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Model specific boards => Golf mk3 => Topic started by: DanChave on 26 October 2012, 11:34
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I have recently rebuilt my ABF and started her up, only to find that she cuts out as soon as the revs drop!
The engine was stripped of all ancillaries, everything was either cleaned or painted, and then refitted with new gaskets and new bolts. I filled her up with manufacturer spec oil and coolant, checked all the loom for damage (repaired a few cracked wires) checked that there was power at all the plugs, checked all the fuses, checked all the appropriate relays got warm after driving around for 15 minutes and thoroughly cleaned the ISV with degreaser and then sprayed with WD40 (the ISV clicks with direct current from the battery but then silent when connected).
I have replaced the white coolant sensor, the crank/speed sensor and vacuum lines, the air and fuel filters were replaced just before I bought it.
Before the rebuild the engine was suffering from hesitation and lack of power around 3000 rpm and cutting out at high temp and were showing an ABS fault and a crank/speed sensor fault. All bar the ABS fault seem to have been cured. Also the oil hazard light is blinking on ignition but clears when the cars started and the oil temp shows -- -- on the clock display, however I believe this is just down to the spade connector snapping on one of the sensors located on the oil filter housing.
Any help would be greatly appreciated as I have only had the car for 4 months and 3 of those has been the rebuild lol!
Cheers.
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Have you hooked it up on vagcom, to see if faults are showing?, I'd say try that as first bet, then take things on from there
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Have you reconnected all the vacuum hoses?
And crank breathers?
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Have you hooked it up on vagcom, to see if faults are showing?, I'd say try that as first bet, then take things on from there
I have the VCDS Lite version, only came up with the ABS fault (Which is next on the list to sort) Also, as a correction from by first post, with the ignition on, I can hear the ISV buzzing, so it's definitely working.
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Have you reconnected all the vacuum hoses?
And crank breathers?
Yep, all replaced with silicone versions as well!
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I still think ISV to be honest. Can you 'borrow' one to test that you know is working?
Does it run normally with the revs above 1200?
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I still think ISV to be honest. Can you 'borrow' one to test that you know is working?
Does it run normally with the revs above 1200?
I'm trying to find someone with a 16v who is near by at the moment. Before hand it used to idle around 1000 rpm. It's between 1000 and 1200 when it drops off and cuts out :(
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It wouldn't be vacuum then!
Seems to be ISV
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It wouldn't be vacuum then!
Seems to be ISV
It's just weird, I can here it click open and shut from direct current and with the ignition on I can hear it buzz so it should all be working ok.......
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Have you checked the throttle stop switch wires, and the switch itself?
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Have you checked the throttle stop switch wires, and the switch itself?
I checked the wires for splits, stuck a multimeter in the plug and checked for power (which there was) left it unplugged and it wouldn't fire up at all so I guess that's working!
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What if your throttle body needs aligning, I'm pretty sure once you take it off, you have to re-align it,
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Any idea how I would go about doing this?
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Search it on google, how to re-align or check YouTube, and you use vagcom to re-align aswell
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I only have VCDS Lite so I'm not sure it will let me do it! I have also ready that you can only align Auto MK3's or Fly By Wire cars like the mk4's etc.......
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Yeah I've just read that TB alignment is only for those with motorised function. As the 16v has an ISV, there is no motorised feature on the TB.
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Yeah I've just read that TB alignment is only for those with motorised function. As the 16v has an ISV, there is no motorised feature on the TB.
Yeah, just ready that here http://wiki.ross-tech.com/wiki/index.php/Throttle_Body_Alignment_(TBA)#Cable-Throttle_Engines
Does this point back to the ISV then?
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Orite ok, my bad... :shocked:
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Orite ok, my bad... :shocked:
That's alright bud, thanks for the input anyhow :) I have been reading about and aparently its not a good idea to take off the throttle body micro switch? (not the potentiometer but the one closest to the bulk head?) I took both off when I cleaned the throttle body......
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Go onto, 'vw Audi forum', there's a member in the name of 'crasher' pm him, he knows his stuff about vw & audi's he's a proper vw technician and will help you, as my car had problems and ever since I spoke to him, he pin pointed me in the right direction,
Try him bud
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Cheers bud, I give him a shout :)
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Run the engine, open the throttle by hand enough to touch the idle switch and the engine running will noticeably change.
Release the throttle and make sure that the mechanism goes back and then touches the switch you were pressing.
