Author Topic: 2.6 Diplomat Stalling & Erratic Tickover  (Read 8741 times)

melinx

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2.6 Diplomat Stalling & Erratic Tickover
« on: October 16, 2006, 02:13:08 PM »
For 12 months or so my Diplomat engine speed has occasionally 'surged' slightly at tickover, this only rarely happened under a specific set of circumstances ie, engine hot, allowed to cool somewhat ( park at supermarket, shop then come out and restart )
when you put your foot down even a little to move off, it came out of that mode and did not return to it.
However it recently started to surge and then stall, this is much more annoying, so time to do something about it.
Reviewing the comments on this forum about this sort of behavior it all pointed to the idle air control valve (  ICV or sometimes IAV )
On the 2.6 engine this valve is hidden under the inlet manifold on the nearside and is all but invisible ! there is a ribbed pipe with a sharp 'u' bend leading from it to the rear of the inlet manifold  retained with a hose clip, unscrew the clip and with a wide bladed screwdriver, ease the hose off the manifold.
The other hose is a smooth one with numerous bends and is push fitted to the underneath of the inlet manifold in front of the accelerator linkage, ease it off.
The valve is push fitted into a large rubber sleeve fixed to the inlet manifold, gently ease it out because on the end of the valve inside the sleeve is the electrical connector, there is not much free cable to play with and ripping the connectors off the plug would indubitably cause mutters of 'oh dear' 'tut' or even 'bother'.
I found that unplugging the valve to be the worst part of the job, finger and thumb pressure on the retaining clip is supposed to enable its removal !!!
Remove the hoses and use your chosen cleaning fluid ( Carb cleaner etc. ) I dumped mine in a pint of petrol and went for a cup of tea !
After soaking for a while, give it a good sloshing round then leave it to drain.
Looking inside the hose connector at 90 degrees to the valve body, you will see what looks like a silvery segment of a cylinder, don't poke or risk scoring it, look in the other connector and you should be able to see where to push a 3 or 4 mm wide screwdriver blade down to rotate the valve.
keep pouring some very thin oil onto the silvery cylinder segment and rotating and wiping that surface until the oil no longer gets stained black.
Clean the hoses also before re-assembly.
My car has only done about 80,000 and the crankcase oil residue in the inlet manifold and ICV was minute, but still enough to intermittently jam the ICV; an engine with more wear and consequently more piston blow by is likely to jam this valve fairly regularly, a new valve is about 125 I believe !!
The Bosch part number is 0 280 140 516 with the number 011 circled below this number.
It is a 2 wire rotary solenoid with an internal spring return operated by a variable pulse width signal, almost certainly from the engine control unit.
My engine is now perfectly behaved !

Murph

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #1 on: October 16, 2006, 05:23:05 PM »
Good post!

melinx

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #2 on: November 02, 2006, 11:01:26 AM »
Prior to cleaning the idle air control valve, I always felt that the tickover was not as smooth one would expect from a six cylinder, I could feel the tiniest intermittent tremor on the steering wheel !
Not any longer ! smooth as silk

Pedro

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #3 on: November 02, 2006, 09:41:01 PM »

Nice work, Mr. Linx!

Would it be worth turning this post into a "How To......."?

melinx

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #4 on: November 03, 2006, 08:06:29 AM »
You're probably right; who transfers it though ?

Murph

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #5 on: November 03, 2006, 09:14:37 AM »
Sorted by Mr Mad!  ;D

Rusty Arches

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #6 on: November 06, 2006, 03:29:40 AM »
This post rocks i had the same tick over/stalling problem on my 2 litre dippy
and after reading this and talking to tettlysmooth i set to and completed the job
in under 15 minutes with no problems except the spring clip that holds the plug
in the back went BOING  ::) now she runs perfect again my thanks to all involved
Its probably just a fuse

Tetleysmooth

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #7 on: November 06, 2006, 09:14:04 AM »
Glad it's all ok now Moonraker.
Has it restored your faith in the old girl?
Will you now persevere with it when the next MOT comes around?
Why were you not at Thurrock on Sunday? Much more important than Father Christmas.
These are questions which must be answered.
It's ok chaps, Moonraker and me work together.
Every little helps, eh Dave.
Nils desparandum illegitimi carborundum.

melinx

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #8 on: November 06, 2006, 11:42:55 AM »
Its nice to know that it has helped even one member correct some of the little Quirks and Foibles ( they can't touch you for having em ) that our cars develop.

