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The map seems faulty if not the map someone ripped you on the tune . Some advise . Get a gm 2 bar sensor I forget the part number but the guys should have it here . Wouldn’t hurt to get a hpt device . I could make it run after that pretty dam well but you would need a deka 60 injector .
Is the cobalt ss 2 bar not a GM 2 bar sensor or is there another? I have a HPT device too thats how im doing the remote tune, hes a pretty reputable tuner so I dont believe hes ripped me on the tune. I still need finalizing revisions on tune.
Unfortunately you will have to access the MAP sensor and unplug it…with key ON you should see 5 volts on the GRAY wire…to check the signal wire you can jump the 5 volt reference gray wire to the LIGHT GREEN signal wire…your scan tool should show 5 volts on the MAP voltage data PID…you can also put your finger on either battery B+ or on alternator B+ and your other finger on the light green signal wire…your body has high resistance but you should still see around 5 volts…to check the low reference ground black lead on battery negative and red lead on the ORANGE/BLACK wire…with key ON you should see less than 100mV’s (0.1 volts)
Biggest red flag is the MAP scaling in the tune. I used to run this one but I can't find the file anymore, but I searched HPT forum and this sensor scaling should be 200/8. Linear/Offset respectively.
A quick way to test this is key on, engine off. turn on VCM scanner, check MAP. It should be around 100 kPa at sea level.
Definitely need to get this sorted/fixed, if that is off everything else will be useless garbage. It would definitely explain the boost/MAP discrepancy too.
It's likely you're still running out of fuel, but need to get MAP sorted first.
As for the Wideband... C5 is before CANbus was a thing so that one won't work. I'm not real smart on AEM sensors, but if it has a way to output serial, you can easily connect that to laptop to log it. Or last resort is analog output, you can wire that into the EGR port of the PCM which is normally open and not used. Set up a custom scaling in scanner and you can log wideband anytime. I have an Innovate LC-2, but I do this.
In the meantime you can do the key on, engine off MAP test and adjust the MAP sensor scaling, if required.
I tested the map again and it wasnt working so changed linear/offset to 200/8 and it logged at 194 key on eng off. Turned car on and now its running pretty poorly, maps at around 100-110 with engine on. Heres the log for it.
we need a 3/4 pull to 3 rd to really know please try to make it some to look at a def deccent pull to redline
Almost . Guys gonna make me fire up my old top now
There could be 2 different MAP sensor part numbers, thus the different scaling.. I can't say for sure. I ran 200/8 on the 2 bar GM sensor I had
That is way off. Needs to be around 100 kpa engine off and probably like 50 kpa at idle depending on cam and all that.
Could just be a bad sensor. Or wiring issue. Since it was 0 randomly at one point that is concerning too.
I have the part on a the box I’m just waiting to dig it out you know , not to say other sensor maps aren’t compatible but sticking to a ac delco should have been little bit a help
I tested the map again and it wasnt working so changed linear/offset to 200/8 and it logged at 194 key on eng off. Turned car on and now its running pretty poorly, maps at around 100-110 with engine on. Heres the log for it.
These values almost sound like double of what they should be.
Not insulting anyone's intelligence but is it possible it's a 1 bar MAP sensor that's installed? A 1 bar sensor will read close to max possible value at key on/engine off, and around 2.5V or midway at idle. If you were running 1 bar sensor with 2 bar calibration values in the tune, it would act like this. Just another thought.
These values almost sound like double of what they should be.
Not insulting anyone's intelligence but is it possible it's a 1 bar MAP sensor that's installed? A 1 bar sensor will read close to max possible value at key on/engine off, and around 2.5V or midway at idle. If you were running 1 bar sensor with 2 bar calibration values in the tune, it would act like this. Just another thought.
It could be a 1 bar sensor and thats more what im leaning towards. I was told it was a map for a cobalt ss so it had to be a 2 bar since its a supercharged engine. Will any parts stores sell a 2 bar that will fit or do I need to order it? I thought of this a while ago and asked tuner and he just said he was unsure and it should be reading values key on eng off. Would the 1 bar sensor show 210 KPA in the log like it has?
