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Discussion Starter #1 (Edited)
Hi!

I have a late 2007/early 2008 (not sure) coupe with the VQ35HR, about 20.000 miles. Since I bought the car about 2 weeks ago, I was experiencing poor gas mileage (under 14 mpg combined) and some hesitation/tendency to stall. Like an idiot, I decided to clean the throttle bodies (with TB/carb cleaner and a rag) and MAFs (electronic parts cleaner). Didn't unplug the TBs and didn't disconnect the battery, obviously like an idiot who has only had drive by cable cars I moved the throttle plates. Now I have the following problem:

Idle starts very high (2200 rpm). Used to start high, but not this high.
Settles at about 1500 after 30 seconds.
When the car is warmed up, idle fluctuates between 1500-2000 (feels like the car is accelerating by itself)
Horrible accelerator lag.
Horrible rev hang (and then begins fluctuating).
Horrible jerks when it gets back to the 1500 mark and is in gear.
Engine sounds different, shudders when I turn it off.

I have tried:
Disconnected battery for 48 hours (I think this made the problem even worse, which makes no sense)
Pedal dances: ECU reset, accelerator learn, TB learn, Idle Air Learn (with engine up to temp and all electrical load off)

None of which produced any results. The throttle plates do move during the TB learn (and indeed every time I switch the ignition off). Disconnecting the accerator position sensor stops the idle fluctuation and it idles at 1100... WTF.

The one thing I have not tried to do is search for a vacuum leak. The vibration when I turn the engine off points to a leak I think, but up to this point I have been wary of spraying carb cleaner all over searching for it.

Any other ideas before I break the engine down again or take it to the dealership?

EDIT: Also - doesn't throw any codes
 

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Think a trip to the dealer is probably in order - they can do a better reset of the TB and Pedal Position Sensor connected to the TB using the Consult Tool than doing the simple pedal reset or disconnecting the battery.
 

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Discussion Starter #3
Thanks! After the holiday I'm going to take it in so they can have a look. I'm keeping my fingers crossed they don't tell me "you're outta luck, buy new TBs" lol.
 

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:cheers: I forgot you guys with the newer cars have two TB's lol. I replaced one for around $170 a year or so ago - it had a high idle for a year and finally failed altogether. Made me glad I had an older model for once, lol.
 

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OMG, i've been having the same problem for two weeks now(350z 2008 A/T). i have tried all methods. i even unpluged parts three times to make sure every thing is in order. i doubted my self. i downloaded the repair manual and followed it to the letter with not luck. i visited the dealership, tried the consult II & III still not luck. says excuting but stuck. they advised me to change the TB because i've touched it which makes not sence. they say that the ECU is not accepting the relearn because of faulty TBs. i think that this issue related to VQ35HR. bacause older models are easy to reset and relearn. technicians told me if my car had one throttle they could do it in 5 minutes. i started to hate my car and NISSAN for such technology. has anyone faced this issue and got it solved.

Dear GREENGOHOME please let me know what you come up with or how you solved your problem.
 

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Discussion Starter #6
update from dealer

I heard from the dealer on Friday that they were having trouble and they wanted to know if I had touched the screws on top of the TBs.

I haven't heard back from them since then as Chile celebrated its national holiday (5 days of drinking so no need for the Z).

Hope I will have good news today. Parts in Chile are obscenely expensive, and even on e-bay I'm seeing the right and left TBs are at least US$ 250 shipped (each).

It seems like this issue is tricky on the HRs, even more so because the TBs are more expensive and you have to buy 2.
 

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Discussion Starter #7
Well, that was an expensive "cleaning"... dealership says the TBs are BOTH bad and they cost a little over US$2000 a piece to replace new.

Looking at used ones on ebay now, there seem to be a few options under 200 bucks.

This really sucks.
 

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Mine was a rebuilt unit, as good as new, for that $170 on my '03. Where you located??
 

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wait don't rush

:idea:wait before you buy anything. check with your country's nissan regional office. they have experts from Japan to train local dealers as i did. i was told by a technician outside garage that the problem is in the ECU. even if i change the TB still i will have to do relearn which the ECU is not accepting. i have read in a website that certen parameters are required for the relearn to take place like the RPM should be under 850 RPM and air/fuel ratio should be between -5,+5 among other things otherwise ECU will not accept the relearn which is what happening and dealership tech is not paying attention to or unaware of the parameters. then easly tell you that you have to change your TBs. like if they are cheap bulbs. today i was speaking to the nissan regional office and they are looking into the matter and hopefuly problem will be solved without changing anything.
check below links.....will give you an idea

2003 G35: Sedan..replaced the throttle body..idle speed..pcv valve - JustAnswer

Infiniti G35 How can I fix high idle P0507 on 03 G35 seda - JustAnswer

i hope will pass through this.. :(
 

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Discussion Starter #10 (Edited)
Both of the links you posted up are for single TB cars... I have only read about the fluctuating idle problem on dual tb cars, I don't know if it makes a difference. I'm going to bite the bullet and try to get some TBs shipped down to me tomorrow. Summer is just around the corner and I really don't want to be dealing with this when I should be outside enjoying the Z in the nice spring weather lol:lol:

Obviously it is totally possible that I damaged the TBs when I cleaned them, who knows? The dealer tech says he's 100% certain this is what the problem is. I'll buy the parts and let them install them; see if they can figure the deal out. :biggrin:

EDIT: I'm located in Santiago, Chile, so all of this is much more complicated than it would be in the US because there are only a handful of HR cars in the country and dealer prices are just out of control. Thank god for air express shipping.
 

