm. Has anyone out there done any work with this engine, and know a supplier for a 2 bar map sensor that will work in my application ?

All info is much appreciated.

Thanks,
Jeff

[RomansDesigns]

I'm sure we can physically make it fit, the question is.. has anyone done it or tried it? I'm assuming the transmission tables would all have to be rescaled to maintain pressures. It will need larger injectors, the 42's are static now.. Jeff what was the boost and hp and torque?

[GMV6Power]

Have you looked into the MAP sensor from a supercharged Cobalt?
The next concern would be if there are tables in the PCM to re-scale the MAP values.
For example: Default Max MAP
MAP Scaling Factor
MAP Sensor Offset

Sounds like a cool project, you have any picture or a link to another forum regarding the build?

[jrw.1955]

I have a set of 60lb injectors on the way since with the 42lb are maxed out -- at 8lb of boost we made 470hp and 450ftlb at the flywheel. Now just need to know how the 2 bar map sensor will impact the transmission pressure tables vs. the factory 1 bar map sensor. Any help from some of the Sr. Tuners out there ?

[Leafy]

It should either be this one. http://www.bmotorsports.com/shop/pro...oducts_id/1749

or this one
http://www.bmotorsports.com/shop/pro...oducts_id/1582

If you cant scale your map you will need to "fake" a 2 bar tune. In this case you would just multiply all map values in the pcm to get their real life values. So your 105 kpa column would just be 210 kpa. Moving and shifting around all your fuel and spark tables will be the first thing you need to do as you need to take everything between 50 kpa and 100 kap and move that to the area between 25 kpa and 50 kpa and so on and so forth. Hopefully you can just change your map scaling and not have to worry about that.


UGH! Just looked at the pcm, its fricken retarded. I thought the J-body was bad. It looks like you are alpha-n but you have two extra tables which define the relation between throttle position and "load". Your map sensor does nothing for fueling besides idle, AND your coast down is also alpha-n. I HATE GM for doing this with all these pcms.

[RomansDesigns]

Looks like we will just have to try the 60 lb injectors and use the rising rate fuel pressure regulator to keep the afr's in line. We will have to pull timing from the 105 kpa parts of the table and the ecm won't know the difference between 7 lbs and 15 lbs of boost. There in lies the challenge of some of these pcm's!
Mark

[Leafy]

Looks like we will just have to try the 60 lb injectors and use the rising rate fuel pressure regulator to keep the afr's in line. We will have to pull timing from the 105 kpa parts of the table and the ecm won't know the difference between 7 lbs and 15 lbs of boost. There in lies the challenge of some of these pcm's!
Mark

You can still run the 2 bar map, but it will only effect your idle fueling, spark, the engagement point for coast down, and a few other things.You have have to fake a 2 bar tune. Look up how to face a 2.5 bar tune on a j-body pcm and use the same idea.

[scotte]

i have the same engine (4.2l) in a 98 wrangler and ive been thinking about giving it some boost for a bit now
(was thinking eaton m90 with a custom intake @ 6psi not a powerhouse but cheap and reliable power + i have most of the parts to do it)

in a standalone application (engine swap) the easiest way i found would be repinning the pcm connectors and runnning the engine on a 06-07 pcm (maf)
this is the same pcm hardware the hummer h3 used with the inline 5 (turbonetics
made a turbo for it with a tune that i happen to have a copy of

i've compared it to the 06 4.2 file and all the tables they modified are very similar/the same