O2 Sensor / Missing Fuse / High Idle / Help?

[peaceofmindinhim]

Hey all,

It's me again, with a brand spankin' new J30 question.

So, I was checking out my fuses today, because I was bored and was trying to figure out why my A/C wasn't working (another issue, another day) and noticed I was missing the injector fuse in my fusebox under the hood, and my O2 sensor fuse under the dashboard.

So I replaced both fuses, and noticed 2 things:

A). My idle is waaaay high - like 2,000 RPM. I tried to clear the idle memory using the following technique:

1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch OFF and wait at least 10 seconds.
3) Confirm the accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
4) Repeat the following procedure quickly 5 times within 5 seconds.
1) Fully depress the accelerator pedal.
2) Fully release the accelerator pedal.
5) Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds
6) Fully release the accelerator pedal within 3 seconds
7) Start engine and let it idle.
8) Wait 20 seconds.
9) Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.

It seemed to work at first, but after letting the car sit while I went to Walmart (soda run), and came back, the idle was back at 2,000 RPM.

B. The car was like a ROCKET at first. Literally - I've never had that much performance out of the car. Hit the gas on a turn and the car fishtailed. I had to make sure I wasn't driving a Ferrari!

But after about 20 minutes, the rocket turned back into my normal car, and the performance went away. Meaning, when I initially hit the gas from a standstill, it wouldn't shoot off like a rocket anymore.

In about 6 hours I'm taking the car into a mechanic to have them pull codes and tell me what's wrong, but I was hoping you wonderful and knowledgeable folks can help me out.

In the meantime, I took the fuse out for the O2 sensor, because it scared me having the resting idle be at 2000 RPM.

Thank you in advance for your replies!

Eric

[Ozzie]

Sounds like your O2 sensor might have gone bad, or your TPS is playing up.
You will have a better idea (hopefully) once the mechanic pulls the codes for you.

[peaceofmindinhim]

I was thinking both - looking forward actually to the mechanic pulling codes and getting this fixed once and for all.

The other night I did a Trans diagnostic (from the DIY stickie), and TPS came back as an error, but I have not been able to replicate the same error. The next time I did the tests (and subsequent tests), it didn't come back as an error. However, my research of TPS symptoms match what I have been experiencing. Walks like a duck, quacks like a duck...

Second, is the J30 SUPPOSED to be a rocket ship, or was I experiencing the car malfunctioning?

Thank you for the quick reply.

Eric

[peaceofmindinhim]

Got the car back from the shop. Mechanic pulled codes: Speed Sensor and Knock Sensor - cleared both codes. It turns out the MAF sensor wasn't properly fitted and connected - this, combined with cleaning throttle body seems to have taken care of the rough idle.

However, as stated before, ever since putting O2 sensor fuse back in the car, the car will start idling at 2000 RPM when I turn the car on. More often than not, it will eventually drop down to 800 after 25-30 seconds or so.

Should I be worried? I'm looking at getting a new(er) car soon, so I don't want to put more money into this vehicle.

Thoughts, ideas?

Should I try idle re-learn again?

Should I disconnect ground from battery to force ECU to lose data and re-learn?

Eric

[yodawill2000]

I know from experience if the TPS is set on the high side the throttle response is almost spooky !!
But it will also idle high.
Also , if your knock sensor is cracked it will be fine until the engine heats up and the cracks expand from heat.