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2.2 cold start high RPM


Sutty2006
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Hello folks. I’m currently re-commissioning an 86 2.2 Carlton. When I start the engine from cold, it revs straight up to near 4000 rpm. This is too high for cold start. Does the 2.2 have a 5th injector? I can’t see one. If not, am I solely looking at a fault idle control valve? Once 5 mins have past of trying to rev it to get the rpm back down, it will settle to a respectable 800 rpm. 

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hi. 

the idle control valve regulates the speed ,there is no 5th injector like the 2 litre has.

they are prone to gumming up. (not usually failing) thou

the idle speed when warm should be around 500 rpm if you squeeze the pipe flat  .the valve then brings it ip to the correct idle. if you squeeze the pipe and the idle speed doesnt drop you have an air leak or the bypass screw is wrongly adjusted.

controlled by a 4'x4" ecu just above the injection ecu.

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its a motorised valve. dissconnceting the plug just make it stay where it was driven to.its not spring loaded.

yes it gets a signal from a seperate element in the temp sender.one element goes to the injection ecu to control mixture and the other element goes to the idle ecu to control idle speed as it warms up.this ecu monitors idle speed as you load up the alternator too to keep a set speed. good system realy when working ok. 

these dual temp senders are used on other similar cars of the era with a idle speed control valve such as senators and monzas  etc.

many people (including garages) make the mistake of replacing them with the single type as on our gte's which are physically the same . colour isnt always an indication either !

 

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every day is a school day !

i still find out things about our cars that i didnt know.all part of the fun .

 

yes if you are familiar with the standard gte injection system then the 2.2 is basically the same idea with a few tweaks.same tank system and fuel supply components.same injectors.same ignition system to a point.the 2.2 has a fixed distributor in relation to mechanical advance.this is done electronically.vacuum still the same.

you dont get an initial fuel system priming ,this is due to the ignition control unit not having the cutoff if it doesnt see a rpm signal from the distributor hall sensor.but this doesnt seem detrimental to it !.

cold start enrichment is done by the varying the pulse of the injectors dependant on the temperature sensor readings.and a higher idle is given via the air valve too.  no 5th injector or timer or heated air valve .

the aforementioned dual temp sensor,an inlet vacuum sensor switch and an oil temp switch linked to auto gearbox lockup.a feature earlier cars never had. 

all probably explained in the carlton haynes manual better than i have but you get the general idea. this system identical as mentioned on senators and monzas 83-86 after which i beleive it all switched to motronic 4 .next step up again with crank sensor timing .

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yes thats fine. better than being seized. 

so .see what happens once you have cleaned it.

when warm see what speed it idles at.(idealy around 650-700  ish on an auto ,750 -850 on a manual.when you squeeze the pipe flat the idle should drop to around 500 ish and the system will think its too low so should open the valve to allow more air through.when you let go of the pipe the revs should suddenly rise until the system sees this and regulates it back down again.

if it works fine when warm then it 'should' work from cold also but a faulty control unit or temp sensor may confuse it !

see what happens.

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Thanks. I’ll get it super clean at work tomorrow, then refit. Once it’s warmed up, it sits nicely around 700 rpm I think. I’ll see what it does Saturday night when it’s refitted and report back. 

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no. none are earth as such. 

ive removed my working one and checked it for you.

obvoiusly our  multimeters may vary the readings slightly.

looking at the pins with the single locating rib uppermost the pins are 3 4 5

on 200 ohm scale                3-4=21 ohm        3-5=40 ohm     4-5=19 ohm

infinate to metal casing.

using a pair of 1.5v batteries joined to make 3v        test as follows

pin 3 negative pin 5 positive closes the valve

pin 5 negative pin3 positive opens valve

 

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1 hour ago, cam.in.head said:

no. none are earth as such. 

ive removed my working one and checked it for you.

obvoiusly our  multimeters may vary the readings slightly.

looking at the pins with the single locating rib uppermost the pins are 3 4 5

on 200 ohm scale                3-4=21 ohm        3-5=40 ohm     4-5=19 ohm

infinate to metal casing.

using a pair of 1.5v batteries joined to make 3v        test as follows

pin 3 negative pin 5 positive closes the valve

pin 5 negative pin3 positive opens valve

 

Thanks very much I’ll give it a go later on. Don’t think we have anything at work with that low a voltage but I’ll have a look. 

