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-   -   Question about Port / DI changeover (https://www.ft86club.com/forums/showthread.php?t=141834)

radroach 08-09-2020 11:46 AM
Question about Port / DI changeover
 
I've wondered something regarding the Port / Direct Injection changeover point. I know that the car switches from port to direct injection some time after warmup and the car is stopped, idling for ~5 -10 seconds.

My question is, what happens if you don't stop and let it idle down / switch injection modes? What if I leave my house right now and get on the highway and drive two hours without stopping? Will it stay stuck in port injection mode?

Gloonge 08-09-2020 11:48 AM
Quote:
Originally Posted by radroach (Post 3356271)
I've wondered something regarding the Port / Direct Injection changeover point. I know that the car switches from port to direct injection some time after warmup and the car is stopped, idling for ~5 -10 seconds.



My question is, what happens if you don't stop and let it idle down / switch injection modes? What if I leave my house right now and get on the highway and drive two hours without stopping? Will it stay stuck in port injection mode?
It should switch the injectors as necessary. I don't believe that the port injectors are only used for startup.

Fred E 08-09-2020 04:26 PM
Quote:
Originally Posted by radroach (Post 3356271)
I've wondered something regarding the Port / Direct Injection changeover point. I know that the car switches from port to direct injection some time after warmup and the car is stopped, idling for ~5 -10 seconds.

My question is, what happens if you don't stop and let it idle down / switch injection modes? What if I leave my house right now and get on the highway and drive two hours without stopping? Will it stay stuck in port injection mode?
Once you start driving and pressing the gas pedal, the ECU changes over to 100% direct. The port injectors only inject at higher loads for supplemental fueling.

Kodename47 08-09-2020 07:33 PM
Quote:
Originally Posted by Fred E (Post 3356305)
Once you start driving and pressing the gas pedal, the ECU changes over to 100% direct. The port injectors only inject at higher loads for supplemental fueling.
Incorrect.

This is the ratio map for Port Injection - 0% is DI only, 100% is PI only (table is slightly modified, the red boxes should also read around 35%)

https://www.ft86club.com/forums/atta...1&d=1422886610

That is for original cars, the facelift actually run PI more at higher loads, likely to do with better fuel mix.

@radroach it makes no difference when you set off. What you have read is about idle only.

Fred E 08-11-2020 09:17 AM
Quote:
Originally Posted by Kodename47 (Post 3356356)
Incorrect.

This is the ratio map for Port Injection - 0% is DI only, 100% is PI only (table is slightly modified, the red boxes should also read around 35%)

https://www.ft86club.com/forums/atta...1&d=1422886610

That is for original cars, the facelift actually run PI more at higher loads, likely to do with better fuel mix.

@radroach it makes no difference when you set off. What you have read is about idle only.
I'm confused; doesn't that table confirm what I said? 0% port ratio at lower loads (less than .4) and a non-zero ratio at higher loads? My experience is limited to what I've observed on my own car, but it must have been tuned that way if that's different from stock; sorry for any confusion.

DarkPira7e 08-11-2020 01:28 PM
Quote:
Originally Posted by Fred E (Post 3356824)
I'm confused; doesn't that table confirm what I said? 0% port ratio at lower loads (less than .4) and a non-zero ratio at higher loads? My experience is limited to what I've observed on my own car, but it must have been tuned that way if that's different from stock; sorry for any confusion.
The verbiage you used was that once you start driving and adding load, the ECU switches to 100% direct. I think that's why he was confused

Kodename47 08-11-2020 05:03 PM
Quote:
Originally Posted by DarkPira7e (Post 3356889)
The verbiage you used was that once you start driving and adding load, the ECU switches to 100% direct. I think that's why he was confused
Correct, perhaps I was a little eager to jump the gun @Fred E. On a stock engine the only time it's 100% DI is at idle and at WOT between ~2300RPM and 4800RPM. The rest of the time it's a varying mixture.

You don't want to run too much DI only due to the cleaning of the valves and mixture formation.

Turdinator 08-12-2020 12:24 AM
Quote:
Originally Posted by radroach (Post 3356271)
I've wondered something regarding the Port / Direct Injection changeover point. I know that the car switches from port to direct injection some time after warmup and the car is stopped, idling for ~5 -10 seconds.

My question is, what happens if you don't stop and let it idle down / switch injection modes? What if I leave my house right now and get on the highway and drive two hours without stopping? Will it stay stuck in port injection mode?
If you drive before the system is out of its warm up cycle it still uses a mix of port and direct except at idle.


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