Cleaned Throttle Body, Now Revs High

[Pete82]

Hello,

Today I cleaned the throttle body/plenum because it was absolutely caked with black oily/soot/dirt

Now i have performed the Accelerator Pedal release position learning, throttle valve closed position learning, and idle air volume learning.

The car use it idle fine around the 650-700 RPM.

After cleaning the throttle body off all the dirt, i noticed it had a gap all around the body which would let air through.

when performing the throttle valve closed position, i notice that the butterfly valve moves all the way back to the closed position then back to original with a gap. obviosly because our cars dont have idle air control valves this gap is necessary to allow idling.

Now when i perform the idle air volume learning the car starts fine then slowly drops the idle to around 800 rpm, which is still high. when you rev the car a few times it still returns to 800 rpm.

However when you stop the car and restart it the idle goes back to 1000rpm, which means it hasn't learnt the new idle air volume. Also if you put it into D or R it drops back to 800rpm.

Other than putting all the dirt/oil back around the throttle body/butterfly valve does anyone know how to get the idle back down.

Ive tried all the procedured numerous times.

Thanks

Pete

03' V35 Sedan 350GT-8

[g33k]

Id adjust the idle using OBDII computer cable....... but thats just me - im not au fait with those procedures but my idle is computer set at 625.

[zei20l]

hmm Andy and his M35 is doing the same thing! if he finds something then ill get him to post here

[andy65b]

I feel some sanity. I thought I have been going insane for the last few months with exactly the same problem.

When I had my throttle body cleaned is the same time this problem started for me.

So it sounds like it is some thing to do with the position of the butterfly in the throttle body. It sounds like the adjustment of the butterfly is changed slightly during the cleaning process. It was suggested to me that the screw on the top of the throttle body can be adjusted to alter idle. I want to some reading on this before I change mine and also mine would not move.

I have read in other threads about the calibration be out if the butterfly is moved by hand.

But thank you, at least I now know I need to focus on the throttle body to fix this problem.

Cheers

Andy

[Pete82]

Hi Andy,

I dont think it has anything to do with moving it by hand when cleaning.

I to tried adjusting that screw, however its seems to have a loctite sealant holding it in place, plus the lock nut.

Ive been reading the G35Driver, and a 350z forum, and some say that when they took it to Nissan the used consult to reset it. i dont think anything they do with consult is any different to what we do with the non-consult way.

Ive disconnect the battery tonight and will try again tomorrow.

Cheers

Pete

[andy65b]

Hi Andy,

I dont think it has anything to do with moving it by hand when cleaning.

I to tried adjusting that screw, however its seems to have a loctite sealant holding it in place, plus the lock nut.

Ive been reading the G35Driver, and a 350z forum, and some say that when they took it to Nissan the used consult to reset it. i dont think anything they do with consult is any different to what we do with the non-consult way.

Ive disconnect the battery tonight and will try again tomorrow.

Cheers

Pete

When I took mine to Nissan they were no help, they said the idle should be 800 even though there is a sticker on the bonnet showing it should be 650 +- 50.

I have been trying all sorts of idea's but it is good to know that it relates to the throttle body cleaning.

I will keep serching and let you know what i find out.

Cheers

Andy

[zei20l]

see, i cleaned mine months ago, and it was fine before and after......... i did the same thing to andys car.

andy your plugs have been changed yes? pete how about yours?

i did mine at the same time. but idle was fine beforehand. i had a stutter at low rpm but has now been attributed to the gearbox

[andy65b]

see, i cleaned mine months ago, and it was fine before and after......... i did the same thing to andys car.

andy your plugs have been changed yes? pete how about yours?

i did mine at the same time. but idle was fine beforehand. i had a stutter at low rpm but has now been attributed to the gearbox

No, I haven't changed my plugs yet. That is coming very soon.

I have been out in the cold tonight remounting the throttle body as I realized we had the gasket in the wrong way. We had one of the tabs pointing up and apparently the one side without a tab is the top.

I am thinking more along the lines that some how the base setting is out and I suspect the adjustment screw that is fairly firmly fixed is the way of fixing it.

Will talk to North Shore Prestige tomorrow along these lines.

Cheers

Andy

[central coast person]

Did you reset the ECU and take it for a 20min drive???

[andy65b]

Did you reset the ECU and take it for a 20min drive???

No, I haven't reset the ECU, but I have done a 20 minute drive after setting the idle speed through the idle learning procedure.

I am not 100% sure how to reset the ECU on the M35.

I have seen that on the C34 people have said to disconnect the battery, pump the brake to remove residual power and then reconnect battery.

Can any one confirm if this is correct?

[central coast person]

yeah, just pump it a few times. I usually turn the light on in the car just to see if Ive pumped it enough.

Once thats done take it for a drive.

[BLISTC]

cant you perform the ecu reset like the one on the V35

isnt it the same thing?

[andy65b]

cant you perform the ecu reset like the one on the V35

isnt it the same thing?

How do you reset the ECU on the V35?

Cheers

Andy

[andy65b]

How do you reset the ECU on the V35?

Cheers

Andy

Tried and FAILED.

Reset ECU (battery disconnected and brake pumped), drove 10 mins to warm up. Reset TPS, Throttle body and Idle volume learning. Idled at 725rpm. Drove 50 minutes to work, idle now at 800 rpm.

Turned car off, restarted, idle still at 800 rpm.

