Idle going mental after disconnecting battery, please help!!

[AP350GT]

Hi all,

 

I'll keep this as simple as possible - so today I changed the brakes on my 2003 350GT (VQ35DE, automatic transmission) from the peasant-spec single pot calipers to the standard Brembo 350z calipers.

 

I disconnected the battery at the negative terminal about halfway through the caliper swap (remembered the manual said to do this, too late maybe), and the key was in the ignition (I couldn't remove it with the drive in neutral),

 

Swapped the calipers, disks and brake lines over, bled them off, refilled the fluid reservoir, wheels on, lowered off the ramp.

 

When I start it, the revs are jumping between around 1500-2000 constantly. Slip, VDC and ABS lights are on.

 

Nothing in the engine bay has been touched at all except the brake fluid reservoir and battery.

 

I had a quick google while I had 3G for all of 30 seconds and found ECU and throttle position reset procedures, tried them (counting seconds in my head, no stopwatch available at the time) and the ecu reset seemed to have it settled for around a minute, but as soon as I touch the accelerator it starts hunting again.

 

It hasn't moved off the ramp space, I didn't dare try to drive it out in case it started doing it again.

 

Has anyone experienced this or have a solution?

 

Thanks in advance

 

Andrew

Edited May 27, 2015 by AP350GT

[glrnet]

You need to carry out the ECU reset and the throttle idle learning position again properly i think.

 

ECU Resetting Procedures

 

Please read all instructions and be familiar with them before any attempts.

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

 

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.

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

 

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 is ?ON?.

3. Turn ignition switch is ?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.

 

Operation Procedures

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. Conform that accelerator pedal is fully released, 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.

[AP350GT]

Thanks I'll try again tomorrow, printed that out so I can use my phone as the timer instead of reading off it

[AP350GT]

Well I tried the above numerous times today, cleaned the MAF sensor, had a look at PCV, throttle body looked clean. All vac hoses seem to be ok, plugs and wires seem ok.

 

I took a video before, you can see in this that it idles ok and then decides to have a fit again. I've had it idling normally but every time I did something that puts load on the engine, a small rev, turning on heaters, even windows up and down it goes into spazz mode again. I'm thinking the ECU might be shot if that controls the idle..?

 

Excuse the boring bit in the middle, I wasn't expecting it to idle properly, usually each time I start it, it goes straight to erratic idle. Skip to 1:07 for that.

 

Edited May 28, 2015 by AP350GT

[Tricky-Ricky]

Might be worth getting the fault codes read, I am starting to wonder if its down to the cam position sensor.

[Keyser]

That's not erratic idle that's boy racer mode

 

Just for my own morbid curiosity and as you did the brakes - pull the brake servo to plenum pipe off and bloke it so no air goes into the plenum - then try again - see if it still does it - prolly will as that seems like a TB or ECU fail but will cost nothing to try

[jumping350]

might not be relevant but my civic has done that same rev thing before and it was the idle air control valve, not sure if the zed has one but im sure it would be something similar to that or along those lines thats causing the problem, try keysers idea

Edited May 28, 2015 by jumping350

[AP350GT]

Tricky it didn't flag up any fault codes, this is why it's baffling. It's getting trailered home tomorrow so I'll try the dash light fault code method to see if I get anything that way.

 

Thanks Keyser I'll give that a try, anything is worth a go at the moment.

 

Jumping350 from what I've read the idle is controlled by the MAF, TB and ECU together, there is no IACV.

 

Hoping it isn't an ECU fail, what's involved if that's the case? I'm assuming it's not as simple as one-for-one swap going off how complicated everything is so far ha

Edited May 28, 2015 by AP350GT

[Mopedmark]

Hi mate when you got out of the car and went to the engine it sounded as if it was sucking in air a bit like a pop charger but its got a std air box, strange, there's got to be a fault code pop up, also have you managed to successfully do the pedal dance as above because this should reset it, I had to do it once similar thing I had the plenum off etc and then put the key in the ignition and turned the radio on, the instant I did it I knew I should not have, I did the pedal dance and it was fine.I tried using a stopwatch etc but in the end I just read through loads of times so I knew in my mind and then counted it in my head worked first time.

[AP350GT]

Hi mate, I've tried the pedal dance a load of times, maybe the engine temp condition wasn't right, I'm getting it trailered home later so will try again this afternoon.

 

Also when I did the throttle closed position learn, I didn't hear the throttle move at all, tried it a number of times.

Edited May 29, 2015 by AP350GT

[Mopedmark]

Make sure the conections on the maff and the throttle body are in right also did you manage to get the pedal dance done absolutely correct as per Graham's thread

[nodge69]

I had exactly the same problem on my Zed after cleaning the throttle bodies. The idle air volume learn is impossible when this is happening. Bit of a brown trousers moment but I managed to resolve it by doing the following:

• Disconnect the battery for a long time (2+ hours) and ensure the engine is completely cold
  
• Re-connect the battery and turn everything off (fans, lights, radio etc)
  
• Start the engine and let it idle for a long time (20+ minutes) until the engine gets up to temperature, don't rev it or touch anything
  
• At this point hopefully you'll have a stable albeit high idle
  
• Perform the three learning functions listed earlier in this thread (idle air volume may need multiple attempts)
  

Hope you get it sorted!

[AP350GT]

Lovely thanks bud. Is that disconnect both battery terminals?

