table filled with 1.
How I understand , this is a multiplier. What does it do, multiplies FlowRate vs. KPa table for each cylinder?
table filled with 1.
How I understand , this is a multiplier. What does it do, multiplies FlowRate vs. KPa table for each cylinder?
www.turbofirebird.com tuned with HPT MPVI Pro, LC-1.
injector pulse width of cyl #
Correct. 1 would be 100%. If you were running rich on 1 cylinder, you cold use this to lean it out. For example, .95 would spary 95% of the fuel, .80 would spray 80%...
Here's the trick if you want to add fuel to a cylinder - you have to lower all of the other cylinders. The PCM sometimes does wierd things when you try to add fuel over 1 (100%). If you wanted to add 5% to #3 for example, you would lower 1, 2, 4, 5, and 6 to .95 (95%) so #3 was still getting 100%. In doing this you would have to go back and adjust your IFR table by 5% to bring 1, 2, 4, 5, and 6 back up to the pre-skew flow rate.
Clear as mud?
-Eddie
1998 GTP - 3.4 [3.2] [3.0] MPS - custom CAI - F.1 Ram Air hood - XP Cam - Ported Heads - 1.84/1.60 Si valves - 1.6 HS Roller Rockers - 72mm Ported TB - LQ4 MAF - 42.5# Lucas Injectors - Pacesetters
1/4 PB - 13.025 @ 106.81 MPH w/ 2.069 60'
2021 Chevrolet Colorado 2.8 Baby Duramax
... and the most important reason... don't just randomly adjust the skew rates, but LOOK at your spark plugs and they will tell you what (if any) cylinders need compensation.
On some cars, it does make a nice difference. On my car, after several verifications, setting all cylinders to 1 made all spark plugs the same proper light brown colour that indicates a proper burn.
'99 Black GTP Sedan
3.4-2.6" PB Quick Change pulleys, Custom CAI, XP Cam, N* TB, LQ4 MAF, SLP headers, 42.5# Injectors, 180/195* thermostat.
13.501 @ 103.392 on 91 (2.4 60-foot).
13.82 @ 105.28 on 87 octane! (2.42 60-foot).
263kph top end as shown on the GPS.
All this and 39MPG to boot. What more can a man ask for?
* Just another enthusiastic amateur tuner! *
Eddie, I've read this before, but what kind of wierd things are you referring to? I have a couple of my cylinders skewed slightly based upon the results from my cylinder balance tests along with a visual inspection of the plugs. I don't recall experiencing anything too wierd after doing this. Is this something that is pretty subtle, that you would have to be looking for specifically in order to find?Here's the trick if you want to add fuel to a cylinder - you have to lower all of the other cylinders. The PCM sometimes does wierd things when you try to add fuel over 1 (100%). If you wanted to add 5% to #3 for example, you would lower 1, 2, 4, 5, and 6 to .95 (95%) so #3 was still getting 100%. In doing this you would have to go back and adjust your IFR table by 5% to bring 1, 2, 4, 5, and 6 back up to the pre-skew flow rate.
Things like random untraceable misfires, tranny not shifting where it is supposed to, TCC no locking in... things like that.
And it is not something that happens on all cars, however after 3-4 years of playing with injector skews on the DHP board with several hundred people doing the same thing, a few things were found out... lowering the IFR numbers NEVER gave issues, whereas on some cars, raising it would cause the symptoms we discussed.
In other words, there are 2 ways to do it... one known to work on some cars, and another way that is known to work on all cars. Better to be safe than sorry... and its no effort to correct the IFR table globally by the few percentage points needed to make this change.
Last edited by JerryH; 05-21-2008 at 03:18 PM.
'99 Black GTP Sedan
3.4-2.6" PB Quick Change pulleys, Custom CAI, XP Cam, N* TB, LQ4 MAF, SLP headers, 42.5# Injectors, 180/195* thermostat.
13.501 @ 103.392 on 91 (2.4 60-foot).
13.82 @ 105.28 on 87 octane! (2.42 60-foot).
263kph top end as shown on the GPS.
All this and 39MPG to boot. What more can a man ask for?
* Just another enthusiastic amateur tuner! *
the table goes from 0 to 16. for example if i have twice as lage injectors installed , can I just multiply entire table x2?
www.turbofirebird.com tuned with HPT MPVI Pro, LC-1.
Negative Goose, you want to input the correct injector size into the IFR vs KPA VAC table.
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