Pajero idle control and ECU
Submitted: Thursday, Sep 09, 2004 at 19:14
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ian robbo
My mechanic tells me that he thinks my ECU is a bit dicky.
My Pajero is 92 model NH series GLS 3.0 litre EFI petrol version which I bought brand when it was brand new, with just under 240,000 km on the clock.
It was fine until about a week ago when all of a sudden and out of the blue the engine started stalling when the engine revs were allowed to drop , the revs would drop right down and the red light would come on and the engine would stall , ie when pulling up .
Until today - when I could finally get the the right end of the queue and my mechanic had a go at fixing the problem , I have been running the vehicle with the throttle pulled out a tad to stop the idle speed dropping below about normal + a few 100 rpm - to ensure the engine didn't stall.
The mechanic tells me he "fixed" the problem but don't know if it'll keep as he thinks the ECU is the problem - he had pulled it out and wiggled the capacitors about a bit to fix the problem - so he thinks the solders have deteriorated.
I have maintained my pride and joy regularly - and yes it's done a few long - long tours (the longest being
Port Hedland via
Darwin and
Cairns back home to
Newcastle a few years ago ), and it has from time to time been on
Stockton Beach and Hawks Nest Beach and others. So it hasn't been just a town truck.
The mechanic - put the engine onto the tester and didn't find any other issues.
Anyone else had a similar experience with there Pajero's - what's an ECU for NH pajero cost ?
Should take the vehicle the local Mitsubishi service centre and have them check out the throttle position sensor and throttle control soleniod as
well as the ECU and replace these.
Anyone got a handle on the cost of these items if they need replacement?
Will a dicky ECU cause damage to the engine ? The fix is not perfect the idle speed still looks a bit erratic, but at least it hasn't stalled yet.
Very disturbing
Reply By: NissanofOld - Thursday, Sep 09, 2004 at 19:47
Thursday, Sep 09, 2004 at 19:47
Your mechanic 'wiggled the capacitors about' on the ECU? I would think about changing mechanics at this stage. However, while an ECU can start to play up, there are a few other things that should be checked out first. I don't know if your mechanic has diagnostic equipment, but even if he has, these will not usually pick up mechanically related problems.
Poor running/idling can be due to fuel or timing issues. Since your car runs, it seems that timing should not be a problem, else it would be evident at other times. Your mechanic should have been able to do a diagnostic check on this part at least. So it sounds like it could be a fuel problem.
Have you ever had the fuel pump replaced for example? A fuel pump will eventualy wear out and will not be able to maintain the right pressure, the problem can show up in many ways. Many ECUs vary the pump pressure by varying the pump voltage and, if the pump is on its last legs, at a lower voltage, it may not be able to provide enough fuel pressure for idle. The way to check this is with a fuel pressure gauge connected to the fuel rail and refer to the manufacturer's specifications. Then there are also a myriad of vacuum hoses and valves etc that affect fuel pressure that also need to be checked.
It sounds like you've done all the right maintenance, but have all the right mechanical checks been done?
AnswerID:
75867
Follow Up By: Member - AndrewPatrol - Thursday, Sep 09, 2004 at 19:59
Thursday, Sep 09, 2004 at 19:59
In addition to the above - obviously check all simple things, one of which is the fuel filter. I'm no mechanic but these have caused problems like you describe in a car I once had.
Also go to www.pajeroclub.com.au and ask on their
forum.
FollowupID:
335683
Follow Up By: Member - Clive G (WA) - Thursday, Sep 09, 2004 at 20:50
Thursday, Sep 09, 2004 at 20:50
I had very simular problems, I was told it was electrical to injectors, but tons of grease monkeys, until I finaly took it to this mechanic who checked and disconnected the air flow meter and even tho running a bit rich with it disconnected, problem solved, cost me $220 for a recon one, my 4by hasnt missed a beat sinse.
Clive
FollowupID:
335687
Follow Up By: Member Eric - Saturday, Sep 11, 2004 at 08:13
Saturday, Sep 11, 2004 at 08:13
Andrew , your heart is in the right place , what your knowledge in electronic fuel injection is a little behind lol . The problems your talking about , I would agree if you were talking about a kgtronic (spelling?) system, were it was up to a high pressure fuel pump to fire the injectors that worked on pressure . I think our friend has a air flow meter issue .
FollowupID:
335845
Reply By: ian robbo - Thursday, Sep 09, 2004 at 21:05
Thursday, Sep 09, 2004 at 21:05
Thanks for that NissanofOld.
"Your mechanic 'wiggled the capacitors about' on the ECU? I would think about changing mechanics at this stage." - that concerned me too - bleep tered my confidence - considering there is an autoelectrical mob is right next door to him - I would have thought he would have had the ECU straight over to them to have it checked out if he thought it was problem , to checked out with an oscilloscope and to have any dicky solders fixed.
Last week when I spoke to on the day the problem started he was talking about my perhaps getting a bad batch of ULP from Wooly's last time I filled her up , but the problem didn't happen straight away. He was convinced on the strength of that maybe it wasn't a crook batch of fuel, but an electrical problem.
He used a diagostic test machine - which is what I had to book time on.
I do not recall ever replacing the fuel pump, the fuel filters have been replaced every 10k or 20k regular as clockwork . I think it's the original pump that came on the engine (I believe ?)
I'll ring him and ask him tomorrow about the pump , and will also ask the local Mitsubishi dealer if he can check out the ECU , idle controls and sensing, and the fuel pump and make a booking to get these checked out (likely to be a couple of weeks before they can get me in - i'm hoping I don't wind up doing damage to the engine by driving it in the meantime).