And even if it's revving itself silly just let it run?

[nodge69]

Just disconnecting the nagative terminal will do. When I had this problem the silly revving only occurred once the engine was warm but didn't happen after the battery disconnect and idle to warm. Hopefully you'll get the same.

Edited May 29, 2015 by nodge69

[AP350GT]

I've had the battery off, done everything you said above and tried the 3 procedures probably 7-8 times now, a couple of times it started and idled well but within a minute it started doing it again.

 

It's running very rich whilst it revs it's tits off if that helps.

 

I'll keep trying the learn procedures.

[nodge69]

Aww annoying. At the point when you start the car during the idle air volume learn do the revs drop down to usual idle speed for about 10 seconds, then "give up" and return to surging? If so it could be the learn is being rejected. A few more things you must satisfy:

 

Engine should be at normal running temperature.

Steering wheel should be perfectly centred.

 

Also, do you have access to an ODB interface? A cheap Bluetooth one will do.

Edited May 30, 2015 by nodge69

[Randy_Baton]

I don't know if this makes any difference, but it may be worth highlighting to everyone that you don't have a 350Z but a 350GT. I know it states it in your opening line but many people gloss over things like that. I doubt most people (me included) have any experience of a GT over Z.

[AP350GT]

Nodge, I've ordered a decent OBDii tool, one that can display realtime sensor data. I had the engine up to temp and wheels straight. It just goes straight to erratic revving as soon as it's started. The odd occasion where it's started normally it's around a minute before going mad again as per the video.

 

Randy, yeah that's a fair point, I got the impression the Z and GT share the same engine, sensors and ecu, all the info I've read on both cars give the same answers.

 

I've ordered replacement cam position sensors, throttle body, going to give the maf a good spray with maf cleaner, double check pcv hoses.

 

All this happens a week after selling my other car, gutted!

[glrnet]

Sorry i've not commented for a while, just to pick up on something mopedmark said, you definitely have an intake "suction" noise when you are revving the car. How long have you ahd the car? Take the air filter out and see if the previous owner has drilled holes in the bottom of the air box, I've heard of this before to create the suction noise effect you have. I'd check the WHOLW air in take system for leaks if I were you. Just a thought, anyway hope you get it sorted mate.

[nodge69]

The reason I ask about the ODB is that there's an Android app available which will perform the idle air volume learn at the touch of a button. Much easier and it was the only method which got my idle to normal. Search the forum for Nissan Data Scan or NDS.

 

I think you're right about the 350GT, engine wise it's the same as early Zeds albeit the JDM version.

[AP350GT]

Sorry i've not commented for a while, just to pick up on something mopedmark said, you definitely have an intake "suction" noise when you are revving the car. How long have you ahd the car? Take the air filter out and see if the previous owner has drilled holes in the bottom of the air box, I've heard of this before to create the suction noise effect you have. I'd check the WHOLW air in take system for leaks if I were you. Just a thought, anyway hope you get it sorted mate.

 

Thanks bud. I've had the car a couple of months now. I've had the airbox out already and there's no holes drilled that I could see. It hasn't made that sound before. I'll check the intake system when I get time.

 

The reason I ask about the ODB is that there's an Android app available which will perform the idle air volume learn at the touch of a button. Much easier and it was the only method which got my idle to normal. Search the forum for Nissan Data Scan or NDS.

 

I think you're right about the 350GT, engine wise it's the same as early Zeds albeit the JDM version.

 

I have an iPhone, don't think I know anyone with an android phone. I'll look it up though thanks mate.

[AP350GT]

Found the NDS2, ordered a Hudl and bluetooth v1.5 scanner, thanks for the tip Nodge.

[AP350GT]

Bit of an update, got nds just waiting on the Bluetooth interface.

 

I did a resistance test on both cam position sensors this morning, and both of them had readings of zero across 2 of the 3 pins. I tested the spares I bought and they checked out ok, registering resistance across all 3 pins (1-2, 1-3, 2-3) so swapped them over. Started it up and it's still the same.

Cleaning the maf sensor made no difference either. Double checked for loose anything, split vac lines, all good.

[AP350GT]

Throttle body changed, still the same. Losing the will to live with this thing now!

[nodge69]

When mine went wrong I spent hours reading so many stories of people with this and idle problems all over the world. Nissan garages don't have a clue and many people have replaced the throttle body(ies) and ECU only to find it hasn't fixed it. One guy bought three different throttle bodies, ECU re-flashed, new ECU, then just happened to try his old throttle body while waiting for a forth, Suddenly the idle air volume learn just worked and he was back to normal! I guess what I'm trying to say is - hang in there and hopefully NDS will help you sort it. At least you can run it multiple times easily rather than pressing pedals all day.

 

I've come to the conclusion that the Nissan "idle air volume learn" is, for want of a better word, @*!#! They use it on a whole range of their cars and you'll find the Internet full of horror stories. It might work when the car is in the factory but once the engine ages it doesn't seem fit for purpose. Unless you have an actual error code relating to the throttle body then I don't think they are ever at fault, and I also believe it's nearly impossible to damage them by cleaning them. Nissan stealers seem happy to throw new bodies and ECUs at the problem though but Nissan themselves must know the nature of the problem by now? Either the garages aren't informed or they are aware but would rather sell you parts (£££) than do a proper diagnosis. Rant over hehe!

 

Good luck with it though mate, I know how frustrating it can be.