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General => The garage => Topic started by: Deefadog on 13 September 2004, 12:41
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on my MK 16V!
What does it do? what is it connected to? what other (if any) valves switchs does it control?
if the elctrial connection is disconected would I lose power at all?
any info would be great
Thanks
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sorry to seem impatient.
Anyone got any info or can point me in the right direction?
Thanks
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no you wouldnt lose power.
basically all it does is keep the rev's that little bit higher for a fraction of a second when you come up of the gas saying for changin gear. it helps improve fuel economy by about 1mpg ::) but more importantly makes gear changin that little bit smoother.
the wee duffer (looks like a silver disc) on the back left hand corner of the airbox, sense's a vacuum when you come of the throttle it then opens the air tract runnin from the base of the airbox into the inlet tube and basically bypassing the airflow meter for that split second - if that makes any sense
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Thanks, this was the cause of all the other problems I had, kangaroing and a bad flat spot between idle and 2000 rpm. I have only disconected the electrical connecton at the moment, so does this little valve sound like it could do all that or is there another process involved that would cause the problems?
Is there a vag part number on the valve at all? as today i phoned my VAG dealers and they said "er we can't seem top find it on the computer, do you have a part number?" - Stupid gits :)
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yes it has been known to cause problems - i wouldnt worry about it. it'll cost you an arm n a leg to replace
u'll probably find its not the we vacuum sensor but the actual air bypass valve connecting into the airbox as these are usually saturated in mucky oil that comes up the breather
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Aha, i see, is that part the the electrical connection connects into, it's about 4" high and has stumpy pipes coming from it if i remember?
Might be worth taking it apart and giving it a good clean, it's the part of the pipe system i have not cleaned, typical :)
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it connects into the back of the airbox and the underside of the air intake pipe.
the pipes are about 1/2 inch in diameter, there is no electrical wires going into it. it only has a vacuum pipe running to that we duffer on the airbox.
its usually boggin with oil so be prepared for mucky hands
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right I see, I am confused now as i disconnected the electrical connection just up from that, it's two wires in black plastic housing with metal spring clip and plugs up into something straight upwards (which I thought was the over run cut-off valve), what does these wires control?
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i dunno you've confused me also! i'll need to go look round an engine bay
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Thanks mate, I can't take pics at the mo, I'll try tonight and show exactly where it is.
take care
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Here we are: the first pic shows what i was told was the overrun cutoff valve, you can see the disconected wire below where it should plug into:
(http://www.realitydesigns.co.uk/forum images/overun 2 - web.jpg)
Here it is in full:
(http://www.realitydesigns.co.uk/forum images/overun 3 - web.jpg)
and form the other side:
(http://www.realitydesigns.co.uk/forum images/overun 1 - web.jpg)
Make any sense?
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Gamit, did you get chance to check, also from the pics I posted?
Thanks
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actually forgot to look ::) as i was busy getting the car ready to sell
but looking from them pics it looks strangely like the one that is meant to connect to the diagphram on the corner of the airbox
is the one on the airbox connected up?? back left corner of the airbox as you look from the front of the car
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Not too sure, i suspect it is but I'll check later, maybe take a pic :)
So you can see the electrical connection hanging below, what is that called it connects to?
If i get a chance tonight I'll take the whole thing off and give it a good clean and take pics :)
Update:
Firstly the overun cutoff valve, this is what i have taken pictures of isn't? it's a big plastic bit with a 1" rubber pipe connecting to the centre back of the airbox and the other 1" rubber pipe conecting straight up to the intake pipe, a small vacumme pipe going to a t bar connector to two other vacum pipes. and an electrical connector at thye bottom with two wires???
If so i took it all out cleaned it up with gunk and wd40 (there was hardly any oil in it, about half a teaspoon if that) and put it back together. I have only tested it on idel but it still seems the same.
"is the one on the airbox connected up?? back left corner of the airbox as you look from the front of the car "
There is no connector or pipe on the back left of the airbox when i am looking at it from the front of the car, there is a roundish (looks like a sauce shaped alien craft) with a connector and vacume pipe, but it's only mounted to the airbox, not connected.
Back bottom right is a large open pipe (part of the airbox) I thought this was the intake? should it be left open with no pipe there?
