Need help!! Pilot Injection

[Jdavis1986]

I have an LLY and my question is according to my CTS3 my pilot timing will get up to 33 degrees when say I go from a stop and somewhat get on it to get up to speed and of course have that bad knock and I am wanting to know why it’s get that high because I don’t believe it should. I have EFI Live flashscan V3 also. Truck has built motor, 68mm turbo, 60 over injectors, full y bridge and intake therefore no egr, 165 lift pump btw. Needing any kind of guidance and would be extremely appreciative for the feedback.


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[2004LB7]

Sounds like someone didn't do any adjustments for pilot when making adjustments to the main timing

Pilot is referenced off the main timing. If the main injection timing is set at 10° and pilot is also at 10° then pilot will be injected at 20°

Fix the tuning and you'll fix your problem

 

[Jdavis1986]

Man I appreciate it. So basically 10degrees in between the 2?


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[Bdsankey]

Sounds like someone didn't do any adjustments for pilot when making adjustments to the main timing

Pilot is referenced off the main timing. If the main injection timing is set at 10° and pilot is also at 10° then pilot will be injected at 20°

Fix the tuning and you'll fix your problem

Bingo

Man I appreciate it. So basically 10degrees in between the 2?


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There's multiple timing calculators on this site that will help with your question should you be tuning it yourself.

 

[Jdavis1986]

Ok thank you I’ll try and find some.


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[2004LB7]

Man I appreciate it. So basically 10degrees in between the 2?


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That was an example. There is no fixed number to use. There is going to be a lots of timing differences between the low and high rpms and low and high fueling. No single number will work. It helps to study the stock tune and see what timing they used and get an idea what they where trying to do. But no one here is going to be able to tell you what number is going to work in your tune

Start with logging and make notes when it rattles and make adjustments to those areas in the tune

When it knocks, what is the main timing at ?

 

[Jdavis1986]

Thank you. It’ll be at 6,7 even when pilot gets that high.


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[Jdavis1986]

I just used timing table spreadsheet and knocked down pilot and tiny bit better but now I have the bad lag when shifting especially when taking off from a stop 1st to 2nd. Falls on its butt bad then for couple seconds has nothing.


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[2004LB7]

Yep, timing is one of those things you can spend weeks on. I think my first time tuning my LB7 I made over a hundred revisions testing out different values.

Going to need to play with both main and pilot timing

Less main timing may help spool the turbo but is more smoky. Find the sweet spot

 

[Jdavis1986]

Hear that lol. Timing table I did 50/50 with minimum set to 4. No lag in shifting before doing this revision. Go figure.


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[2004LB7]

Try lower timing on the middle left of the table and gradually rise up as you go right. And up as you go down. In your cruising RPM range, anywhere around 6~10 or so degrees is normal.

Limit total main timing to something like mid 20's

Remember, when you are spinning faster, you need more timing as you have less time between injection and when the piston starts to move back down again. But when you are going from a stop, the engine isn't moving much more then idle and you can put too much timing on it and it will raise cylinder pressure and knock. It will also hurt spoiling

And as always, don't forget that fuel pressure and boost pressure all play into the speed of combustion. So if you raise pressure, lower timing. Raise boost, increase timing

 

[Jdavis1986]

Man I truly appreciate the feedback. I’ll do that in next couple of days and do an update. Thank you again and to the others for their feedback.


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[Woody35]

Adjusting Pilot Timing when Base Timing is changed?

Adjusting Pilot Timing when Base Timing is changed? I would like to know how important it is to scale back pilot timing as you increase base timing. One of the first thing I experimented with on my tunes was to use a timing calculator to set my timing tables with a minimum of 50% injection...

forum.efilive.com

I too have spent a lot of time making timing revisions. Make small changes, log, and listen to the engine. Be aware temperatures are changing which will complicate making comparisons.

 

[Jdavis1986]

Woody35, any thoughts as to why since I played with my pilot and main timing the truck is a lot more responsive which I love but now also the throttle at low speeds say pulling in my driveway which is long it’ll do the bouncing rpm’s up down just enough to where you can hear it and I still have the slow gear changes where when it shifts it’ll pause for a sec pulling head forward in the seat before taking off even though I never messed with the TBI so I’m lost with this dilemma.


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[Woody35]

Woody35, any thoughts as to why since I played with my pilot and main timing the truck is a lot more responsive which I love but now also the throttle at low speeds say pulling in my driveway which is long it’ll do the bouncing rpm’s up down just enough to where you can hear it and I still have the slow gear changes where when it shifts it’ll pause for a sec pulling head forward in the seat before taking off even though I never messed with the TBI so I’m lost with this dilemma.


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Without looking at your file its hard to say. I would keep Low RPM/Low Load Timing pretty close to stock. Take a look at your ECT and IAT multipliers to make sure its not getting too out of whack. That should cure your lope.

 

[Jdavis1986]

Without looking at your file its hard to say. I would keep Low RPM/Low Load Timing pretty close to stock. Take a look at your ECT and IAT multipliers to make sure its not getting too out of whack. That should cure your lope.

Ok I do know I haven’t touched any multipliers because I still have no clue on those lol. Different question I do have and apologize for my ignorance for all this but how do you guesstimate low load when looking at the maps? Again I appreciate your feedback.


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[2004LB7]

Ok I do know I haven’t touched any multipliers because I still have no clue on those lol. Different question I do have and apologize for my ignorance for all this but how do you guesstimate low load when looking at the maps? Again I appreciate your feedback.


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Logging is your friend. No matter how much someone holds your hand in tuning. Nothing beats good logs and real world data from your own truck. If you have trouble making sense of a log, post it up and we will halp out

I like to do steady MPH down a flat road at the cruising speeds found in my area. 45 or 55 on back highways. 70 on the freeway, etc. get at least a few minutes of logs from each area. With as flat and level road as possible. Then look at the average mm3 and timing used. That will tell you where on the table the truck sits while cruising under low load

 

[Jdavis1986]

Ok can definitely do that. I’ll update once done.


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[Woody35]

Ok I do know I haven’t touched any multipliers because I still have no clue on those lol. Different question I do have and apologize for my ignorance for all this but how do you guesstimate low load when looking at the maps? Again I appreciate your feedback.


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Multipliers will make adjustments to timing based on changes in Coolant Temp, Intake Air Temp, and Fuel Temp.

 

[darkness]

I don’t think you want to mess with any of your multipliers. But for sure know what they do. You need to look at both tables, the multiplier and the actual table. You will find out that most of them don’t affect the tune much but in very specific areas. If you’re having an issue in an area, check your logs and then you can think about changing the multipliers.