3 Bar MAP sensor doesn't work with 3 Bar scaling!

[Redline Motorsports]

Finally making headway, thanks to Jesse, with the cutsom OS 3/bar application on a wild TT C5. What I am totally puzzled by is that the car has a 3 Bar MAP sensor but runs like crap with the scale set at 288. The FS reports a real high Kpa reading . When changed to 194 (2 Bar) it gets closer and finally at 94 it runs great. WTF??

When the scale is set to 94 the MAP reads 102 KPa with the key on. What is the problem?

Also I am disappointed with the Autotune tutorial as after 4 times going through the steps it still wouldn't run. After Jesse got involved I realized there ae things that need to be done that are not discussed. Needless to say I got a good lesson tonight! :D

Howard

[red12secz28]

Is the three bar sensor brand new. I had a problem with my buddies turbo'd ss. We put the supercharged buick 3.8 2 bar sensor on it and it was till the 15 time I started it till the sensor showed the kpa it needed. For instance stock idle kpa was 38 on 1 bar. The first time I used the new 2 bar it was reporting like 75 almost 80 kpa corrected. But I guess we fattened up the mixture too much and it bogged the engine, since then the sensor worked perfectly. It showed 20 kpa through the normal map pid. Put it through the 2 bar pid and it showed 40 kpa. I guess It was a fluke of some kind. Maybe that is the same problem you have. Its kind of like you have to break in the sensor by a massive fluctuation in kpa.

[GMPX]

Howard, if you scaled the MAP to 288 and it would not run and the MAP reading at keyon was nowhere near 100kPa, then it was wrong!!, rescale to suit?.
Are you 100% certain it is a 3bar MAP?.
The 3bar MAP I have here is #16040749
From the GM Parts Direct Website -

DESCRIPTION: NO STOCK LEFT ON 16040749 ORDER NEW PART #12223861
This is the first design map sensor for 1989 turbo t/a's.
This part number has changed to the 2nd design and will require using a new connector 15305891 when replacing the first design sensor with the new 2nd design map sensor

If you are installing this on a vehicle other than a 1989 turbo T/A there will not be a warranty on this part.

This is an electrical part which is not returnable per our site policies.

This old part number will be sent until stock is exhausted. Once stock is exhausted the new part number 12223861 will be sent in its place.

[Redline Motorsports]

Ross,

That is the correct MAP # was have......plus I have two of them! I have a question....what is the difference between SAE.MAP and GM.MAP??

[lplott]

Howard (Redline Motorsports),

Once you have the AutoTune working with table B0101, how are you going to fine tune the Boost VE table (A0009) so it is not so rich but still rich enough to prevent KR?

I have a C5 TT that I am planning on doing the Custom OS and AutoVE on it so all information is important to me.

Thanks,
Lonnie

[Redline Motorsports]

Ross,

That is the correct MAP # was have......plus I have two of them! I have a question....what is the difference between SAE.MAP and GM.MAP??

What are the differences between these two pids?

[GMPX]

Sorry, Howard, forgot to answer that.

GM.MAP is the raw voltage from the MAP sensor.
SAE.MAP is the actual manifold pressure.

In our custom O.S's we changed the SAE.MAP PID so it extends to 255kPa (The max it can go to), this is the one you should use when tuning 2/3 bar.

Cheers,
Ross

[Blacky]

GM.MAP is the raw voltage from the MAP sensor.

Actually GM.MAP is the same as the SAE.MAP PID (kPa or inHg), except (as Ross said) it pegs at 105 kPa, while {SAE.MAP} continues up to 255kPa.

There was another PID {GM.MAPS} that was the raw sensor voltage, but that has been removed in the latest version. It was not compatible with black-box logging. To obtain the raw MAP voltage, create a calculated PID with the following expression: RAW({GM.MAP})/51

Regards
Paul

[Redline Motorsports]

Thanks for the clarification.

I still don't understand why this 3 Bar MAP sensor is reading valid numbers when scaled at 94. When the sensor is scaled at the 288 it is reading incorrect.

Howard

[GMPX]

Thanks for the clarification.

I still don't understand why this 3 Bar MAP sensor is reading valid numbers when scaled at 94. When the sensor is scaled at the 288 it is reading incorrect.

Howard

You got me too Howard :?
What was the part # of the sensor you have?.

Cheers,
Ross

[caver]

Whats the voltage out of the map sensor at key on? May be a problem there.

[GMPX]

Howard,

Does this match what you see.....this is from the 3bar sensor I have here # 16040749.

Measured voltage at the MAP sensor, engine not running = 1.54V
Here's the comparison between what the scaler is set to {C6301} and what the MAP value in the scan tool is showing....