It could be a 1 bar sensor and thats more what im leaning towards. I was told it was a map for a cobalt ss so it had to be a 2 bar since its a supercharged engine. Will any parts stores sell a 2 bar that will fit or do I need to order it? I thought of this a while ago and asked tuner and he just said he was unsure and it should be reading values key on eng off. Would the 1 bar sensor show 210 KPA in the log like it has?
your local dealer or auto store more than likely has these on hand . I’ll dig out the box if I still got it for a part number
the original ls sensor was a 1.5 bar actually. Does not support 2 bar speed density tune in which 85-90 % of us run or ran . Unless your running 15 lbs of boost or more you will need 3 bar . Which maybe you could fill us in about a single mount rear turbo . To even speculate a 3 bar possibly. Turbo spec or model please list
manifold pressure
Last edited by Speedy007; Jan 14, 2025 at 08:01 PM.
It could be a 1 bar sensor and thats more what im leaning towards. I was told it was a map for a cobalt ss so it had to be a 2 bar since its a supercharged engine. Will any parts stores sell a 2 bar that will fit or do I need to order it? I thought of this a while ago and asked tuner and he just said he was unsure and it should be reading values key on eng off. Would the 1 bar sensor show 210 KPA in the log like it has?
The MAP sensor just sends a voltage to the PCM, the PCM (calibration) determines what the reading is.
Ballpark voltage numbers for illustration, not exact or measured
Stock 1 bar MAP key on engine off will read 4.8V On a stock 1 bar MAP 4.8 V = 100 kPa
2 bar MAP key on engine off would read 2.5V... PCM if tuned right would correctly interpret this as 100 kPa, all is well
1 bar installed in the car, but the PCM thinks its a 2 bar because that's what's filled in the tables. Voltage from MAP is 4.8 volts. ECU interprets this as 197 kPa (or whatever).
It's been so long, I can't remember what sensor part number I got, but I would definitely coordinate this with your tuner so you're on the same page and get the correct scaling in the tune.
OK I dug it up. I used 12580698. Apparently this is the Cobalt SS "baro" sensor and is only 2 bar, and the scaling is 200/8 as listed above.
There is also a cobalt SS MAP, which is 2.5 bar. IDK part number.
And there's others out there. Def discuss with your tuner so you're on the same page.
SU1078 This is the part number to the map that’s in the car right now, paid I believe $70 for it. I’ll probably end up going with the part number you just gave me since the other ACDelco part listed will take til february to arrive supposedly.
your local dealer or auto store more than likely has these on hand . I’ll dig out the box if I still got it for a part number
the original ls sensor was a 1.5 bar actually. Does not support 2 bar speed density tune in which 85-90 % of us run or ran . Unless your running 15 lbs of boost or more you will need 3 bar . Which maybe you could fill us in about a single mount rear turbo . To even speculate a 3 bar possibly. Turbo spec or model please list
manifold pressure
It’s not a crazy big turbo, only 70mm through 2.5in pipe both ways. I won’t be going above 10-11psi since it’s still SBE. 2 bar should be good enough for my needs currently.
Discussion here seems to indicate that sensor is 1 bar, but other threads across the net there seems to be some discussion/confusion on it. Betting that's the issue and it's 1 bar.
in the meantime if you want to tinker more or make it more driveable, put the stock MAP values back in and check the readings. Not sure if it will run better or worse. If you've already done VE tuning, youve been tuning around this issue.
Discussion here seems to indicate that sensor is 1 bar, but other threads across the net there seems to be some discussion/confusion on it. Betting that's the issue and it's 1 bar.
in the meantime if you want to tinker more or make it more driveable, put the stock MAP values back in and check the readings. Not sure if it will run better or worse. If you've already done VE tuning, youve been tuning around this issue.
Yeah I believe he’s been tuning around this which is why it’s taken so many revisions and still hasn’t been right. He did a good job tuning around it honestly, the car daily drives great I just can’t WOT and get a pull out of it. Summit had the ACDelco 2 bar sensor so I got that and it’ll be here friday, hope it fixes everything.
part # Camaro/Firebird/Corvette LS1/LS6 LSX 2 Bar MAP Sensor New OEM GM *19418810
Do I just snap the extra clip off the sensor so it’ll fit? Since the C5 only has one holder on the manifold but the sensor comes with a clip on both sides
please try to make it some to look at a def deccent pull to redline
