Anyone played with Injector Timing?
no reason for name calling jesus he was just giving you a friendly poke!! When i changed my settings accordingly at low RPMs the wideband is alot more steady and my part throttle was more crisp!,I have been messing with getting my AFR correct right down to the decimal point for a 70 degree day and i really noticed a alot more steady AFR reading after i messed with these tables.So it works.
Well I did some testing on this tonight with a car I've been tuning. Using the spreadsheet I calculated the degree difference between the stock exhaust valve closing point and the new cam's closing point and divided by 90 and added that value to the tables. The result was that the AFR, which I had dialed in to 14.6-14.7 at low rpms changed to 11.9-12.0. So after retuning the VE table, the part throttle values below about 3000 rpms changed from being upper 80's to 50's and 60's. Thus making a much cleaner VE table. Throttle response improved greatly and there was a definite noticeable increase in torque. Also, it being a 6 speed with 3.08 gears, it had a good bit of cam surge. The injector timing change cured that too. So it appears this is something to be seriously considered when tuning.
I'm hoping for some much nicer VE tuning sessions this time, because before, I could never really find a happy medium in a few areas.
Well I did some testing on this tonight with a car I've been tuning. Using the spreadsheet I calculated the degree difference between the stock exhaust valve closing point and the new cam's closing point and divided by 90 and added that value to the tables. The result was that the AFR, which I had dialed in to 14.6-14.7 at low rpms changed to 11.9-12.0. So after retuning the VE table, the part throttle values below about 3000 rpms changed from being upper 80's to 50's and 60's. Thus making a much cleaner VE table. Throttle response improved greatly and there was a definite noticeable increase in torque. Also, it being a 6 speed with 3.08 gears, it had a good bit of cam surge. The injector timing change cured that too. So it appears this is something to be seriously considered when tuning.
Wish I knew what the values in HP Tunners ment long ago. The custom PCM we are using on our project has that table defined in degrees of crankshaft rotation from 360 to -360 so it is much easier to understand then the way GM did it. Now we know so I bet the tunes will get even better.
The oil field is booming out here! Housing is scarce and very high for this area. Not to mention we have one of those nuclear inreichment plants (yes the kind we are mad that Iran is building) going in down the road, as well as a few nuclear waist storage facilities going in too. Unemployment here is still less then 4%! The only people here not working dont want to.
I moved to Odessa and have not yet changed my location. Back in Texas were I am from
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That is actually one of the smaller engines we use in the Gas Compression Fields. 10" bores and 10.5" strokes in a straight 8 cylinder config, we have some that are the same bore and stroke but in a V16 config. Up to 4500hp at 900rpm. The old iron from the 40's are what we call slow speed 2 stroke engines, with 14" bores and 14" strokes, running 300rpm, making over 2000hp. Pig Iron!
I moved to Odessa and have not yet changed my location. Back in Texas were I am from
.That is actually one of the smaller engines we use in the Gas Compression Fields. 10" bores and 10.5" strokes in a straight 8 cylinder config, we have some that are the same bore and stroke but in a V16 config. Up to 4500hp at 900rpm. The old iron from the 40's are what we call slow speed 2 stroke engines, with 14" bores and 14" strokes, running 300rpm, making over 2000hp. Pig Iron!
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Verdad Gallardo I will be heading to San Antonio this weekend for my step sons graduation. Going to stay on the River Walk and take my mini Texican shildren to all the important historical sights. I drench them in Texas History every year, Austin, San Antonio, Houston, Washington on the Brazos. My wife is a Daughter of the Repiblic member, three different links back to the O-300 (first 300 families that came to Texas with Stephen F Austin)! I am eligibale for the Son of the Republic, my line came in in 1845, but no famous Texans like my wife has. 
A couple of parts that aren't clear to me:
1) In the spreadsheet, it calculates Shifted/Actual EVC/IVO/ISP EVC/ISP IVO. You take the difference between one of these values and your warm normal value and add/subtract it to the entire normal/makeup tables. So if that new value is 5.55, and the old value is 4.55 when the engine is warm, you add 1 to the entire table... is that correct? If so, which of those 8 calculated values do you use?
2) Does it matter whether you use seat or .050 timing? Does the spreadsheet give correct results with either timing method?
1) In the spreadsheet, it calculates Shifted/Actual EVC/IVO/ISP EVC/ISP IVO. You take the difference between one of these values and your warm normal value and add/subtract it to the entire normal/makeup tables. So if that new value is 5.55, and the old value is 4.55 when the engine is warm, you add 1 to the entire table... is that correct? If so, which of those 8 calculated values do you use?
