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lostsoul

Injector Timing

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Best way to check is with a wideband, and you'll find the ideal timing changes through the rpm range. 

Get your AFRs stable through the rev range, then set the timing statically to one number (say 400deg BTDC end of spray) then do a full throttle run.

Then 350 degrees, then 300 degrees, etc and log all of the results.

Put results into a table and see what gives the richest readings, this will be best timing.

Unless you've got big injectors with small pulsewidths though (like 30%) you'll find injector timing to be fairly irrelevant as most of the time its spraying on back of shut valves anyway.

This is how mine ended up:

iiymk2f4.bl4.jpg

Edited by Davidv

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The mixture will be richest when the engine is burning the most fuel. As the injector timing is being adjusted (and not the volume of fuel) when the reading is richest the engine is burning the most fuel, and not wasting it by passing it through unburnt.

Scott

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TO Davidv

Have you tried the mixture test at lower RPM, say from idle up to 4000. Also have you tried doing this test at smaller throttle openings, say half throttle. Would you get the same best injector timing.

 John

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Hi John, below 4000ish it was all the same results, where it essentially wants to spray on the back of hot valves with as much time to spare before valves open. 

So it was 400 or 450 degrees end of injection before TDC gave best results. I wouldnt expect this to change at part throttle, but I havent tested. 

From memory 400BTDC end of injection is the default timing in the Link setup.
 

Edited by Davidv

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hi all

only for memory, richer afr by earlier injector timing ( closer to 360°) have more effience. the correction are made by ve table ..

anybody experience with timing under load? up to 140kpa (MGP)

benny

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Seeing as this topic has been brought back, what would be the preferred Y axis setup in your injector timing table? Let's say for a boosted engine application running ITB setup? MAP or TP? 

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4 hours ago, Typ17 16vg60 said:

hi all

only for memory, richer afr by earlier injector timing ( closer to 360°) have more effience. the correction are made by ve table ..

anybody experience with timing under load? up to 140kpa (MGP)

benny

What's your duty cycle at 140Kpa?  As per DavidV's comments above once you are over about 25% inj DC, injector timing will have very little influence.  At 50% DC you injector is open for one whole crankshaft revolution...

 

2 hours ago, Jefferson.C said:

Seeing as this topic has been brought back, what would be the preferred Y axis setup in your injector timing table? Let's say for a boosted engine application running ITB setup? MAP or TP? 

In most cases Y axis is not needed, ideal injector timing will be related to transport time (RPM) and intake resonance (again RPM related).  If you have VVT then cam position would be a good Y axis.  If you have staged injection with vastly different primary/sec locations then choose something that reflects the % secondary.

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This is the INJ table on the new firmware R32-34 GTR map. Now, lets say you are using an RB25 cylinder head with RB26 ITB setup. The VCT is not variable and just ON/OFF with selective RPM points.
If I were to explore the outcome of adjusting the table, would you recommend leaving the Y axis MAP? 

 

inj.timing.png

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