NicD

iTrader: (7)

For what computer?

If you are using an LS2/3/7 ECM I would just use the ZR1 map sensor because it's very accurate and reads all the way down to 20 kpa so the decel and potential cruise areas aren't muddy. Plus the values literally just plop into the ECM.

For an LS1 computer if you really needed a full 3 bar and the 2.5 bar sensor won't work I would probably use the ZR1 map sensor anyways even though it's scale will be off a little bit since you can't use a negative offset value in the LS1 PCM. I would take the small offset difference with that sensor over the shitty accuracy and bad resolution in the vacuum areas of the OLD school GM 3 bar block looking map sensor. Otherwise if you can get away with 22 psi boost max I would get the 2.5 bar map sensor since the values easily plug into the LS1 PCM, it's very accurate, and it reads down to 20 kpa vacuum.

Mr. Trick

iTrader: (19)

Do 98 LS1 pcm's support 2.5 bar map sensors?

stevieturbo

Why are you having problems with the GM ? Or is it the ecu that has the problem ?

I've been using GM 3 bar sensors on various cars and ecus for over 10 years and never had a problem. Read linear from 10kpa thru to 310kpa.

They are pretty much the industry standard 3 bar sensor and have been for many years.

NicD

iTrader: (7)

Yeah I've used them countless times over the years too but no they don't read down to 10 kpa, and it's only been the industry standard because it's been out for forever and there really isn't another 3 bar sensor out there besides the newer LS9 map sensor.

When I was bench testing loads of map sensors many years ago with a multimeter and pressure tester the typical block style 3 bar map sensor only got down to around 40 kpa at best, same with the "newer" smaller diesel 3.3 bar sensor. I thought that was kind of strange and maybe I was missing something so I went online with the part number and found the OE spec sheet for that sensor. Low and behold it's only rated down to 40 kpa at the bottom with a "typical" accuracy of 8% at the top and bottom of that chart. If I had it on hand I would post it up but it should be easy to find.

NicD

iTrader: (7)

I don't believe so, 2 bar only but I suppose you could scale the tune and make it work.

NicD

iTrader: (7)

Ahh, found a link to the OE data sheet for the old 3 bar map sensor.

http://www.powerandsignal.com/docs/P...s/12223861.pdf

The Alchemist

iTrader: (19)

So how does the 2.5 bar sensor work with setting up a 3-bar OS system in an LS1? I'm in a quandry right now. I am hitting roughly 205kpa at 6900rpm (redline) with my current setup, but I have a smaller pulley to put on, but unfortunately, don't have any more workable space with my current 2-bar OS and map sensor. If I pick up a 2.5 bar sensor, and then upgrade to a 3-bar OS, are the scales going to be off? I'm guessing that with the new pulley, I'll hit roughly 19-20psi.

Thanks.

NicD

iTrader: (7)

You just run the 3 bar OS and set the appropriate map sensor settings for your 2.5 bar sensor. The scale will be accurate, you just won't be able to read past ~255 kpa even though the tables go up to 310 kpa or so.

Tally TransAm

iTrader: (17)

im in the same boat, seeing right at 205-206 kpa. a 2.5 bar would be fine as the turbo wont support more than 22 psi.

on a related note, does anyone know if going from a 2bar SD system to a 3bar SD system requires more HPT credits?

stevieturbo

I just scaled one last week on a GEMS ecu on a Subaru. Using a Mityvac it went down to 10kpa at 0.12volts and 310kpa at 4.6v as read at the ecu.

Internal pullups on some ecu's may be different, so voltages read there may differ slightly. But they absolutely do read way below 40kpa.
Most Subaru's I fit them to and tune with various ecu's will idle at around 30-40kpa, so if they couldnt read below 40kpa they'd be totally useless. On the overun, they pull down to about 20kpa usually.

Ive one on my own car, and on the overun it pulls down to 21kpa and idle around 40kpa.

there is no question that they read lower than 40kpa.

NicD

iTrader: (7)

That's interesting since the one I tested stopped at ~40 kpa and the data sheet from the manufacturer says 40kpa is the floor. It has nothing to do with the ECU since that's not even part of it, it's the sensor itself. Besides it's accuracy is 8% up top and down low, 4% in the middle where as all of the newer ones are around 2% all over and less affected by temperature, etc. I'd much rather run a newer generation sensor with all of it's benefits than something that was originally designed with 80s tech.

stevieturbo

Obviously the ones I'm buying are new, but they are just GM 3 bar sensors. Dont have a part number to hand.

I use what I know works. Unless the sensors you tried were a different part ?

There have definitely been part number changes over the years, although the one on my own car is at least 6 years old.

The Alchemist

iTrader: (19)

Yes, to go from 2-bar to 3-bar is 2 credits, so it's $100 if you don't have any credits left. It's no different than going from a regular tune to a SD OS. Honestly, when I started down this FI path 2.5 years ago, I never thought I'd be above 10psi, much less 15psi. Honestly, do I need to go with more, NO, but I already bought the pulley and belt, so hell, might as well.

Fall Line

iTrader: (5)

2 credits gets you all the custom enhancements for one file in HPT. You don't need to pay again to go from a 2bar to a 3bar.

http://www.hptuners.com/forum/showthread.php?t=38638

The Alchemist

iTrader: (19)

Interesting. I didn't know that. I thought I'd have to pay another 2 credits again to go from 2 bar to 3 bar.

Hmm, it just got $100 cheaper to run the smaller pulley. Guess what I'm doing this winter....

Is anyone else having troubles with HPtuners forum? I can't type anything there. All of the text boxes are greyed out. I can type, but it just doesn't show up. I can quote people, but can't post anything. I'm logged in, and it says I have permissions to do everything, but nothing I type shows up when I reply.

gpr

iTrader: (6)

I purchased the GM ZR1 map sensor... If you want to use it in a Ls1/LS6 manifold it will not work. first off the physical dimensions of the sensor are much different. has that bolt hold down which the stock one on the f bodies do not have. Also the hole require for the ZR1 sensor is much larger.

Also the plug in for the zr1 sensor is different then the factor connector. So even if you modify the intake for the sensor to fit, the connector will not plug into it and will not work.

The Alchemist

iTrader: (19)

Can you post a pic GPR?

Camper

iTrader: (1)

I recommend using the ZR1 3 bar

gpr

iTrader: (6)

I'll get some pics. but earlier in the post someone put the 3 bar map sensor on here, and you can see where the bolt hole is on the sensor. The ls6 intake doesn't have room for it, and you would need to cut it off. That is an easy fix.

The biggest issue is the connector on the ZR1 map is completely different then the ls1 i have on my 2002. If the connector was the same simple modifications could be made to install it, but i can't run it cause I have no idea where i would get a connector to work.

gpr

iTrader: (6)

I'll get some pics. but earlier in the post someone put the 3 bar map sensor on here, and you can see where the bolt hole is on the sensor. The ls6 intake doesn't have room for it, and you would need to cut it off. That is an easy fix.

The biggest issue is the connector on the ZR1 map is completely different then the ls1 i have on my 2002. If the connector was the same simple modifications could be made to install it, but i can't run it cause I have no idea where i would get a connector to work.