Urgent: Need help with Infiniti Dealer BS Meter going off

[Kenrik]

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Ok took the G35 into the dealer to figure out why it was running rough (like 1970s Ford Pickup rough) They called back and said that it was caused by the Radiator Fans being bad which causes the ECU to retard the timing causing misfiring etc.. They quoted $850 for the repair. My BS alarm bells are going off with this, anyone here know if bad Radiator Fans could cause this issue on G35? HELP!


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[AZhitman]

Hmm.

Assuming the fans were bad, you'd overheat, which could temporarily tell the ECU to pull timing... but you'd likely also get a CEL and high temp readings at the gauge.

I'd ask a LOT more questions. Are they suggesting the fans need to be replaced? If so, you can handle that on your own.

[Kenrik]

Nope it starts running rough the instant you start it, that's one of the reasons It triggered my BS meter.

Their reasoning was the ECU would detect the fans were not working and would pull the timing, maybe that could be true but out of the entire internet I could not find a single example of someone having that issue.

I declined their $850 blamed it on the wife , Actually they had a whole list of other "caution" items like new suspension bushings and new belts they would have been glad to charge me $3000 to fix.

Paid the $157.50 diagnostic fee with my free Car Wash / Detail and took it home.

Ordered a new fan assembly for $170, will install tomorrow and report back if that solved it - if it does I will have saved $550 for 1 hour of work installing the fan.

[PapaSmurf2k3]

Yeah, I highly doubt its the fan from what you're saying.

Is there a check engine light on?

[darylzero]

Why not open the hood and get the car up to temp and see if the fans are working before ordering new ones?

[Kenrik]

No the fan does not come on - so that did need to be fixed, though I have not had a chance to install the new one yet.

Yes the CEL is on - code pulled are for O2 Sensors and multiple misfire, however I've replaced the O2 Sensors twice (thought first set might be bad) they are a red herring. I don't have CATs so whatever is messing up the timing will trigger the O2 Sensor codes.

I checked all the coils by unplugging them while running and it does run much worse if you unplug any of the 6 so they should not be the problem, also it has new properly gapped plugs.

So what has been replaced before this fan and not fixed it: MAF, Exhaust Cam Sensor, O2 Sensors (2x), Plugs.

Will report back after the install.

[AZhitman]

NO cats? Well, are you running an O2 sim? No reason to replace O2 sensors if you don't have cats - they're gonna read wrong anyway.

Cam sensor on my G went bad, so that's something to check. Are you going through the steps in the FSM?

[BusyBadger]

Fix the O2 sensor misread and see what happens and go from there.

[the converted]

Which O2 sensors are you getting codes for (pre/post cat or all of them). Also tell me more about your cat delete. Nissan used exhaust back pressure and cam phasing to effectively have an EGR function without the plumbing. If you disconnect the battery for a few minutes and reconnect it does it run better?

[Kenrik]

Codes were for Post Cat sensors - Which I've tried to brand new sets without it fixing it. I ran with the Cat Delete's installed for the past 5 years - Had the O2 sensors go bad before and hit a similar issue but new sensors fixed it. I installed O2 sims after the problem started without any change. O2 sensor codes don't start until you drive it after a reset and hit the gas.

Disconnecting the battery or resetting the ECU has no effect - runs rough as soon as it starts. Back when the issue first started it was intermittent, it would be rough and then bam just smooth out. Whatever sensor that is causing the issue failed slowly over a few weeks.

The only sensors I have left that FSM mentions are the Driver side CAM sensor (replaced the passenger) and the Crank Sensor.

Still have not been able to install the Fan, Sprained my ankle today can't walk.

[Kenrik]

Replaced radiator fan - In total it took 45min and $170, without the "screw you" margin in the $850 they quoted.

AC works now which is a plus, and I don't have to worry about it overheating.

However IT DID NOT FIX THE PROBLEM. Car still runs rough as soon as you start it even after a ECU reset or battery disconnect.

[PapaSmurf2k3]

Yeah, I highly doubt its the fan from what you're saying.

Sounds like you should go get your $157.50 diagnostic fee back.

If timing is jumping all over the place, it honestly sounds like either a cam or crank angle sensor.