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Sequential Injection Timing

EFI Tuning Fundamentals

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I recently started to work with an EMS 4860 ecu wired to a sr20vet AWD setup and noticed there’s a table I didn’t understand. After all my searches, I failed to find a definite answer as to what would be proper values to input. This ecu has been tuned before by someone else and the engine has been dumping fuel from idle throughout to rev limiter (10.5 AFR) on idle. The table is called “Sequential Injection Timing” and it has been modified by who ever did this tune before... (not necessarily saying this table is the fault, jus saying if other aspects of the ecu has been improperly setup... maybe this table has faults as well)

Anyone here has a working understanding of this table? I would like to understand what this is about, thanks in advance.

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Do you have more documentation on what the units mean? Usually an injection timing table for sequential port injection is either start of injection or end of injection, and then you need to understand if that is in relation to TDC firing or TDC intake or maybe even something else. Based on the "injector timing" blue line in the upper right hand corner, it's injecting late into the compression stroke, and then the fuel is sitting in the intake port until the next cycle. That's not automatically good or bad. You have to move the values in the table around and see what happens.

It's more common to see the end of injection somewhere around TDC intake (near when the intake valve opens). If I had to guess this isn't the root cause of your super rich condition. However if it is end of injection based table, typically you start out by keeping it fixed to a point before or after the intake valve closes (open valve injection or closed valve injection).

Attached is all the documentation from the ecu software manual, I’m thinking the safer confirguration would be to setup multipoint 720? Since it’s 1600cc injectors?

Attached Files

Multipoint 720 is basically early 80s style. It's at type of batch fire injection. You can certainly try it but it's not as precise as full sequential injection.

Since I'm still not completely clear on what the units for the injection timing map are, just keep in mind that typically you want the blue "injection" part in the upper right corner to be in the "intake" part of the graph.

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