pcfiii

iTrader: (1)

Okay so as many of you DIY'rs know one of the best mods or tune ups you can do is clean your throttle bodies. It is also very simple to do with just some throttle body or maf cleaner and best part is it frees up some lower grunt at idle to feel much more responsive. Now after noticing my idle to be a bit low and boggy at 750~800 I decided to do a quick cleaning on them. I believe (and correct me if I'm wrong) did the correct procedures disconnect the battery, removed and disconnected throttle bodies, cleaned them thoroughly. After reconnecting everything I broke out into a deep sweat with my car idling high 2k~, surging between gears at stop lights 1.5k~2.5k, and jolting when letting of the gas. I then proceeded to take it to my tech who has a CONSULT III machine and diagnosed the problem, after many hours of trouble shooting and trying to force learn the idle air volume procedure both manually and using the machine we decided to just flush my coolant, change spark plugs, oil, etc all random miscellaneous things (since i was there) and most important made sure there was no VACUUM leaks. Still my ecu could not learn the procedure so he told me to take it to the stealership and have them run it on there updated CONSULT III labtops. After there diagnosis and myself playing really dumb like nothing happened they said i needed to replace both throttle bodies because of micro sensors which were damaged and could not accept the learn (which after he told me the cost) i really started to freak out. Not having the 2k to drop right there on new throttle bodies (and being pissed at myself) I just got my keys and decided to leave. After some researching on the forums it seems many people have this issue but your in luck because i found the fix. The ecu will learn itself with your driving now i happened to stumble upon this by accident because i had to travel 200 miles up north (yes high idle reving and all) and what i noticed is my revs slowly decreasing at idle after about 400 miles (7 days) the check engine light turned off and normal idle is at 875~900 no surging, no jolting, no nothing just back to normal. Steps that i would recommend anyone taking on this task do is DO NOT disconnect the battery or unplug the throttle bodies to clean them just carefully remove them and clean both sides WITHOUT moving throttle position what so ever. If you happen to get a check engine light on try the manual idle air volume learn procedure, if that doesn't work 90% of the time it will work with a consult III force learn, and for you freak cases like myself just drive the hell out of it knowing you checked for vacuum leaks. Hope this helps i will also include the manual learn procedure steps bellow.


1.PRECONDITIONING
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 - 105°C (158 - 221°F)
• 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
- A/T models
• Drive vehicle for 10 minutes.
- M/T models
• Drive vehicle for 10 minutes.

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.

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.

INSPECTION AND ADJUSTMENT
1. Perform, "Accelerator Pedal Released Position Learning" .
2. Perform, "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.

ToXIc

iTrader: (2)

thanks for the info... sub'ed

sendindaninja

I thought I had to take to the stealership and also replace throttle bodies, until I stumbled upon this. It's friggin godsend and I'm gonna try this. Love the friggin forums...

SonicVQ

FYI: If you have an 2007 G35/350z (with VQ35HR) motor, there is a bug in the ECU software and the idle air volume won't run to completion, resulting in a high idle and surging as the ECU tries to correct it.

Some dealers will update the ECU software to resolve the issue, but most aren't aware of the update (ECU ID ending in "B")
Some owners have replaced the 07 ECU with an 08 ECU and then had a locksmith program the keys to work with the new ECU
and other have used Eugene at Enthusiast Auto Care (https://www.yelp.com/biz/enthusiast-auto-care-concord) in California to update the software.

If you have an Android device and a bluetooth scanner you can use a free app to run the "Idle Air Volume"
Quick & Easy Idle Air Volume Learning: Motorvate's DIY Garage Ep.28

The first post mentions that the throttle bodies have "micro sensors which were damaged" which is not correct.
The throttle body on the G37 (an most engines) are a VERY simple device - it has a DC motor, a few gears and a variable resistor (just like a volume control)
Below is a video that shows the inside of a G35 HR / G37 throttle body:

How it Works - Electronic Throttle: Motorvate's DIY Garage Ep.30

As mentioned at the beginning of this thread, after cleaning the throttle body there are three procedures that need to be done.
Here they are in a easy to follow video:
G37 & 370Z After Throttle Body Cleaning: Motorvate’s DIY Garage Ep.27

One last point, the factory spec for a hot idle is 600-700 RPM (with A/C off)

I hope this post clears up some of the confusion around our throttle bodies.