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Old 04-08-2012, 12:35 AM   #1
Scooby Specialist
Member#: 179014
Join Date: May 2008
Location: Oklahoma City, OK
'06 WRX/STi
Built Motor/6766/E85

Default Changing Injector Pulse Width?

Never had to change the IPW on stock injectors but since I have Five0 Motorsports 1400cc's injectors, im needing to change the IPW because im getting misfire's at idle.

Ive done alot of research on these injectors, and everybody said that I need to set the IPW to to .8000+

So, how do I go about changing this?

Here's a screenshot just for reference at what its at.

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Old 04-08-2012, 12:47 AM   #2
john 1badSTI
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04 sti [email protected]
on [email protected] 30psi--spinning


iirc you can log ipw but not directly change it like in a standalone ecu,the calc's for the ipw on the stock ecu is done in the background of the ecu which is not available to you that is why the fuel map is in afr's not pw.
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Old 04-08-2012, 12:55 AM   #3
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05 Stage Free LGT


I think what you really want to adjust is the injector latency. RomRaider's ECU editor will let you edit that table - you're looking at RomRaider's logger in that screenshot.

The ECU automatically adjusts IPW based on what it knows about the injectors (the injector latency and injector scaling) along with the load and the desired AFR. (Plus some compensations.)
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Old 04-08-2012, 01:00 AM   #4
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What would I need to do to the latency to make the IPW raise?
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Old 04-11-2012, 11:43 PM   #5
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What mods do you have?
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Old 04-12-2012, 05:00 PM   #6
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Originally Posted by banshee04 View Post
What would I need to do to the latency to make the IPW raise?
Are you rich or lean?

Latency is pulse width that is added to the base pulse width to compensate for the time it takes the injector to react.

Latency has the most effect on idle and the least effect at WOT. If you are lean at idle, then you need to increase latency. If you are too rich, you need to decrease it.

It looks to me like you latency is probably too high which is causing your base PW to bottom out at the ECU's limit (.5) but without knowing what the AFRs and fueling are doing I can't say for sure. Take a look at the AFR, the AFR learning and the AFR correction to see whats going on.

Also - you should make sure you have a really solid understanding of the principals of tuning for different injectors if you are going to play around with this. You can blow your engine in a hurry if you don't know what you are doing.
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Old 04-18-2012, 06:47 AM   #7
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Do you have an actual flow sheet for the injectors? If so do the following:

Set the injector scaler to the lowest flowing injector.

According to the 50 motorsports website the latency for that series injector is 1.0ms at 14V.

Set your latency at 14V to 1.0ms.

To find the rest of your latencies use the following formula.

---- = ----
1.0 X

Substitute A for your stock latency at 14V.

Substitute Y for the stock latency from the voltage you want to find the new latency for.

Solve for X (cross multiply) You will get 1.0Y=AX

then divide Y
--- = X

X is the new latency for the voltage you are figuring out.

Repeat for all your new latencies to get your baseline and flash the new latencies and scaler to your ECU.

Use romraider to reset your ECU. Then start your car and monitor AF Correction #1, AF Learning #1, coolant temp, and RPM.

Once the car has cycled, coolant temp risen until the fans come on and RPM at 700, look at your AFC1 and AFL1. Once they stabilize add them together. If they equal + or - 5% or less you are OK. If not you need to fine tune.

To fine tune, open the latency table in ECU flash. If the AF is off positive, add that percentage to all the latencies using the increase 1% option. If the AF is off negative subtract that %.

Reflash and repeat until under + or - 5%.

Most people will stop here and will be totally fine (Your factory injectors aren't even tuned this well). You can however fine tune further.

Go for a drive and find a long, empty hill. Start logging you AFC1 and AFL1 and open/closed loop status. Slow down to where you can shift into 5th or 6th at a slow speed and accelerate smoothly. You want to put the engine under max load while staying in closed loop. Can also be done by accelerating slowly through 2nd or 3rd to high RPMs, but you will need more room. And is a bit trickier depending on how quickly your car likes to go into open loop (you can always flash the car to stay in closed loop however).

Take a look at your logs. Where the AFC1 and AFL1 stabilize add them up again. This is the correction for you scaler. Again if it is off by more than + or - 5% adjust your scaler. But this time if it is off negative add that % to your scaler and if it is off positive subtract that number from your scaler.

Now go back and fine tune your latency as described above.

Once you are + or - 5% on both you are pretty much as close as you are ever going to get. And any other fine tuning can be done via your MAF scaling.
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