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Thread: $EE / LT1 Injector Swap Running Rich

  1. #16
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    There you go, I updated Steve's EEX.xdf with some parameters, including minimal injector PW.
    Stock minimal PW is 1.4ms.

    EEX injector parameters.png
    Attached Files Attached Files

  2. #17
    Fuel Injected! spfautsch's Avatar
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    Quote Originally Posted by dzidaV8 View Post
    There you go, I updated Steve's EEX.xdf with some parameters, including minimal injector PW.
    Stock minimal PW is 1.4ms.
    Well thanks, but this just raises about a dozen more questions.

    1) if the minimum is 1.4ms why am I seeing 0.75?

    2) I must have been using an extremely outdated version of steveos xdf, or have you added / changed a lot more?

    1st Prime Pulse Width Vs. Coolant Temp. table controls the injector pulse width of the first prime fuel pulse during cranking as a function of engine coolant temperature.
    Similarly the 2nd Prime Pulse Width Vs. Coolant Temp. table controls the injector pulse width of the second prime fuel pulse during cranking as a function of engine coolant temperature. These tables were in the '96/97 LT1 calibrations. In the '94/95 LT1 calibrations these two tables are combined into a single table (Prime Pulse Width Vs. Coolant Temp.).

    If the engine is still cranking after the time specified by the 'Added Prime Pulse Enable Crank Time Vs. Cool. Temp.' table then another (Added) prime pulse is output and the pulse width of this added pulse is specified by the 'Added' column.
    <mind blown>

    The version I was using had these three tables separate, and none had any info about what the parameters effect.

    Questions 3-12) can anyone explain the $EE startup routine in detail? The description of the prime pulse width table makes it sound like there are no AFR calculations happening during this "prime" sequence. What are the conditions for the prime sequence to be entered? What is the function of the "Ext. Crank AFR vs. Low Res Pulse vs. Coolant Temp" table? This one also makes it sound like AFR calculations are not referencing VE or the injector flow constant.

    When cranking, the AFR must be determined using the low resolution pulse only, as not enough stable data is available from the MAF or SD systems. This table configures the ratio of fuel to low res pulse.
    This has me wondering if there's an annotated disassembly floating around somewhere. I'm too old to try deciphering motorola byte code again - my brain will turn to dust.

  3. #18
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    Yes, I modded the XDF here and there to suit me better.

    Commented disassembly is here.

    Basically, at startup there will be two prime pulses delivered (1st and 2nd, as per tables) at each low res pulse (IIRC). After the first 2 prime pulses, fuel is delivered using Crank VE table and Cranking AFR table. If the engine doesn't go above running RPM in certain time (Added Prime Pulse Crank Time table), there will be another (added) prime pulse, as per 3rd table.

    As for PW lower than minimal, I think that prime pulse might not be limited by that? Need to check the disassembly.
    Last edited by dzidaV8; 07-19-2017 at 01:44 AM.

  4. #19
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    Quote Originally Posted by dzidaV8 View Post
    Commented disassembly is here.
    Thanks! Apologies for not having found it on my own.

    Quote Originally Posted by dzidaV8 View Post
    Basically, at startup there will be two prime pulses delivered (1st and 2nd, as per tables) at each low res pulse (IIRC).
    Having not scaled the prime pulse tables for the bigger injectors explains why I'm flooded before the cranking VE table takes effect.

    Thanks for the simple and direct answers. Had I known there was a commented disassembly right under my nose I'd have at least made an effort. Though looking at them I would have spent days or weeks trying to find those answers. Good stuff nevertheless!

  5. #20
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    Quote Originally Posted by spfautsch View Post
    Having not scaled the prime pulse tables for the bigger injectors explains why I'm flooded before the cranking VE table takes effect.
    That's why I combined those three prime pulse tables into one - to make scaling them for different injectors just one multiply or divide operation.

  6. #21
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    I can't thank you enough. Had I known about the prime pulse width table(s) not referencing injector constant it would have saved me dozens of E-side flash cycles and a lot of frustration. I got close enough on the first attempt by scaling VE and the prime table according to what I thought would work that I'm not sure fine tuning will be needed. I'll report back once it cools to 60c.

    Since it sounds like you've done a few of these, are there any other pitfalls you can think of warning me about?

    I also applied all the SD / VE logging I've done since the injector swap, which produced some changes in the neighborhood of 5-6%. I was looking for a distinct pattern of shifting from lean to rich with RPM that would indicate having the wrong offsets, but saw nothing of the sort.

    From here I'm off to building a vss + gps driven arduino based performance computer so I won't have to rely on butt dyno "numbers".

  7. #22
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    I am glad I found this thread. I have had problems with flooding during hot starting which I traced to the larger 30lb Bosch III injectors from FIC I am running. I have two questions.

