My 1st noob log. 95 Gmc

[uhlhazard]

Awesome find vandura!

[vandura95]

"http://www.gmtuners.com/tech/MAF_MAP_IAT.htm
"When the engine is started, the ECM uses the MAP sensor readings to determine engine load. This is the primary sensor it uses to determine fuel and spark delivery to the engine. The MAP sensor reading is factored in with engine RPM to calculate volumetric efficiency. This is known as Speed Density (engine speed and density of the air charge). Volumetric efficiency (VE) is the term used to describe the amount of air an engine is ingesting vs. the amount of air it can actually hold, expressed in a percentage. If the engine is ingesting the maximum amount of air it can hold, then that engine is considered to be operating at 100% VE. Most naturally aspirated engines never see 100% VE; but engines using specially-tuned intake manifolds can accomplish this. Of course this can also be accomplished and exceeded with a turbo or supercharger by adding boost. Most naturally aspirated engines typically see up to 80-90% VE without a tuned intake design.

Obviously if there is a problem with the MAP sensor, or the vacuum/pressure readings it is getting are not accurate, this is going to greatly affect the way the engine runs. GM MAP sensors aren’t easily prone to failure, but I have seen them fail if exposed to great pressures such as what could occur if the engine backfired thru the intake. The most common situation that I see that can cause issues with the MAP sensor is a vacuum leak. Any kind of vacuum leak will cause the pressure levels the MAP sensor sees to be lower than expected. This tends to cause the Air/Fuel mixture to go rich (because the ECM thinks the engine is under a load)."...
http://www.gmtuners.com/tech/MAF_MAP_IAT.htm"

I am not getting any codes or ses light.
Based upon the Barometric pressure reading in Tunerpro, do you think It wound be a good idea to test the MAP sensor?

[Fast355]

"http://www.gmtuners.com/tech/MAF_MAP_IAT.htm
"When the engine is started, the ECM uses the MAP sensor readings to determine engine load. This is the primary sensor it uses to determine fuel and spark delivery to the engine. The MAP sensor reading is factored in with engine RPM to calculate volumetric efficiency. This is known as Speed Density (engine speed and density of the air charge). Volumetric efficiency (VE) is the term used to describe the amount of air an engine is ingesting vs. the amount of air it can actually hold, expressed in a percentage. If the engine is ingesting the maximum amount of air it can hold, then that engine is considered to be operating at 100% VE. Most naturally aspirated engines never see 100% VE; but engines using specially-tuned intake manifolds can accomplish this. Of course this can also be accomplished and exceeded with a turbo or supercharger by adding boost. Most naturally aspirated engines typically see up to 80-90% VE without a tuned intake design.

Obviously if there is a problem with the MAP sensor, or the vacuum/pressure readings it is getting are not accurate, this is going to greatly affect the way the engine runs. GM MAP sensors aren’t easily prone to failure, but I have seen them fail if exposed to great pressures such as what could occur if the engine backfired thru the intake. The most common situation that I see that can cause issues with the MAP sensor is a vacuum leak. Any kind of vacuum leak will cause the pressure levels the MAP sensor sees to be lower than expected. This tends to cause the Air/Fuel mixture to go rich (because the ECM thinks the engine is under a load)."...
http://www.gmtuners.com/tech/MAF_MAP_IAT.htm"

I am not getting any codes or ses light.
Based upon the Barometric pressure reading in Tunerpro, do you think It wound be a good idea to test the MAP sensor?

IMO the best place to look would be the TBI base gasket if the MAP reading is suspect. A vacuum leak is common there and will greatly effect the MAP sensor function and fuel delivery.

[vandura95]

IMO the best place to look would be the TBI base gasket if the MAP reading is suspect. A vacuum leak is common there and will greatly effect the MAP sensor function and fuel delivery.

I just replaced the base gasket prior to the test, the rebuild kit came with two base gaskets. I can swap them out to see if it make a difference.
I will most likely do compression test and change the intake gasket when I get back to my shop next month.


Attachment 7927

[vandura95]

The barometric pressure is 97.8
Is this normal?

In the Tuner Pro dash it reads 97.8 Barometric.
Is this a concern?

[Fast355]

In the Tuner Pro dash it reads 97.8 Barometric.
Is this a concern?

That number will vary depending on barometric pressure and altitude.

[vandura95]

I have figured out how to get the basic log recorded,
I have this loaded in Tunerpro: Advanced $0D.xdf and the BJYN for the 1995 GMC van


Should I follow the instructions in the following link now?
http://www.gearhead-efi.com/Fuel-Inj...-data-Tutorial

Should I smooth out the VE fuel in the open throttle vs map vs rpm and run another log?
I do not have the burn 2 yet. I still think I am a long way off from that point anyway.

I don't want to start another newbie thread, I'd like to just keep working off of this one.