Rb25 With Rb20 Loom And Rb20 Ecu Wont Run?

[aussy-boyz]

Hey guys we have a rb25 running a rb20 loom with rb20 ecu. Car fires at start then just wont rev and dies. but when we plug rb25 computer it runs fine. then pluged rb20 computer into r33 and runs fine. so both computers are ok, Reason for wanting to use rb20 computer is for remap purposes. Also has 550cc injectors. Any ideas to try would be great, cheers

[Bsa]

Did you change the tps to rb20

[BOOZTJUNKEY]

Yeah 25s have a different tps from memory .

[aussy-boyz]

Yeah have tried both man

[aussy-boyz]

is running a rb20 afm,25 knock sensors as well

[Bsa]

20 and 25 knock sensors are the same from memory you getting spark or fuel? Is the ecu ok

[Bsa]

The injectors in guessing rb20 only suppors 270 tge 550 will flood tge motor and die

[BOOZTJUNKEY]

So it's a factory ecu with 550cc inj?

It won't start with them go bact to stock or tow to get tuned

[aussy-boyz]

that was my thoughts but runs with 25 computer????/

[Bsa]

Yeah they are 370 STD so will allow more fuel controll you need it tuned for the rb20 injectors to work

[DVS JEZ]

Is it a series 1 rb25???

Need's a nistune

And some new spark plugs

[aussy-boyz]

Yeah series 1. Also has 25 injectors not 20.

[Bsa]

I'm just saying you can't just throw in injectors and drive it needs to be tuned to suite

[aussy-boyz]

Yeah i no but it should run just super rich?

[BOOZTJUNKEY]

No not necessarily if they are two big they could flood the chamber and not run at all go back to stock or tune it!

[Moodles2]

Injector sizes are different that's the obvious part, but the injector latency will be completely different. The aftermarket injector having a completely different lag time vs the factory injector, those 550cc's might be injecting too early or too late than the factory ECU is expecting which will most likely explain why it can't idle.

[Birds]

Wouldn't even contemplate a slight upgrade in injector size without a tuning the ECU.

[aussy-boyz]

I know it needs a tune im not retarded. I just wanted.it actually running when i took it

[Bsa]

Get a tune and it will run

[DVS JEZ]

Get a NIStune and it will run

fixed