94.4 = 39kPa
180 = 68kPa
288 = 99kPa

Cheers,
Ross

[Redline Motorsports]

Ross,

I am going to check out these voltage readings tomorrow. I have a fluke meter hanging out of the back of the MAP sensor harness to pickup the readings. It seemed correct everytime we made a MAP or scaling change. IK was just wondering why it never matched the FS's voltage PID.

One of the posts stated something about creating a new PID to read the raw voltage. How do you do that and has is that different then the current PID that is show in the selectable list?

Finally, is it possible that the way the custom OS is designed that some PIDS don't work as normal??

Thanks for the continuing help!

Howard

[GMPX]

Ross,

I am going to check out these voltage readings tomorrow. I have a fluke meter hanging out of the back of the MAP sensor harness to pickup the readings. It seemed correct everytime we made a MAP or scaling change. IK was just wondering why it never matched the FS's voltage PID.

One of the posts stated something about creating a new PID to read the raw voltage. How do you do that and has is that different then the current PID that is show in the selectable list?

Finally, is it possible that the way the custom OS is designed that some PIDS don't work as normal??

Thanks for the continuing help!

Howard

Hi Howard,

Between the email's and forum posts I get so confused sometimes :bawl:
Anyway, for others reading this thread one way to confirm what MAP sensor you have is to read the voltage (with a voltmeter) at the terminals of the sensor with the key on, engine not running.
A 1 bar will read about 4.8V or there abouts (depends on alt as well).
A 3 bar will be about 1.5V and a 2bar somewhere in between.
But remember, the PCM MAP scaling calibration will have no effect at all on what a multimeter reads at the MAP terminals.

The voltage PID's were changed in the scantool not long ago, Paul has said they were causing an issue with black box logging (feel free to chime in Paul).

No problem with the help Howard and big thanks to Jesse too, I hope after all this we have all learn something to help in the future.

Cheers,
Ross

[QUICKSILVER2002]

Did the MAP sensor offset (c6302) somehow get changed.

I have a 2bar sensor in my car and the scaler is set to 190.

[Redline Motorsports]

Here is where I stil stand with this issue;

3 Bar Map sensor part # 12223861

Key on (no start) 1.579 volts

2 Bar Map sensor part # 16254539

Key on (no start) 2.290 volts w/scaler set to 194


The Flashscan with the 3 Bar Map reads .830 volts at 55 KPA
The Flashacan with the 2 Bar Map reads 1.030 volts at 51 KPA

The only way the car runs clean is when the scaling is set to 94. This is regardless of which MAP sensor is used. As soon as I scale the MAP to the rerquired values (194 for 2 Bar) and (288 for 3 Bar) that car runs worse. Actually when the scale is set to 288 it runs the worse and as you go to 194 and eventually back to 94 it runs noticably better.

The Flashcan kpa readings also match my kpa readings off my dynos 5 bar map.

WTF is the problem??

Howard

[VetPet]

Howard, I would be very much obliged if you could outline what is missing from the AutoVE tutorial as I'm sure others would also benefit from what you've learnt.


:thankyou2:

[Redline Motorsports]

Here are a few more things I checked;

2 Bar Map scaled to 194

Dyno map reading was 62 KPA and the Flashscan read 114 KPA

Same Map scaled to 125

Dyno map reading was 60 KPA and the Flashscan read 80 KPA

Same Map scaled at 94

Dyno and Flashscan read the same.

:nixweiss:

[QUICKSILVER2002]

Here are a few more things I checked;

2 Bar Map scaled to 194

Dyno map reading was 62 KPA and the Flashscan read 114 KPA

Same Map scaled to 125

Dyno map reading was 60 KPA and the Flashscan read 80 KPA

Same Map scaled at 94

Dyno and Flashscan read the same.

:nixweiss:

This may be a stupid question. But are you 100% sure you wired the new sensor into the correct wires/connector.

Also, what does c6302 read in your file.

[Redline Motorsports]

Not a stupid question. but....I did check it. This was backed up by the volt meter readings that I monitered with a volt meter. Ground, +5 volts, and voltage output!

The {6302} MAP Sensor Offset is set to 10.

For whatever its worth its COS # 02040003.

Howard

[MN C5]

Howard, I may have missed it but what OS does the vehicle have?

[Redline Motorsports]

It was stated a few post back but its COS # 02040003.

Howard

[Redline Motorsports]

How about I reloaded the original MAF tune, left the 3 BAR map in place, left the MAP scaling at 94.................the car reports the correct KPA at idle and idles like a champ....

HT

I'm done with the custom OS on this car and will try it on another car.

[odd boy]

Good info