[rjahl]

Originally Posted by philtr

Yes, I agree that the DME has the ability to control individual injectors. I just don't see how it fine tunes AFR on each cylinder since there are only 2 O2 sensors. Even the fuel trims are divided into bank 1 and 2 which likely confirms it meters fuel to each bank based on that O2 sensor and other feedback. I wonder in what cases it changes individual injector metering?

Are you sure about this. The DME has tables that indicate how far downstream the O2 sensors are located. It's not a temp based table, it's time.

Why care about the time between the exhaust port and the sensor unless you are tracking each exhaust cycle?

Another clue would be the injector adaptations. Do you have two groups of three or 6 individual values?

[upshift_downshift]

Originally Posted by rjahl

Are you sure about this. The DME has tables that indicate how far downstream the O2 sensors are located. It's not a temp based table, it's time.

Why care about the time between the exhaust port and the sensor unless you are tracking each exhaust cycle?

Another clue would be the injector adaptations. Do you have two groups of three or 6 individual values?

It sounds to me like a transport delay. There will be a delay between when the ECU changes fueling, and when the sensor sees the change. This will be a lot slower than the exhaust pressure wave, which travels at the speed of sound. The transport delay is the time it takes the actual gases to flow to the sensor location.

The sensor also has its own intrinsic delay as well, which can be longer than the time between engine cycles at higher rpm.

I suspect the ability to change fueling individually is only for the purposes of coding them in the first place. There may also be some internal balancing going on, as each cylinder may not receive equal airflow. This shouldn't happen with a properly designed manifold, though.

[florida2002m3]

Came across this thread researching where to buy as well since Advanced auto is out of stock. A search of FJ1284 brought up summit racing $109 each Found the same price on their ebay store as well. Says new, comments say they are -12.

https://www.summitracing.com/parts/smp-fj1284

[6ixSpd]

Originally Posted by florida2002m3

Came across this thread researching where to buy as well since Advanced auto is out of stock. A search of FJ1284 brought up summit racing $109 each Found the same price on their ebay store as well. Says new, comments say they are -12.

https://www.summitracing.com/parts/smp-fj1284

Nice find!

[florida2002m3]

FCP has decouplers for $1 a piece. $5 ish for shipping. I got 12 just in case.

[philtr]

Originally Posted by florida2002m3

Came across this thread researching where to buy as well since Advanced auto is out of stock. A search of FJ1284 brought up summit racing $109 each Found the same price on their ebay store as well. Says new, comments say they are -12.

https://www.summitracing.com/parts/smp-fj1284

Nice! I found these last month but they were out of stock with no guaranteed availability in sight according to Summit. Thanks for letting us know they are back.

Has anyone ordered and received these that can confirm exactly what they are? (index number, etc)

[florida2002m3]

Mine should be delivered mid next week. I will update with my findings.

Their ebay store said “more than 10 in stock”. So lets hope they stocked up!

[florida2002m3]

Ordered on thursday, showed up today, monday. Should have rish shipped the decoupers

[mweisdorfer]

Originally Posted by philtr

I'm still rocking index 1 injectors and they seem to be working reasonably well but I'm also noticing occasional stumbling and roughness at idle even with walnut blasting and new plugs/coils so I think the writing is on the wall. Also, seems prudent to replace them before cranking up the boost with upgraded turbos

With that said it looks like I missed the boat on reasonably priced index 12 injectors. I've seen some good advice here on the options from places like Advance Auto but these "standard intermotor" FJ1284 injectors are sold out pretty much everywhere. I see one reputable place has them for $108/ea but again out of stock and over a month to get in (going to call them tomorrow). So a few questions:

Anyone know of sources for reasonably priced injectors that are in stock?

Have the intermotor and other differently branded injectors that aren't refurbished truly verified to be OEM or at least fully equivalent to index 12's?

Finally, any crazy people that would vote to keep going with my index 1's until there is an obvious problem beyond occasional idle roughness without fault codes?

Thanks!

How's your vacuum lines?

Getting any codes or shadow codes ?