I have taken some pics of everthing, but i forgot the lead from work so i can't upload them untill tomorrow night :(
update of pics:
here is the overrun cut off switch (I hope):
(http://www.realitydesigns.co.uk/forum images/orcs 1.jpg)
From the top:
(http://www.realitydesigns.co.uk/forum images/orcs 2.jpg)
and here is a shot of the back of the airbox:
(http://www.realitydesigns.co.uk/forum images/orcs 3.jpg)
Hope it all makes sense :)
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"is the one on the airbox connected up?? back left corner of the airbox as you look from the front of the car "
There is no connector or pipe on the back left of the airbox when i am looking at it from the front of the car, there is a roundish (looks like a sauce shaped alien craft) with a connector and vacume pipe, but it's only mounted to the airbox, not connected.
connect the electrical connector onto that round saucer shape thing, this is what controls the over-run cutoff valve
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There is already an electrical connection plugged into this! when i said not connected I ment not connected to the airbox in any way :) also there is a vacume pipe on this which is also connected up.
so the pic I took "Here it is in full:"above is of the over run cutoff valve? and the diagphram controls that valve, is this correct?
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Bump :)
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I did some tests the weekend, i disconnect the electrical connection on the diagphram and it made no difference! only difference is made when i disconnect the electrical connection on the over run cut off valve!
I have been told that there is a control boc behind the center console whcih could be at fault rather than the valve it self? any ideas???
Also just to clear it up:
"so the pic I took "Here it is in full:"above is of the over run cutoff valve? and the diagphram controls that valve, is this correct?"
thanks
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the control unit behind the centre console is for the ISV. the diaphragm definitly controls the over-run cut off valve
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Thanks Gambit, so if the diaphragm (silver suacer) controls the over-run cut off valve, what is the electrical connection that goes to the overrun cut off vale for? and why does disconnecting this solve my problems?
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leave it with me and ill have a study tonight. im even wrote Overrun on the back of my hand so i dont forget
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Thanks mate, owe you one!
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there is a control unit behind the dash for it also. to be honest i'd just leave it disconnected if it has sorted out your kangaroo problem
there is a way to test it using a voltmeter if your interested, haynes manual actually details it quite well. that'll tell you if its the control unit or not that is banjo'd
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Thanks for checking gambit, I would leave it but I have to get it sorted as the mpg has droped by 10mpg!!!!
Got in the post this morning a used valve from a fellow kind gti member :) I have given it a blow (no comments please) and the valve seems to pop nice, my original one didnto seem to do this but gurgled a bit, so hopwfully i swap em over and it will be fine :) I'll check haynes out and test it, i did know about this but was not sure what setting my multimeter should be on.
Thanks again mate, i'll let you know, it's been a looooong problem :)
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I swapped the cut off valve over but it seems the same, so i guess it's the eletrical module behind the dash :) could not test it propally on the road as I have a really bad short and the electrics are going crazy at the moment, bet it's that module. :)
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Anyone got ant info on this module? what's it proper name, how much can it be repaired/overhauled??
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Does it have a part code on it mate? And what year is it?
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I have no idea what it looks like :) I think it is located behind the centre console!
As I have replaced the actuall caut-off valve and it has made no difference I have been told it's the module!! :(
tha car is a MK2 16V November 89
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bump
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Anybody got any pics of this module or can describe what it looks like, and also the location of it.
Thanks, need to sort this out on the weekend
take care
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You say your electrics are up the swanny ?
Is this part of the same problem im thinking ?
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Well i have changed the valve and the same problem occurs, so it's not the valve!, problem disapears when i disconnect the electrical connection to to the over run cut off valve, so it must b the module (I have been told), anything else it could be, maybe something the module tells something else to do with the data from the over run cut off valve is knackered, i don't know??
Any help would be great as I know nothing of this :(
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What i am getting at is it may not be the box behind the dash , it might be the feed to it if you are having electrical problems .
you could change the box out and still have the same problem , because the feed is shagged into it .
Did the two symptoms occur at roughly the same time ?
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Thanks mate
The kangarooing has always been there since i bought the car! also it has a big flat spot between idal and 2500 rpm.
Could be the wiring i guess, but the wiring is sleeved and then sleeved into the main sleeve, if you get what i mean :)
I want to check it all out but need to know where this module is first so I know where i am going to and from!
what else does this module control, any ideas?
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bump
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i might be able to help you now mate. i managed to fry my ISV controller of the weekend due to two wires on the throttle switch breaking and mangling the ISV control unit.
so over the weekend i went thru everything with a fine tooth comb and now understand fully how it all works.
1. if you disconnect the ISV only does it drive normally? basically it idles of the idle screw and is usually a bit rough in the mornings till heated up.
