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16.4 LTFT after Injector install



91parkave said:
Or you could adjust the MAF to see the actual amount of airflow its getting. And not rape your pe table.
Click to expand...

The maf is a MEASUREMENT OF ACTUAL AIRFLOW coming in.

Think of it this way...

Guy at gate of stadium = MAF sensor
Guy seating people = Motor

There is a guy at the front of a stadium with a watch and counts how many people are walking in the door.. If the rate of people coming in the door changes the guy counting and watching his watch will still report back how many people are coming in, regardless of why. These people can be getting pushed in, or the people could be less restricted to their seats after they get in the door, but the guy at the gate is JUST counting air coming in.

The guy seating people is your motor.... The cam makes your engine seat people faster, but there are still just as many people to seat. The cam makes for less congestion after people get in the door so more people can get in, and the guy at the gate will count more people going in.
 
It goes like this....Factory puts together your engine and calibrates the PCM so that it expects a given amount of g/sec measured from the MAF at that SPECIFIC HZ rating, However things happen to that specific calibration once a aftermarket airfilter assembly ported tB...etc etc get installed. The g/sec value changes for the HZ rating reported to the PCM. I understand your against maf tuning in general due to the complexities of fitting a 3rd order poly to it to keep the math correct. But understand that raping your IFR table isnt the only way to get what you want...Theres alot who will say youre way is bat **** cray cray, and there are some who might agree with you, But until that day comes ill take my knowledge base from people who actually write factory software for a living.
 
First you were talking about adding a cam... then you are talking about building a new maf from scratch... lets get your stories straight.

Also the "air filters change it" story has been played out and its easier to make linear changes like that to the injector table if you put a air filter on that creates some lame airflow thing.
 


Fuel trim got a little crazy again but gas cap light came on so think that what it is


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Did take a look at my maf tune last night and it's not as linear as the stock one so prob a contributing factor


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wa04compg said:
Ok so my fuel trims where within 5% +- with stock injectors. I installed some cobra 39lb injectors and scaled the IFR table according to new injector size. Now at idle and light to moderate throttle fuel trims are pegged at 16.4...when I get into PE drops to 0 like normal my Wideband is also showing me cruising down the road at 14.4 to 14.7 AFR. What am I missing? Did I do something wrong? I sprayed around vacuum lines and didn't change anything. Also noticed at idle the BBV opens and closes every 5 seconds or so...can't say I have ever noticed that before...Please help I am a newb at this tuning business
Click to expand...

Interestingly enough, I installed 60lb EV1 injectors this morning into my 99 GTP.. Set the injector IFR tables appropriately (between 62 and 67). Driving around a bit and getting on it, my AFR's with the wideband look great as usual (14.7 cruise, 12 at high throttle, 11 at WOT). Similar to your case, my LTFT's are way off. I see high values (up to 16.4 sometimes, and usually at least around 7 or 8) but then when I get into the throttle/PE mode, they drop to zero. Everything else looks fine... :th_coocoo:
 
Note that I have never touched or changed the MAF table yet. Only my PE tables and injector tables (and when I say injector tables, I only mean IFR).
 
darkhorizon said:
The maf is a MEASUREMENT OF ACTUAL AIRFLOW coming in.

Think of it this way...

Guy at gate of stadium = MAF sensor
Guy seating people = Motor

There is a guy at the front of a stadium with a watch and counts how many people are walking in the door.. If the rate of people coming in the door changes the guy counting and watching his watch will still report back how many people are coming in, regardless of why. These people can be getting pushed in, or the people could be less restricted to their seats after they get in the door, but the guy at the gate is JUST counting air coming in.

The guy seating people is your motor.... The cam makes your engine seat people faster, but there are still just as many people to seat. The cam makes for less congestion after people get in the door so more people can get in, and the guy at the gate will count more people going in.
Click to expand...
http://www.youtube.com/watch?v=kBk0KudOVAg Skip to 9:00
 


I didnt watch it because I am at work but I can tell you that just because some idiot made. Youtube video on it it does not mean he has any idea what he is talking about.
 
darkhorizon said:
I didnt watch it because I am at work but I can tell you that just because some idiot made. Youtube video on it it does not mean he has any idea what he is talking about.
Click to expand...

This dude has real credentials plus he actually can prove how things work.

You forge the tuning process. The computer never knows the real stoich value of the fuel its using. You falsify injector data and when airflow charteristics are changed you ignore them. Your method was viable with really old tuning software, but with all the ability now to get the PCM better able to handle real world driving you have to take a look at what needs changing
 
Im an engineer who works with people with real credentials and real experience but they have no ability to logically work through a problem.
 
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