Dialing in low LSA cam idle

[blkscooby]

Idle clip from this morning, when I got to work. It idles better in gear.

http://youtu.be/OTxiIqL9B-Y

[IDRIVEAG8GT]

Oh you're Enginerd off the G8 forum aren't you? License plate gave it away

Sounds good to me, now you need to time your injectors to the cam (so do I) and rid yourself of that crappy axleback setup. I hated my Magnaflow as it sounded like that too, till I changed to this:

http://www.youtube.com/watch?v=Rth8K...g&feature=plcp

[blkscooby]

Oh you're Enginerd off the G8 forum aren't you? License plate gave it away

Sounds good to me, now you need to time your injectors to the cam (so do I) and rid yourself of that crappy axleback setup. I hated my Magnaflow as it sounded like that too, till I changed to this:

http://www.youtube.com/watch?v=Rth8K...g&feature=plcp

Nope, I'm blkscooby on all forums. I have the Dynomax ST axlebacks that I welded 'cause I have a limited budget. I like how it sounds. It sounds brutal at idle, quiet at cruise, perfect at WOT.

[IDRIVEAG8GT]

Nope, I'm blkscooby on all forums. I have the Dynomax ST axlebacks that I welded 'cause I have a limited budget. I like how it sounds. It sounds brutal at idle, quiet at cruise, perfect at WOT.

Hmm, I was about to say, I didn't know you (assuming you were the other person) had cammed your car.

Eh, I hate the plugged up popping sound at idle, that's essentially from tip resonance which is excessive back-pressure created at the Y in the tips. It hurts performance, but not enough to care about if you like it like that.

Have you looked into injector timing?

[blkscooby]

Yeah, it added 13* to the EOIT boundary last week and it seemed to cut down on the raw fuel smell but it also changed the exhaust note. Not sure where it should ultimately end up, hopefully someone else can help. I read through the whole Gen 3 thread discussing it but it was very helpful for tuning a Gen 4.

[IDRIVEAG8GT]

PM sent.

[DSteck]

Pay close attention to when your intake valve opens and when your exhaust valve closes.

[blkscooby]

Pay close attention to when your intake valve opens and when your exhaust valve closes.

I plan to get more scientific about the tuning EOIT later; I just wanted to see if increasing the boundary and positive or negative would affect the desired change. It seems advancing the boundary values does do what I assumed it would.

[IDRIVEAG8GT]

That's what Steck and I are discussing.

So you added degrees to the boundary target to clean up the fueling? I always tried to retard it. Maybe that's why it seemed to get worse when I messed with the boundary target

[blkscooby]

Ehh, bored at work today, soooo...

I attached a spreadsheet that calc'd my valve events but the summary is

0.050" lift closed
IVO- 354.4 IVO- 327
IVC- 573.5 IVC- 602
EVO- 129.5 EVO- 103
EVC- 362.5 EVC- 398

Stock EOIT normal, warm engine, at idle is (520-110)=410* ATDC. My new target is (533-110)=423*.


Quote from Chris on LS7 injection tables( same logic as the G8), borrowed from the EOIT thread...

Quote:
Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle.

Normal End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the normal pulse (the main pulse) should finish. The hardware calulates the start of injection time from the EOIT and the desired PW.

Makeup End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the first makeup pulse should finish. Makeup pulses are extra pulses that can be injected to inject more fuel during an injection cycle rather than having to wait for the next cycle. There can be more than one makeup pulse but the makeup EOIT specifies the EOIT of the first makeup pulse.

The makeup PW minimum is a minimum PW for the makeup pulses, they cannot be shorter than this (if they are they don't happen).

So you have the boundary that defines the injection cycle, a normal EOIT that specifies the EOIT for the main pulse, and finally a makeup EOIT that specifies the EIOT for any makeup pulses that might be needed if a fuel increase is commanded during an injection cycle but after the main pulse has occurred.

Hope that helps.

Chris...

[blkscooby]

That's what Steck and I are discussing.

So you added degrees to the boundary target to clean up the fueling? I always tried to retard it. Maybe that's why it seemed to get worse when I messed with the boundary target

I tried to retard it first and it had no affect. Then I advanced it and it was better. +13* may not be ideal for me but now after researching further I believe that advancing the boundary some amount will improve the idling.

[blkscooby]

Now that I have the idle airflow fixed and the low end MAF correct, I pushed the EOIT out to 20* advanced and the car is awesome. So I'm not quite sure how to get from cam overlap to required EOIT advance, but 20* EOIT for my 8* overlap cam works great. Just have to fix an exhaust leak and I'm on to E85 tuning.

[DSteck]

20* may not be mathematically perfect, but definitely a step in the right direction. I think you mean you retarded EIOT though. Advancing would be spraying sooner and losing more through the exhaust valve.

Ideally, 0.006" events should be used if you really want to get great results. Bigger injectors give more flexibility too because of the drastically reduced crank rotation of the firing.

