Engine Cuts Out And Idle Hunting

[DanRM 0 1 Cars]

Theres a problem with my 1.6 gti when it comes to junctions/traffic lights/ general idle. When I'm driving as soon as I dip the clutch the engine will just cut out, not every time but too often to ignore, the revs will drop and sometimes the counter just drops straight down and doesn't go to idle speed , it'll either drop down low to near stallling and find its way up to around the 1 again or it'll just go straight past and cut out.

The idle is also dodgy in the way that it'll sit fine at idle speed for anything up to 3 mins, then it'll slowly start hunting, getting worse over the next minute or so, to a point where it's hunting between near cut out and about 2000rpm, then it just dies. Even worse with heaters and lights on (bought a new alternator too as the old one was grinding)

 

This used to be hell of a problem for me as there was a dead spot on the starter so every 1 in 7 times or so it cut out I'd have to push start it (not good in the middle of the road), But i've replaced the starter and wiring so at least it'll start when it cuts out.

 

Any ideas or advice on what this could be? As with some of the situations I've been in when it cuts out recently, I'm hesitant on driving anywhere in case it does

 

Cheers

[paul mcgrath 2 1 Cars]

Hi dan,

 

I have had my car since it was new 2/8/1986 and mine has always done it - well actually it was my mothers but I remember it doing it. Mine is obviously an early one 115hp but has no lambda sensor to confuse things. I found adjusting the idle speed (brass screw on the induction manifold) improved things. As you point out this is exaggerated when the lights are on or something else that pulls a fair bit of current. Having said that mine hasn't turned a wheel for 12 years - it's full of 4 star and still on its original tyres!!. I'm really itching to get it road ready again but just haven't got the time!!!

[Grim.Badger 15]

Probably a few problems iirc Try searching around the forum for ECU temperature sensor and air-leak problems

[DanRM 0 1 Cars]

OK thanks for the replies I replaced the ECU temp sensor a few months back, Today I've changed the fuel filter (needed doing as it was black as hell in there), air filter, distributor cap and rotor arm and ignition lead. And whilst the air pipes were off I cleaned the breathers, from the oil cap. the smaller one being ok, but the larger one was mayo'd up like hell.

I also gave the TB a squirt with carb cleaner, and I noticed a little "mayo" near the butterfly flap. Anyway, after doing all of this its made some improvements to the running, but it still hunts like hell eventually cutting out, I've bought a SH AFM today but wont get that till January now, hopefully this will help, if not I got some spares.

 

It ran better (for 5 mins or so) after all this and adjusting the idle screw up a little, but as soon as I turn heaters and lights on it cuts out, I've got a new battery and alternator on it from only about a month ago,

[welshpug 1,621]

you really do need to look through it thoroughly and actually test parts rather than just swapping and randomly adjusting stuff.

 

The 205 haynes workshop manual is a very good starting point here, but also finding a helpful local garage with an exhaust gas analyzer would be extremely helpful.

 

 

 

To give you an example, my own 205 has been running Motronic for some years (from a ZX volcane, not the 205 Motronic system), and recently I noticed a thread suggesting a lambda could be utilised, great I thought, I had a spare one.

 

This improved initial idling and response significantly, but I still had an annoying propensity to stall when the clutch was dipped when cold, I thought nothing of it and just lived with it.

 

Cue this week's MOT, the ruddy thing was running at 3.948 CO%, the limit is 3.5%, these buggers run best at around 1.5%...

 

 

As I hadn't the time to mess around sourcing another Lambda and also did not have a gas analyser, I re-fitted the mixture potentiometer and left it with the garage, £20 later it's running sweet as anything at 1.5% and I have a clean MOT sheet for another 12.5 months

[pug_ham 240 3 Cars]

As suggested above (not the converting to MP3.1 ) make sure it is all set up properly as per the haynes & to add that the throttle body, idle speed bypass screw, AFM are spotlessly clean (not that they'll stay that way long) & all breathers are in good condition (& also clean).

 

If you are feeling extra keen, its only four nuts to undo & remove the TB to clean both sides of the idle bypass & throttle butterfly.

 

With the standard cooling system layout you can't remove it fully because its plumbed in but there is enough slack to move it far enough to give it a full clean.

 

g

[Tom Fenton 1,524]

The stalling after a drop from high revs in my experience is usually due to wear in the throttle body stop meaning the butterfly gap is too small. The idle screw usually has been wound out to compensate, and the net result is an OK idle speed, but the tendency to stall when the clutch is dipped. Open up the butterfly gap a touch, wind in the idle screw, and hey presto your problem will be gone. All good in theory however in practise the throttle stop adjuster won't have been touched in years and so probably won't move.

[pug_ham 240 3 Cars]

To give you an example, my own 205 has been running Motronic for some years (from a ZX volcane, not the 205 Motronic system), and recently I noticed a thread suggesting a lambda could be utilised, great I thought, I had a spare one.

 

This improved initial idling and response significantly, but I still had an annoying propensity to stall when the clutch was dipped when cold, I thought nothing of it and just lived with it.

 

Cue this week's MOT, the ruddy thing was running at 3.948 CO%, the limit is 3.5%, these buggers run best at around 1.5%...

 

As I hadn't the time to mess around sourcing another Lambda and also did not have a gas analyser, I re-fitted the mixture potentiometer and left it with the garage, £20 later it's running sweet as anything at 1.5% and I have a clean MOT sheet for another 12.5 months

That sounds like mine was with the mixture pot in place, a struggle every MOT to get it through emissions & the reason I changed to a lambda.

