8v running issue

[V33DUB 0]

The trusty 8v has decided that snow is not for her and she's thrown a hissy fit. Started off with a judder on acceleration, as if in too high a gear, struggling kinds thing. This progressed to sounding like a tractor and for want of a better word 'suffocated' feeling... hard to rev high. Felt down on power and the judder was still there. Eventually it was spluttering, back firing and the engine was bouncing around like a metal gummy bear. There was also a clicking/tapping noise.. regular... every couple of seconds.

 

So far...

 

Relays all checked (think 30 and 167 are the ones that can cause such running issues but both seem to be fine)

 

Unplugged MAF and it ran much worse so I'm thinking that's working ok?

 

Throttle body was cleaned not that long ago and when it was it was pretty clean anyway.

 

Lambda sensor was changed last year with a new genuine one.

 

Checked all the hoses I can see and all seem to be split free and the ends are all clamped on.

 

Replaced the vacuum hose from the throttle to the fuel rail.

 

Cleaned up all the wires by the 2 earthing points on the block and all seem to be sound.

 

The wires from the sender on the dizzy (hall sender I think) seem to be ok

 

I checked the HT leads and one wasn't working so replaced the set. This didn't seem to make much difference. I'm no mechanic but seemed to me like it should've at least improved things? Double checked the new set and all are working and all spark plugs are working. The plugs are pretty black and sooty so I'm guessing it's running rich? Got a new set in the post so will pop them in when they arrive.

 

I found a brand new dizzy cap and rotor arm that I had lying around so put them on. Fired her up and sounded much better. Engine wasn't juddering as much, clicking/tapping noise seems to have gone... 5 mins later and it was sounding bad again... not quite as bad as before but not good. Sounded a bit like it was hunting and every now and again was like it was going to cut out but never did.

 

Took her for a short drive, sounded like a wounded tiger, really throaty roar which came and went, juddered still on acceleration but intermittent between that and running ok.

 

Any ideas on what to do next before I give up and book it in at a garage?

 

Cheers for any pointers ;)

[owen g60 10]

Sounds like the coil breaking down.

Had the same issue about a year ago.

[V33DUB 0]

Doesn't the coil just affect the start though? It starts every time. It's the running that's rough/not right.

[davidwort 0]

Doesn't the coil just affect the start though? It starts every time. It's the running that's rough/not right.

no, your coil generates the spark for every turn of the engine :)

hall sender or coil could be going dodgy.

[V33DUB 0]

no, your coil generates the spark for every turn of the engine :)

hall sender or coil could be going dodgy.

 

Ah! Thank god you lot know what you're talking about! haha

 

Is the hall sender the thing attached to the side of the dizzy?

 

Cheers

[davidwort 0]

Ah! Thank god you lot know what you're talking about! haha

 

Is the hall sender the thing attached to the side of the dizzy?

 

Cheers

yep, the hall sender (on the dizzy) uses a magnetic field being broken by the rotation inside your distribitor to tell the ECU when to trigger a spark for each firing point, they can fail entirely when a wire breaks etc, but also seem to suffer from a more sporadic breakdown of the signal sometimes, an LED test light is needed to test for total failure, intermittent problems are harder to diagnose. Make sure the inside of your distributor and cap are clean and free from oil or moisture. An exchange complete distributor is often a better buy than just the hall sender which is quite expensive on it's own and hard to fit (a pin needs to be pressed out of the distributor shaft). Often the distributor shaft and seals have worn too although 8v ones are generally better than the 16v ones that are prone to oil leaking into them due to the angle they are installed at.

[Supercharged 2]

The coil is a well known point of failure on MK3 based engines - especially if plugs are not changed reguarly...

 

http://www.vwspares.co.uk/product_info.php?products_id=31

[V33DUB 0]

Cheers both. The coil was changed about 2 years ago for a new VW one but suppose it could've gone again. I do change plugs every 6 months or so.

 

As it happens I have a brand new distributor. As I'm mechanically inept and I'm assuming the spline at the bottom of the distributor connects to something involved in the timing of the engine I'll get a local mechanic to change it over. Will try that first and then if no better will get a new coil.

 

thanks again.

[seanl82 23]

Where are you based? Maybe someone is local and could give you a hand to save you some pennies?