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R33 25det - runs with afm unplugged, dies with canister vacuum blocked

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Hey guys, Hope this is in the right place.


Looking for some help with an issue, have done lots of searching\reading but still unsure. Will try and explain as best I can.

Have an r33 sedan, the factory 25det was really tired. So when doing manual swap I put in a plus t I had that had been freshened up.


All back together, car will not start or run with AFM plugged in. Will start and idle with it unplugged, plug it in while running and car will die. Some have pointed towards fuel pump being an issue. I have a walbro intank pump I will put in over the weekend to try. Have tried a second AFM, same result.


Also, the vacuum line from intake plenum that would normally go to the canister at front of engine bay. If I block this while engine running it will die also which has me stumped.


Any ideas of where to check etc. would be much appreciated.


Cheers in advance.

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What ECU?  Asking DET ECU to run from DE AFM or vice versa would not be recommended.

As to the vacuum line....it sounds like it is breathing through this hose at idle.  If you cannot close it, it implies that the idle control valve is not working.

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Cheers for the response man,


Car is factory det, loom is all s1 25det, connected to det ECU. and the AFM is the one off the original det motor.


Thanks for the insight on the vacuum issue. Was not sure when it was supposed to be flowing or not. It is breathing through it from idle, so will check the idle control valve plug, piping and clean the valve I guess.

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