If it doesn't touch the switch then the switch needs to be aligned again
If the engine running does not change then this may indicate a idle switch/wiring/ISV issue
With VCDS also check the coolant temp status just to make sure everything matches up. How did you cure the hesitation and cutting out problem before the rebuild?
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Just to add, I discovered recently when putting my abf into the mk2, that just because the ISV buzzes doesn't mean its working! I had to try 4 (from breakers) before one worked, all the time I was sure it wasnt the ISV an searched for something worse but my friend who is a specialist with vag cars was adamant it was ISV.... Yet I was lost how I could have 4 buzzing ISV and only one of them allow the car to idle!
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Run the engine, open the throttle by hand enough to touch the idle switch and the engine running will noticeably change.
Release the throttle and make sure that the mechanism goes back and then touches the switch you were pressing.
If it doesn't touch the switch then the switch needs to be aligned again
If the engine running does not change then this may indicate a idle switch/wiring/ISV issue
With VCDS also check the coolant temp status just to make sure everything matches up. How did you cure the hesitation and cutting out problem before the rebuild?
Thanks for the advise, I'll open the throttle by hand, enough to depress the microswitch with my other hand and see if there is a change! I only have VCDS Lite, so I don't think I can check the coolant temp etc, but I'll look into it as well. The hesitation was caused by worn vac lines and a damp ecu from all the years of wet leaves under the scuttle panel, the cutting out when warm was a suspected ISV problem before hand, but when. I checked it and it buzzed and clicked in and out I presumed it was working and it was more likely to be a wiring problem. After checking the wiring and soldering up a fracture, then checking there was power at all the plugs with a multimeter, I think I have ruled that out now so back to ISV or idle microswitch.......... Hopefully today I can borrow a mate's ISV from his corrado G60 (he has a spare as well) and we'll see what happens lol!
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Just to add, I discovered recently when putting my abf into the mk2, that just because the ISV buzzes doesn't mean its working! I had to try 4 (from breakers) before one worked, all the time I was sure it wasnt the ISV an searched for something worse but my friend who is a specialist with vag cars was adamant it was ISV.... Yet I was lost how I could have 4 buzzing ISV and only one of them allow the car to idle!
I know, its bizarre right! All I can think is I know there is a few different part codes for the ISV's used on different models and maybe they allow different tolerances of air through? Either that or even when you can here the needle clicking in and out, its not opening/closing to its full potential? Bloody things.
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I know, its bizarre right! All I can think is I know there is a few different part codes for the ISV's used on different models and maybe they allow different tolerances of air through? Either that or even when you can here the needle clicking in and out, its not opening/closing to its full potential? Bloody things.
Damn right it's bizarre! I only used mk3 items to rule out any differences between the mk2 and 3 although physically they look the same, but like you say I'm not sure of the opening tolerances, however I did notice all of the ISV I have each have different buzzing sounds!! Some loud some quiet and the one that's working I have to put a stethoscope to hear it buzz!! I'm still not convinced they are all buggerd because we tried some on another abf an 2 of them worked, however the one on my mk2 abf didn't work on my mates abf in a mk3, the car is acedimic, the dam things should all work the same as they are mk3 an the part numbers are the same!! Far too hit and miss could be the age of them tho! The 4 I have we're all checked working on my engine before removal from mk3, left in the tool box for a few months an now it's the ISV lottery!! Poxy things!! Lol
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Feel free to send me one ;)
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I managed to get the car to idle today by adjusting the throttle cable at it's tightest setting so the micro switch wasn't depressed. This allowed me to test a few things, I was able to depress the micro switch whilst the engine was running to see if there was a change, which there was! So, idle switch and wiring are ok :) I also disconnected the ISV breather, with no effect, meaning the ISV was stuck closed? I then connected the ISV straight to the battery, I could hear it click but made no effect to the running of the engine. then I pulled to ISV out of the inlet and the engine stalled, I am 99.9% sure it's the ISV, I bought one from Ebay and I'm picking up one from Plymouth later today. Hopefully It'll work, I can't wait to have it drivable so I can get it up to Volkscraft in Exeter and get the timing light on it and check it all over :)
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Did the new one make a difference? Hope it is working!
Just to confirm does the throttle mechanism on idle touch the idle switch? If it does, that's how it should be. From what I read, you adjusted it so the throttle was open? This bypasses the need for the ISV as the engine is getting it's air supply from the open throttle, when the throttle is closed only then should the ISV kicks in.