2. u can test the throttle switch/bypass valve. operating the throttle by hand and hold it constant above 2krpms. it should hold constant rpm's - no fluxuation
then with your other hand push & hold the little throttle switch closed. u should here the air bypass valve/ diaphram open and the rev's will drop as it tries to drop the plate in the airflow meter. it will then rev back up then drop again, and continue like this for aslong as you keep ur finger on the switch. if its does this then all that is operating correctly.
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Good timing Gambit, I am off for the week and wanted to test all this anyway :)
I will try all this tomorrow!
Just a few checks -
1)when disconecting the isv, you mean pull the connector out from it? or disconnct the red wire from the coil?
2) and am i right in saying that I shouold not disconnect the isv when the engine is running, as i think i read that this can damage the isv?
3) The air bypass valve/ diaphram -? is the saucer shaped one that is at the back of the air box?
Cheers again mate!
btw I still can't see you new car from your sig, i get the 'this page can not be found'
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disconnect it from the actual ISV itself. i havent damage mine by disconnecting it when running.
yes air bypass is all them tubes & silver saucer thing at the back of the airbox. you will hear it operate when you work the switch
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Ok, done the tests (sort of)
with the isv disonnected, my idle was 780 is this ok? it idled ok though
With everything connected except the isv i tried to hold the revs at 2000, but i would not hold, it would raise to 1700rpm and then shoot to 3500rpm on it's own!
I re-did this with the the isv connected, same thing happened
I then disconnected the overun bypass valve connection and the revs went up normally and held at 2000, but once i held the throttle switch closed, the revs shot up to 3500!
Any ideas on this? or more tests? obviously something is very wrong!!!
Cheers
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try just disconnecting the throttle switch and see will it hold the rev's
are you able to test the throttle switch itself??
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i disconnected the throttle switch and it still would not hold the revs!
I can't test the throttle swtch at the moment as it's a right b!tch to get at! I'll have to take the intake off to get at it, i'll do this tomorrow.
I did test the over run cut off valve, and it had zero volts at idle and then registered 12.4 when I increased he revs!
when the throttle switch was disconnected I got 12.4 volts at idle on the over run cut off valve! is this any help?
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u can rule out the ISV module as being faulty if it still wont idle with it disconnected.
sounds like wiring is it at fault somewhere on the throttle switch or the overrun switch
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I'll have to cut back all the sleeving on these switches i think and see if there is a break/short somewhere!!
Can you breiflly explain how these all work together and what they actally do, please, just so i have a small understanding of the process!
Thanks again mate, will keep you informed!
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when the throttle switch closes it sends a signal to the ISV control module to tell the ISV to control the idle
it also tells the bypass valve to open, so that air can travel along the pipe and into the ISV, this is then fed into the inlet manifold
when the throttle is closed. no air passes thru the throttle body at all. so u got to understand that air passes into the airflow meter, and into that pipe that branches off the airflow track to the ISV
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I see! thanks.
I tested the throttle switch, and it is working fine, resistance switches when opened or closed!
from the other test on the over run, thetrottle switcht did send a voltage to it as it should right! so what is next??
I cut the sleeve back for the over run switch an diaphram as far back as i could to the bulk head, but it is really tight back there with the power steering container
right in the way!
pic -
(http://www.realitydesigns.co.uk/forum images/wire.jpg)
So what's next, do you thin it's the module behind the dash? and why when it's all connected does the revs move from 1700rm to 3500rpm all on there own?
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if you disconnect the over run cut off, and leave just the throttle & ISV connected will it idle?
im afraid mate its just a case of playing with all three of these switches individually & in combination until you find out which one is the problem.
im near enough sure the module behind the centre console will only control the ISV and nothing else, although maybe it sends a signal to the over run cut off - im not sure
i guess the only way would be to get a hold of a spare and test it??
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Yes the car idles and runs fine with the over run switch disconnected, I am loosing around 6mpg though and the revs allthough steady are slow in increasing, kind of like a steady climb no matter how much pressure is applied to the accelorator.
Do you know he correct name or part number for the module?
thnaks
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have a look at my post in "Parts Wanted", there is a pic of it with the part number
i dont understand how you can be loosing 6mpg though. there is no way that could cause that much of a loss
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Thanks got the pic :)
'll post one also for that, i dread to think how much they are fromVW!
I thought that also about the mpg, but when connected on average i am getting 30-32mpg when it's disconnected i get 25-27mpg!!
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I did the check on the diaphram (saucer valve, on the back of the airbox) and I dont think think it changes resistance as it should when the throttle is opened, I can't be sure as i was on my own doing it and i really need 3 hands :)
If this is not working do you think this is the problem?
