GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: Waspy on 03 August 2014, 16:32
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So, my car idles at about 1k, not solid as a rock, but not so problematic. But it does have the classic drop the revs when coming to a stop and sometimes dropping them so far it stalls.
I have read countless threads about this, and still havnt solved the issue.
So far I have:
Checked the ISV, including checking it vibrates when the electrics are on, and cleaned it thoroughly with carb cleaner.
I have checked for vacuum leaks and can find anything, although see the pic below, the pipe below the connector is supposed to be blanked, right? However it makes no difference to the issue when I block it.
Took the TB off today to check the idle switch with a multimeter. The switch clicks just as you open the throttle and the multimeter showed no issues. I also completely cleaned the TB since it was off.
After putting the TB back on and connecting everything. It idled solidly at 950, and didn't drop the revs at all! I was delighted, however 60 seconds later it was doing it again.
So, anything else I should be looking at?
(http://s29.postimg.org/m30qsddlf/image.jpg) (http://postimg.org/image/m30qsddlf/)
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Still sounds like vacuum. Did you change the to gasket?
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Still sounds like vacuum. Did you change the to gasket?
Ill ordrer some new lines then, not like they are expensive.
As for the gasket, it wasnt until after had the TB off that it even crossed my mind. So I had to reuse the one that was already on. However looking online it is impossible to find! Does anyone know where I can get that gasket?
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VW dealers still sell the TB gasket, despite online rumours to the contrary. 037133073A
As for your idling problem; if you unplug the two-way connector from the throttle body while it's idling (fully warmed up) does anything change?
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VW dealers still sell the TB gasket, despite online rumours to the contrary. 037133073A
As for your idling problem; if you unplug the two-way connector from the throttle body while it's idling (fully warmed up) does anything change?
Brilliant, thanks for the info!
And I am not entirely sure which connector you mean? Do you mean the connector which connects to the idle switch?
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The one and only electrical connection to the throttle body. Goes to idle- and wide-open-throttle switches.
If unplugging it makes no difference, suspect a wire break somewhere between loom connector and ECU.
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I would assume vacuum as it changes with engine load aka coming to a stop. Or does the idle continue to go loopy on any form of idle once warm?
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It messes the revs up when I dip the clutch from say 2000 it will drop them to 500 then recover. If the revs are climbing quickly, then clutch it, it will drop them so fast it stalls. If I come to a gradual stop and let the revs fall to 1.2k it will handle it fine. The idle is around 1k, but it does move about +/- 50 while idling, so it's not solid.
But the more I think, the more I see you are probably correct. Vacuum is likely. The hoses look tired, bound to be leaks. Buying new hoses now. Anyone know where you can get hose blanks from? I can't find any the right size (for 3mm) and I don't want to be doing the old screw in the end trick really...
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For the benefit of anyone hitting this page from searches for gasket 037133073A (I found lots, with conflicting info, as mentioned above)
I can confirm these ARE still available. Leeds had 16 in stock.
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My vacuum blanks are pop rivets
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Does sound like an idle switch problem. Engine off - move the throttle open by hand. Can you hear any clicks? Should be a click at the start of opening. Then a click with the throttle wide open.
I've had a few with the throttle closed idle switch not making contact. These are adjusted by Phillips head screws.
wires to the switch are also known to break. Right at the back of the inlet.
If that's all ok...I usually wave butane gas or carb cleaner around every vacume pipe. If the revs increase...there's the leak
Also inspect the rubber bung under the oil breather.
Everyone assumes its an isv issue. They rarely go wrong. If the revs bounce, the isv is trying to recover a stall :grin:
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Like I said, the switch clicks etc and multimetered the connection with no apparent issue
I'll give the carb cleaner trick a go (how does that work btw, sounds like witchcraft)
The bung seems okay. But if after I have changed all the vac lines it still persists, that will be replaced too.
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The carb cleaner gets drawn into the cylinders from the leaks in the vac pipes and affects ignition.
Be very careful with carb or other spray on liquids, they can catch fire on dodgy leads or hot manifolds and burn your garage down :lipsrsealed: Best use a butane torch.
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Ahh missed that part you mentioned. :)
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Right, vac lines (all the ones I could find) replaced. There may be more, I don't know. Anyway, started her up, reved her up quick a few times then let them drop. It caught them every time. But about 3 mins it it started doing it again. I'm running out of ideas. It is far less drivable like this, and it's tarnishing the driving pleasure somewhat. Also see attached image. What is the downward pipe, where does it go? It had a bit of rubber hose on it to start with, but when I touched it, it crumbled. So I replaced it temporarily with the hose in the pic. Still not great though.
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Image?
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Crap sorry
(http://s27.postimg.org/iag307p5r/image.jpg) (http://postimg.org/image/iag307p5r/)
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Ah, that one. Goes through the bulkhead to the back of your clocks module. Allows the clocks to figure out your MFA mpg reading by them knowing engine load / manifold vacuum level.