Got to be that adjustment screw.

[whtbox]

this is the right procedures of doing it.

How to reset your ECU and perform the Throttle Pedal Release and Idle Air Volume Learning procedures on an Nissan 350Z.

Before attempting any of the following procedures, it is advisable that you read through the instructions thoroughly and familiarize yourself with them.

A stop watch or an analog clock with a second’s needle will be useful.

**a quick reset can be accomplished by disconnecting the negative battery terminal, and depressing the brake a few times.

ECU Resetting Procedures

Timing is extremely critical. If it is NOT DONE within the specify time, the ECU will not reset and the Check Engine Light (CEL) will continue to remain ON.

Operations Procedures

1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.

2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.

2a. Fully depress the accelerator pedal (HARD).

2b. Fully release the accelerator pedal.

3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.

4. Fully release the accelerator pedal (while the CEL is still blinking)

5. Wait about 10 second.

6. Fully depress the accelerator pedal and keep it for more than 10 seconds.

7. Fully release the accelerator pedal (The CEL light will continue to blink).

8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone.

If the CEL light continues to remain ON, repeat the above steps. Timing is EXTREMELY critical to resetting the ECU.

Accelerator Pedal Release Position Learning

Operation Procedure

1. Make sure that the accelerator pedal is fully released.

2. Turn ignition switch “ON” and wait at least 2 seconds.

3. Turn ignition switch “OFF” wait at least 10 seconds.

4. Turn ignition switch “ON” and wait at least 2 seconds.

5. Turn ignition switch “OFF” wait at least 10 seconds.

Throttle Valve Closed Position Learning

Operation Procedures

1. Make sure that accelerator pedal is fully released.

2. Turn ignition switch to “ON”.

3. Turn ignition switch to “OFF” wait at least 10 seconds.

Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.

Idle Air Volume Learning (Throttle Position Learning)

It is better to count the time accurately with a clock. 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. Turn ignition switch “OFF” and wait at least 10 seconds.

5. Confirm that the accelerator pedal is fully released, then turn ignition switch “ON” and wait 3 seconds.

6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.

7a. Fully depress the accelerator pedal (HARD)

7b. Fully release the accelerator pedal.

8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON.

9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.

10. Start engine and let it idle.

11. Wait 20 seconds.

12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the specifications.

[whtbox]

i cleaned my throttle bodies just by spraying by not Touching the fly. Lot's of people that touched it stuffed up the idle.

but my idle is still normal now at 700 - 600rpm after the cleaning.

[andy65b]

i cleaned my throttle bodies just by spraying by not Touching the fly. Lot's of people that touched it stuffed up the idle.

but my idle is still normal now at 700 - 600rpm after the cleaning.

My mechanic cleaned mine when this happen so I don't really know what was done but this is starting to make a lot more sense.

I am hoping (please, please, please) that the adjustment screw on the top will help resolve this problem. Enquiries are being made.

Cheers

Andy

[zei20l]

ok after looking at the throttle body online, that screw probably doesnt adjust the throttle position, but it MAY adjust the sensor attached to it. this might be why its idling high. that said, it shouldnt have really affected the idle at all, and that screw probably only adjusts the 'idle' voltage sent to the ecu which is calibrated from the factory. short of opening it up, you wont really know.

but if you were going to muck around with it, check the idle voltage (while engine is at operating temp) BEFORE you stuff around with it. maybe adjust it down a few 0.xs of a volt to see how it goes. if it doubt. put it back where it was before.

maybe a few cars can measure their idle voltage and post it in this thread. both 'working' and 'not-working' cars.

also might be the engine water temp sensor is stuffed causing the high idle thinking the engine is still slightly cold and keeping the revs up.

[andy65b]

OK UPDATE

I have just been down and NorthShore Prestige have a further look at the problem and exploring solutions.

The adjustment screw is FAIL. It will not move so no hope of checking it.

I have thought this through further and now I do not think it is anything to do with the throttle body, except that by cleaning it I changed the volume of air that gets past at idle.

We pulled off the hose that comes from the PCV valve on the right bank in to the manifold.

* If this is blocked off the idle is lower.

* When the motor is revved a couple of times, when the car comes back to idle a hissing noise can be heard from this pipe. (it is not leaking, pipe has been replace and checked for leaks).

* This suggests that the one way valve in the PCV is not shutting off at low RPM as it should.

I have had 2 problems that I thought were unrelated.

1. when pulling up fast (hard braking) idle would dip and sometimes stall. I then had the TB cleaned and the TPS / Idle volume reset.

2. The car now can have the idle set correctly by the set out procedure. Go for a drive and the idle creeps back up.

Whilst I first thought these were unrelated I now realize that the dirty throttle body was creating the dipping idle and covering the leaking PCV valve.

Fixed the TB (cleaned) and the volume of air getting through is now higher and add to that the air from the leaking PCV valve and I think this is leading to the higher idle. As I said earlier, I can set it correctly and then it sticks open and idle increases.

This sort of explains why no ECU faults are showing.

I have ordered the new PCV. Got to come from Japan so about 7-10 days I will know some more.

Fingers and legs crossed now this is right.

Cheers

Andy

PS. Ben also said that the PCV is replaced on a lot of V35's

Edited July 9, 2009 by andy65b

[zei20l]

ahhh can they not be cleaned

and what goes faulty about them??