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Max Throttle = Disabled Injectors During Cranking/starting?

Paulusc44
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Paulusc44 Enthusiast

Paulusc44

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Hey all,

I have a factory ECU with tuned EPROM and RX7 550cc injectors that run the same resistance as factory RB20DET items..

Just a quick question, is it true that the injectors are 100% disabled if the throttle is at WOT (Max throttle/wide open throttle) during cranking/startup? I know this is the case for some vehicles and some aftermarket ECUs depending on tuning etc, but cant find any info for the S1 RB20DET/RB25DE?

At the moment I believe my cranking pulse width is too big and want to double check this..

Cheers

Paulusc44 Enthusiast

Paulusc44

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Posted

For sure yeah can throw the multi meter over em, just wanted to see if anyone knew before I possibly throw waay to much fuel in there + Im a Autotronics student and have not been told about this as of yet, was watching an American compression + leak down test and they stressed to depress the throttle all the way to the floor to disable the injectors rather than removing the EFI fuse, pump relay etc.. Just thought it was interesting and wanted to know if it was universal and if Nissan used the same idea :)

GTSBoy Grand Master

GTSBoy

Posted
Posted

It's not universal. More to the point, the RB20 TPS does not have any way to register WOT other than resistance - there's no switch. So the 100% requirement would not be particularly robust/reliable.

Furthermore, the ECU will ignore throttle position when cranking, at least with respect to how much fuel it injects. The cranking map is pretty flat!

Paulusc44 Enthusiast

Paulusc44

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Posted (edited)

It's not universal. More to the point, the RB20 TPS does not have any way to register WOT other than resistance - there's no switch. So the 100% requirement would not be particularly robust/reliable.

Furthermore, the ECU will ignore throttle position when cranking, at least with respect to how much fuel it injects. The cranking map is pretty flat!

Ok cool, I know theres no switch but was wondering if maybe the ECU could sense max voltage output from the TPS or if the TPS had a max voltage contact or something like that.. Obviously not though haha :)

Im simply going to apply + Temperature to the 2 pin Coolant temp sensor before cranking to see what effects this has on starting, have just done a resistance test on it and all working fine, surprising how flat the cranking pulse width variance is but there is a quite a difference between say 0 and 40' C.. Should give me a good idea on whether or not the pulse width is to large at startup.. Only have limited time to spend on it as Im at uni and have to travel between Citys to work on her :/

Edited by Paulusc44

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