Did you try disconnecting the TB connector yet, to see if anything changes?
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Ahh well, that has never worked (not that i need it).
Yeah, disconnected it and it rev'ed like crazy.
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OK, so you've proved that the idle switch is being 'seen' by the ECU, that's one thing ruled out.
I haven't seen you mention having checked or replaced the blue temperature sensor?
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Yeah definitely change blue temp sensor
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Yep, changed that a couple of months ago. Made no difference to anything. And yep, it was an official VW one.
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Tried turning screw on maf air box?turned mine a couple of turns and idles spot on now
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Nope, I havnt tried that. Its not the idle that I am worried about though, it is the cutting out when I drop the revs too quickly.
Oh, coming back to the blue temp sender. I installed it, but I have seen talk about having to "re-set" it or something after the install. Anyone know anything about that?
This is turning into a serious trouble shoiting thread! Like I say, running out of things to try!
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The reset is rev it past 3k half a dozen times I think,have you altered idle screw on throttle body?
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The reset is rev it past 3k half a dozen times I think,have you altered idle screw on throttle body?
Ahh, well I did that. EDIT: Actually, not I didn't. I remember now. Every time I unplugged the Blue temp sender to do the reset the car died. So I couldn't do it.
Nope to the idle screw. I havnt touched any setting screws. Thats just for setting the idle though, right?
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To be honest mate I would be trying anything to get it drivable,tinker around it can all be reset back as long as you remember how far you've altered them.my revs were all over the place and I swapped temp sensor tried cleaning ISV and cleaning throttle body with no joy so I was pissed off with it one day and tinkered with idle screw and maf screw and it's great now
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To be honest mate I would be trying anything to get it drivable,tinker around it can all be reset back as long as you remember how far you've altered them.my revs were all over the place and I swapped temp sensor tried cleaning ISV and cleaning throttle body with no joy so I was pissed off with it one day and tinkered with idle screw and maf screw and it's great now
You are right, I will give it a try. My only reluctance is because it was fine before, with all screws exactly as they are, and now its not fine. So Changing setting is just going to be hiding the real issue. But I will have a play and see.
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Good luck and keep us informed
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The maf screw is the fuel mix. I wouldn't f**k around with it. If you have a gun check your timing and if you have a friendly garage that will check your co for free during lunch. It should go rough but shouldn't stall when unplugged.
Another thing, is the engine modified in any way, because mine is the timing both static and ignition is set differently to factory settings. If not set up like this the engine would stall if the sender was unplugged.
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Thanks, I will check the timing at the weekend.
As far as I am aware, the engine is not modified (as in I havnt touched it). But at some point it has had a chavvy owner, since it has a redbull ca covering the starter (what) and a nice big K&N filter. But I am pretty such there are no serious mods.
Im not sure I follow the last bit of yopur post, are you saying it will stall when unplugged if the ignition is set up differently to stock?
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If the ignition timing isn't set up right the car can stall when the blue temp sender is unplugged.
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Got ya.
Yeah I'll do the timing tomorrow!
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Right lads.
I can't do my timing as my strobe isn't playing ball.
I have had a play with both the CO screw and the idle screw. And by a play I mean I screwed them as far as they would go in both direction and then returned them to where they were. At no point did the engine change note, or idle differently or anything. This worries me, it feels like there should have been at least an idle change since I was playing with the idle screw!
Thoughts?
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Ignoring the co screw on the maf, your saying the idle didn't move at all when the screw was moved?
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Correct, not a bean.
I actually doubted I had the right screw. But I did.
If it wasn't posing down outside I would make a video.
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maybe your isv hose is partially collapsing under the higher engine vacuum when your slowing down???
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I would be more inclined to think that the idle switch wasnt function correctly still, that the car doesn't know it should be idling. I'm pulling that theory completely out my arse though.
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Have you cleaned the idle screw? If the outlet is bunged up turning it won't alter the amount of air coming in. Also, I think the blue temp sensor needs to be unplugged for it to make any difference, as per the set-up guide.
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I dont think the blue sensor needs to be unplugged to adjust the idle screw, when I turn mine the revs drop and rise accordingly, also the engine should change when the mfa screw is adjusted...mine goes from smooth to rough.
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Just remembered mine used to do this when stopping at junctions and stopping on steep hills..i chased mine around for years...it ended up being the hall sender wires were hanging on by a thread further up the loom. You could try idling the car and moving the wires see if it cuts out? Just a thought hth
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Replaced the TB gasket yesterday, while I was at it I cleaned the idle screw and re-checked the breather grommet.
No improvement. Although I did notice there was minor damage to the grommet, nothing that looked like it would cause an issue, but I ordered a new one anyway. I will then re-do rub Johnny's guide and see where I get to.
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Update: It isn't the breather bung, although admittedly the old one I took
Off was in a much worse condition than when I last out it back on. Regardless, the new one mad no difference. Sigh.