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#2862 - 10/20/08 02:49 PM Re: Injectors offset voltage times not created equal [Re: ]  
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That is the whole purpose of this thread, injectors cannot just be changed and NOT also redo the offset table to suit the design and flow of the injectors.

Pretty bad that not only are those installing injectors but ask the vendors selling them what the values are for the injector being sold and they have no clue.

Also as to F-body, look at how much the LSA changes were which effect vaccum and timing


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#2863 - 10/21/08 01:19 PM Re: Injectors offset voltage times not created equal [Re: teamzr1]  

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So you think that in case of the 98-99 F-body the injectors were so different (28.5 vs. 26.3 Lbs-Hr) that the delay had to be increased by 30%?

Notice that the camshaft was exctly the same for both years.
Heads are the same too.

At the beginnig of this thread you describe the situation before and after programming the correct delay time.
How did you find out this time? From the manufacturer? Try and error? If by try and error how did you find out the opitmal values? Dyno? Scanner?

Stefano

#2865 - 10/23/08 04:32 PM Re: Injectors offset voltage times not created equal [Re: ]  
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As I stated all injectors will have their own reaction delays and/or with CAM changes require the offset table tuned for the makeup of each powertrain.

I do not believe in dyno tuning as known the PCM requires good amount of relearn time not done on most static dyno's

All testing and tuning should be with realworld street driving and OBD scanner rscording.



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#2903 - 11/13/08 02:24 PM Re: Injectors offset voltage times not created equal [Re: teamzr1]  
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Here is long term test after 1 1/2 months since the SVO30s were installed and injector offset table modified.

Weather was 57 degrees, elevation from 3500 to 4,000 feet ( loss of 52 HP due to elevation).

PCM non WOT recorded OBD-II cycles was 42,800 with only 624 WOT cycles over 33 miles in 38 minutes drive time. OBD-II scanner capture rate was 40 F/ps of 25 concurrent PIDs.

We see both long and short term fuel trims right around a perfect zero. Max air flow at 43 lbs or 610 CFM.

WOT timing good at 28 degrees.

SVO30s around max duty cycle of 78% with average NON WOT fuel injector pulse width of 4 mSeconds with a WOT peak of 16.3 mSecs.

Engine produced in short WOT 405 ft/lbs torque at 468 flywheel HP at 122 MPH with just under the 6,800 rev limiter.

WOT AFR was between 12.7 to 13 as water/methanol is being used spraying at around 600 mL a minute.

Again this 1999 LS1 is 372 CI stroked with 11.3:1 AFR with 91 octane gas and during this run had zero knock or misfire.

Non WOT fuel mileage was 20 for city and averaged between 28 and 32 MPG depending on how stable speeds were maintained.


Attached Files Nov08.jpg

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#2904 - 11/13/08 08:24 PM Re: Injectors offset voltage times not created equal [Re: teamzr1]  
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Here is the data when going from slow speed to WOT to 122 MPH and then to see how our model/simulator reported to see how it matched up to real world

Simulator results at top and scanner data in bottom graph. Numbers closely matched.


Attached Files test.jpgChart1.jpg

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#3147 - 09/24/09 06:37 PM Re: Injectors offset voltage times not created equal [Re: teamzr1]  
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Here is another case if where not properly tuning or understanding how PCM functions costs how engine functions which effects performance

In this real world case a C5 Corvette using 18 PSI of boost was having engine knock problems even though the owner installed and ported water/methanol so that there was a nozzle for each cylinder that flows as much as 3 gallons an hour per cylinder.
They are using 70 plus lb/hr injectors and still had real lean conditions by only 4,000 RPMs.

Owner had PCM tuned by others and problem still existed.

Owner sent us a scanner recording and our results showing fuel trim values ( top graph) was as lean as 13% even with those large injectors.

Owner sent us the PCM flash file we then analyzed to find the injector offset table values incorrect for the injectors used.

We corrected that and the fuel trims went from real lean to at least 10% rich which again shows that values for offset that are wrong will cost more fuel being used as PCM was trying to drive the lean trims values back down and by properly making the adjustments for those injectors that we then not only gor rid of the lean conditions but was still able to reduce injector flow by 10%.

Bottom graph is after base tune, after owner does a drive relearn we will do a final tweak to lean up even more at the low engine loads.

Attached Files cmp.jpg

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