1.8 kr missing under load. ignition? fuel? both? Help please

[Ralphead 0]

So, a week or so back I was struggling to get any power without my engine missing. A couple of times the idle would be high and steady or low and hunting around between 400 - 800rpm. I replaced the fuel filter and everything went back to normal, until two nights ago. I dipped the clutch as I stopped at a junction and the idle was low and hunting again. I realised that the engine was cutting out when the indicator lit up and would fire again when it went off! Also when I flashed my lights the rev counter would jump, going to the redline if I held the stalk long enough!

 

Today it's become undriveable, anything more than quarter thottle has the engine missing and even backfiring. It will happily rev to 5k under light throttle but will miss at any revs when pulling a decent vacuum. I'm thinking that there's a bad earth somewhere and I'm getting feedback in the ignition system, the same as you see in trailer lights sometimes. Thing is the lights and indicators don't always make a difference. I got my old Lucas electronic ignition manual out and tested all the components I can and they all check out. Just to rule it out I checked all the induction pipes for leaks and found one small one but patched it and it made no difference, so I'm a bit stuck now. Any suggestions, please?

 

---------- Post added at 4:44 PM ---------- Previous post was at 4:42 PM ----------

 

Oh yes. I went though some water a while back and soaked the distributor. I could see the HT tracking across the outside of the dizzy cap and it gave just the same sysmptoms I have now. But the cap checks out for insulation with my meter.

[owen g60 10]

Found this issue on a friends 16v turned out to be duff leads and dizzy cap.

 

I would suggest pulling the leads one at a time an cleaning the contacts. Chances are something will be broken.

[Ralphead 0]

I've just this minute put a new cap and rotor arm on just for the hell of it. I found that having left the motor to cool for a while that it revved cleanly on starting up. But by the the time I'd closed the bonnet and climbed in it was back how it was.

 

At idle it will, usually, be smooth as. So I'm happy that they're all firing. Now it's getting dark I'll go and see if theres any HT escaping out the leads.

Edited February 15, 2013 by Ralphead

[Ralphead 0]

Right. I've ruled out ignition. Got a strong spark at all revs, put a good coil (off my Volvo) on just to confirm it was as good as it could be. There's still a definite unburnt fuel smell, I don't like that. I went for ignition first, but starting it from stone cold today told me that it starts playing up as the hoses get warm, i.e the themostat opening. I was wondering if crap got through my old, or new for that matter my new, fuel filter into the k-jet's warm up regulator. That or the head gasket has gone. There is a fair bit of dampness in the tail pipe. Although I havn't had a chance to warm it up enough to rule out condensation. No water in oil and vice versa, neither are there bubbles in the header tank.

Edited February 16, 2013 by Ralphead

[Supercharged 2]

You might want to stick some insulation tape around the leads where they drop down to the sparks - just in case they are breaking down around here due to heat

[Ralphead 0]

Good idea, thanks! I'll try that tomorrow.

[Wullie 1]

Just a thought. It sounds possibly as if the cold start (5th) injector is not shutting off. Have you tried it disconnected? Mind you. I'm just in from the pub.

[vw rule 19]

Hello there,

 

courses of misfire are:

 

spark plugs

HT leads

rotor arm

distributor cap

distributor it's self (there is a hall sensor in side the distributor, symptom is the vehicle won't be able to get above 50 ish when driving,

or sometimes the engine won't rev up.

ignition timing

knock sensors (when these play up they can be similar to the hall sensor or you can just get a slight misfire)

vacuum hoses (including brake servo hose as this is connected to the inlet manifold

air leak from a inlet manifold (but this would have to be quite a bad leak though)

fuel filter (mainly when it's old and hasn't been changed in ages and has become blocked)

fuel pressure (when fuel pressure is low some cars won't start at all or some just have a very bad misfire)

fuel injectors

main fuel pump in tank

secondary fuel pump under Corrado next to fuel filter.

fuel accumulator again next to fuel filter (when these play up your car won't rev well when cold)

but tend to be a little better once engine has warmed up

 

air flow meter (can have symptom of engine not reving or on some cars they won't start up at all if the air flow meter is totally dead)

fuel distributor (these are normally working or not working, but can be similar to air flow meter)

coolant temp switch (when these are warn they course the ECU to dump loads of fuel via injecters,

and can be a real git to start up even when the engine is warm.

 

cold start injector (but this is governed by the coolant temp switch, but the cold start injector can play up)

exhaust lamda senda (when these don't work the ECU goes in to safety mode and can dump loads of fuel in coursing a misfire)

exhaust catalytic converter (these have a honey cone inside and can break up and lodge in the exhaust system)

you may not even hear the damaged honey cone rattle around if it has lodged tightly.

 

valve timimg (the timing belt has jumped a few teech, which it can on the 16v & 8v golf / corrado heads)

which will course a misfire and engine my not like reving up.

the cam belt tensioners on the 16v & 8v engines are well know for seizing up or becoming notchy,

always replace the tensioner when you do the cam belt to be safe.

