That's my understanding of it. Further refinement of final AFR .Quote:
all that matters is in what happens when the voltage changes
FWIW.
Cheers,
joel
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That's my understanding of it. Further refinement of final AFR .Quote:
all that matters is in what happens when the voltage changes
FWIW.
Cheers,
joel
The attachment shows the ltft's for my normal driving. It seems that the offset curve depends on GM MANVAC and BATTERY VOLTS.
Been lurking for a while and have a few questions...
What does this table actually do/represent? It appears this table will adjust the IPW based on MAP and battery voltage. Are we sure that's what it's doing?
What physical properties of the injector/fueling system warrant molestation of this table? I would think coil resistance and valve design (pintle, disc, etc..) would warrant changes, but are those the only factors? Which factors have the most significant impact to this table?
Given an OLSD tune, can an error factor for Injector Off Set table be calculated?
Based on John's posts, if you have a known good MAF calibration, and your IFR table is correct, you now have 2 constants to tune the offset table with. However, in OLSD, with the IFR as your only constant, if you tune your VE table to a commanded 14.63 AFR, then change commanded AFR to say 13.0, it appears you VE table needs more tweaking, when the culprit may be the off-set table. Can the subsequent VE table error somehow be used to calculate a correction factor for the IOS table?
If an error factor cannot be calculated for the IOS table, how do you actually create a valid IOS table?
The fuel injector is basically a selinoid
Reluctance (NOT RESISTANCE) is a form of electrical resistance unique to coils. Electric current flows through the coil’s windings, it builds a magnetic field pulling the pintle off its seat and releasing the fuel. The time it takes for this to happen is directly influenced by the voltage applied to the circuit. And as that field grows, its lines of magnetic force pass through the same windings, causing a reversed-polarity voltage resisting the applied current. As the reluctance disappears about the time the coil reaches full saturation, the lines of magnetic force become stationary and theapplied current reaches its maximum. When the PCM cuts the injector coil circuit, the magnetic field collapses. But as it collapses those same magnetic lines of force pass through the coil windings in the other direction, thus extending the duration of the magnetic field and the opening of the nozzle.
The injector offset is I think there to allow you to tune for different sized coils and adjust for there reluctance. Different sized coils will act differently depending on the number of windings/turns and other factors. I've used the injector offset as a tool to help bigger injectors idle.:muahaha:
Dennis
Quote:
Originally Posted by TAQuickness
Originally Posted by TAQuickness
Been lurking for a while and have a few questions...
What does this table actually do/represent? It appears this table will adjust the IPW based on MAP and battery voltage. Are we sure that's what it's doing?
......Have to log GMMANVAC to link for tuning. The table is from 0 to 80.
......It must adjust IPW. When I lowered my MAF to stock I had to increase IO. It can also be seen in the logging afer making changes.
What physical properties of the injector/fueling system warrant molestation of this table? I would think coil resistance and valve design (pintle, disc, etc..) would warrant changes, but are those the only factors? Which factors have the most significant impact to this table?
......I don't feel like a molester. Whatever the mechanical differences of SVO's I don't know. We think they have a different curve. That's what I'm trying to see.
Based on John's posts, if you have a known good MAF calibration, and your IFR table is correct, you now have 2 constants to tune the offset table with. However, in OLSD, with the IFR as your only constant, if you tune your VE table to a commanded 14.63 AFR, then change commanded AFR to say 13.0, it appears you VE table needs more tweaking, when the culprit may be the off-set table. Can the subsequent VE table error somehow be used to calculate a correction factor for the IOS table?
........I'm trying it from the other end. Hopefully I can get reasonable trims across the board with the MAF and then run in SD and see the affect on PE and VE's, if any. There should be on PE if IPW is affected by IO. PE would seem to be the hard part because it requires so many WOT runs to get good info and the make changes. I was told by a tuner not to bother. Just get close and adjust PE accordingly. He said he has done thousands of tunes and has never seen perfect PE math. Might get lucky.
Given an OLSD tune, can an error factor for Injector Off Set table be calculated?
........Good luck.
Cool. :mrgreen:Quote:
Originally Posted by jfpilla
My idle (open loop, through the MAF) was more stable in terms of AFR and quality once I inserted the GM Offset table for the GTP/WCC/36lb injectors.
Have a Great weekend Joe!!
Cheers,
joel
is that 36 ls/hour@58 psi or 43.5
Joel,Quote:
Originally Posted by bink
Rub it in. Where can we get a table for SVO's?
Enjoy yours too.
Joe
Dirk,
I'm using 43.5. It seems to work as far as tables lining up. I know that there is 40.0 as a possibility. Given the end game it doesn't matter too much.
I may need bigger injectors late spring anyway. I may have to go with injectors that have tables available. LIKE JOEL's.
Joe
My comments are just my opinions, feel free to correct me if you think I'm wrong.
You shouldn't adjust the IPW with offsets.. You can affect IPW by not understanding the values you put in the offset table. Adjusting these values will increase or decrease the amount of time the PCM thinks it takes to reach fully open and fully closed for the injector.
Injector offset affects both the opening and closing of the injector.
I think someone posted that you can adjust IPW's by tweaking the offsets. You should read my previous post in this thread. My guess is that the injector manufacturers base their offset values from the performance characteristics of the coil portion of the injector.
Some more food for thought.
The 98 Corvette and the 98 Z28 uses the same 28.8lb injector but the injector offset tables are different for all entries. TheVette values are higher except from 4.5v – 6v where they are lower. At 13v/50kPa they are 0.167173ms longer.
Maybe this is due to a longer wiring harness and more resistance or maybe just IPW trim.
John