1999 infinity qx4 rough idle problems

[linus73]

i recently purchased a 1999 qx4. i had the rear main seal, trans seal, crankshaft seal replaced due to oil leaks. i also changed all the belts and did a full tune up, including ngk spark plugs, wires, cap and rotor, pcv valve and a maf sensor. also had a cat convertor replaced and the truck still!!! idles rough and smooths out intrmittently., the other day it stalled at the light. i even tried fuel injector cleaner on 2 seperate fill ups. the truck still idels rough!!! cant figure it out, any help will be most valued.

[linus73]

p.s replace the timing belt and water pump.

[linus73]

well i took it to the dealer and they say it needs 1 new fuel injector and 2 oxygen sensors. so i decided to fix it myself since they want 3700 dollars! i will be changing all 6 injectors and all 4 oxygen sensors. that should solve the problems.........i hope total cost to do it myself approx 1000 dollars.

[FavreOnSunday]

....get those O2 sensors off eBay... I did all 4 on my '01 for around $100... I say try that 1st, then injector... Is the Service light on?

[linus73]

i changed all 4 oxygen sensors, all 6 injectors, idle is smoother but has a p0505 code which is a idle air control valve. truck does not accelerate as fast as it should(something is wrong) had a new timing belt installed and rechecked the timing!..... it is good!!

[linus73]

yes service light is on, p0505. i will be taking the truck to the dealer now, tired of guessing what is the problem. pretty sure it is the iac valve but will need a volume relearn done with that as well. already put close to 4000 in repairs, so i got no choice to go ahead and replace the iac valve and let the dealer diagnose it correctly.

[linus73]

well i took it to a infinity dealer and they say they dont want to touch it because i have aftermarket fuel injectors and they cant diagnose it correctly because of that. wtf? i told them just replace the valve and do the idle relearn. they also cant explain or diagnose the misfire. is it possible maby a bad distributor causing multiple random misfire?

[linus73]

oh by the way, is anyone or has anyone had these symptoms. rough idle and hesitation when accelerating, anyone? hello out there, i cant possibly be the only one!

[katielynns23]

Hi Linus! I have an 01 QX4 with the same problem. It really scares me when I am sitting at a red light and my vehicle almost dies! After checking around on other forums it sounds like it might be the MAF sensor? I really don't know! I am taking my QX4 to my mechanic (not a dealer!) on Friday. Hopefully it works, I will let you know! Also let me know how yours turns out!

[linus73]

well i changed alot of parts, 4000 worth! same problems!
although i did need most parts, i am convinced the rough idle and p0300(multiple random misfire is due to carbon build up and sludge in the engine. i am currently running a cleaner through the engine and will run it through the intake as well. awaiting some auto-rx cleaner in the mail!. ill keep yoou posted. and by the way it is most likely that your maf sensor is good! if you cann accelerate good then dont change it, taht part is 140 dollars and can be cleaned with maf sensor cleaner!!!!!!