viking1

Hi folks!! My 95 Max idles and runs fine when in neutral and stopped. However, if you even wiggle the shifter, put the car in any gear (manual tranny), turn the steering wheel, or are rolling at all, the idle shoots up to around 1800 rpm and stays there until the car is stopped and in neutral (where the idle returns back to normal). It has strong acceleration through all the gears and runs like a clock, except the high idle is like having the cruise control on all the time when driving.

I have thus far:

1)cleaned the ICAV and throttle plate
2)replaced and calibrated the TPS (and checked the wiring)
3)replaced the MAF & knock sensor
4)lubricated the throttle cables, linkage, and checked for vacuum leaks
5)replaced the air cleaner boots (all of them)
6)reset the ECU (via disconnecting the battery overnight) multiple times
7)replaced the EGR valve & cleaned the tube
8)run sea foam through the engine

It is throwing a PO120 (TPS) code every time, yet all appears to be copasetic re: the TPS circuit. I'm really at a loss, and hate to keep throwing $$ at the problem without having a better idea what it could be. I have the FSM, and it isnt helping me. I also searched all the forums here for a similar idle problem (to no avail). If someone has an idea what this is, I would be VERY appreciative. Thx much

Kevlo911

iTrader: (36)

Sounds like the iacv gets stuck when it gets a signal. Might be a bad iacv, I had to replace mine once as well.

Grn4thgen

+1
maybe take it apart at first and see if you can clean it if it persists change it out.

cashoit

Check for vacuum leaks and check IACV and clean grounds.

viking1

No vacuum leaks, and I DID clean the grounds and ICAV once already. Is there any actual way to test it (the ICAV)? I have also always wondered why you have to change the whole thing, and cant just do the individual solenoids etc?

viking1

Oh, BTW: why does the car throw a PO120 code if its not a TPS problem? I thought computers were here to make our lives easy (hahaha)... :-)

ThurzNite

iTrader: (13)

I had an issue with my iacv before (dunno what an icav is though). Threw a CEL, car stalled sometimes, especially if I'm cruising and planning to hypermile to the next light, push clutch in and rpms drop till it almost stalls, sometimes it does.

But, doesn't sound like your issue. Sorry for thread crapping. Good luck!

Dr J

Kevlo911

iTrader: (36)

If the wiring is fine and the tps is new, i dunno why it is throwing the code. But there have been codes fixed by replacing other parts lol

jholley

iTrader: (13)

Pages EC-309 and EC-310 of the FSM will guide you in testing the IACV. It will show you the wires to test for continuity, the 30 ohms you should read on the IACV-AAC, and how to manually test the solenoid within the IACV-AAC.

viking1

Thx for that info, Sir. I saw the pages, but I guess what is throwing me is the code is PO120 (NOT PO0505 as specified). I actually found a new ICAV for $73 online. Might just behoove me to try that and see if it makes a difference. I actually am feeling a bit queasy about disconnecting the ECU harness for testing in a car this old (and maybe creating other shorts/problems).......

viking1

Sad, but true.....

cashoit

Big giant enormous +1!!!!

Listen man. If u have already replaced the defective part then, U have to diagnos the ENTIRE system involved.

The car is throwing a code cuz something IS wrong and the ECU senses it. If the car stallin, then it has to do with air or fuel. Since i know the max, ima say its an air issue.

If u gettin a code, chances are its electrical/sensor related to somethin with an air sensor.

A bad TPS would respond differently than what u describe. Since u MT, the car would buckle during acceleration cuz the ECU dont know when the car is WOT or only partial throttle.

Since u replaced the TPS and cleaned everything. My only guess would be to clean all hoses and replace IACV.

The IACV has a lot more functions than jus idle. AND its step motor so it can work open or close but may be malfunctioning in between. I personally would hit the JY for another 2 or 3 and try them all before buying a new one.


I had a Evap problem and my car was throwing a code. I replaced everything and cleaned everthing related to that code and RESEARCHED. Fix turned out to be something else not code related. So i know where u coming from.

But u can fix it bro word!

njmaxseltd

iTrader: (19)

It's throwing a TPS code at you.

Did you recheck the new TPS?
Check the signal from the TPS?
Check the reference voltage (5v) to the TPS?
Check the wiring from the TPS back to the ECU with an Ohm meter?
Check to make sure the signal from the TPS is actually making it back to the ECU and is correct?

maxed_out_99

YUP!

i would just for the hell of it unplug the tps and see if the symptoms change or persist if they change your tps is prolly fine

viking1

I'm really hesitant to unplug the ECU harness for fear of causing more problems, as this car has 239,000+ miles on it. Am I being overly cautious? I DID check the 5v+ signal to TPS.......

viking1

Yes, I DID unplug the TPS in this manner, and the exact same problem persisted. That's how I assumed my TPS is not the issue (despite the PO120 code). Very frustrating; I guess the IACV is my next stop.......

viking1

Air boots are ALL new (as is the MAF sensor), so think I can eliminate those. I guess its ICAV time. I dont like the idea of spending the time pulling/installing junkyard valves in russian roulette style. My time (in 110 degree heat, haha) is worth more than the $76 for a new ICAV. It IS really frustrating though, because the car runs so well otherwise....