Cam belt should be changed about every 70 to 80.000 miles or 5 years whichever accurs first,

any longer on these engines and the tensioner or cam belt will let go.

 

blown head gasket (this can have a misfire symptom but engine should still rev up though)

cracked cylinder liner (same as above really)

when a head gasket / cracked cylinder head / cracked cylinder liner,

happens you usally get water in the engine oil, simptom is white deposits on dip stick, oil filler cap,

or you can have oil / fuel deposits in the coolant this will show as a rainbow colour in the water,

or you'll be able to smell oil / fuel in the coolant,

another sign is the engine will run very hot or you can be losing water and there are no visable leaks anywhere,

this is where the engine is burning the coolant.

Or there can be excessive pressure in the coolant system where the hoses become rock hard,

and in some cases can blow the coolant hoses off.

When there are no visable signs of a head gasket blown you can have a block test carriered out,

this is where they use a blue liquid which sniffes for oil / fuel / combustion fumes,

when the blue liquid does so it will change colour from blue to yellow in no time at all.

This test can be carriered out at a back street garage or main dealer.

 

Just one more thing always use the black steel head gasket for the 16v golf / corrado heads,

as it's a lot stronger than the cheaper ones, as the 16v engine has got quite high compression,

I believe it's around 280 psi well I know it is on the 2.0 16v engine.

And that goes for the exhaust manifold gaskets as well,

always go for the genuine ones they are made so much better and will last for years.

 

I hope this helps good luck mate, I hope you sort it.

 

Cheers

 

Si :thumbleft:

[vw rule 19]

Hello there,

 

courses of misfire are:

 

spark plugs

HT leads

rotor arm

distributor cap

distributor it's self (there is a hall sensor in side the distributor, symptom is the vehicle won't be able to get above 50 ish when driving,

or sometimes the engine won't rev up.

ignition timing

knock sensors (when these play up they can be similar to the hall sensor or you can just get a slight misfire)

vacuum hoses (including brake servo hose as this is connected to the inlet manifold

air leak from a inlet manifold (but this would have to be quite a bad leak though)

fuel filter (mainly when it's old and hasn't been changed in ages and has become blocked)

fuel pressure (when fuel pressure is low some cars won't start at all or some just have a very bad misfire)

fuel injectors

main fuel pump in tank

secondary fuel pump under Corrado next to fuel filter.

fuel accumulator again next to fuel filter (when these play up your car won't rev well when cold)

but tend to be a little better once engine has warmed up

 

air flow meter (can have symptom of engine not reving or on some cars they won't start up at all if the air flow meter is totally dead)

fuel distributor (these are normally working or not working, but can be similar to air flow meter)

coolant temp switch (when these are warn they course the ECU to dump loads of fuel via injecters,

and can be a real git to start up even when the engine is warm.

 

cold start injector (but this is governed by the coolant temp switch, but the cold start injector can play up)

exhaust lamda senda (when these don't work the ECU goes in to safety mode and can dump loads of fuel in coursing a misfire)

exhaust catalytic converter (these have a honey cone inside and can break up and lodge in the exhaust system)

you may not even hear the damaged honey cone rattle around if it has lodged tightly.

 

valve timimg (the timing belt has jumped a few teech, which it can on the 16v & 8v golf / corrado heads)

which will course a misfire and engine my not like reving up.

the cam belt tensioners on the 16v & 8v engines are well know for seizing up or becoming notchy,

always replace the tensioner when you do the cam belt to be safe.

Cam belt should be changed about every 70 to 80.000 miles or 5 years whichever accurs first,

any longer on these engines and the tensioner or cam belt will let go.

 

blown head gasket (this can have a misfire symptom but engine should still rev up though)

cracked cylinder liner (same as above really)

when a head gasket / cracked cylinder head / cracked cylinder liner,

happens you usally get water in the engine oil, simptom is white deposits on dip stick, oil filler cap,

or you can have oil / fuel deposits in the coolant this will show as a rainbow colour in the water,

or you'll be able to smell oil / fuel in the coolant,

another sign is the engine will run very hot or you can be losing water and there are no visable leaks anywhere,

this is where the engine is burning the coolant.

Or there can be excessive pressure in the coolant system where the hoses become rock hard,

and in some cases can blow the coolant hoses off.

When there are no visable signs of a head gasket blown you can have a block test carriered out,

this is where they use a blue liquid which sniffes for oil / fuel / combustion fumes,

when the blue liquid does so it will change colour from blue to yellow in no time at all.

This test can be carriered out at a back street garage or main dealer.

 

Just one more thing always use the black steel head gasket for the 16v golf / corrado heads,

as it's a lot stronger than the cheaper ones, as the 16v engine has got quite high compression,

I believe it's around 280 psi well I know it is on the 2.0 16v engine.

And that goes for the exhaust manifold gaskets as well,

always go for the genuine ones they are made so much better and will last for years.

 

I hope this helps good luck mate, I hope you sort it.

