LetsTurboSomething

So after getting things wrenched back together and getting it running finally, I'm finding the map readings not going over 90kpa even when it pushed up to 8psi. This was not an issue when I parked the truck for the winter. I changed the tune for new injectors and got the changes in needed to get it fired up with the new cam but didn't mess with anything else.

I checked the 5v reference wire on it and it had 5v. I deleted the channel in the scanner then re-polled and added the channel back in to try and get ti reset or something...nothing worked. AF err histogram wont go above 90 kpa. I just chunked a 30% increase to the fuel in the VE table to everything above 100kpa and looking at the dash AF reading it seemed like it took the AF in boost from 14 or 15:1 down to 10:1 so I think the ECM is still seeing the full reading and it may just be the scanner?

Im getting stumped on this one.

If you look at the VE corrected over 100kpa scan, when it hits 90kpa in the 3600rpm area the kpa reading starts going back down as the rpms go up...the kpa starts reading backwards and descends with increased pressure or something when it hits boost.

RonSSNova

iTrader: (3)

Which sensor is it? GM? Aftermarket?
Maybe it's just busted?

LetsTurboSomething

EFIsource LS style 3 bar.

AwesomeAuto

You have to poll the right MAP reading in the table, and then manually go in and change the histo/graph to use that specific one, it will not do it on its own.

Darth_V8r

iTrader: (4)

THis -- you have to use the 3-bar map channel, not the regular map channel

RonSSNova

iTrader: (3)

I believe he has the correct map channel.
His log stated 3 bar

LetsTurboSomething

Ya that was the first thing i went back and checked. It had the correct 3 bar and I deleted the channel then re-polled and then added the 3bar channel back in and double checked the AF/err histogram setup to make sure it was looking at the 3 bar and it was the whole time.

Over on HPtuners forum I was suggested to change some MAP setting in the engine diagnostic tab. Calculated MAP max: set everything that was 15.23psi to 46.4psi. Then set P0121 Err MAP max to 100 and Min to 0.

I'm going to try that today if it dries up some here. I'm not sure what they would make it work now when it wasn't changed before when it worked. But I did change the cam and I had to swap to another stock throttle body because the blade set screw broke. And those settings have to do with TPS.

I have another sensor on the way just in case but it just seemed strange because it was reading **** like 10kpa at idle now too and its a 231/234 cam with .600 lift. I would think i would get no where near that much vac from this cam because i never got more than 25 with the factory lm7 cam.

RonSSNova

iTrader: (3)

Although no specific examples, I remember hearing about failures with the EFI source 3 bar map.

The best go to is the GM LS9 sensor. But it’s not plug and play. And is physically bigger. I recommend it to all my turbo customers.

AwesomeAuto

With the scanner open, do you get a MAP reading when you key-on before starting the engine?
If you do, its not setup to use the 3-bar correctly. The 3 bar setting in HPT will not give a kpa reading until the engine is cranking/running.

LetsTurboSomething

Ya, the MAP will start out reading 0kpa with the key on engine off. Then after a couple cranks or its gets shut off it will read about 80.

What isn't plug and play about it Ron? The way mine are currently mounted in there is with a mount I made to just press straight down on the sensor a little bit because both the plastic bits that clip into the sensor like normal were snapped off. So any sensor with the same size nipple end on it can be mounted on mine and the clamp I use to hold it is basically universal. Is it any more than just the two settings in the tune file to change for it, the max kpa and the kpa per volt? I ordered one for the hell of it since i have another junkyard turbo ls setup to cobble together here soon. So I'll have another EFIsource on and the GM one here by Friday probably.

Darth_V8r

iTrader: (4)

M previous reply I was on my phone and could not see the logs or tune. I see it is already mentioned in an earlier post on the diagnostics tab to bump up the calculated max map to 320 from 105 kpa (i use metric, it's actually easier). I see maf fail high frequency is set to 1500. I recommend setting to zero.

Have you pulled the map sensor to see if there is a bunch of oil in there? I've had that before.

LetsTurboSomething

Sorry, I should have included more info. Same guy over there on HP had me set the MAF to fail at 0 and set the first 3 MAF errors to MIL on the first error instead of the 2nd.

EDIT: miss-read you, I haven't really looked inside the MAP. Ill do that I just checked the connection and voltage from the reference.

I'll post the freshest tune when I get to my tuning laptop. I haven't had the chance to try the change to the calculated max table yet though or the MAF fail changes on account of the rain.

AwesomeAuto

You can set the tune and scanner table up for a stock 1 bar map sensor. Then remove the map sensor from the intake but leave it plugged in.
Then connect the scanner and key-on. You should get a really low reading from the map sensor, like 32 kpa depending on elevation.
Put a short piece of hose on the end of the map sensor and stuff an nozzle it in from an air compressor and give it some positive pressure.
If it goes above 32 kpa, then the map sensor voltage range is working correctly, and your tune/scanner settings are wrong.

LetsTurboSomething

Ill do this too, not sure ill use a compressor because that's a lot of psi for something that stops at 28psi but ya.

AwesomeAuto

Its basically just a simple way to test the voltage of the sensor. Slightly less awkward than trying to apply positive pressure and use a voltmeter on the output at the same time.
You can pull up raw MAP voltage in the scanner table as well. Any reading above what you get when you key-on can be taken as a sign the sensor is working.

LetsTurboSomething

OK I tried the pressure test. Ran 10' of 1/4" hose off of it and into the cab so i could watch the scanner and put pressure to it with a hand held bike tire pump.

Nadda. It read 1.5psi and 1.5v and nether changed a bit with 20psi put to it.

RonSSNova

iTrader: (3)

You have to crank the engine, take a reading. Put some pressure to it, crank the engine take a reading. It won’t work by just turning the scanner on.

Ive done this test many times.

LetsTurboSomething

sitting in the truck doing it now, its not changing any readings. 1.5psi on the map pressure and 0.00v after cranking it once. Applied about 15psi, cranked it while holding that pressure and it doesn't change..

RonSSNova

iTrader: (3)

I’m used to reading the map in kpa, what is that saying?
When does your new one arrive?

LetsTurboSomething

its like 10-15kpa. The new EFIsource one gets here on Friday. The GM one is back ordered about a week out. So 2-3weeks for that one.

It reads up and down between 0 and 90kpa when I test drive it, can the scanner and/or ecu just guess what the MAP is or something? How would it show a shifting MAP through the RPM without some sort of working sensor? When I cranked it I think two times it actually fired up in a single crank and started just fime without the MAP in the hole...it just showed the MAP at 30 in the 400-800-1200-1600 columns when it did that. Instantly turned it back off each time.