By removing the ISV you created a big air leak, enough to stall the engine I'd assume as the fuelling wouldn't cope.
If the throttle set-up is ok, switch and wiring are proven to be ok and you are still having problems I'd check the voltage supply to the ISV if you haven't already. You are giving it 12v from the battery but maybe the ECU isn't?
Hope it's all working anyhow!
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Auto data says there should be 5v at the ISV plug when the ignition is on, I would check this, if there's nothing at the plug fuse 15 is at fault
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>the ISV clicks with direct current from the battery but then silent when connected
yeah. On ISV's (that I've used before) you don't apply 12v from a battery to them, else they go bang (done that). the ISV receives pulses of 5/12v from the ECU to control how much it opens. Its not just open/closed, but varies depending on engine load, etc
>Auto data says there should be 5v at the ISV plug when the ignition is on, I would check this, if there's nothing at the plug fuse 15 is at fault
Looks like yours should be a 5v feed from DogBots autodata post....
That would explain the lack of idling as the ECU cannot control the air intake.
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Cheers for the info guys! In the end it was pointless to get the ISV because I tried starting it again and it wouldn't fire up! Took the spark plugs out and they were black, checked for a spark and there was one at first turn of the key and then nothing, connected a spark lead and plug straigh to the coil and still no spark! Each time, the plugs were grounded on one of the cam cover nuts.
So no, its not fixed :(
Just to confirm does the throttle mechanism on idle touch the idle switch? If it does, that's how it should be. From what I read, you adjusted it so the throttle was open? This bypasses the need for the ISV as the engine is getting it's air supply from the open throttle, when the throttle is closed only then should the ISV kicks in.
By removing the ISV you created a big air leak, enough to stall the engine I'd assume as the fuelling wouldn't cope.
If the throttle set-up is ok, switch and wiring are proven to be ok and you are still having problems I'd check the voltage supply to the ISV if you haven't already. You are giving it 12v from the battery but maybe the ECU isn't?
Hope it's all working anyhow!
Yeah, I adjusted the throttle cable to bypass the ISV so I could perform some checks to see if any differences occured ie, depressing the idle switch, pulling out the ISV, disconnecting the ISV to Air Box breather etc. from what I can tell, the micro switch works and the wiring to it is good/repaired, removing the airbox breather made no difference (meaning the ISV is in the closed position?) But pulling it out made the sudden rust of air stall the engine (confirms ISV closed?)
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Auto data says there should be 5v at the ISV plug when the ignition is on, I would check this, if there's nothing at the plug fuse 15 is at fault
The plug is getting power and I have checked fuse 15, which is fine! Unfortunately, my oldskool multimeter just tells me if there is power or not lol! I will go out today and see if I can get hold of a more modern one.
I am downloading AutoData at the moment but it is taking a lifetime, could you dig out the values for the other plugs as well for me please?
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>the ISV clicks with direct current from the battery but then silent when connected
yeah. On ISV's (that I've used before) you don't apply 12v from a battery to them, else they go bang (done that). the ISV receives pulses of 5/12v from the ECU to control how much it opens. Its not just open/closed, but varies depending on engine load, etc
>Auto data says there should be 5v at the ISV plug when the ignition is on, I would check this, if there's nothing at the plug fuse 15 is at fault
Looks like yours should be a 5v feed from DogBots autodata post....
That would explain the lack of idling as the ECU cannot control the air intake.
I just put the ISV to the 12v to see if the valve was stuck. we did this initially while the engine was stripped down, maybe this blew the ISV in the first place, hence why it wont idle now? School boy error on my part I guess :(
I will get hold of a better multimeter today and check the actual values that the different plugs give out.
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easily done. :smiley:
worth checking the cam/crank sensor is attached and working else no sparks will be triggered.
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Cool, I'll check that as well. Although, it should be fine as I replaced the crank sensor with a new genuine part when I built the engine back up!
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So, I checked all the Volts at each plug and I got the following
ISV - 0v/0v
Throttle Microswitch - 10v
TPS - 3.5v/0v
Crank Sensor - 10v/10v
Knock Sensor - 0v/0v
Anti Knock Sensor - 10v/10v
Coolant Temp Sensor - 3v
Coil Pack - 12v/0v
Hall Sender - 10v/10v
In regards to the ISV reading, I then replaced fuse 15 (the fuse in there was still intact though) to no avail. Next step I guess is to check the wires from the ISV plug back to the multi plug and check the corresponding pins there as well.........
