rest 1994 q45 ecu

[cjnicks]

whats up everyone. i have a 94 q45. My problem is that it will not......pick up rpm; like it dosent go over 20000 rpm. it will just sputter. i have already changed a fuel pump and fuel filter and there is no difference. Now i am looking at the ecu. Does anyone know how to reset an ecu? Or does anyone have any other suggestions. PLEASE HELP!!!

[PapaSmurf2k3]

Moved.

If your Q is anything like other Nissans, it sounds like maybe your Mass Airflow Sensor is bad.

[cjnicks]

Do you know how much that would cost?

[Q45tech]

Pre OBD2 [1996] ecu don't have much of a memory other than for codes and a fine tuning at cruise which goes away when the battery voltage is removed for a few hours.

The same keep alive circuits for clock, radio, seat position supplies the voltage.

ECU memory doesn't have anything to do with failure to start or limits of 2,000 or 3,000 rpm which are fail safe limits caused by a loss of CRITICAL signals from sensors like CAS, MAF, TPS.

[cjnicks]

ok thanks. but how do i check to see which one is the one that has gone bad?

[PapaSmurf2k3]

like CAS, MAF, TPS.

TPS is considered critical? I've disconnected mine on my 240 many times, with minimal effects.

[cjnicks]

ok thanks guys for the help. I will have a pic of my q45 for everyone to see soon.

[cjnicks]

i just talk to my father and he said that he already changed the tps sensor. Soooo, that leaves us to check the maf senor and the cas. by the way what does cas stand for?

[PapaSmurf2k3]

crank angle sensor.

IIRC, you should be able to hook up a multi-meter to the MAF and make sure it is within spec. I recommend you download a factory service manual.

[cjnicks]

i will. i just got back in the house from looking at the car; looking for the maf sensor we could not find it. n i dont know what it looks like. i am such an amateur at this. do u know where it is located on the engine?

[maxnix]

Right after the air filter.

Got FSM?

http://www.nicoclub.com/FSM/Q45/

[Q45tech]

Crank Angle Sensors [CAS] rarely fail but the connector and harness connections do get corroded and intermitent.

The CAS send out 360 INDIVIDUAL pulse per rpm signal [with one triple wide pulse where 0 degrees is located] and a seperate every 90 degree pulse used for cranking and emergency use [fail safe].

This is the Master Clock which tells ecu where #1 cylinder is timewise and each subsequent cylinder occurs 90 degrees later [on a V8].

Important to mentally and physically view all the pulses from CAS and understand their relationship timewise.