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i wish you luck. i'm taking my car to the dealership to day as advised by the Nissan regional office and they are sending a technician to inspect my car why is it not accepting the relearn although no codes were given. i hope i wan't have to change anything and it is just a simple configuration.

Note: i have crack opened my TB and nothing inside there that can be damaged. it really suck if they could be damaged this easy. also they is a code for damaged TBs in the service manual and it should be up if the TB is faulty as your technician said!!!

good luck, we'll need it.
 

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Hi all,

I had the same high idle issue (no error codes were displayed). Where the 350 was hunting for idle between 1200 - 2000rpm cause the car to jerk and was UN-drivable.

Here is what is what I tested
1. Tried manual relearn around 50 times - same issue
2. Tried relearning the ECU with computer - same issue
3. Paid Nissan Australia to relearn $250 later and a quote that could exceed $5000 - told them to get F'ked and put a complaint to nissan for poor customer service
4. Tried to relearn computer while driving to keep the RPM low so it could find idle - same issue
5. Tested all 240 wires to the ECU with a Voltage meter and a gragh plotter - No issue found (Pointing to an issue with the ECU)
6. Removed Throttle bodies, car still idled and responded witht he accelerator
7. Blocked 1 of the throttle bodies and tried the relearn -same issue
8. Removed manifold and disconnected 3 of the injectors and tried to relearn (Nissan advised this may work) - same issue

So after all the above I can conclude it was an issue with the ECU not being able to find the lowest point of idle. An ECU swap and relearn would fix the issue but this is an expensive process so here is how we fixed it...

The Fix
When putting the manifold back together we forgot to both the throttle bodies to the engine (Water and Electrics were connected) when the car started it stalled... From that point the ECU had re-learn its lowest position and around 20 ECU relearns tests later the car is not idling at 900rpm.

So try unbolting the throttle bodies from the engine and make the car stall hopefully this will fix your problem
 

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Discussion Starter #13 (Edited)
Wow... MikeGSXR sounds like you tried about everything... but 900 RPM is still high. Did driveability improve as well?

I bought a pair of used 2007 G35 TBs from a junkyard in Alabama (FU to Chilean customs... on top of the 370 bucks to buy and ship them, I got hit for another 80 bucks in tariffs) and put them on last night... The loping/surging (revving between 1500 and 2000 every 1-2 seconds) is gone.

But idle is still very high, about 1500. Driveability is greatly improved but still not perfect as there's a lot of lumpiness around the 1500 mark which is a PITA in first gear. Also cruise control works now. So I feel like I did fix something, but I'm still not at 100%. Also I think I picked up some power as the car now chirps nicely when upshifting to 2nd gear at high RPM.

I did the pedal dance a few times last night and I was able to get a stable idle at about 1000, which is quite a bit better, but as it was night I had the headlights on so the computer didn't complete the re-learn and this morning it was back at 1500.

So... who votes to keep dicking around with the pedal dance and who says to take it to the stealership right away? (BTW girlfriend looked at me like "pedal dance? you're fcking kidding me" and cast her vote for dealership right away, but I had to be the stubborn one and at least try to put the TBs on myself)

EDIT: anybody know if I can sell the bad TBs to an outfit doing re-manufactured? I'd love to be able to recover some of the money I have spent on this misadventure.
 

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Pedal dance only worked for me until I shut the car and then back to high idle the next time. My vote is the dealer - sux but you want the car to behave like it should, correct?
 

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Discussion Starter #15
Pedal dance only worked for me until I shut the car and then back to high idle the next time. My vote is the dealer - sux but you want the car to behave like it should, correct?
correctamundo at this point I basically just want the car to work right. it's at the dealer right now... keep your fingers crossed.
 

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Gl !
 

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Discussion Starter #17
****...:xZ!o:

dealer called to say that the used TBs are bad too and they couldn't bring the idle down; additionally this time there was another Z in the shop and they put my TBs on the other car and they idled high, and put the other car's TBs on mine and it idled right.

So... I guess I'm going to get to buy new TBs. Lucky me. I think I'm probably going to wait for my next trip to the US and just buy them while I'm over there, meanwhile continue to try the pedal dance and see if I can get anywhere.

Sucks. If somebody offered me an even trade for any other car I'd jump on it right now. :xZ!o:
 

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Discussion Starter #18
Got the car back from the dealer, basically it's exactly the way it was before I changed the TBs. Surging is a little better and it's a little less jerky.

Sucks to be me.

Any ideas on where to get a good deal on new throttle bodies?

Also I hate that tons of posts (especially on G35 boards) have this problem and NOBODY EVER COMES BACK TO SAY HOW THE SOLVED IT!!!!
 

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hi,
i have given my car to the dealershi and they have changed the throttle bodies but still the problem presist then they changed the ECU from another car and the problem gone. i was told by outside technician from the begining that my ECU software was corrupted and this is a commen problem with the Z's but i didn't belive him back then. after trying the dealership, i went back to the same old technician to change my ECU with a used one because i couldn't afford the dealership charges of changing TBs & ECU. tomorrow i will find out what the technician did and if it was sucessful.
 

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Discussion Starter #20
i was told by outside technician from the begining that my ECU software was corrupted and this is a commen problem with the Z's
Dealership has repeatedly assured me this is not my problem... I will be pretty close to torching the car to collect insurance if I have to buy an ECU.

Good luck and keep us posted.
 
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