Good ol' idle issues (3.5 pajero)

[pjb]

Folks, I've got a 3.5 Pajero.
I've trawled all the old idle posts, but I'm stumped.

Past few days I was having an intermittent low idle/stalling problem. I suspected the IAC, so opened it up to discover it's pristine inside. Also coil resistance is all good. The tip was a bit gunked up.
Took the throttle body off and gave it a good clean, put it all back together last night, started it up, 800 rpm once warm, and about 900 with the AC on; all good.
Today, 1500 rpm all the time, with about 800 rpm with the AC on.
Not sure what the problem is. My first thought is the IAC, but it looks to be in such good condition!
What should I try next?

[date]

Firstly, I would check for air leaks in the vacuum hoses (or a hose fallen off). This could make the beast idle roughly until the ECU caught up with the airflow and mixtures. Then, it may overcorrect, causing it to idle faster.

Another possibility may be the Oxygen senson in the exhaust. If that is old or clogged up, it may be slow in reacting to changing engine speed/load conditions.

Look for the air leaks / hoses fallen off first.

[DRides]

have u had a falt battery / has the battery been disconnected?
if so, u need to reset the base idle.

[pjb]

Flat battery! Yes - just put a new one in...
Will look into that tonight.

Cheers fellas!

Man I wish I could change the topic title!

[NJV6]

You can - just edit the 1st post and it changes it.

I want a 5.3 Pajero too though!

[date]

By coincidence, I have just put a new battery into my 3.5 NL Pajero. The idle is now marginally slower, but infinitely smoother. I attribute the smoother idle to a stronger spark.

Question: How do you reset the idle? The idle speed on my wife's Magna is erratic - ranging from stalling to over 1500 r/min. I would like to get that one sorted out as well.

[DRides]

Petrol 6cyl.
to reset the base idle u need to put the engine into "SAS Mode", and then adjust the idle air bypass screw (or speed adjusting screw - SAS).
set the rpm to 700rpm and take the engine out of sas mode. the engine will idle @ aprox 1200rpm for a few min (once) and then start to come down.
the best thing it is let the idle come down a bit then go for a short drive. (can take up to a few days of normal driving to set itself)
THE THROTTLE BODY SHOULD BE CLEANED B4 DOING THIS!!!
ENGINE @ NOT

Note. pending on the year of vehicle, you will need a laptop to put engine into sas mode. - mid 90s and newer need laptop.

[date]

DRides:
Thanks for the info on idle speed adjustment. I have a laptop, but no means of connecting it to the vehicle, and also no software even if I could join it up. Is there an alternative way, or would I have to go to my 'Friendly' Mitsubishi dealer?

As an example, could I disconnect the ISC motor and set the idle? I guess not because no doubt the ISC has already screwed itself out a bit and you would be starting froma funny base level.

[DRides]

hi,
Friendly Mitsubishi dealer mate (there not all bad!!).
the laptop i am talking about is the mitsubishi laptop.
some scan tools may b able to do this as well, but dont know.

[pjb]

From what I've read adjusting the idle screw is not necessary...
Last night I pulled the battery for half an hour. Started up and left for 10 minutes. Working fine. This morning, wouldn't idle.
Gonna keep driving it like this for a bit to see if it settles down.

[DRides]

i am a mitsubishi mechanic... adjust your idle.

[pjb]

Crap, guess I'll have to take it to Mitsi to get that done
Cheer DRides.

[NJV6]

Mr Mitsi mechanic - why would it need adjusting all of a sudden??

[DRides]

you need to "adjust" (reset) the idle after the battery has been disconnected/flat battery.

[DRides]

if you have this terminal on your wiring harness you do not need the laptop, just ground out the wire and that will put the engine into "SAS Mode"
(The brown one)

[date]

Drides: to coin an old phrase - "Where do ya get it?" What I am really saying is "Where is that socket located?" What model Mits did you photograph that on? I don't remember seeing a plug like that on mine, but it probably is there somewhere.

[DRides]

the pic is from my NH, my 3L NJ has it as well, some magnas ect.
the terminal location is on the firewall, RH top corner (looking @ engine bay from front of vehicle) near the mitsu plate.

[DRides]

[DRides]

engine bay pic is not my NH (just a pic of the net) but you can see the terminal

[DRides]

the terminal may be taped to the main wiring harness

[date]

Thanks Drides. I'll go & have a look at my vehicles and see what is (or isn't) there. I vaguely recall something like this. I assume that you earth the plug out and then set the idle via manually via the idle screw. Correct?

[DRides]

yes, earth out the pin, start engine (will prob idle @ aprox 300 to 600rpm) and adjust idle.
engine needs to be @ NOT.
(I just use a bit of electrical wire to earth out pin)

[NJV6]

I have had my batteries out many many times and never needed to do this. Start it up and drive off.

[DRides]

same, on both the nh & nj, but sometimes you need to do this.
THIS IS ONLY DONE IF YOU HAVE A IDLE ISSUE AFTER THE BATTERY HAS BEEN DISCONNECTED!!!!!!!

[pjb]

Good stuff, will check that out for sure. Don't need to mess with anything else? TPS, idle switch etc?

[DRides]

just the idle screw adjustment

[fast 4g54]

howdy DRides...I have just converted my carby 4g54 triton to efi using a ts magna as a donor including the wiring harness. This socket is present. Am i correct in thinking that using the same method of grounding this terminal, is the right way to adjust my ignition timing? cheers mate...

[DRides]

yes, but it has been a few years since i last worked on one so....
the socket is black in color on the magna harness? eather way its the same thing.
engine @ NOT. can not remember what the timing is set @ sorry

[fast 4g54]

thanks mate... Yes the socket is black on the magna...i discovered yesterday that with the terminal grounded, timing should be set at 5 deg. BTDC, when ground wire is removed timing should be 13 deg. BTDC...thanks.

[pjb]

Stupid idle...

I've had the throttle body off again, and re-cleaned to make sure.
Backed the speed adjust screw out until the butterfly was completely closed.
Refitted, grounded the brown plug.
Started up, ran up to temperature (and then some).
Can't get the thing to idle any less than 900-1000 rpm. Certainly can't achieve the specified 700 rpm.
I'm thinking an air leak somewhere? Or cold start solenoid problem?

Sometime when driving the idle drops right away - maybe leak/solenoid finally closing off?

I'm sure a mechanic would have this sorted in seconds...