[IDRIVEAG8GT]

Now that I have the idle airflow fixed and the low end MAF correct, I pushed the EOIT out to 20* advanced and the car is awesome. So I'm not quite sure how to get from cam overlap to required EOIT advance, but 20* EOIT for my 8* overlap cam works great. Just have to fix an exhaust leak and I'm on to E85 tuning.

Post your latest tune up. I'd like to pit it against this stock file I have in front of me.

[blkscooby]

20* may not be mathematically perfect, but definitely a step in the right direction. I think you mean you retarded EIOT though. Advancing would be spraying sooner and losing more through the exhaust valve.

Ideally, 0.006" events should be used if you really want to get great results. Bigger injectors give more flexibility too because of the drastically reduced crank rotation of the firing.

Yes, retarding the injection to end later in the intake stroke. By advancing, I meant adding to the timing of the injection boundary.

Here's my current tune.

[bluegoat06]

Ehh, bored at work today, soooo...

I attached a spreadsheet that calc'd my valve events but the summary is

0.050" lift closed
IVO- 354.4 IVO- 327
IVC- 573.5 IVC- 602
EVO- 129.5 EVO- 103
EVC- 362.5 EVC- 398

Stock EOIT normal, warm engine, at idle is (520-110)=410* ATDC. My new target is (533-110)=423*.


Quote from Chris on LS7 injection tables( same logic as the G8), borrowed from the EOIT thread...

Quote:
Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle.

Normal End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the normal pulse (the main pulse) should finish. The hardware calulates the start of injection time from the EOIT and the desired PW.

Makeup End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the first makeup pulse should finish. Makeup pulses are extra pulses that can be injected to inject more fuel during an injection cycle rather than having to wait for the next cycle. There can be more than one makeup pulse but the makeup EOIT specifies the EOIT of the first makeup pulse.

The makeup PW minimum is a minimum PW for the makeup pulses, they cannot be shorter than this (if they are they don't happen).

So you have the boundary that defines the injection cycle, a normal EOIT that specifies the EOIT for the main pulse, and finally a makeup EOIT that specifies the EIOT for any makeup pulses that might be needed if a fuel increase is commanded during an injection cycle but after the main pulse has occurred.

Hope that helps.

Chris...

Jeremy, this is awesome, how're you arriving at this values in the calculation, for instance where does the 520-110 or 533-110 comes from ?
"Stock EOIT normal, warm engine, at idle is (520-110)=410* ATDC. My new target is (533-110)=423*"

[DSteck]

Look at the modifiers and read the descriptions.

[HRD]

Ehh, bored at work today, soooo...

I attached a spreadsheet that calc'd my valve events but the summary is

0.050" lift closed
IVO- 354.4 IVO- 327
IVC- 573.5 IVC- 602
EVO- 129.5 EVO- 103
EVC- 362.5 EVC- 398

Stock EOIT normal, warm engine, at idle is (520-110)=410* ATDC. My new target is (533-110)=423*.


Quote from Chris on LS7 injection tables( same logic as the G8), borrowed from the EOIT thread...

Quote:
Boundary is the latest point in time that fuel can make it into the cylinder for the current injection period. It is measured in degrees AFTER TDC compression. It is also the earliest the injector can fire again after the completion of the last injection event. ie. the boundary defines the start/end of a complete injection cycle.

Normal End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the normal pulse (the main pulse) should finish. The hardware calulates the start of injection time from the EOIT and the desired PW.

Makeup End of Injection Target (EOIT) is the angle before the boundary (in degrees) that the first makeup pulse should finish. Makeup pulses are extra pulses that can be injected to inject more fuel during an injection cycle rather than having to wait for the next cycle. There can be more than one makeup pulse but the makeup EOIT specifies the EOIT of the first makeup pulse.

The makeup PW minimum is a minimum PW for the makeup pulses, they cannot be shorter than this (if they are they don't happen).

So you have the boundary that defines the injection cycle, a normal EOIT that specifies the EOIT for the main pulse, and finally a makeup EOIT that specifies the EIOT for any makeup pulses that might be needed if a fuel increase is commanded during an injection cycle but after the main pulse has occurred.

Hope that helps.

Chris...

Would you please post a link to the original thread about the LS7 injection tables? I have searched and found this same quote in many threads, but can't find the original. Thanks.

[blkscooby]

Jeremy, this is awesome, how're you arriving at this values in the calculation, for instance where does the 520-110 or 533-110 comes from ?
"Stock EOIT normal, warm engine, at idle is (520-110)=410* ATDC. My new target is (533-110)=423*"

This is simply the boundary minus the normal. I pushed the boundary so that it affects both the normal fuel pulse and any makeup pulses. I could have adjusted the normal but low RPM was 0* and I wasnt sure it would work with a negative value here and the makeup pulses would not have been shifted.

[blkscooby]

Would you please post a link to the original thread about the LS7 injection tables? I have searched and found this same quote in many threads, but can't find the original. Thanks.

http://www.hptuners.com/forum/showthread.php?t=32510