I've been checking out these forums since 2010 when I purchased my G35 Sport Sedan, and here I am at my whits trying to find out what's the problem on my car.

My issue? The dreaded idle surge. It starts either right away, or a minute after warm up. It stays consistent between 1.5 and 2k RPM.

A little background:

This past summer, I had an issue with a sticking caliper. I was fortunate to have a friend with a plethora of tools, and I was able to do the work myself in his driveway.
What I found out during the week it sat outside as I waited for parts? That I had a leak coming from a clogged sunroof drain, or the corner windshield area. My passenger floor was SOAKED. I had a few centimeters of water on the floor, and immediately dried everything with towels. It had rained 2-3 days in a row, so I can only imagine how bad it was. I never ripped up the carpet to fully dry everything out.

Fast forward some time, and the idle starts to run high, which eventually turned into the surging. I pull a code which I'm blanking on exactly, but basically tells me I'm idling high, and replace TB's. I clean my MAF sensors, no luck. I finally order remanufactured TB's and no luck. My mechanic even bogged down the idle to get it in range to relearn to no avail.

Finally, I bring my car to a new mechanic. He tells me theres no communication between his computer and my car, and the idle doesn't respond. He takes a look at my ecu, and finds the under carpet is pretty wet. There is a grounding wire there that he cleans up, but nothing changes. The ECU visually looked okay, until he found signs of mold under a magnifying glass. He recommends finding a used ECU on ebay. So while away for work, I find one listed for my year, make, model, and trim(MT), but the code doesn't match. We hook it up, and it no longer surges,(idled at 1k sometimes, then 2k others) but I lacked a bit of power before 4k RPMS. (also pulled a U1000 and U1001 code at the time) HOWEVER, it finally ran smoother! Albeit on a AT ECU or whatever. So I find an ECU that matches my car exactly,( besides last 4 digits) swap it out, and BAM. Surge is back. I'm not throwing any codes for now, and have been driving it all day. Idle didn't relearn on its own, or improve. I guess next step is the manual relearn, but everything is striking out that I feel like driving my car into the Hudson River haha I'm thinking maybe look at a grounding kit? The rings look clean, but theres a tiny bit of rust showing about an inch up the wire. I dipped them in vinegar, then in baking soda, toweled off, to no improvement.

Any ideas much appreciated! I probably left out a ton of details, but I don't know how to begin nor end with this car, as the past 6 months has been pushing me to the edge!

ps-I believe my alt was running high as well, until I believe he sprayed my ecu to clean it a bit. but no improvement on the idle.

 

What do you mean the mechanic bogged down the motor so the idle could relearn, also what do you mean by it automatically relearning.

There's two ways to reset the idle air, the pedal dance method or using software to toggle the relearn from consult-II, or NDS2, etc.

http://nicoclub.com/archives/g35-350z-ecu-reset-procedure.html

 

 

No it won't recalibrate itself.

Consult-II doesn't care what the current idle is, the only things that matter is that the engine must be up to temp, if an AT it must also be up to temp (drive for 10 minutes) AC controller/window heater/other electrical loads are turned OFF, you must be in PARK, the steering wheel needs to be straight forward, and battery voltage > 12.9v. Then you run through the Accelerator pedal relearn, throttle valve closed relearn, and THEN the idle air recalibration in that order.

You can do the pedal dance method that I linked as well, only once the vehicle is up to temp you park the vehicle and turn the engine off THEN do all the resets. Both work just fine, both are listed in the FSM.

 

You also might shop around for a mechanic that knows how to work on these vehicles.

 

 

I have no idea honestly. If it were my car I'd just pedal dance the thing myself, all it takes is a stopwatch and you can do all those resets yourself.

 

UPDATE

Went to Infiniti of Lynbrook (Long Island, NY)

They flashed my ecm, and boom. Idle hunt gone. I told them about the water issue and they began talking about me replacing my BCM, ECU, and main harness. Also, told me the refurbished TB's were trash and needed to be replaced too. I told them to shove it where the sun don't shine and just do the flash. It worked, and they just looked angry it did. Car is normal

They were snakes. Stay away from Infiniti of Lynbrook. The advisor said flashing the ecm was a 2 hour job because the reprogramming had to be done blah blah, but I knew it was a 15 minute procedure and made him look like a fool in front of other customers. At least the car is back to normal idle

 

I'm from Long Island originally, so thanks for the heads up to never bring my car there if need be.

Dealers are shady like that. When I was living in Tampa; I got into a huge *** fight with a service advisor. My BCM was fried due to water intrusion and she tried saying it was from the AMP wire causing it. The real problem was another dealership did some work for me in the BCM area and I guess they forgot to put the cover on completely, so water was getting in. She tried sticking me with the bill and I said go look at your records the last person to touch it was another dealer. I even told her everything I read on the Internet about this dealer was true (they had sh1tty reviews). Had to get corporate involved and they approved to foot the bill.

If you did have that much water though; I would at least pull the carpet back to make sure it's all dry back there.

 

Glad to help!

Did you ever find your leak? I suspected a clog or hole in the sunroof drain in mine, but after ripping top the carpet and inspecting the tube, it was fine. I assume somewhere above the firewall. It sucks, the tech told me that its fairly common for the BCM's frying due to water damage. Made it sound like something infiniti should address. I'm glad you stuck it to them, though. I felt like I was talking to mobsters. When I walked in, the advisor said the $160 diagnostic would cover why my idle was surging and where my exhaust leak was. Including a bumper to bumper multi point inspection. They BS'd me so much about spending all this cash, they never go to the diagnostic, and all they did was the half hour flash that I pushed for. They didn't even want to lift it until I pressed them. And in two seconds I found my own exhaust leak. I was in awe. The tech told me there was a chance to ruin the ECM by flashing it, and that was why they did not want to do it. Mainly because it was an eBay ECM. Is there any truth in this? I didn't know what to believe in the end

 

There isn't any risk to the ECM unless they're dumb and don't know how to do an EPROM flash. It's literally just like any firmware flash, if the install doesn't make it all the way to the end then you brick the hardware. If they're using a piece of **** computer for their consult-II machine and it has a bunch of **** malware on it then yeah there's a pretty good chance they'll brick the ECM. Any professional shop it's pretty much 99.9% chance of success but there ARE random failures if the ECM was previously damaged, in those cases the ECM is usually not working properly anyways so...

 

when you say flashed what do you mean cause I’ve had similar experiences and now have to take it to the dealer and I don’t want them to take advantage of it

 

"flashing" is how you write new firmware software to a cars computer.

Procedure is basically the same as any other firmware update for any device, your computer motherboard, your router, etc. It's the base code system written to an EPROM chip.

This is different than say your operating system (windows) on a computer which is a second layer of programming. The BIOS of the computer is the firmware. Car computers don't use an operating system, they just use a base level of code.

When you first turn on a computer you will see a lot of text and stuff as the machine goes through it's BIOS startup, then you get a screen where Windows loads, then once windows is up and running you use 3rd level software (applications) like your web browser.

Many devices only have that first level, that's your firmware, if you want to update it to a different version you flash it. Basically it stored the entire code into system RAM then overwrites the entire existing system. When Windows or another app has an update it only overwrites PART of the code. A flash overwrites everything.

If you unplug the system when flashing you can "brick" the device meaning you cannot update it and it's now useless unless you send it back to the factory. Newer devices have a sort of "brick protection" where it will always keep the previous bootable version loaded into a partition of EPROM but car computers don't have that.