If anyone could did out what the correct readings are, for the other plugs, that would be great. I'm still waiting for AutoData to finish downloading :(
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Whoever mentioned fuse 15, I f*cking love you :kiss:
Just sorted this idling problem thanks to you, it's been the bane of my life!
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Whoever mentioned fuse 15, I f*cking love you :kiss:
Just sorted this idling problem thanks to you, it's been the bane of my life!
I wish it was as simple as that for me :( Glad this thread has helped someone else at least though!
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Autodata says to test the ISV unplug it and test it directly at the ISV - You should get 3.5 - 6 Ohms
For your reference:
Crank sensor supply voltage - Pins 1 & 3 - 9v
Cam (Distributor) supply voltage - Pins 1 & 3 - 10v
Throttle position sensor - Pins 1 & 3 - 5v
Coil - Pins 1 & 3 - 11v min
Coolant temp testing gave a table of resistances not voltages.
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easily done. :smiley:
worth checking the cam/crank sensor is attached and working else no sparks will be triggered.
Good advice, think a second problem has possibly arisen. Check all your fuses and get it scanned again?
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Whoever mentioned fuse 15, I f*cking love you :kiss:
Just sorted this idling problem thanks to you, it's been the bane of my life!
Aww do stop your make me blush! Pmsl, to the op, sorry. Yours is still a no go, a reading of 0 at the plug an a fresh fuse would suggest a wiring problem trace them back to the multiplug connector (round one) and just age to check them and the terminal connections too
Sorry I can't be of much more help
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Cheers everyone for all the info and advise so far :)
The two wires from the ISV plug are white and black, the black wire goes right round the back of the head to the TPS, the white goes into the multi plug. I checked the multi plug and the pin corresponding to the ISV and got no reading (I'm guessing I would be looking for slightly higher then at the ISV plug?) Tomorrow I will get off the loom tape on the loom going along the right chassis leg and see if I can spot the route of the cause. Most of the loom looks to have been re wrapped in electrical tape, I had planned on re wrapping everything in proper loom tape, but not until I had relocated a few things.
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Soo.... Today I got all the electrical tape off the loom and traced the white wire from the ISV pin in the multi plug, all the way back to the ECU. I then tested the circuit from the ECU plug to the ISV pin to see if there was a break in the wire and it read fine! I did this for the crank sensor as well because I knew everything was fine with that. I then reconnected the battery and the ECU and checked the voltages at the Crank Sensor Plug and ISV Pin in the Multi Plug, again, the crank sensor read 10v and the ISV read nothing. I'm now thinking the ECU may be faulty? I opened it up and everything looked absolutely mint........... Should I send off the ECU to get checked or just but a second hand one??
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I'd say try that as first bet, then take things on from there(http://www.aldg.info/qinping2.jpg)
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Ecu's rarely go wrong!! An usually when diagnosed incorectly as faulty it's because the garage can't find anything else wrong, I honestly sincerely doubt your ecu is at fault, thee has to be something else amiss
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As Dogbot says, an ECU rarely goes down unless water or a hammer gets to it but you never know. I'd verify this:
(http://i115.photobucket.com/albums/n315/Leon-R/ABFISV.jpg)
If you can't zoom in then this is what you can try:
You have measured the resistance from Pin 27 of the 68 pin plug to the ECU to Pin 3 of the ISV (the white wire) - 0.3 ohms and below is good.
Now the bit I'm unsure about is G6 where is called a "positive connection (15) in Digifant Wiring harness" - This is basically the Fuse 15 mentioned earlier so Pin 1 of the ISV should have 12v with ignition on.
Check that Fuse 15 is actually getting power on both sides
Pull back the wiring loom on the ISV plug and make sure the pin/wiring isn't damaged
Try to trace this wire back as best you can round the back of the head....
Now this is the bit which might be tricky to see, these wires round the back of the head bake and get sh!tty. Visually they look ok, only when you pull back the insulation and you see the wires burnt.
I think the voltage from Fuse 15 gets split to the crank case heater plug (the redundant plug that plugs into the crank breather pipe) you should have 12v there and at the ISV if the wiring is good.
The ECU doesn't provide the +ve, it looks like it's an earth switched system so the ECU is hopefully ok so definately check the wiring round the back of the head
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Cheers for all the help guys, I'll get right on this tomorrow :) off the top of my head, there was no reading at the crank case heater plug either and I have already repaired one section of loom that goes round the back of the head so I'll take another look.