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saucer thing shouldnt cause any problems if not working. i ran my white 16v for about 18mths with it disconnected.
i changed the control unit on my 16v on sunday & it cured the current ISV problems i was having. but then i knew my control unit was shafted, where as u dont. they are a 5min job to change over though
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I need a control unit then :), if you know of one, please let me know!
Scrapies are sparce down here :(
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do u not know anybody else with a 16v nearby that u could swap over modules just to test it?
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No, wish i did, testing would be so much easier!
Can i test it without swaping it? maybe disconnect it and see what happens, if there is no difference then i know it's knackered i suppose. But i still would have nothing to compare it to, so mabe not a good idea :(
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the only way you know its knackered is if it wont idle on its own
with mine when you started the engine and let it idle it would just rev all the way up to 4k and just hold at that. hence how i knew it was banjo'd!
ring RadiCool VW. they are very reasonable i've used them loads of times to get parts sent over to me in N.Ireland and also in the Isle of Man
Radicool VW
Unit N, Long Meadow Works, Ringwood Rd, Three Legged Cross, Wimborne, Dorset BH21 6RD
Tel: 01202 823060
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Cheers for the contact, do they supply second hand parts?
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yes they are VW breakers
and are very cheap also
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Nice one, thanks
I never new there were specialist breakers and ones that deliver! I just rang them!
?23 delivered for the isv controll unit & saucer pressure valve!
Bargain, thanks again
will let you know!
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i told u they were cheap
are they taken credit card payments yet? last time i used them it was only cheque or postal order
to get at your ISV module u'll need to take out the 3 screws in the centre console. two are easy enough to find - one on each side and then there is one underneath the gearshift rubber cover thing that usually has people searching for a bit!!
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if you want to check anything out on your valver,your welcome to have a look at my engine as i have got one now ;)
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Gambit - ep still only cheque, but can't complain about the price! thanks for the tip also, that could of saved me am hour wasted :)
eyeletboy - when you say "your welcome to have a look at my engine as i have got one now " are you from Swansea or near by?
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your sig pic aint workin mate
do it like this
[ url=http://your pic url]My 16v (or whatever u want) [/ url]
but take out the spaces in url
also, i think you spelt design wrong ;)
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Thanks mate, i was messing with it last night and forgot about it :)
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deefadog,i'm from skewen.
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Good news so far :)
I fitted the new isv controller today, I have not taken the car out as yet but from the accelerator i can see a big difference, no lag now, so hopefully this has cured me long runnin problem :)
btw hanging down the center console next to the isv controller is another relay, has about 5 wires in it and one of those is a big red ignition lead, is this suppose to be there and if it is what does it do?
Cheers again for everyones help on this especially Gambit (Few beers owed there i think) :)
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After 5 months of this problrems it's finally fixed :) so happy - All it was, was the isv controller! car is flying know, at last i can enjoy it :)
Big thanks to Gambit on this one!
Take care
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5mths!!!! :o and it all was was a 5min fix!!! but at least it was sorted easily & most important...cheap!!!
think of how much you learnt also ;)
as for the other thing hanging down behind the centre console. it'll probably be an immobiliser of some sort, or maybe even an amp
did it have a VAG part number on it, or was it an aftermarket jobby?
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I know 5 months!! :) , i have learnt so much as you said!
Funny thing is that the isv controller arrived this morning from radicool vw :) - so i have a spare now! as the new one i put in was sent form 'bishthe fish' from the clubgti forum (free of charge also) dubbers are so kind! amazing help from alot of people!
The other relay hanging down looks like it's part of the original wiring as the wires are in the foam stuff as it goes back up throught the dash (although it could have been put on afterwards i guess)
It is definately a relay, i can't remember the number on it now, but it was either 21,24 or 28!
i'll check later
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The relay is number 24! here is a pic, it's a bit crap but it's a tight space :)
(http://www.realitydesigns.co.uk/forum images/relay24web.jpg)
Any ideas?
Also here is the sod that caused all my problems, got more circuitry than a Pentium 4!
(http://www.realitydesigns.co.uk/forum images/isv controllerweb.jpg)
Would you pay ?447 for this pile of sh!t:) It does not even play MP3's :) lol
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someone with a haynes should be able to tell you what relay 24 is for
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I have checked the Haynes, says No 24 is vacant?
I'll get my mate to stick his head next to it and i'll try everything in the car, if it's a relay it's got to click yes? should find out what it's for then! (curiosity killed the cat, or maybe my mate in this case) :)lol
So i am assuming you have not got one of these Gambit?
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dunno if i have one or not. would need to have a look behind the centre console
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No worries mate, if you get the chance (if your board) take a look, but no rush :)
Take Care