This post rocks i had the same tick over/stalling problem on my 2 litre dippy
and after reading this and talking to tettlysmooth i set to and completed the job
in under 15 minutes with no problems except the spring clip that holds the plug
in the back went BOING  ::) now she runs perfect again my thanks to all involved

Pedro

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #9 on: November 06, 2006, 09:43:12 PM »

Spread that Lurve! ;D

Rusty Arches

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #10 on: November 06, 2006, 10:10:49 PM »
Tettlysmooth apologies for missing the meet on sunday i didnt finish till 07.30(greed is good) i even missed my appointment with santa......
my faith is now restored until the next crisis but hope to have a solution b4 then !!!!!!!!!
watch this space
Its probably just a fuse

Tetleysmooth

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #11 on: November 07, 2006, 06:43:39 PM »
7.30!!!
You're taking the p**s. You only went to Goodge Street on a rescue mission.
What happened? I last saw you about midnight-ish, when I heard Terry saying something about 'broke down' 'can't get the propshaft off'.
I went to Lakeside after you left, but I was only gone for about 40 minutes. Carving the job up again.
Sorry about this other forum members, Tesco night driver speak. Won't make a habit of it.
Nils desparandum illegitimi carborundum.

Rusty Arches

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #12 on: November 09, 2006, 05:06:55 AM »
This is not carlton related but just to finish yeah a rescue job to goodge st LBTS + ROADY WORKS on the NCR + a SECOND BREAK = i milked it so much i should work for unigate ;D..........

my apologies i will pack it in now ::)


PS hooray i am Rusty Arches :D

thankuthankuthanku
Its probably just a fuse

melinx

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #13 on: May 25, 2008, 01:13:36 PM »
I think that I may be on the verge of discovering why the engine continues to surge even after thoroughly cleaning the ICV :-\ ( a number of posts mention this )

A conversation with the owner of the place that did my air con. conversion started me thinking; he said that they get the same problem on Subaru's and it's the MAF sensor that needs cleaning !

I'm pretty sure that Subaru use a hot wire or film sensor, so I was puzzled how this could apply to the flap operated system in the Carlton.

If you think about it, the original fault is caused by the ICV sticking due to crankcase oil residue and cleaning it radically reduces the problem but later I found that to a lesser extent it crept back and no amount of cleaning or replacing of the ICV did any good :(

The symptoms are exactly the same, so it's likely to have a similar cause and the flap operated airflow sensor is in the same air circuit.

Removing mine and stripping off the plastic cowl that holds it to the filter housing made it possible to get a finger inside to operate the flap.
I found that with the flap closed it obviously abutted a stop somewhere and there was the smallest bit of 'sticktion' when moving it off the stop ???

A small inspection mirror and light enabled me to see that the stop was on the engine side of the sensor housing and is a flat toothed slightly flexible compound insert which the damper flap rests on with the flap in the closed condition.

The contact with the stop is causing the flap to stick to it slightly, due either to a small amount of crankcase oil residue ( most likely ) or the compound is degrading and getting sticky ( I bloody well hope not >:( )

The scenario is : - The ICV is commanded to open a little more by the ECU, but when it does there is no increase in airflow due to the AFM flap not being free to move so it is commanded to open even more and that is enough to unstick the flap in the AFM.
The flap pops off the stop, but there is now too much air so the ICV is commanded to close and the AFM drops back onto the stop and sticks again :(

If the sticking is bad enough the whole process can run out of control until the engine stalls, the same as when the ICV is sticking !

I'm trying to work out the best way of cleaning the residue off this stop, because it is only visible with a small inspection mirror; I reckon that a small piece of petrol soaked rag on the end of a bent wire is the solution ?

Edit : - Just finished cleaning it, there was what looked like a varnish (Probably oil based) on the part of the flap damper abutting the stop.
I reckon that when the engine got the under bonnet temperatures high enough, this got pretty sticky !

I found that the best way of cleaning it was using a small squirty bottle with petrol and putting enough petrol in with the AFM turned on its edge so that a small bath of petrol was formed then working the flap to and fro in this.

There is now no sign of this 'varnish' and no sign of 'sticktion' :)

Time will tell whether this is the cure, or whether everything I've said is utter b*****ks and it's something else entirely :-\

End of edit.

