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R33 Rb25det Build. Safe Mode Cut At 2500-3000rpm, Running Rich.

KaiShin

By KaiShin,
in General Maintenance

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KaiShin Enthusiast

KaiShin

Posted
Posted

Hey Everyone,

Ive been building my rb25det r33 series 2 over the last 12 months or so.

I have it to the stage where it is ready to be registered etc. And have had it running.

However, it looks like it is in safe mode and very possibly the AFM is not working.

Has anyone got any sure fire ways of testing the AFM to see if it is in fact broken or do I need to find someone with a working AFM and hook it up to test it out?

I have checked ohms across all three points on the AFM and none of them read '0' so I am assuming that somewhere inside it is failing at resisting .

Some info. The 02 sensor is a brand new bosch replacement. So this should be working 100% (unless my wiring fails, which Id like to think I wired it correctly). The AFM seems to be the culprit.

Any thoughts from anyone? Or anyone living near Petrie north Brisbane with a spare series 2 AFM we could throw on it to test.

Cheers,

Trent

mad082 Grand Master

mad082

Posted
Posted

try and borrow (or buy) a consult cable. this way you can plug a laptop into the car and see if there are any error codes and check the AFM voltage at the ecu.

as for o2 sensor, it won't make any difference to how it runs. i ran my car for a few months without it being plugged in.

  • 4 weeks later...
KaiShin Enthusiast

KaiShin

Posted
  • Author
Posted

Hey Everyone,

Still having issues here.

Ive got the consult and tested everything over and over again.

It appears that the previous owner of my loom had a safc in it.... not such a huge issue.. traced everything back etc. all good.

The Afm is putting out a voltage signal of around 2.7volts without the engine running. Is this normal?

When the engine is turned over. the air being sucked through cools it to around 2.3volts.

The engine itself wont start while the afm is plugged in. The pulse width on the injectors stays at around 0.8 etc. and the ecu still spits out error code 12 for the afm circuit.

When i disconnect the afm it starts up again in safe mode. injector pulse goes back to normal etc. still with the same error code.

This is a series 2 ecu, loom with pink sticker afm.

Thoughts anyone?

mad082 Grand Master

mad082

Posted
Posted

2.7V is very high for not having the engine running. i think they should be around 1.5V at idle if i remember correctly and 0v if the engine isn't running. it could be a faulty AFM or a wiring issue (such as faulty earth)

gotRICE? Veteran

gotRICE?

Posted
Posted

Hmm sounds to me like a dodgy AFM. If it starts and idles mint without the AFM plugged in id say that would be the case.

Itd be wise to see if some nice person will let you borrow one.

I know a dude that bought a 2nd hand AFM, same problem, then bought a OEM Nissan brand new for $600... same problem. Was a faulty earth in the ECU. I tried to lend him mine, but he was confident it was the AFM haha,

  • 4 months later...
na beast Community Regular

na beast

Posted
Posted

Hey guys

I have the exact same problem, but what do you mean by a faulty earth in the ecu?

Are you talking about the ecu external casing being grounded to the body of the car or is it something else, can anyone please advice as im loosing the plot over this :banana:

Cheers James

  • 2 months later...
jeffworld2 Veteran

jeffworld2

Posted
Posted

faulty ecu earth could be a number of things.. most of the earths collect in a small brown plug near the ecu where they are bridged together, as well as the 4 or 5 pins in the ecu that are earths.

Obviously the ecu has power and so is earthed but it may be the sensor wiring is damaged or misconnected ie wrong wire, or even one of the switches on the board is not operating or has burnt out in which case a new ecu is probably in order.

I vaguely remember with the power fc hand controller i had the afm off the inlet pipe but still connected and i was blowing through it watching it go from 0 to 0.34v or something like that. get someone to watch the pc and see if it changes when you blow through.

I have also had some interesting issues with running different series gtst afm's on cars, maybe you should look at the plug end, especially if thats ever been changed. A series 2 afm for example on a series 1 you need to leave one of the 2 sensor earths disconnected.

karma_syke Collaborator

karma_syke

Posted
Posted

thanks for sharing your experience jeffworld2, i just recently cleaned my AFM with contact / circut board cleaner, it was absoluely filthy... it was amazing if it could measure anything, stupid HKS pod filter filters nothing. car seems to be running a bit better, although i did notice the idle rpm seems to be a bit higher.

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