I done hours of research here on this topic.

1. MAF was replaced 3 months ago
2. O2 sensors were replaced 3 months ago
3. cats were replaced 3 months ago
4. mechanic checked for vaccum leaks, none

SES came on for p0505, then I did a Seafoam treatment through the brake booster and the light went off and comes on randomly but goes off eventually during the day.

I can hear the IACV motor whining/working so I doubt it is busted.

When I start the car first thing in the morning after sitting the whole night, the RPM idles at 1900 then drops to 1700.

Once I put it into drive it idles at 1100 then when the engine warms up, it goes to 750 then shortly after to 500-400. Once the engine is completely warmed up it idles at 400.

What should I do?

I've already spent a sht ton of money fixing the car but need it for another 2 months.

 

Have you tried cleaning the throttle body? Not sure what year your car is but 5.5 gens have idle problems when the TB is dirty.

 

2001 SE AUTO

 

The least expensive thing to do first is to make sure the TPS is adjusted correctly, follow the manual.

There is a TSB on the wiring harness, if it is an intermediate problem, the wiring harness is going to be hard to diagnose. I would look hard at the IACV and if it was never replaced and you have over 80,000 miles it will be a good idea to replace it before it fries the ECM.

I assume you already know about disconnecting your electronic motor mounts.

 

I have the manual but where would I look specifcally to find how to adjust the throttle position sensor?

Also, what wiring harness are you speaking of?

Thanks

 

The TPS adjustment is on EC-111, you should start on EC-67 and then go to EC-429.

TSB NTB01-076b 2000-2001 MAXIMA EGI HARNESS,WIRE BREAKAGE

When you turn on your AC or move the steering wheel, will the idle rise?

 

YES IT DOES!

what does that mean?

 

That is normal, at least the IACV is responding.

Check the TPS and then disconnect the negative battery cable for 2 hours and then see how it idles.

If the idle is still low, you will need to check the IACV (just replace if it was never replaced and the vehicle has over 80,000) check wiring, ECM and MAF.

 

I checked the manual and it doesn't really tell me what to do to the throttle position sensor.

Also, what do you want me to do when checking wires? For splits or damage or voltage?

 

i had the same problem i replaced the iacv and walllaaaaaaaaa problem fixed

 

these look like winning answers to me!

also something that might help but seems totally unlrelated (i know its wierd) ios replacing your battery terminals... my car would die on crank and would not stay on for some reason one day after i drove to a park to hang out with a couple friends.. i had to knock the terminal around and move it back and forth just to crank it on long enough while a friend turned the key and hit the gas to keep it on....

... but yeah, turned out to be my battery terminals.. it was so old when i took it off it litterly chipped in my hands like clay.

replaced it and car fires up pretty strong and never stalled out again since that day (thank god)

its a cheap fix ($8 bucks) but id lean more towards the TPS and iacv/tb area

this is the order id go in from cheapest to most expensive...

TPS and new battery terminals
iacv and then tb (but if u can get a good deal and get them both attached for a good price id get both the tb/iacv together)

anyway good luck and report back with your findings!

 

Check the ohm readings on the IACV. Terminals, i-2, 2-3, 4-5, 5-6. They should all read the same. If one is out replace the valve. Better get the gaskets for the throttle body to intake first, there are 2.