Focus 9 OBD+ DME worth it?

[Tom]

Thanks again Joe. Yes, it dawned on as I mulled it overnight that the single driver sees 4 injectors, throwing a lot of my math off. I'm happy to hear you are digging in on injector compatibility and driver tuning, and feel confident that iron will be better served in your much hotter fire. I've since found psuedo-Seimen's-Deka high-z 52lb injectors at Five-O and am inclined to give them a try for now. They have about the flow I'm looking for, and I assume your driver will saturate them trying to achieve the peak current for the whole pulse.

https://www.fiveomotorsport.com/makes/1 ... long-ev14/

Alternative, seems there are still true 60lb Seimens-Deka injectors floating around on eBay, if anyone has reason to think the Five-O injectors are inferior...

The fuel scaling is buried in the thread below, but I am planning to do a separate write-up/thread spelling it all out now that I have practical experience doing it.

viewtopic.php?t=3574

[chrischrischris]

Spending the morning reading through this discussion from last year while bouncing information off chatgpt. The AI is saying that the stock injector driver is two channel, so even though both channels fire at the same time, electrically there are separated and should be evaluated as two separate loads of two injectors each.

To summarize from the AI: Even though it is batch fire, the driver is not a single channel and the total resistance in the circuit should therefore not be divided by four. In other words, the driver circuit doesn't really "see" four injectors since each channel is separate. Is it more correct that channel one sees two injectors and channel two sees two injectors?

First of all- is any of this true? And would this distinction make a difference when evaluating the effect of swapping injectors with different resistance values compared to stock?

[facboy]

Mk2 on the site now, how long has that been there?

[Tom]

Spending the morning reading through this discussion from last year while bouncing information off chatgpt. The AI is saying that the stock injector driver is two channel, so even though both channels fire at the same time, electrically there are separated and should be evaluated as two separate loads of two injectors each.

To summarize from the AI: Even though it is batch fire, the driver is not a single channel and the total resistance in the circuit should therefore not be divided by four. In other words, the driver circuit doesn't really "see" four injectors since each channel is separate. Is it more correct that channel one sees two injectors and channel two sees two injectors?

First of all- is any of this true? And would this distinction make a difference when evaluating the effect of swapping injectors with different resistance values compared to stock?

That is not true. On the factory/Bosch DME, there is one driver that get separated into two channels on the PCB, and those to channels are then split again in the harness to reach the 4 injectors. All 4 injectors are fired by the same driver. Lower impedance injectors can tax that driver, so most folks added a 1 to 2 ohm resistor inline back in the day. The new modern high impedance injectors have made all that mostly a thing of the past though. I'd have to go back and find it, but believe Joe confirmed here on CP that he used modern components with a much higher current capacity, making lower impedance injectors ok to use on his DME.

[pizatski]

@FTECH9

Does anyone know if the Focus 9 Sports DME is able to run low-impedance injectors (2.7ohm) without adding resistors? I haven't seen anything that suggests it can, but seems like it would have been a logical upgrade. Sent an email to Joe as well, but thought I'd ask here in case anyone here knows. I didn't follow the development/discussion on RL, so checking to see if this is something that's already come up....

Can it? Yes. I'm running these without resistors: https://www.fiveomotorsport.com/lucas-5 ... ance-3102/

I do have off-book settings for the FQS and Injector Dead Time (52 lbs and 1.3 - 0.55 ms, respectively), though, to get them to behave well at idle. I've also had to crush the full throttle AFR targets down to the 8s to get AFRs on my wideband to the low 11s under full load and boost. I don't know if this is a consequence of unexpectedly low impedance, but I thought I'd have to do the opposite.

Can it run them for a long time at a high duty cycle without killing the drivers? Unsure. I previously ran the low impedance 36 lb injectors for a few track days and the DME seems fine. I've now run these 55 lb. injectors for over a month with a day and a half at Road America without ill effect. This car spends a lot of time at WOT on that track which is a pretty good test.

I think I read the same thing you read - the drivers and/or heat sinks are beefier on the Focus 9 Sports DME so you don't really need to run resistors with low impedance injectors with these DMEs. Please consider this information anecdotal.

[chrischrischris]

Great feedback. Why did you use the Lucas ones instead of the 550cc green colored injector style?

https://www.fiveomotorsport.com/ev1-uni ... injectors/

[pizatski]

Great feedback. Why did you use the Lucas ones instead of the 550cc green colored injector style?

https://www.fiveomotorsport.com/ev1-uni ... injectors/

No real reason other than they're the only 55lb injectors that came up when searching for my make/model/year/trim on the site and 55lbs was my target for slightly above stock boost and the exhaust/downpipe combination on the car.

I don't see why those other ones wouldn't work, though.