 

Cheers

 

Si :thumbleft:

[Ralphead 0]

Bloody hell! That was quite a read once let alone twice! Thanks, it's alot easier to have those facts infront of me in black and white. Means they don't have to swim round in my head against the tide of ale and VW part numbers.

 

So far I've changed the rotor arm & dizzy cap for new. Tried a different coil but changed back again, no difference. Triple checked all the plugs and leads for leaks. New fuel filter a couple of hundred miles ago. Tried disconnecting whilst running, and disconnecting then starting, both head temp sensors and the blue plug on the fifth injector, they all make things worse. All these checks have been done hot and cold. I was thinking head gasket but I'm not losing water or compression.

 

It's still running perfectly from cold and will until the top rad pipe is just getting too hot to hold comfortably. It will then start running rough and missing at smaller and smaller throttle opening until the oil is upto about 60deg. and then anything just off the stop has it struggling. I'm becoming convinced that it's fuel. Too much or too little. Not knowing much about K-Jet leads me to think it's the warm up regulator that would cause that.

 

I think the idle hunting in time to the indicators and the tacho jumping about to the tune of the headlights is another issue... It doesn't do it very often, not at all for two days.

Edited February 17, 2013 by Ralphead

[vw rule 19]

I'd do the basic things first mate like check the ignition timing and valve timing,

from there I'd replace the distributor cap and rotor arm as they are only a few quid to buy.

You can have a hair line fracture in the distributor cap & on the rotor arm even if they do look like they are in good condition,

they can still be at fault.

 

If your Corrado is over fueling you'll be able to smell the fuel (it will stink of petral plus the spark plugs will be soaking wet if you check them)

If it is under fueling it will pop and bang out the back of the exhaust, similar to having the ignition timing out.

 

I had what you are talking about on a mercedes some years back with the similar injection system as what's on the 16v Corrado,

the fuel metering head unit had packed up, i,e the air flow meter,

and it had the similar simptoms to what you have now,

that the engine would only rev up at soft throttle & at full throttle it would die.

I traced a decent second hand metering head unit as a new one is over £500.00

and this did the trick for me :cheers:

 

The only over thing I've had is a complete short in the ECU which kept on blowing the air flow meter,

so replaced the ECU and this fixed the fault on my mates car years ago.

 

I hope you get it sorted mate :thumbleft:

[tony_ack 0]

I'd bet the problem is somewhere in the holy trinity of ISV/temp senders/cold start valve.

 

The wiring between these gets pretty brittle on after 20+ years, so check all the wiring between the ISV, temp senders on the side of the head and thermotime switch. It does sound a bit like the cold start valve is stuck open. if the car is fine from cold, but then running rough soon afterwards. The cold start injector should only open for a short burst when the engine is started and only for a couple of seconds - the WUR takes over after this. You can test the WUR with a multilmeter as well - it should read about 22-28 ohms at cold.

 

The indicators/lights doing funny things to the idle could be a bad earth somewhere, or the wiring problems mentioned above, or could be a short in the wiring to the control units. K-jet doesn't have an ECU per se - it has a module that stores the ignition timings and then a separate module behind the dash (on a Golf, not sure where it is on a Corrado) that controls the idle.

 

As mentioned though, set the timing to 6 deg BTDC and CO to about 2% to ensure that's all okay.

[Ralphead 0]

Having rebuilt the warm up regulator once and making things better, then a second time and making it worse I replaced it. The problem's still there but better, I drove it a mile before it played up and then it was almost intermittant.

 

I've run the engine with the warm up injector unplugged but it made no odds. I'll try clamping its supply pipe tomorrow in case it's physically stuck open, is this a possibility? Wiring is definitely worth going through, it was quite a state when I got the car.

[dannyboy 0]

isv sticking,had gti with the kr and idle was sorted after cleaning out the isv. If it idle gets better then month later goes back to the way it was you need new isv. Also the idle speed screw at the back of the tb.Rubber o-ring in there perishes causing wonky idle.

 

also check the k-jet plate as said that it isnt sticking or jammed. all the oil from breather ends up on it and gunk sometimes cause sticky plate movements

 

if youve unplugged the fifth injector it should be fine,if it was stuck open youd have problems starting the car.

Could be ignition too so check and make sure all earth cables arent corroded,this will cause nightmares that even electricains hate

[vw rule 19]

Are you getting a bit of black smoke out the exhaust like it's over fueling,

if you are then switch the engine off and remove the vacuum hose that's on the fuel regulator,

when you remove this vacuum hose no fuel should come out, if it does then that's a sign that the fuel regulator is on the blink.

It would mean that the inner seal / diaphragm has gone or is going.

This can affect the fuel pressure i.e coursing rough running.

 

 

Si :thumbleft:

[Ralphead 0]

Plug leads, bloody plug leads! After a year of messing about with rusty 4x4s it just needed a set of leads..

[vw rule 19]

Hello mate,

 

good to hear you've fixed the problems,

some times the fault can be a real swine to trace / find.

 

Hopefully now you'll be able to enjoy driving it.

 

 

Si :thumbleft: