I'm looking at the decreased fuel efficiency on my A33 Maxima. The car has recently been run against a diagnostic computer and came up clean. Would issues such as partially blocked or inhibited air filter or dirty spark plugs normally create a fault on a diagnostic tool or are they binary in their approach i.e. functioning/not functioning! Cheers
cypherboy,
Mar 14, 11:53pm
Common faults with A33s: Oxygen sensors Airflow meter Coilpacks, Cam, crankshaft posistion sensors IACV valve Idler Stepper motor Ecu blows diodes (usually after the stepper motor craps out) Fuel level gauge.
Diagnostics will not pick up dirty plugs or airfilter as theres no sensors to record the fault.
2lo4ho,
Mar 15, 2:08am
mine had approx 20% power loss and fuel increase. diagnostic came up clear. wasnt until the cam angle sensor failed and i put a new one in that it was the problem all along. Should of fixed it a year ago. Ild say either air flow meter or cam angle sensor. is it harder to start sometimes!
mantagsi,
Mar 15, 2:13am
Coilpacks for sure, my one has been a right pain in the rear for coilpacks, but I imagine overhauling all of the sensors and coilpacks from new would do the trick but would be worth more than the car! :)
modie61,
Mar 15, 3:16am
Got any consumption figures !
utwo,
Mar 15, 3:23am
I experienced the same problem with mine last year. All of a sudden fuel use increased from a consistent average of about 11.9-12.0 litres/100km (city driving) to the high 12s. There were no issues with performance or smooth running, i.e. it still performed like new. It had been maintained by the book. Filters, plugs, etc. all good. Diagnostic scan came up clean. I wasn't about to start randomly throwing money at it to try and improve the fuel economy so just carried on with life. Car is currently sitting in the no access area of Christchurch CBD's red zone and I don't really care if I get it back or not.
doublek,
Mar 15, 2:38pm
Hi Guys - thanks for the answers. Consumption: previously solid 10L per 100kms now averaging around 15L per 100. Idle Stepper just been done, hence knowing it came back clear on the diagnostic side. Would the diodes on the ECU give any other performance feel than just bad fuel economy! Cheers
doublek,
Mar 15, 2:38pm
Not hard to start. Coil packs would show up with a miss or performance reduction!
2lo4ho,
Jul 24, 9:08pm
could be alot of things. Usually coil packs will throw a miss. Good way to check is pull the plugs out, might as well check them anyway. If one is unusually dirtier than the rest then that may point to stuffed plug or faulty coil pack. Would usually feel a miss tho. Otherwise 1 of many sensors, mine was cam angle. $100 bucks but i wouldnt have changed it if it didnt breakdown. Been occasionally surging! Or take out your air flow meter and spray it with contact cleaner. wipe the mesh but dont damage it or leave shit all over it. May be dodgy afm, another common problem. May fix it, may not. Otherwise put up until somthing fails and fix it then. They are bullet proof cars, just minor issues
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