How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Jake Your Own Question
Jake
Jake, Infiniti Mechanic
Category: Infiniti
Satisfied Customers: 4735
Experience:  Nissan / Infinity auto and collision technician
20440119
Type Your Infiniti Question Here...
Jake is online now
A new question is answered every 9 seconds

I have a 2001 Infiniti QX4 that idleing very rough, and is

Customer Question

Hi, I have a 2001 Infiniti QX4 that idleing very rough, and is now stalling when stopped at a light
JA: Is the rough idle intermittent or consistent?
Customer: consitent surging the mechanic resolved the idle problem but now the engine is stalling somewhat intermittently at stop signs, etc.
JA: Are you fixing your QX4 yourself? What have you tried so far?
Customer: im checking with my mechanic at the moment, I believe he replaced the MAF
JA: Anything else you want the mechanic to know before I connect you?
Customer: We have no engine codes being thrown and we are now idleing smoothly but have the stalling problem when stopped
Submitted: 5 months ago.
Category: Infiniti
Customer: replied 5 months ago.
The mechanic fixed the rough idle and did the following things:Replaced IAC motor
Removed MAF and cleaned
Disconnected Battery
Checked for Vacuum Leaks
Expert:  Jake replied 5 months ago.
Hey there, thanks for the question.I have to ask why you replaced the IAC? Did you have a P0505?
Customer: replied 5 months ago.
Not sure, the mechanic chose to. He said he wasnt encountering any error codes
Expert:  Jake replied 5 months ago.
Ok good! Cause that’s a scary code to get on these trucks.
Customer: replied 5 months ago.
The mechanic is baffled! The truck only has 70k miles and is in otherwise excellent shape
Expert:  Jake replied 5 months ago.
the idle is corrected right? Just stalls at stop lights and has no codes? But when you rev into higher RPMS it feels smooth?
Customer: replied 5 months ago.
Yep that's correct
Expert:  Jake replied 5 months ago.
I would bet you anything is there are NO vacuum leaks that’s it’s a distributor issue. Have the mechanic check the fuel trim corrections. If the banks look good then a distributor is likely in order. I even see times where the seal will leak internally and oil will build up in the inside bottom cover and cause it to stall at idle.
Customer: replied 5 months ago.
Great, I'll have him check it out thank you
Expert:  Jake replied 5 months ago.
Your welcome, if you run into more questions just let me know!If not all I ask is you leave a kind rating.Thanks.
Customer: replied 5 months ago.
Will do thank you!
Expert:  Jake replied 5 months ago.
No problem
Customer: replied 5 months ago.
Mechanic says theres no distributor, is that the case?
Customer: replied 5 months ago.
The mechanic describes that when it stalls, he has to put the car in park and cycle the key back and forth several times likes he resetting the IAC
Expert:  Jake replied 5 months ago.

Hey, I apologize for the delay.

Yes, he is likely right. They switched from distributor to coils from 2000 - 2001

Expert:  Jake replied 5 months ago.

did he RELEARN the "Idle air volume" after replacing the IAC?

Expert:  Jake replied 5 months ago.

if he did NOT relearn it with his scan tool, or doe snot have the option he can do it manually.

1. Turn ignition switch “ON” and wait at least 1 second.

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

3. Start engine and warm it up to normal operating temperature.

4. Check that all items listed under the topic “PRE-CONDITIONING” (previously mentioned) are in good order.

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

6. Start the engine and let it idle for at least 30 seconds.

7. Disconnect throttle position sensor harness connector (brown), then reconnect it within 5 seconds.

8. Wait 20 seconds.

9. Make sure that idle speed is within specifications. If not, the result will be incomplete. In this case, find the cause of the problem by referring to the NOTE below.

10. Rev up the engine two or three times. Make sure that idle speed and ignition timing are within specifications.

Expert:  Jake replied 5 months ago.

lastly, since all the mechanic did is CLEAN the MAF.

Have him tell me what the fuel corrections are when idling before it stalls. I am guessing they are the rich fuel mixture is causing it to stall.

have him report the fuel trims at idle to you and get back to me! thanks.

Customer: replied 5 months ago.
Thx will do!
Expert:  Jake replied 5 months ago.

thank you.

Expert:  Jake replied 5 months ago.

If you’ll need anything else just let me know. If not please be sure to leave a kind rating is all.

Thanks.