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That’s great. 
 

I’ve tested it. Here’s the pictures. Figures seam fine. 
 

 

5FCA6158-B9BF-4F84-BC93-3521D4909A23.jpeg

9374042E-3989-4C78-A85A-46EC81A0517A.jpeg

83698E32-8434-455C-9140-DA7D02D96EB6.jpeg

I stole the batteries out of the driver waiting room TV remote and followed your instructions. Opens and closes fine. 👍

 

now i need to refit it and test it on the car again. 

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chances are that its ok then. 

cannot see why it would rev so high from cold unless the temp sensor is faulty (or wrong)

this is tested by checking that each terminal has a very similar resistance to earth. as i mentioned earlier this dual sensor sends signals to the main injection ecu and the idling control ecu.

its not uncommon for someone to replace this sensor with a standard l jetronic one which has only 1 element in it .this would have a resistance across both terminals but NOT to earth.

if its the correct sensor then see what happens with the pipe squeeze test (hot and  cold)

its also not uncommon on these cars (like mantas) to get water coming down the pillar and into the ecu or connectors .the idling ecu lives just above the main ecu. 

if you are down there check for signs of rust/holes/water etc. the inner wing heavy duty reinforcement piece can hide a rust hole behind it that can only be seen from inside the car.quite high ip the footwell and a bugger to get to !.

mine had a hole there !

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So the plot thickens. 
 

I returned home from work and immediately refitted the now ok ICV. I also noticed that the coolant temp sensor by the thermostat housing was unplugged. Bingo, I thought. So I jump started the old girl and after she coughed into life, the revs creeped up to 3500rpm. Bugger. While it was revving away filling my garage with toxic fumes, I squeezed the long pipe to the ICV and the revs died down. To a more manageable rpm. Once warm (couple of mins) and it idled ok, I squeezed the pipe again, nothing happened. 
 

I heard a tale years ago that folk put a 2p in the pipe with a hole in it? to restrict flow, but can’t remember why. 

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if you have a haynes for the carlton it explains the system quite well however i can give you a few more pointers which woukd be worthwhile doing anyway 

i would check for any air leaks on the inlet side of things. this would (could) be done by ear or somepeople squirt easy start or similar around the place to see if idling speed changes. bit dangerous realy especially when engine is hot .BUT some leaks can seal when hot and only there when cold .

check.......manifold to block,injector bases to manifold,rubber seal at base of manifold,any obvious air leaks should be obvious .smaller places to check.  brake servo hose (very prone to going brittle),vacuum pipe connection to distrubutor,vacuum pipeconnection to bulkhead sensor  (top of manifold),rear joining hose to autobox ,vacuum pipe to fuel pressure regulator.

maybee but not as common the big front rubber flexi to the airbox. 

whilst this pipe is off is a good time to clean the throttle body intake and butterfly. these do gunge up regularly due to the design/location of the rocker box top breather pipe. 

hopefully the throttle stop screw has not been tampered  with. the idea here is with a nice clean butterfly you undo the screw untill its clear of the metal and this allows the butterfly to close completely ,you then turn the screw until it JUST contacts and starts to move the butterfly by a quarter of a turn only.all explained in the haynes book.

the idle is then controlled  by a little bypass screw under the throttle body and the air valve that you cleaned. if squeezing  the pipe on a fully warmed up engine doesnt bring the idle down to a lower rpm then it suggests that this bypass screw is too far open and the air valve cannot stop the airflow (you cant get less airflow than a totally squeezed pipe so the valve cant do anything)

 

so 

i think we are getting down to either a badly adjusted bypass screw or a fault in the idle ecu. (after any possible air leaks are eliminated)

hope this lot helps a little. im well used to these systems little quirks after all these years and have a carlton and a cav both with the 2.2 .

