2.0 16V 9A funny idle and coughing.

[horney 0]

Hi Folks,

 

First off nice forum and a confession from me. I don't own a Corrado (although I do love them), I actually run a B3 Passat GT wagon with the 2.0 16v 9a engine. THe reason I'm here is because the passat scene is somewhat small whereas your scene is much bigger and therefore more folks who know about the 9a set up that's in my car. I've been into dubs for years and had 3 MKII Golf Gti 8v's and I also have a T25 Transporter panel van that I've converted into a camper.

 

So onto my issue! I've had a good old search and read lots of the topics associated with bad idle/coughing of the 9a but though I would post up my exact symptoms and see if any of you guys have a eureka moment and know exactly what's causing mine. I'm incredibly skint and can't afford to just start chucking money at it in the hope I get it running right and I also can't afford to put it in a garage at the moment. However I also need it to get to work and back everyday!

 

The Symptoms:

 

* Symtpoms started yesterday.

* Idle will drop to 400 rpm then jump to 1,200 rpm before settling back at 800rpm when warm.

* It's accompanied by a judder so more like a missfire/cut out than just wandering idle.

* This morning it actually cut out 3 times when this happened.

* Every now and again I get a slight cough when cruising at low revs (less than 2,500rpm) but once wound up above that it runs fine.

* No percieved powerloss through the rev range.

* Fuel economy seems the same (32 - 40 mpg depending on traffic).

* Oil and Water temps all good.

 

Now on friday afternoon I forgot to check my water level (It's been using a bit ever since I've had it) and it got a bit hot on the way home, 110 water and 114 oil. I then spent the weekend fitting my coilovers (which was a mare) and not driving it. Journey into work yesterday and all seemed fine, these problems started to appear on my way home last night and then seemed worse this morning. I'm guessing (but hoping not) that the journey home tonight will be worse again so it seems to be a problem advancing in severity quite quickly.

 

So I've complied a list of things from some of the threads on here and tonight I'm going to check/do:

 

* Check all vacum hoses for splits/gunge.

* Check inlet pipe from Metering head to TB.

* Check all pipework to do with TB for splits/gunge.

* Soak ISV in petrol overnight.

* Clean and check Rotar arm and dizzy.

* Clean out TB.

 

Is there anything else you guys would recomend me do/check or have any of you had exactly the same symtpoms and can hit the nail on the head for me?

 

Anyhoo here's some pic's of the car incase there are some passat lovers on here and I look forward to your replies.

 

Nick

 

 

 

[mattkh 0]

Hi

Put up a picture of the engine, a bird's eye view.

[horney 0]

I'll get one up tonight. I did have a quick nosey while on my lunch and noticed what I think is a missing lambda sensor. Looks like it's been replaced by a pipe and a bolt to block it off!

 

Still it's been running fine like that for a while so I don't think that's got anything to do with my problem.

 

Nick

[Jim 2]

I often come back to this whenever bad idling 2.0 16v threads come up but i'd definately suggest sourcing and trying a known good ISV. Just cleaning them sometimes isn't enough - they can just be shagged!

 

I went for months with a nightmare idling problem - sometimes it'd be fine, and then sometimes the revs would drop right down to where the car was virtually cutting out (flickering battery light) then leap back up to over 1,000RPM, and so on. Sometimes it'd even cut out. I was advised that it was unlikely to be the ISV because the preventing of the car cutting out was the ISV 'jumping in' to try and keep the car running so I kept putting that aside as the fault and swapping sensors, looking for air leaks, etc.

 

It was the ISV in the end. Found one off an Audi 80 16v (uses the 9A engine also) on eBay for £10 - idling has been rock solid ever since. Worth getting one just to rule it out!

[horney 0]

Jim: I spent about 45 mins reading your thread, you had a tough time with that one didn't you! The thing that jumps out at me is the fact mine also coughs at low revs while under load which suggests something else is a foot. I'll start working through things and see how I go, will also check out the local scrappies for 9a cars but doubt I'll have much luck on that front. Looked up a new one and decided that's a no goer!

 

Nick

[Jim 2]

Where do you live mate? If you're local to me, i'd happily pop over and let you borrow my ISV to try it out!

 

The 'burping' at low revs could be unrelated. As you probably know the 2.0 16v is so sensitive to air leaks.. after I serviced mine the other day, I found it was being a bit twitchy and low revs (part throttle accelerating at low revs, the car seemed to bog down slightly like I was backing off the throttle, then pick up again) - just been round this morning disconnecting and reconnecting all the plastic / rubber pipework, rechecking the airbox, etc and it seems much better again - I couldn't see or hear any visible leaks!

 

Could it also be something to do with your earth connections or anything like that?

[horney 0]

I'm located on Basingstoke chap so not on your doorstep! One of my best mates lives in RLS though, he's got an Atlas grey MKII GTI 8v on Audi Coupe Multi spokes, give him a awave if you spot him out and about!

 

As for the burping, it feels exactly the same as the idle burp which is why I think they are linked and they both started on the same journey.

 

I can see many hours of fun and games ahead of me, ha ha.

 

Nick

[horney 0]

Here's a vid of the problem.

 

 

Car had done a 45min 21 mile journey home and water temp was 95deg and oil 104deg. If left idling it will do this approx once a minute. Sometime more, sometimes less. Pics of the bay on their way shortly!

 

Nick

[horney 0]

Pics of the bay:

 

 

 

 

And here's a pic of where I would have thought the lambda should be but isn't! As I said though it's run fine for the month I've had it like this.

