Anovice

I have a 2000 Infiniti I-30 with about 82,000 miles.

Last night I was about to park my car and it stalled. While that had not happened before, because it started right up and I proceeded to park the car, I did not think much about it.

Today I needed to go to the store, which is about 5 miles from the house, and on the way I noticed that at each stop sign or light, it was it was idling a bit high. As I recall, it normally idles smoothly and quietly around 800 rpm and it racing a bit and idling at about 1,100 rpm. However, as I drove to the next stop sign or light the car ran fine. And this repeated all the way to the store.

The return trip became more problematic. About a mile from the store the "Service Engine Soon" light came on. Again, between stops, the car ran fine. However, when I would get to a stop sign or light, the idling became erratic. Surging if you will between about 1,500 rpm to 1,800 rpm back to 1,500 and back to 1,800 and so on.

I made it home and a few hours later started the car and it's the same. The "service Engine Soon" light is on and the tachometer jumps from 1,500 rpm to 1,800 rpm back down to 1,500, up to 1,800 and so on. Interestingly, when I give the car gas and even when parked, the engine is responsive. There is no hesitation. But when I take my foot off the gas it goes back to 1,500 rpm - 1,800 rpm sequence.

Before I bring the car to the mechanic Monday, I thought I would post to get some suggestions to see if this is a common and known problem with these engines and if the fix is simple.

Thanks.

Anovice

Fakie J Farkerton

iTrader: (51)

Go to your local aftermarket parts store and use their free code scanner.
Report back with the findings.

vq30nismo

To be honest it could be a bad coil causing a misfire, a bad MAF sensor or a bad IAC valve causing the jumping idle.

A quick trip to autozone or what ever local parts store is around will give you a free code check and that will let us steer you down the right path.

Most of these problems can easily be fixed.

Anovice

Thanks for the suggestion!

I just returned from Advance Auto and the code is PO505 "Idle Air Control System". The employee, who seemed technical, said this is most likely the IAC - Idle Control Value.

I was bit surprised at the cost, which was $210. I do see coupons on line for 20%-30% off, so that's one way to go and have my local mechanic install it. I can also check the cost from Rock Auto tomorrow. However, I have some questions:

1. Is an after market IAC valve fine, or do you recommend OEM?

2. He printed me out a few pictures and it seems the IAC value is located on the bottom side of throttle body. How long should it take a competent mechanic to install the IAC valve (I am trying to figure out approximate labor cost)?

3. Are there any long term benefits in going to the likes of InfinitiPartsUSA.com and replacing the complete throttle body, including the IAC valve, instead of replacing only the IAC valve (assuming the cost is not prohibitive)?

4. As mentioned in my original post, the problem only seems at idle and not while I am driving. Do you think it's a bad idea to use the car for a few days until I can get the IAC valve (or whole throttle body) replaced?

I am not by any means mechanically inclined, so any other thoughts and suggestions would certainly be appreciated.

Anovice

Fakie J Farkerton

iTrader: (51)

We need someone else to jump in here and let you know if your cars ECU is affected by a bad IACV. I can't remember the years affected.
You may need to disconnect your electric motor mounts too~but wait for confirmation on that..

This is something you can definitely do yourself.
Post a WTB in the classifieds here.

Stru

Yep, you probably pulled a Stru and bought a lemon. I thought "Oh Idle Air Control malfunction, that's nothing! I'll change the IAC valve and I'll be good to go!" NOPE. When the IACV, it fries the ECU in the 5th Gen Maximas/i30s.

Here's a free diagnosis you could try. Disconnect your battery, wait about 20 minutes, then get under the dash and remove the ECU. There are 4 bolts [i think 8mm] holding it to a mount behind the kick panels. You could access them from the floor by removing those plastic pieces by your feet and then it's accessible, but the bolts are a total b***h to remove just because you have NO room to work with. Once your ECU is out, get a phillips screwdriver and take the lid off of the ECU. Look at the STA509A chip and check for burn marks, cracks, etc. in the mosfets of the motherboard. If so, you'll need a new ECU (which cost about $1200 brand new, but about $270 at junkyards)

Let me know what your ECU looks like. If it's good, then I'd immediately replace your IACV and unplug your electric motor mounts. If not, do some research among the forums to help you with your journey. It's a headache and a half, jsyk

Fakie J Farkerton

iTrader: (51)

Thanks Stru for the facts, I thought it was his gen, but didn't want to scare for no reason.
I guess, BOO!

Anovice

I went to YouTube and while not good videos, this person does indicate that when the IAC value gets shorted out, it then burns out the ECM, so the ECM needs to be replaced too (some sequence like this)!









Now I am absolutely lost!


More questions:

1. Is it definite that I need to replace the ECM?

2. Should I not drive the car and get it into the mechanic tomorrow to see if the ECM is now bad too?

3.Or by driving the car can I burn out the ECM if it is already not?

3. If the ECM is now bad, how can I find one from a junk yard?

4. What year Maxima or I-30 can the ECM come from?

5. If I am am able to go the junk yard route, should I also get the IAC valve at the junk yard?


Advice and direction would really be appreciated!

Anovice

Anovice

I had the IAC valve changed yesterday because of the code PO505 and erratic idle. The battery was removed first and then the IACV changed. The mechanic started the car up, the "Check Engine soon" light went off, no re-learn, no more erratic idle, the ECU was NOT fried, and the car purrs at 700 RPM.

Anovice

thefranks5

I'm experiencing the Idle Control Valve issue on my 2001 Maxima and read your recent string of posts in 2013.

I'd like to follow up, please. Now that it's been several months, have you experienced any issues with your ECM?

Thanks for your time.