Oddball question

[02greysixer]

So I will be buying a v2 here shortly and I hope it can fix my problem. My truck is completely ignoring the barometric pressure sensor. Its like its not even plugged in and I've checked all I know to check. Can the barometric pressure values be set to "0" with efilive? And by 0 I mean slightly above sea level. I am in Fl so changes in altitude don't happen all that often :rofl:


Sint frum tha orijinul smert fone

 

[Mike_S]

Why is it that youre worried about it? Unless its reading wrong and forcing you to run in a high altitude table rather than the correct one i wouldnt worry. I live around 6500 ft. And mine never reads low enough to leave the low altitude tables.

 

[02greysixer]

Why is it that youre worried about it? Unless its reading wrong and forcing you to run in a high altitude table rather than the correct one i wouldnt worry. I live around 6500 ft. And mine never reads low enough to leave the low altitude tables.

It is forcing it to run like its super high altitude or waaayyyy below sea level. The baro isn't talking to the map so it's thinking there's 2psi boost when it should be 0. Which makes It overfuel at start up which causes it to smoke when it first cranks. Truck runs fine, the smoke is just annoying and makes it look like I've got a tired motor or bad injectors.


Sint frum tha orijinul smert fone

 

[Mike_S]

Have you changed the barometric sensor? Does the boost pressure seem to track properly? What are you using to read the data from the truck? There are several pids that comonly get confused. Baro. Pressure, turbo boost pressure (absolute pressure, boost +atmospheric pressure) and actual boost pressure (absolute pressure - atmospheric pressure). Need to know which of these you're using. Also, cranking fuel quantity is a set 2d table based on temperature, barometric pressure does not play into the cranking injection quantity. Also, the fueling is generally based uppon airflow measured from the MAF for low boost limiting, not the MAP. I would start by looking at the baro. Sensor though since you say it seems to be reading wrong.

 

[02greysixer]

Have you changed the barometric sensor? Does the boost pressure seem to track properly? What are you using to read the data from the truck? There are several pids that comonly get confused. Baro. Pressure, turbo boost pressure (absolute pressure, boost +atmospheric pressure) and actual boost pressure (absolute pressure - atmospheric pressure). Need to know which of these you're using. Also, cranking fuel quantity is a set 2d table based on temperature, barometric pressure does not play into the cranking injection quantity. Also, the fueling is generally based uppon airflow measured from the MAF for low boost limiting, not the MAP. I would start by looking at the baro. Sensor though since you say it seems to be reading wrong.

I have changed the Baro out with a known good one yes, no change. The boost pressure does track properly from what I can tell, I am only using my Diablo Preditor to read the values until I have the v2. Once I have the v2 I'll be able to log it properly. The tables i am looking at are "manifold pressure" and "boost pressure". That's the only description I get from my crappy diablo. When you say "generally" based off the maf not the map do you mean the map doesn't change the amount of fuel injected when throttle is applied? Cause thats when i see the smoke is when the truck is warmed up and i rev it up from idle to about 1500rpm. I have zero haze at idle and once its revved up theres no more smoke. Thanks for all the info! :thumb:


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[Mike_S]

Ok, the manifold pressure PID should read anywhere from 10 to 14 pounds at idle or key on engine off, depending on your elevation and increase from there. The boostressure PID should track with your boost gauge, it is a calculated PID based on the barometric pressure, its simply manifold pressure minus barometric pressure.

As for the fuel limiting, i say gennerally because the mass majority of these trucks are programmed to limit fuel based on readings from the MAF sensor, not the MAP sensor, although there are the oddballs and the option is there in EFI Live as well.

From the sounds of it, youre just getting smoke on bottom as you start out, and maybe between shifts? Try putting your stock callibration back into the truck, and see if the smoke goes away. If it does, i would say its just the diablo programming bringing in fuel earlier to help the turbo wake up more quickly.

 

[02greysixer]

I have tried putting the original program back into it, there was little to no difference. That was my first thought too actually. I am going to hold out for my v2 and see if I can alter the tables. The boost pid does track with the guage, it's just 2psi higher than what the gauge is reading because it's not subtracting the barometric pressure value like it should be. This Just gives me an excuse to get efi sooner

 

[Mike_S]

2 PSI is not what the barometric pressure is, though. If it was not subtracting the barometric pressure it would be 10-14 PSI higher reading. Are you 100% positive that there isnt a leak in your boost signal line to your gauge? When was the last time you cleaned/replaced your air filter and/or your fuel filter? If your truck is throwing out copious amounts of smoke with the stock tune installed then there is something awry. I might take a look at cleaning the MAF sensor as well. What does the manifold pressure read with the key on but the engine not running? Boost should read 0 and manifold pressure should read 10-14.

 

[02greysixer]

2 PSI is not what the barometric pressure is, though. If it was not subtracting the barometric pressure it would be 10-14 PSI higher reading. Are you 100% positive that there isnt a leak in your boost signal line to your gauge? When was the last time you cleaned/replaced your air filter and/or your fuel filter? If your truck is throwing out copious amounts of smoke with the stock tune installed then there is something awry. I might take a look at cleaning the MAF sensor as well. What does the manifold pressure read with the key on but the engine not running? Boost should read 0 and manifold pressure should read 10-14.

Yes I am sure there isn't a leak in the boost gauge line. I even ran the truck with one of the ic pipes off to be sure it wasn't somehow really building boost at idle, still the same readings. And it's not a lot of smoke, just enough to annoy me. Most people don't even notice it, but I do and it bugs me. The fuel filter was replaced when I rebuilt the engine about a thousand miles ago, also added an airdog at the same time. and the air filter is also clean. I didnt notice if this was happening before I pulled the engine for the rebuild or not, never checked it. It always had a bit of a haze and rough idle because the injectors were bad. I will look into cleaning the maf. The readings with the engine off key on are 14.3 intake pressure and 1.8-2.0psi boost. On my dads Lbz the intake pressure is 12.3 and boost is 0 so I assume mine should be the same as his, since the trucks were parked side by side when I checked them?


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[BlkMax]

This may sound silly, but do you have a wiring issue from the baro sensor? You said you rebuilt the engine, are the bale connectors making the circuit? Could you simply have a bad connection (increased resistance due to corrosion etc.), and the light haze be something else? Did you increase the size of the injectors without making changes to the tuning, or are you running stock injectors?

It may not be the case this time, but you have to be careful when comparing the readings from different electrical transmitters. Unless each one was calibrated from a known source, some amount of variance should be expected. For example, I had an electric boost sensor, and the stock sensor reading from the same area on the truck. The aftermarket one would always read about 0.8 psi higher than the stock transmitter, and the pressure in the intake was the same.

Just some thoughts.....

 

[02greysixer]

I took the harness all apart and tested all the wires to both baro and map. Both power wires had the proper 5v, both ground wires had a strong ground with zero resistance, and I even traced and tested the signal wires all the way from the sensors to the big plug going into the ecm. They both had very little to no resistance there either. The bale connectors were the first connection I checked, all the prongs were seated good and once I found which prongs were for the baro and map I even bent them down just a little to see if that was my issue, no luck. Thats whats got me so puzzled about this, all the wires seem to have good strong connections!
Oh and its all stock injectors, turbo, ect.