2) Does it matter whether you use seat or .050 timing? Does the spreadsheet give correct results with either timing method?
bigger cam, bigger eoit number. you want to delay injection. yes the intake opens earlier but the exhaust also closes later. the exhaust closing event is the key. a stock cam intake opens and closes before the exhaust even opens so they can spray a closed intake valve.
Originally Posted by Higgs Boson
bigger cam, bigger eoit number. you want to delay injection. yes the intake opens earlier but the exhaust also closes later. the exhaust closing event is the key. a stock cam intake opens and closes before the exhaust even opens so they can spray a closed intake valve.
12 Second Club
Joined: Dec 2008
Posts: 281
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From: A small town, MS
A couple of parts that aren't clear to me:
1) In the spreadsheet, it calculates Shifted/Actual EVC/IVO/ISP EVC/ISP IVO. You take the difference between one of these values and your warm normal value and add/subtract it to the entire normal/makeup tables. So if that new value is 5.55, and the old value is 4.55 when the engine is warm, you add 1 to the entire table... is that correct? If so, which of those 8 calculated values do you use?
2) Does it matter whether you use seat or .050 timing? Does the spreadsheet give correct results with either timing method?
1) In the spreadsheet, it calculates Shifted/Actual EVC/IVO/ISP EVC/ISP IVO. You take the difference between one of these values and your warm normal value and add/subtract it to the entire normal/makeup tables. So if that new value is 5.55, and the old value is 4.55 when the engine is warm, you add 1 to the entire table... is that correct? If so, which of those 8 calculated values do you use?
2) Does it matter whether you use seat or .050 timing? Does the spreadsheet give correct results with either timing method?
2. I'm not sure what the difference would be using seat vs @.050 timing. I've always used the @.050 data. Maybe one of the other guys would be able to clarify that.
I adjust the timing all the time on many different size cam car's. Driveability will greatly improve as well as throttle response in lower rpm from it. You want to delay the end of injection pulse because the factory values have the end of injection before the exhaust valve is completely shut especially on a larger camshaft with some overlap. In stock form the fuel will get pulled in and right out the exhaust, this is why you have a horrible fuel smell on most cam'd car's that havent had the injector timing properly tuned. I use a certain formula to decide where to put the EOIT based on the camshaft, however it's kind of a trade secret that gives me an edge if you will haha. I will say that the formula for the EOIT is this (Thanks to Bluecat for his R&D on this info):
-784 + ((Boundary + Normal) * 90)
This gives the End Of Injection Timing in crank degrees ATDC compression stroke in a 720* engine cycle. Factory fbody values gives an EOIT of ~300*
There is alot of people's interpretation of this in his thread over on HPT forum's but you can sift through the posts and get an idea of what needs to be done and experiement to find the best results!
http://www.hptuners.com/forum/showth...highlight=EOIT
-784 + ((Boundary + Normal) * 90)
This gives the End Of Injection Timing in crank degrees ATDC compression stroke in a 720* engine cycle. Factory fbody values gives an EOIT of ~300*
There is alot of people's interpretation of this in his thread over on HPT forum's but you can sift through the posts and get an idea of what needs to be done and experiement to find the best results!
http://www.hptuners.com/forum/showth...highlight=EOIT
Can you refresh my memory on the specific steps you used to select your EOIT values? Are the EOIT & transient fueling dependent upon one another, or can I try your transient values without further adjusting my EOIT (I based my values on a really old Excel workbook posted by Scott fka Soundengineer)?As long as you have the MAF properly calibrated, VE properly calibrated & calibrated injector data these value in the Fuel > Transient screen will be ideal in any Gen3 PCM? No worries about different displacement or combinations of parts?
Last edited by JimMueller; May 19, 2015 at 06:28 PM.
Staging Lane
Joined: Jan 2009
Posts: 59
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From: Bella Vista, AR
Found Problems with Tune I deleted tune because it had problems. It was one of those cases where one change worked well and masked problems caused by some other changes I had made.
I do not feel I have figured out much about EOIT after all, except that it would be best if one could increase EOIT with RPM from 1500 through 4000 RPM as some after market PCMs allow one to do. This way you can move up the injection timing for a better idle without hurting WOT performance.
I did learn that filtering MAF above 400 RPM for dynamic air computations in my PCM instead of above 4000 RPM seems to give me a lot more steady AFR at various MAPs and throttle positions and a much steadier cold start idle.
I do not feel I have figured out much about EOIT after all, except that it would be best if one could increase EOIT with RPM from 1500 through 4000 RPM as some after market PCMs allow one to do. This way you can move up the injection timing for a better idle without hurting WOT performance.
I did learn that filtering MAF above 400 RPM for dynamic air computations in my PCM instead of above 4000 RPM seems to give me a lot more steady AFR at various MAPs and throttle positions and a much steadier cold start idle.
