Hi guys,
got a 94 Q45 with check engine on. ECU gives a 51 code meaning 'injector analysis' what the heck does that mean please!!!
please explain what ecu code 51 'injector analysis'
Re: please explain what ecu code 51 'injector analysis' (Q45dude)
anyone.... anyone at all.....
TTTTT
TTTTT
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Q45tech
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- Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl
Re: please explain what ecu code 51 'injector analysis' (Q45dude)
Code 51 is tripped by an open or shorted injector [resistance above or below the mean value]....................it is a guess not an actual measurement.
The O2 sensor monitoring a bank should switch high and low in the time slot for each cylinder AVERAGED over a few rpms.
If the ecu notices 3 cylinders of the 4 monitored by an O2 are good and one is bad................it assumes that the injector is at fault and points the technican towards doing test to comfirm.
A bad coil would flow a slug of richness into the exhaust, a low/noflow injection will flow a slug of leanness.The problem is 25% [12% OF TOTAL] is tough to zero in on especially if non continuous or doesn't occur at idle.
Why we recommend periodic measurement of the resistance of each injector.
As even a few ohms from the average says the injector is beginning to have problems. Oem says 10-14 ohms but we know after 17 years that they should be EXACTLY equal give or take the errors caused by measurements.
Because of position, the heat levels will vary which changes the resistance of the copper winding +- say 0.5 ohm MAX.
The O2 sensor monitoring a bank should switch high and low in the time slot for each cylinder AVERAGED over a few rpms.
If the ecu notices 3 cylinders of the 4 monitored by an O2 are good and one is bad................it assumes that the injector is at fault and points the technican towards doing test to comfirm.
A bad coil would flow a slug of richness into the exhaust, a low/noflow injection will flow a slug of leanness.The problem is 25% [12% OF TOTAL] is tough to zero in on especially if non continuous or doesn't occur at idle.
Why we recommend periodic measurement of the resistance of each injector.
As even a few ohms from the average says the injector is beginning to have problems. Oem says 10-14 ohms but we know after 17 years that they should be EXACTLY equal give or take the errors caused by measurements.
Because of position, the heat levels will vary which changes the resistance of the copper winding +- say 0.5 ohm MAX.
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goody90q45
- Posts: 3679
- Joined: Wed Aug 17, 2005 2:07 pm
- Car: 1992 Infiniti Q45 (sold)
- Location: Orangevale, CA
Re: please explain what ecu code 51 'injector analysis' (Q45tech)
The actual measurement would be found by ohming your injectors at the harness. The only tool you need is a voltmeter. All should be 10.0-14.0 measured cold. Might as well measure the knock sensors while you're there. Measure them first and let us know the readings and we can go from there.Q45tech wrote:Code 51 is tripped by an open or shorted injector [resistance above or below the mean value]....................it is a guess not an actual measurement.