Any idea what a replacement fuel pump is worth ?
I do notice that the engine idles a bit rougher when I getting close to an empty
tank , and performance "feels" a bit better after fiiller her up - is that an indicator that the fuel pump is playing up perhaps ?
AnswerID:
75875
Reply By: mik*2 - Thursday, Sep 09, 2004 at 21:38
Thursday, Sep 09, 2004 at 21:38
Ian,
I know on my '92 Paj, I had a similar problem to yours. The paj has an idle speed control motor which, when worn out, or most common----jams up with carbon and all the rest of it, is to give an erratic idle. This fault in particular is discussed in depth on www.pajeroclub.com.au. Check out their site and do a search on the
forum about it. There is stacks of info.
Sounds like your prob to me. On
mine, I pulled the motor off, cleaned it and reinstalled it. No probs after. As for the ECU wire wiggling, yep, get another mechanic.
cheers
mike
AnswerID:
75878
Follow Up By: mik*2 - Thursday, Sep 09, 2004 at 21:40
Thursday, Sep 09, 2004 at 21:40
By the way, its a common fault...
mike
FollowupID:
335691
Follow Up By: Groove - Thursday, Sep 09, 2004 at 22:03
Thursday, Sep 09, 2004 at 22:03
I had the exact same problem with
mine, dud idle control motor.
Its a very easy part to remove and test, requires a multimeter to test.
Full instructions can be found in the gregories manual for that car.
A new ICM cost me about $140 a few years ago.
I dont have the car or the manaul any more otherwise I could email you a scan of the page.
Cheers
Groove
FollowupID:
335694
Follow Up By: flappan - Friday, Sep 10, 2004 at 09:02
Friday, Sep 10, 2004 at 09:02
Another here.
Originally thought to be the Airflow Sensor , (another mechanic) , bought a 2nd Hand one (thankfully, $900 new) , to find it was NOT that at all , but the Idle control motor.
BEFORE outlaying big bucks , get a 2nd opinion. Someone with ALL the lecky gear to
check.
FollowupID:
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Follow Up By: David O - Friday, Sep 10, 2004 at 09:04
Friday, Sep 10, 2004 at 09:04
Yes I would be looking at the ICM, as this fault sounds a very much like that. Also try to ensure there are no vacuum leaks due to old vacuum hoses partly failing or bad joints or bad seals. If an air mass meter is used then any leak after the airmass meter can be a problem.
FollowupID:
335737
Reply By: ian robbo - Thursday, Sep 09, 2004 at 21:49
Thursday, Sep 09, 2004 at 21:49
Clive G (WA) and AndrewPatrol , thanks and I have also on your suggestion joined that other
forum too and asked the same question there.
Crossing fingers - I hope it tunes out to be just a dicky fuel pump or something cheap to fix or replace. I don't fancy shelling out several hundred dollars to fix this problem unless I have too.
I recently shelled out $1000 to replace the steering column , and this was necessary - as I would have got past rego without it and there was a risk of it failing (I don't want to even consider that prospect). --- $750 to replace an entire steering column when a $5 bearing had failed in it - what a rip off !
AnswerID:
75879
Reply By: Member - Hugh (WA) - Friday, Sep 10, 2004 at 01:57
Friday, Sep 10, 2004 at 01:57
Hi Ian,
Not a Pajero but a few years ago we had Magna wagon with 3.0L engine. Same symptoms, with cause being idle bypass control valve sticking due to build-up of intake deposits. Pulled apart, clean gum from surfaces and all OK.
EFI engines typically have throttle blade seal the throttle body at idle, with idle controlled via air bypass circuit and ECU controlled motor. Sticking is common problem on the 3.0L V6 due intake deposits - refer similar feedback above. Cleaning this valve and rest of throttle body should improve your idle quality and general driveability.
I'd be very surprised if you have an ECU problem. Suggest you get your mechanic checked out instead.
Regards,
Hugh.
AnswerID:
75895
Reply By: ian robbo - Friday, Sep 10, 2004 at 03:34
Friday, Sep 10, 2004 at 03:34
I'll let you fellows know what the prognosis and remedy is when I get a second opinion from the local Mitsubishi dealership's mechanics.
AnswerID:
75896
Reply By: MrBitchi - Friday, Sep 10, 2004 at 08:38
Friday, Sep 10, 2004 at 08:38
As mik*2 said the first thing to
check is the idle stepper motor.
The computers do have a habit of failing due to poor solder joints (dry joints) My
old truck left the missus stranded in the middle of a busy main road trying to turn right. Just stopped dead. Again, a common fault in early Pajeros so your mechanic was not too far of the mark. Cost around $600 for a recon one.
AnswerID:
75911
Follow Up By: Utemad - Friday, Sep 10, 2004 at 13:21
Friday, Sep 10, 2004 at 13:21
Never pulled an ECU apart but dry solder joints are a common problem with any vibration (i.e. car) getting to electronics. Takes years to develop but is very easy to fix.
FollowupID:
335786
Reply By: ian robbo - Thursday, Sep 16, 2004 at 15:43
Thursday, Sep 16, 2004 at 15:43
HunterCity (Mitsubshi-Nissan) replaced the throttle stepper-motor which they found to be causing the problem.
The idle was set a little higher as valves are worn (engine has done 255,000 km) and mixture is a little rich on idle (generates smoke).
Cost to resolve problem (Wubbles $82 + HunterCity $389 + $60 taxis) part = $254.
So much for Wubbles (Gateshead) assessment - clueless.
AnswerID:
76651