[IllSic_Design]

Originally Posted by florida2002m3

Came across this thread researching where to buy as well since Advanced auto is out of stock. A search of FJ1284 brought up summit racing $109 each Found the same price on their ebay store as well. Says new, comments say they are -12.

https://www.summitracing.com/parts/smp-fj1284

Wish i saw this when you posted it, I would have bought some. They are now at $250/ea

[noorj]

yeah it's crazy how fast summit increased their price


anyone else know a good source for the intermotor injectors?

edit: here's the cheapest I found

https://www.oreillyauto.com/detail/b...q=FJ1284&pos=0

[IllSic_Design]

yeah o'reilly was the cheapest I could find

[rjahl]

Originally Posted by IllSic_Design

yeah o'reilly was the cheapest I could find

Advance auto has better deals when you consider their discounts but they don't have stock and I can't get them to commit when they will have stock. Lifetime warranty, so I may hold out a few days to see what comes up.

[rjahl]

Originally Posted by rjahl

Advance auto has better deals when you consider their discounts but they don't have stock and I can't get them to commit when they will have stock. Lifetime warranty, so I may hold out a few days to see what comes up.

My bookmarked OReillys page now shows a discount code FEB20 for 20% and the details show lifetime warranty.

Not sure if that's new, but it's good enough for me.

[IllSic_Design]

feb20 only took off a total of $50 of the $924 price. Definitely doesn't work out to 20% lol, if so i'd probably grab some.

[noorj]

I did 3 separate purchases of 2 injectors (6 total) so I paid $775 and free shipping

[IllSic_Design]

Originally Posted by noorj

I did 3 separate purchases of 2 injectors (6 total) so I paid $775 and free shipping

hmm from oreiily? Might have to do that

[noorj]

Originally Posted by IllSic_Design

hmm from oreiily? Might have to do that

yep, ordered them yesterday and the tracking shows delivered an hour ago. I'll confirm when I get home that they're the index 12's everyone else seems to be getting

Came in - all seem like legit index 12’s just without decouplers like previously mentioned

[rjahl]

Can anyone provide a real answer to why injector index numbers can not be mixed on a single bank?

I've read all the parrot responses based on BMW suggestions however BMW is the group that clearly screwed the specs in the first place. Not really a completely trustworthy group on this issue.

The DME has unique calibrations for power and flow for each injector so why would a bank need to be matched?

Looking for a technical reason.

[rjahl]

Advance Auto finally has these in stock again. New parts with Life time warranty at $110.39 after 20% discount. Used a different different discount code and order for each otherwise a $50 max discount would apply.

[MysticRob]

Originally Posted by rjahl

Can anyone provide a real answer to why injector index numbers can not be mixed on a single bank?

I've read all the parrot responses based on BMW suggestions however BMW is the group that clearly screwed the specs in the first place. Not really a completely trustworthy group on this issue.

The DME has unique calibrations for power and flow for each injector so why would a bank need to be matched?

Looking for a technical reason.

Doubt you'll find one, as it doesn't make any sense as you stated. Even TSBs and service manuals get things wrong sometimes. The need to not mix sub-11 injectors with newer ones appears to be one of those times, especially seeing as how there are multiple people here doing just that without ill effects.

[Jeff@TopGearSolutions]

Originally Posted by rjahl

Can anyone provide a real answer to why injector index numbers can not be mixed on a single bank?

I've read all the parrot responses based on BMW suggestions however BMW is the group that clearly screwed the specs in the first place. Not really a completely trustworthy group on this issue.

The DME has unique calibrations for power and flow for each injector so why would a bank need to be matched?

Looking for a technical reason.

The logic about mixing index 12 with older injectors was that their flow properties were different.

That's why you usually hear people saying at least replace the entire bank, cyl 1-3 and 4-6.

Your Air Fuel Ratio is controlled by averaging the 3 cylinders exhaust gasses of 1 bank. So if you have 1 Cyl with an index 12 performing well with fuel atomization and the other 2 cylinders off, this can screw the AFR reading and you won't be fueling appropriately per bank since it's an average of the 3. You may be sending too much or too little fuel to that bank of cylinders as a result since it's just an average of the 3.

I understand folks are on a budget but there is really no reason to keep index 10 or less, they are all problematic injectors that can either leak or atomize poorly. Leaking injectors are arguably worse as it washes the oil and that's why you see a lot of crank bearing failures and such.