    1. How do I determine the minimal injector pulse? Would this come from FIC?

    2. What would be the correct way to scale the prime pulse width table for the larger injectors? Would I just take 24/30=.8 and then multiple the entire table by .8?
    1996 Camaro SS #308, M6, 3.42 (4.10 on the way), OBD-I Conv, OBX 1-7/8" Stainless Headers, Custom 3" Stainless Y Pipe, 2OTL
    355-Stock Crank, 6" Forged Rods, Forged Pistons-11.5:1 SCR
    LE2 Heads, LE2 Ported Intake, LE/Lunati 231/239 110 LSA Cam, Comp Pro Mag 1.6 RRA, Bosch III 30-lb Inj, Stock TB, Tune In Progress

  8. #23
    Fuel Injected! spfautsch's Avatar
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    I meant to post an update on this as more fine-tuning was needed. I still don't think I'm "dead on" but it's definitely improved. The way I've been comparing is to warm the engine up to normal operating temp by driving and then let it cool to 60c/140f which is where gasoline stops vaporizing readily. I'll then log the start with eehack and step through the number of frames between when the knock count first increments (caused by the Bendix drive engaging) and when the ECM has determined the engine is running by entering cell 16. For "cold" starts (anything below about 40c) it's generally about 7-8 frames or roughly 750 ms. I've gotten warm and hot restarts down to around 8-9 frames. Unfortunately it's a time consuming affair because once you start and run the engine for any amount of time it quickly heats the intake valves back up, improving the fuel atomization and warm start characteristics.

    Quote Originally Posted by Casey96SS View Post
    1. How do I determine the minimal injector pulse? Would this come from FIC?
    I doubt the minimum pulsewidth is a factor for you, especially with 30lb injectors. It doesn't appear to apply during startup anyway, and at idle I'm guessing you're around 1.8ms? Nevertheless FIC should be able to supply you with this, or if they left any identifying numbers on the injectors you can "sleuth" it. Did you get a flow sheet with yours? I didn't, and I'm slight annoyed by that. :-\

    Quote Originally Posted by Casey96SS View Post
    2. What would be the correct way to scale the prime pulse width table for the larger injectors? Would I just take 24/30=.8 and then multiple the entire table by .8?
    Sounds about right. Another table you may want to experiment with taking some fuel out in the warm start temps is called "Crank AFR vs. Low Res Pulse vs. Coolant Temp". The factory tune has some fairly large values in the first two pulses in this warm / hot start region. I basically halved the entire table (*0.50) for everything starting at 44c and above, but keep in mind I'm running 42 lb injectors so you may want to start at *0.80 and work your way down. Over the last few days I've been taking about 15% off the first two (leftmost) columns from 44c and up, and retesting. It currently looks like this.

    Code:
    	01	02	03	04	05	06	07	08	09	10	11	12	13	14	15	16
    -40	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8
    -28	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8	0.8
    -16	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0	1.0
    -04	1.8	1.8	1.5	1.5	1.5	1.7	1.7	1.7	1.7	1.7	1.7	1.7	1.7	1.7	1.7	1.7
    08	2.3	2.3	1.9	1.9	1.9	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1	2.1
    20	5.6	5.6	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2	3.2
    32	6.6	6.6	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3	4.3
    44	7.5	7.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5	5.5
    56	9.2	9.2	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    68	9.2	9.2	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    80	10.8	10.8	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    92	11.7	11.7	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    104	11.7	11.7	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    116	11.7	11.7	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    128	11.7	11.7	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4	6.4
    I'd really like to have a better understanding of how exactly all these tables factor into the pulsewidth calculations, but I'll settle for results.

  9. #24
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    Cool, thanks for all the info. I always wondered why I get the knock every time I start the car, makes sense that it would be the starter!

    No, I did not get any data sheets with my injectors. They did email me the offsets after I asked twice. I will ask them about the minimum pulse. Unfortunately they ground off the original part numbers and put theirs on there. They have really done a lot for me though. My first set of orange 30lb Bosch III from them were really hard to start when the engine was hot. It would crank for 5 to 10 seconds and then barely fire up. I sent them back for testing, they found no problems and sent them back. I contacted them again after starting was still bad. They went ahead and sent me a whole new set of gray 30-lb Bosch III. This set has been much better. Hot starting is pretty good, but I think I can get it a little faster and crisper if that makes sense.

    I will try playing around with those tables today to see if that makes any difference.
    1996 Camaro SS #308, M6, 3.42 (4.10 on the way), OBD-I Conv, OBX 1-7/8" Stainless Headers, Custom 3" Stainless Y Pipe, 2OTL
    355-Stock Crank, 6" Forged Rods, Forged Pistons-11.5:1 SCR
    LE2 Heads, LE2 Ported Intake, LE/Lunati 231/239 110 LSA Cam, Comp Pro Mag 1.6 RRA, Bosch III 30-lb Inj, Stock TB, Tune In Progress

  10. #25
    Fuel Injected! spfautsch's Avatar
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    Hope it helps, and good luck! I wish there was a more scientific method for this other than trial and error. Evidently it's a problem that's a lot more prevalent for those of us who've stuck with the 3.48" stroke crank.