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and also one more thing to check ( because you dont know what anyone before you has done)

obvously making sure the acc cable has a tiny amount of slack and cannot hold the throttle open is a given 

but also check that in a quiet moment if you very slightly open the throttle you should hear a click from the little black box on the side of the throttle body.and a click when it closes too.(it tells the system that the engine is idling or at full throttle)

this is the signal to the idling ecu that its at idle and ready for the air valve to do its job.if there is no click the switch may be faulty or just need adjusting via its mounting screws.  obviously if you check the buttefly adjustment as mentioned above and alter it you need to checkthe switch afterwards is still ok adjustment wise.

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3 hours ago, Jessopia74 said:

Popped into other post, but drop here for reference as these came up when looking at running megasquirt setup. 

https://www.msextra.com/forums/viewtopic.php?t=47025

Unfortunately due to it being American or my complete lack of electronic brain thoughts, I can’t understand any of that. Just nothing at all. Nope. 
 

my heads about to explode with this fault anyway. If I can’t get to the bottom of it with the next few steps to check, then I’ll either have to bodge it with a restriction in the line or give up completely. I struggle at the best of times to get anything done. 😢

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Slight update. 
 

I have found the idle control ecu. All connections seam fine, no corrosion to terminals. 
 

BBF58D61-EFCF-407C-8B1E-1DEC5309D432.thumb.jpeg.2b472ecb9c4432153a04e4fd04cabd94.jpeg

 

I’ve disconnected the main ecu and checked for corrosion, nothing. 
 

if I disconnect the ICV, the idle value seams to be much better circa 1800. Still too high, but better than 3500. 
 

BE016096-E137-4A98-A06F-9FC600DA0743.thumb.jpeg.5186b189115ea54ca2ae435482f7052c.jpeg

 

I’ve checked the position switch clicks when opening and closing the throttle. This is correct, and so seems the idle adjustment screw. 
 

the small hose to the ICV is perished but I’ve seen worse. Going to change that anyway. 

image.jpg

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I replaced that small hose, nothing has changed. 
 

I let it get up to temperature with the ICV disconnected, once up, I plugged it back in and the revs went straight up to 3500. I squeezed the inlet pipe to the ICV and the revs dropped back down to normal idle. I let it idle for 5 mins then shut it off. 
 

I attempted to restart 5 mins later and it shot back up to 3500 again. I squeezed the pipe again and it settled down. 

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I have a completely different iacv to you on my V8 but I did experience similar issues. I messed around on the laptop changing the settings in the Emerad software but my changes had no affect!

It turns out that switching on the ignition pushes the iacv plunger out and I expected it to return when I’d switched it off. It didn’t so I thought it was buggered and bought a new one.

I did the same with the new one but its operation was the same. Any how if I switched it on again it pushed the plunger out even further, and it still didn’t return when switched off. I realised that that is why the iacv is sometimes called a “stepper motor” 💡

I suspected that the plunger wasn’t being pushed forward (out or closed) enough so I reinstalled it and did the following;

1. turned the ignition on (pushing plunger out one step) but not starting the engine.

2. switched it off (plunger stays still, out one step).

3. switched it on again moving the plunger a second step but still not starting the engine. In my mind it must now be fully closed.

4. switched it off (plunger stays still, out two steps).

5. Third time I turned the ignition and fired up the engine with a happy tick over around 750rpm. Result! 😁
 

sorry this looks like an idiot guide but it all looked confusing in one long sentence.

I guess from this point the ecu has taken control and pulls back the plunger to allow the required amount of air through to achieve the preset tick over. Now any changes I make in the software are accepted and put into action by the ecu and now it works fine every time.

 

I know this is for a different engine but the control valve on yours may work in a similar fashion and I don’t think it can do any damage so must be worth a try. 
 

Good luck 🤞 

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