 

 

So does this all look the same as the coraddo setup?

 

Nick

[boost monkey 0]

Looks pretty similar Nick, afaik.

 

 

Do you know whether these two pipes are connected together properly? That will be a vacuum leak if not, and could lead to your hiccup-like symptoms.

 

hth,

 

Jon.

[horney 0]

Not sure on that pipe chap, I'll have a butchers tonight and report back.

 

I have a few more observations from todays journey into work.

 

* Cleaning the ISV seems to have had little effect.

* It only does it once warm/hot

* Twice it happen while I was holding on the foot brake and I felt the peddle move suggesting a vacum problem.

* I have an feeling it maybe linked to the fan cutting in and out. Will investigate this further.

 

Nick

[horney 0]

With a friend last night we clenae dout a few bits and bobs and swapped the dizzy cap for a spare one he had as mine looked a bit old and knackered. THought this had done it but again this morning it started playing up. THis time however it took a lot long so I'm thinking it may be related to under bonnet temps.

 

I've got a spare set of leads so going to try swapping those today and see if that helps.

 

Nick

[mattkh 0]

so I'm thinking it may be related to under bonnet temps.

Hi

next time it happens, open the bonnet and swap the spade connection on the temperature sensor used by the ECU. See if that cures it.

[horney 0]

Oh Cock!

 

Broke one of the old leads off in the head and to top it off these leads are different to the set I was given by my mate. They are essentially the same but lead No1 on my enginehas some sensor on it that plugs into the wiring harness, the others don't. It seems like it's to measure the spark/timing

 

Looks like I'll be training it to work tomorrow and then walking the 1/2 mile and back to ECP in my lunch break!

 

Nick

[horney 0]

so I'm thinking it may be related to under bonnet temps.

Hi

next time it happens, open the bonnet and swap the spade connection on the temperature sensor used by the ECU. See if that cures it.

 

I don't think that's the problem, I meant more the air temp under the bay causing something to not work not the actual temp of the engine. I'm pretty sure the it's the leads or coil but as per my post above it's gone a bit wrong!

 

Nick

[mattkh 0]

They are essentially the same but lead No1 on my enginehas some sensor on it that plugs into the wiring harness,

Hi

That lead according to the photo is Lead no. 4.

[boost monkey 0]

so I'm thinking it may be related to under bonnet temps.

Hi

next time it happens, open the bonnet and swap the spade connection on the temperature sensor used by the ECU. See if that cures it.

 

I don't think that's the problem, I meant more the air temp under the bay causing something to not work not the actual temp of the engine. I'm pretty sure the it's the leads or coil but as per my post above it's gone a bit wrong!

 

Nick

 

If your leads are getting so hot that they turn brittle and snap off in the spark plug holes, you definitely need a new set!

 

could well be why the car is running bad too. Worth changing them anyways if the old ones are that bad.

 

hth,

 

Jon.

[davidwort 0]

looks like you've ruled out the hall sender on the distributor as you have swapped the dizzy over

IIRC there are two electrical connectors on the metering head if you disconnect both it should run in 'average settings' ignoring temperatures and emissions readings and can often point to the lambda probe (if the car has one) if by doing this you improve the running.

Vacuum leaks tend to casue problems at idle more than driving as that's when manifold vacuum is at it's highest, so vac leaks from boots/hoses are one of the favourites.

[horney 0]

Cheers guys.

 

Swapped over to the set of leads my mate gave me and it's much worse, in fact I had to leave it home today and get the train to work. I'm going to splash out on new leads, plugs and arm tomorrow and see how that goes. If it's still not right I'll admit defeat and drop it into my local VW specialist (Who are very good, I'm just very skint!).

 

You guys have been such a great help especially as I don't even own a rado. And yes you're right I mean't lead No4 not No1, got the wrong end of the engine!

 

Nick

[Albie 0]

Check the underside of the rubber turret directing airflow on top of the metering head for splits inside the corrugations running along their length. This is apparently relatively common.

 

If you just gently lever the airflow plastic tube up while you listen closely you may hear the sound change. The corrugations at the other end just before the throttle body could be checked too. Mine had split badly, and I mean badly. This caused similar symptoms to yourself with idle, and also eventually a kangarooing on acceleration.

[horney 0]

Well I've fitted a brand spankers new set of leads and that so far seems to have done the trick.

 

I haven't however refitted the ring sensor on lead 4. I can't get the lead through the hole without mashing the end and I don't want to have to shell out another £40 if I break one.

 

How do you folks get the metal end through that tiny hole?

 

Nick

[Jim 2]

Heh - it's a real fight. When I did mine I was using a biro to widen the hole on that reference sensor a bit, and then I just got a bit of washing up liquid on there to help ease the passage a bit and just spent ages fighting to get the bastard in.

 

Alternatively you can uncrimp the end of the lead, remove the metal bit of the spark plug, and recrimp it back on once its on! Either way its a PITA!

[horney 0]

Yeah I was thinking the uncrimp, through, recrmp method may be the easiest way. I'll have a dabble later in the week. Seem to run fine without it though which is odd!

 

Just want to say again a big thanks to everyone on here, you've all been dead helpful.

 

Nick

[Jim 2]

You should definately try and get the sensor on if possible - it helps detect knock!

[horney 0]

You should definately try and get the sensor on if possible - it helps detect knock!

 

Nothing worse than un detected knockers! (I'll get my coat :lol: )

 

I figured it was something to do with timing advance and retardation. I'll get it back on and sorted by the weekend.

 

Nick