    With your cam you might want to take about 30-40% off the Cranking VE vs TPS vs RPM table also. Alone that made very little difference for me but that seems like a pretty choppy cam so it may factor in. I also like zeroing all the cells above 12.5% tps in that table so if you do flood it you can stab the pedal and clear the flood while it's cranking.

    Out of curiosity, what valve springs are you running?

  11. #26
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    Running the same double springs you are. I used to have beehives and then upgraded to the Lunati springs last year when I had Lloyd freshen the heads up. I figured it was worth the piece of mind to have a double spring vs a single.

    My first hot start went well after I adjusted the tables. I'll have to get some more runs on it to see how it goes. Glad I know what to adjust now!
    1996 Camaro SS #308, M6, 3.42 (4.10 on the way), OBD-I Conv, OBX 1-7/8" Stainless Headers, Custom 3" Stainless Y Pipe, 2OTL
    355-Stock Crank, 6" Forged Rods, Forged Pistons-11.5:1 SCR
    LE2 Heads, LE2 Ported Intake, LE/Lunati 231/239 110 LSA Cam, Comp Pro Mag 1.6 RRA, Bosch III 30-lb Inj, Stock TB, Tune In Progress

  12. #27
    Fuel Injected! spfautsch's Avatar
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    I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

    I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.

  13. #28
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    Quote Originally Posted by spfautsch View Post
    I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

    I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.
    I built a standard displacement LT-1 as well. where is your rev limiter at? I set mine around 6300

  14. #29
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    Quote Originally Posted by spfautsch View Post
    I'm happy to see someone else building a standard displacement LT-1. I've always preferred building a smallblock that puts the fat part of the power band over 5000 rpm. As long as your rod bolts are decent, your rod bearing clearance isn't over 2 thousands and your valvetrain will handle it, a moderately built 350 with a nodular iron crank will happily produce good power at 7000 rpm all day long. What's your rev limit set at, and have you hit it yet?

    I've yet to get my warm start "perfect", but have been distracted by numerous other things wanting tweaks. It is firing immediately and running without having to crank a long time (or a second time) now, but doesn't quite breathe to life as it did with the factory injectors + tune. Even if I can't get it perfect I'm happy not to have to pedal it to clear the flood.
    I would have done a 383 but this was my first full engine build so it was a bit of a learning experience. I did not want to put the extra money into it in case I really screwed something up. It does has forged 6" Scat rods with ARP bolts and lighter Wiseco pistons. I kept the quench pretty tight. The plan was to be able to rev it to 7,000.

    Currently have the rev limiter set to 6,600. Have only had it to about 6,300 so far. Only have about 500 miles on it. Working on getting the fueling a timing dialed in better before I really wind it up. Will eventually set the limiter in the 6,800 to 7,000 range when I am comfortable with how it is running. It does like to pull up top though. Looking forward to getting my 4.10 rear swapped in.

    It seems the changes I made to the cranking tables really helped with hot starting. It starts about like it did stock. It fires after a couple revolutions. It could probably get better but I am much happier with it now.
    1996 Camaro SS #308, M6, 3.42 (4.10 on the way), OBD-I Conv, OBX 1-7/8" Stainless Headers, Custom 3" Stainless Y Pipe, 2OTL
    355-Stock Crank, 6" Forged Rods, Forged Pistons-11.5:1 SCR
    LE2 Heads, LE2 Ported Intake, LE/Lunati 231/239 110 LSA Cam, Comp Pro Mag 1.6 RRA, Bosch III 30-lb Inj, Stock TB, Tune In Progress

  15. #30
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    I almost went 383 when I found out that it's no longer cost effective to have rods re-sized, and what speed shops are charging for crank balancing these days. But I decided I didn't want to cobble on connecting rods or the block, and the 4x3.48 bore x stroke combo is pretty well proven.

    I've hit my 6800 rev limiter a couple times when the pavement was cold and it would just bake the tires off immediately above 4500 rpm. But now that the roads have warmed up I'm finding the extra revs are nice in the 1/4 because I'm able to finish in 3rd gear.

    Ultimately I'd like to tear it back down and go the 6" rod + single eyebrow forged slugs route and possibly have the decks zero cut. But with what I spent on this go-round I may not have the disposable income to do that for several years.

    I'm pretty much done fine tuning VE and am waiting for a GPS board to build my performance computer for tuning WOT. I may have time this weekend to do more fine tuning on hot starts. I've gotten to the point it's starting reliably but not very "enthusiastically" between 120F and 150F. Hot starts are a little less "enthusiastic" also. As I mentioned previously it seems to fire on the first full compression stroke, but instead of picking up revs exponentially like the stock tune it sort of comes up to speed over two or maybe even three revolutions. I guess I'll start working in small increments on hot start to see whether it wants more or less fuel.

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