so what exactly is the min. needed to start up my 13bt to see if it will run? right now i dont have the BAC valve hooked up, the coolant temp guage isnt hooked up, O2 sensor isnt hooked up, AIR control motor on intake manifold isnt hooked up and i dont plan on using it either, the water thermo sensor (behind water pump on water pump housing) isnt hooked up, i dont have the water pump housing on so i have no alternator hooked up either. I have routed all new vaccum lines and have no emission soleniods either. i wired up a S4 NA engine harness to a S4 tii, is there anything specail i should have done while wiring the engine up that i might have not known about or failed to do, oh yeah almost forgot the knock sensor isnt hooked up either and somebody even told me that the knock sensor is pointless. Well thats about it, and engine doesnt start but cranks all day long. any ideas? please and thanks

 

The minimum the ECU will run the engine with is the CAS and AFM. It will run like crap, but it will run.

Nothing you've mentioned should prevent the engine from starting, though I'm very curious by what you mean when you say "Air control motor".

Why are you trying to start an engine without a water pump? Bad, bad idea. Localized hot spots will develop VERY quickly without coolant present.

Maybe you should finish connecting all the appropriate sensor and then try to start and troubleshoot the engine?

 

well if you don't have the Alternator hooked up,that would probably Not Be Good!..another thing,do you even Have the CAS hooked Up,the Coils hooked up?..the plug Wires?..(I have no idea WHY you would want to Try to start up an Engine with Half the Engine parts OFF the Keg..you are just asking For Problems!..) my suggestion 1.3mazda,is to get all the stuff on the Engine.That way you Start Off "fresh" .with the Engine ALL stock...Then Once you know the Engine is all together Correctly,you can start to Figure things out.Right now you are at a point where you have a Big Puzzle with Missing pieces.

 

The water thermo sensor on the back of the water pump housing, if disconnected, will make for a somewhat difficult start if the engine is cold. The ECU will default the water temp to 176* F and therefore not pulse a normal amount of fuel to the engine during START. After the engine fully warms up the starts will be normal. Only cold starts will be effected.

Also the BAC during START goes full open during START. After start it goes to a normal pulsing mode.

There's nothing on the n/a harness that will keep it from starting (the turbo engine). They both have Lead and Trail coil assy, a boost sensor (NEED a turbo one), a afm, four spark plugs, four injectors, a air intake temp sensor, tps etc. The n/a harness on a turbo engine just needs the twin scroll solenoid wiring extended from the ACV elec plug. NOT a player in starting and running if not done.

The ECU gnd point on top of the rear rotor housing HAS to be bolted down or the guts of the ECU see no gnd and therefore you won't get spark/fuel. You'd have said something if you had no spark/fuel so that must be ok.

 

okay i am getting spark at least on trailing 1, will check leading 1 and trailing 2 and leading 2, also will check compression but compression sounds really good with the trailing (top) plug out and feels good to the touch. Will check fuel pressure also. Also is the knock sensor needed to be hooked up or is it true that the knock sensor is pointless?

okay, but i was just going to start it right up and shut it off by pulling egi fuse once start up was accomplished. I wasnt going to troubleshoot or even think about running the engine more than 10-15 sec.'s.

so is it true that the knock sensor is pointless?

so anybody have any advice on whether or not to worry about the knock sensor or not??? please and thanx

 

Be safe and hook the knock sensor up if you have everything else for it.

 

The knock sensor is pointless in that it can only detect knock at low RPMs.

 

does that have to do with the sensor or the ECU detecing at only low RPMS?
you got me sort of confused??

 

It's a limitation of the sensor and ECU. As the RPMs increase, there is too much natural noise for the ECU to differentiate between engine noise and knock.