 

Have you got the K ight wired up? When my mums Lambda had failed it put the MIL on so you knew something was wrong.

 

Mine only stalled (very occasionally) when cold when I had the mixture pot in, since fitting the lambda it hasn't yet but I haven't used it outside the warmer months so don't know how it'll cope with lights, heaters etc on.

 

g

[DanRM 0 1 Cars]

Cheers for the replies, I managed to get an AFM, inlet manifold with rail and injectors and a TB for £40 the other day (stocking up on spares at least), swapped the AFM and made it a little better but the hunting and cutting out is still there unless the idle is turned up. I've now decided to take to a garage to book it in and hopefully they can get it up and running properly for me (fingers crossed)

[pug_ham 240 3 Cars]

I've now decided to take to a garage to book it in and hopefully they can get it up and running properly for me (fingers crossed)

 

You could end up with a nice bill for things you can do at home to solve this problem, generally hunting is due to a build up of grime in the inlet system or wear to the throttle body but the 8v body doesn't suffer this as badly as the Mi imo.

 

Have you followed the haynes manual set up guide first? A few hours max with basic tools & a multimeter, some rags & carb cleaner could save you a few hours garage labour & needless parts replacement.

 

g

[DanRM 0 1 Cars]

Yeah I got a mate to try the haynes set up as this was out of my hands a while back, this allowed me to stop using a brick to keep it idleing when demisting haha. I'm expecting quite a bill but after having it for 3 years and having to buy a 2nd car with the amount of times this one has been off the road, I reckon its better to bite the bullet and have it running the best I can with someone who knows what they're doing to sort it out

[pug_ham 240 3 Cars]

I reckon its better to bite the bullet and have it running the best I can with someone who knows what they're doing to sort it out

 

Good luck finding such a garage now, even when the 205 GTI was a common sight on the road it was hard to find a garage with the knowledge to fix the hunting 100%

 

g

[Kezzer30 40 1 Cars]

Mine does the same thing but seems fune once warmed up , i was also told that carbs if set up correctly can help , well i can let u know if r1 bike carbs work as mine will hopefully hve aome fitted in a few weeks .

[Simes 248 2 Cars]

Mine does the same thing but seems fune once warmed up , i was also told that carbs if set up correctly can help , well i can let u know if r1 bike carbs work as mine will hopefully hve aome fitted in a few weeks .

 

If you mean carbs can cure the idling well that's because you're removing the actual issue.

 

Mind you you'll have a whole new world of pain setting up the bike carbs!

[Kezzer30 40 1 Cars]

 

If you mean carbs can cure the idling well that's because you're removing the actual issue.

 

Mind you you'll have a whole new world of pain setting up the bike carbs!

Well ive been told these ones in fitting are less hassle than webbers an are one of the best set ups you can get , a few people have raved about them , weather thats true il have to let u know , if worse comes to worse , il just put it back to standard etc

[Carbs4me 45]

I've found that playing with the throttle position screw and then moving to the idle screw is the best way, i have cured a couple of engines of hunting by doing it this way...

 

Get the revs up with the throttle position screw and bring it down with the idle screw, always works a treat for me

[pug_ham 240 3 Cars]

I've found that playing with the throttle position screw and then moving to the idle screw is the best way, i have cured a couple of engines of hunting by doing it this way...

 

Get the revs up with the throttle position screw and bring it down with the idle screw, always works a treat for me

 

When setting it this way, does the throttle position switch still click closed at idle or is it adjusted so it doesn't when you've finished?

 

g

[Tom Fenton 1,524]

That description above is the same as I said further up. Yes you have to reset the throttle switch afterwards.

[pug_ham 240 3 Cars]

I realise that Tom but Luke doesn't mention resetting the throttle switch so it works correctly, which is why I asked because I know of garages that have set cars up this way but not reset the throttle switch afterwards which is masking the problem rather than fixing it properly.

 

g

[Rjuhar 52]

Since I also suffer from this I have 2 questions - where is the throtle position screw and how do I later reset it? Thanks

[DanRM 0 1 Cars]

Had a call off the guy at the garage today, he said he's managed to get it running better but not spot on, but he is looking around for an air leak. I've just bought the silicone breather pipe set and SAD pipes from BakerBM, to send down to him as a couple of those pipes where perished a little so this may be the problem. Unless he manages to sort it over the next few days I'm going to have to say get it the best he can and I'll have to put up with it until I get a job again to throw more money at it

[shooter mcgavin 37]

If it was me I'd have spent a few hours doing what's mentioned above rather that paying someone that's not really to sure what the problem is either.

[DanRM 0 1 Cars]

That's the problem, I have spent a long time trying to get it to run the best it can but with doing everything said on here over various topics in the last year and none of them working I had to give up and hand it over to someone who has more of an idea than me.

[DanRM 0 1 Cars]

Just an update on this after having the car back at the beginning of the week. After putting a S/H AFM on along with all the oil breather pipes, and setting the mixture right. The garage managed to get the car currently Idling at about 1500rpm when cold, then dropping down to a steady 1000rpm as it heats up, Idle is pretty steady at that now especially when warm. Which is the best it's been since buying it (and probably the best it'll be).

 

I still get the cut out when dipping the clutch every now and then, the mechanic said that when he took it for a test run he brought it back and there was a small puddle of water at the back of the head, so now I'm saving to get that done. After having to change the HG 3 times in the last 2 years, clearly something isn't right there so I've sourced a new head hoping that it'll be ok after that one has been put on.

 

So cheers for the input and advice over the last few weeks

[welshpug 1,621]

I would check the Throttle switch has been adjusted correctly, and is working as intended.