If you do strip off the plastic cowl, make absolutely sure that when you put it back together you use threadlock on the bolts inside it, because if they subsequently work loose and get sucked into the manifold intake you can say goodbye to your engine :'(

For 12 months or so my Diplomat engine speed has occasionally 'surged' slightly at tickover, this only rarely happened under a specific set of circumstances ie, engine hot, allowed to cool somewhat ( park at supermarket, shop then come out and restart )
when you put your foot down even a little to move off, it came out of that mode and did not return to it.
However it recently started to surge and then stall, this is much more annoying, so time to do something about it.
Reviewing the comments on this forum about this sort of behavior it all pointed to the idle air control valve (  ICV or sometimes IAV )
On the 2.6 engine this valve is hidden under the inlet manifold on the nearside and is all but invisible ! there is a ribbed pipe with a sharp 'u' bend leading from it to the rear of the inlet manifold  retained with a hose clip, unscrew the clip and with a wide bladed screwdriver, ease the hose off the manifold.
The other hose is a smooth one with numerous bends and is push fitted to the underneath of the inlet manifold in front of the accelerator linkage, ease it off.
The valve is push fitted into a large rubber sleeve fixed to the inlet manifold, gently ease it out because on the end of the valve inside the sleeve is the electrical connector, there is not much free cable to play with and ripping the connectors off the plug would indubitably cause mutters of 'oh dear' 'tut' or even 'bother'.
I found that unplugging the valve to be the worst part of the job, finger and thumb pressure on the retaining clip is supposed to enable its removal !!!
Remove the hoses and use your chosen cleaning fluid ( Carb cleaner etc. ) I dumped mine in a pint of petrol and went for a cup of tea !
After soaking for a while, give it a good sloshing round then leave it to drain.
Looking inside the hose connector at 90 degrees to the valve body, you will see what looks like a silvery segment of a cylinder, don't poke or risk scoring it, look in the other connector and you should be able to see where to push a 3 or 4 mm wide screwdriver blade down to rotate the valve.
keep pouring some very thin oil onto the silvery cylinder segment and rotating and wiping that surface until the oil no longer gets stained black.
Clean the hoses also before re-assembly.
My car has only done about 80,000 and the crankcase oil residue in the inlet manifold and ICV was minute, but still enough to intermittently jam the ICV; an engine with more wear and consequently more piston blow by is likely to jam this valve fairly regularly, a new valve is about 125 I believe !!
The Bosch part number is 0 280 140 516 with the number 011 circled below this number.
It is a 2 wire rotary solenoid with an internal spring return operated by a variable pulse width signal, almost certainly from the engine control unit.
My engine is now perfectly behaved !
« Last Edit: May 25, 2008, 03:50:23 PM by melinx »

mrogers

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #14 on: May 25, 2008, 10:08:35 PM »
Nissan 300zx's suffer a similar problem.  The main issue is that people put on aftermarket Induction kits, but the these sit low down in the bumper behind the reg plate.  No this is fine normally as the std bumper had a guard for the Air filter, but a many put on aftermarket bumpers (me included) the ne induction is a tad exposed to the elements and this the water ingress causes the MAF to break down and ultimatly fail.  The sysptoms are the same as mentioned above.  Another problem with the 300zx with the same symptoms is the PTU (Power Transister Unit) but i dont thinks carltons have these so it wont relate
1998 Citroen Xantia Activa Turbo Manual
1990 300ZX Twin Turbo Manual UK Spec
1993 Carlton 2.6i Diplomat Auto
1993 Skoda Favorit 1.3i GLXi Estate Manual

melinx

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Re: 2.6 Diplomat Stalling & Erratic Tickover
« Reply #15 on: June 02, 2008, 01:38:30 PM »
Cleaning the Air Flow Meter flap definitely works :)

In all the situations where previously the tickover speed would have been up and down like a yo yo, it now behaves perfectly ;D

On the first trip immediately after I had cleaned it, I thought that I had made matters worse because the engine speed 'hunted' in a situation where it previously hadn't :( however, a quick 'blip' of throttle got it out of that mode and it has never happened again ???

'Blipping' the throttle never previously had any effect !

The way it acted suggests that the Motronic M1.5 ECU software works in adaptive mode ??? I can not find any information, despite extensive searches, that mention adaptive mode for this particular ECU ?

Motronic ECU's previous and following it have adaptive modes so I would have thought it odd that the 1.5 wouldn't have it !

Another Carlton mystery ? ::)