Nissan 370Z Forum

Nissan 370Z Forum (http://www.the370z.com/)
-   Intake/Exhaust (http://www.the370z.com/intake-exhaust/)
-   -   P0300, high idle, (http://www.the370z.com/intake-exhaust/70263-p0300-high-idle.html)

Sidz 04-24-2013 09:26 AM

Quote:

Originally Posted by cheshirecat (Post 2282487)
OP, any mods? intake/exhaust, etc? This code is generally thrown with an aftermarket intake.

no intake and no exhaust. no mods that would directly have a connection. Only suspension

Sidz 04-24-2013 09:34 AM

Quote:

Originally Posted by Sh0velMan (Post 2282495)
There's multiple places you can get a vacuum leak without removing the manifold.

The symptoms you're getting are strongly indicative of either

A: A sensor failure somewhere in the closed-loop system.
- MAF sensor
- Primary O2 Sensor
- MAP sensor (unlikely)

B: Vacuum Leak

C: Horrific exhaust leak at the header/head interface...very unlikely. You'd hear/smell/see it immediately. And you'd probably catch something on fire eventually hahaha.

I'm not jumping to throttle bodies' replacement as quickly as nissan. i mean MAYBE an exhaust leak somewhere considering I maxed out my coilovers.. i could have hit the exhaust but I don't hear anything high pitch when I get on it.

we shall see. still haven't gotten a call to pick her up.




MAP? is it the sensor by the right throttle body?

chrischhorn 04-24-2013 11:22 AM

its the sensor on the back driver side of the intake manifold. You have to take the top part of the intake manifold cover to see it. Its plugged in and held in by a single screw.

Sidz 04-24-2013 03:58 PM

According to Nissan, if it's not bad spark plugs, they now don't know what it is. They are replacing the spark plugs hoping they were gaped wrong.

oh joy

chrischhorn 04-24-2013 09:20 PM

I had to drop the gap on my plugs. they were getting blown out at 7700 rpms. all good now :-) Did you buy the plugs from Nissan?

Sh0velMan 04-24-2013 09:22 PM

Chris, what was the symptom of spark blow out? Also, how damned high are you spinning it???

roy'sz 04-24-2013 09:55 PM

I would have seafoamed the car as a last ditch effort....in for the results. Good luck!

chrischhorn 04-25-2013 12:10 AM

Quote:

Originally Posted by Sh0velMan (Post 2283797)
Chris, what was the symptom of spark blow out? Also, how damned high are you spinning it???

Running this bad boy to 8k and I make power all the way till then. Basically it was very clear in the dyno chart where it would cut out real bad in the pull. It would dump rich right at 7700 and be normal. Created a dip in the dyno chart multiple times between 7700 and 8k. Even once at 7500. Tuner charged me $50 and told me to bring it back after I dropped the gap in the plugs. Sure enough, runs smooth up till redline after I dropped the gap to .026 and he was able to get a better tune out of it to the top. The 4.08 gears with the 8k redline should be a wonderful pair :)

Sidz 04-25-2013 07:51 AM

Quote:

Originally Posted by chrischhorn (Post 2283791)
I had to drop the gap on my plugs. they were getting blown out at 7700 rpms. all good now :-) Did you buy the plugs from Nissan?

No I had hks


-v and her z

cheshirecat 04-25-2013 09:15 AM

Quote:

Originally Posted by Sidz (Post 2282498)
no intake and no exhaust. no mods that would directly have a connection. Only suspension

At that point I would definitely side on the issue of bad/dirty MAF sensor(s) or faulty O2 sensor in one of the cats. You should not be throwing this code in an unmodded car.

If those are fine, like others have said, I would check the coil packs and also for vacuum leaks.

Sidz 04-30-2013 08:16 AM

Heard from Nissan this morning- last word is fuel injectors.

cheshirecat 04-30-2013 09:21 AM

Quote:

Originally Posted by Sidz (Post 2292800)
Heard from Nissan this morning- last word is fuel injectors.

Sounds like they're just crossing off things on a list.

Sidz 04-30-2013 09:41 AM

Quote:

Originally Posted by cheshirecat (Post 2292892)
Sounds like they're just crossing off things on a list.

Ya, I told him to stop guessing and have my car ready for pick up.

what a headache

Kmccarthy714 11-14-2013 01:13 PM

Your idling high because your car is LEANING OUT, most definitely start with vacuum leaks, hoses throttle body intake manifold. Move onto sensors that read air flow, I.E Bank 1 Air Fuel sensor and bank 2 Air/Fuel sensor. Next move to MAF's(not likely as you would throw a Air Fuel code and the air fuel sensor.

Bottom line
1)Vacuum leak
2)Sensors monitoring vacuum and air
3)Exhaust leak BEFORE A/F SENSOR
4) Fuel drop off causing car to throw more air through the chamber

Check by disconnecting MAF's and seeing if idle changes or fluctuates at all that will rule out the sensors.

Sh0velMan 11-14-2013 01:22 PM

Quote:

Originally Posted by Kmccarthy714 (Post 2569041)
Your idling high because your car is LEANING OUT, most definitely start with vacuum leaks, hoses throttle body intake manifold. Move onto sensors that read air flow, I.E Bank 1 Air Fuel sensor and bank 2 Air/Fuel sensor. Next move to MAF's(not likely as you would throw a Air Fuel code and the air fuel sensor.

Bottom line
1)Vacuum leak
2)Sensors monitoring vacuum and air
3)Exhaust leak BEFORE A/F SENSOR
4) Fuel drop off causing car to throw more air through the chamber

Check by disconnecting MAF's and seeing if idle changes or fluctuates at all that will rule out the sensors.

First off, this is a 7 month old thread that was already resolved.

Second, you're re-hashing what others have already said (including myself in a bulleted list on the first page).

Third, in testing I've performed since this thread was concluded, I can actually say that MOST vacuum leaks on this car, the car will adjust idle around it and stabilize somewhat close to the commanded idle speed unless the leak is absolutely massive.

Case in point, i can disconnect one of my catch cans from the intake manifold (big nipple on the front of the plenum), and briefly (3-5 seconds) it will surge up to around 1800rpm, but it will quickly adjust and go back to almost normal.

This wasn't something I was doing for fun, was doing some diagnostics, and I never tried disconnecting both of them, that would likely be too much of a leak.

Anyway, yeah. Thread is over and done with anyway.


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