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Old 07-15-2014, 01:41 AM Thread Starter
JTR
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high idling after cleaning TB

Hi Guys,


I have a 2008 track coupe with the VQ35HR, about 60,000km. Recently had the car service and the mechanic recommend I have the throttle body cleaned due to the build up of dust. Since having the TB clean, the car is now idling high in neutral gear.


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 jerks when it gets back to the 1500 mark and is in gear.

The mechanic have tried:
Disconnected battery for 48 hours
Manual Pedal dances: ECU reset, accelerator learn, TB learn, Idle Air Learn
Swap the TB with second ones - still same issue.
Search for vacuum leaks.


They just can't get into the ECU since it's idling high in neutral.


Spoke to several other Nissan services centres to find out the issue, however none of them seem to have a real solution. Has anyone else face the same problem? This is been dragging on for over a month and this car is driving me nuts.


Please provide any ideas/feedback or solution or whom have gotten their issue fixed before.


Cheers.
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Old 07-15-2014, 09:12 AM
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If he manually messed with the buttefly rather than just spray cleaning it without touching it, you are looking at a dealer reset. That is a big no-no with a throttle by wire system. Guessing this was not at a Nissan dealer? Regardless, I think the "mechanic" owes you one on this - and there are tons of threads with people in your exact same situation so don't feel alone.

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Old 07-15-2014, 09:30 AM
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since you switched out the trottle body, try these. especially the idle air volume learning. be sure your timing is exact. if not start over:

Accelerator Pedal Released Position Learning
DESCRIPTION
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF and wait at least 10 seconds.

Throttle Valve Closed Position Learning
DESCRIPTION
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.


Idle Air Volume Learning
DESCRIPTION
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed under any of the following conditions:
 Each time electric throttle control actuator or ECM is replaced.
 Idle speed or ignition timing is out of specification.
PREPARATION
Before performing Idle Air Volume Learning, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.
 Battery voltage: More than 12.9V (At idle)
 Engine coolant temperature: 70 - 100°C (158 - 212°F)
 Park/neutral position (PNP) switch: ON
 Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, if the parking brake is applied before the engine is started, the headlamp will not be illuminated.
 Steering wheel: Neutral (Straight-ahead position)
 Vehicle speed: Stopped
 Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “ATF TEMP SE 1” in “DATA MONITOR” mode of “A/T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.

Without CONSULT-II
NOTE:
 It is better to count the time accurately with a clock.
 It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction.
1. Perform EC-42, "Accelerator Pedal Released Position Learning" .
2. Perform EC-42, "Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Turn ignition switch OFF and wait at least 10 seconds.
6. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
7. Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.
13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carried out successfully.

2013 370Z w/Sport Package, Midnight Blue
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Old 07-16-2014, 08:53 AM
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This is interesting, I'm experiencing the same symptoms! Pretty much identical, car warms up at 2k as usual, but then it's just constant surging from from 1500 to 2000 back an forth. I have an 07 though, and... ahem, I cleaned the TBs myself. It just happened yesterday. I had just started it after being on jackstands for 3 weeks with the battery out as well.

I've been doing some research and am getting nervous. I'm not seeing a lot of confirmed fixes with the throttle relearn. The only conclusive ones i've seen are the people getting new TBs or ECUs which can cost over a grand. I haven't had a chance to try the relearn key dance yet, going to try it later today. I'm praying it works.
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Old 07-16-2014, 12:07 PM
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the throttle relearn is straight out of the service manual on how to do this and it does work if you follow the instructions exactly. if you get a new TB you still have to do the throttle valve and the relearn since that is the final step to program it to work correctly, or pay the dealer over a grand to do it for you

2013 370Z w/Sport Package, Midnight Blue

Last edited by steve350z; 07-16-2014 at 12:11 PM.
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Old 07-16-2014, 12:30 PM
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I'm just afraid something stupid happened like some cleaning solution got through the shaft seals and bearings and into the electronics. I've read that the TBs connection to the ECU is unfused, so any short can easily take that part of the ECU down with it. There's a guy on this forum who gently cleaned his TBs with a qtip and didn't even open the plate (I went at it way more aggressively) and he ended up with new TBs and an ECU. Other forums have some guys, just getting a new ECU. The thing is, this isn't just a high or funny idle, these are significant 500rpm sweeps, like someones blipping the throttle all the time. I haven't even tried driving it yet.
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Old 07-17-2014, 09:08 AM
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The single TB went out on my '03 - actually it was the throttle position sensor which is part of the TB but not replaceable and I got a reman unit from the dealer for $160.00. Bolted it on, hooked it up and away I went - no programming or learning required. These cases sound different though and although I hate to say it, a trip to the dealer may be in order, although the latest one sounds like a vacuum leak to me.

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Old 07-17-2014, 12:05 PM
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Tried the manual throttle relearn. Not working out, but may just be cause I suck. I'm going to keep trying, at least get it on the ground, drive it around and hope it sorts itself out. I tried some other things, confirmed the throttle is moving; but i really just need a Nissan Consult to just really confirm the problem. There's not check engine light. Dealership will be an absolute drop dead last resort, and have a lot of aftermarket parts, and mods that'll have issue with. My experience with dealerships have always, at best, been horrible.
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Old 07-29-2014, 08:31 PM Thread Starter
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I tried the relearn over 100 times. Replaced the throttle bodies as well and still the same problem. The car is now with the dealership and they said it's a known problem with the dual intake 350z. They said there's no issue with the TB or ECU. The ECU is stubborn and you have to keep doing the relearn.
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Old 07-30-2014, 04:37 PM
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Thanks for the update. I've gone ahead and replaced my throttle bodies as well. I got a used set off ebay from the same year and model. I got lucky; immediately after very gently and carefully installing the new TBs, I was able to start it up and everything was as it should be. Falling in love all over again. Before this though, tried everything;
- Had a friend come over and try to force a relearn through his Snap-On scanner
- Tried the manual method several times.
- Just drove around with it like that and hope the car figures it out (lots of ugly looks)
- Started the car with a controlled vacuum leak.
- Started the car with the throttle bodies unbolted (per post of success story in this forum)
- Started the car with TBs unbolted and shimmed just right to create a consistent leak.
- Disabled 1 then 2 then 3 fuel injector to drop the idle enough to stay in relearn mode.
- Dozens of ECU reset methods to clear out the bad learn.

I'm just thankful I haven't had to take it to the dealership or buy a new ECU. Pretty surprised your dealership said the ECU and TB were ok. I may try to give my old TB another try one day. Personally I think moving the plate even somewhat quickly or slightly aggressively screws them up.
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