Timing Chain Symptoms

[Macdaddy 10]

Hi all,

 

So far the VR has been in the garage being "fault found" for almost three weeks. We've had the Lambda replaced which hasn't solved the issue and now the garage are suggesting changing the timing chain as they consider this to be the reason for the rough running.

 

Symptoms are rough idle / missfire so it sounds like a tractor and makes driving impossible.

 

Thoughts on this from anyone more technical please as I didn't consider this would be the fault. Thanks

[fla 9]

Dont think timing chains would cause rough running. Is it misfiring or running lumpy? Take the sparks out and look at their colour. Post up up some pics - will.give you a good starting point before spending loads of, perhaps unnecessary, cash!

Also, what error codes have been shown on vcds?

[Macdaddy 10]

Symptoms were refusing to idle as kept cutting out unless you kept your foot on the gas and misfiring.

 

So far I've changed changed the coolant temp sensor, tried a different MAF and coilpack.

 

Scanned and it initially threw a Lambda fault code which didn't come back. The usual cam position fault is the only other thing and that's been checked.

 

We've drained the tank in case of off fuel which it wasn't and a new Lambda fitted.

 

Cars at the garage so I can't get any pics, I'll ring them tomorrow to find what they've done comprehensively.

 

Plugs and leads are certainly no more than perhaps 1500 miles old however it had been sat.

[robrado974 1]

What year is the car ?. As Hasan said , I agree with his comments about the chains and it will cost a lot of dough. Has the ISV been cleaned, all air pipe work vacuum hoses checked for leaks , if an early VR what condition is the dizzy in , late car coil pack .

Edit , just reread post , you have changed the coil pack .

[sexybourbon 0]

This might sound daft but check the two green nipples that are on the brake booster line on the right hand side of the engine , there down near the aux water pump area

[Harrier 1]

The timing chain would only really be an issue if the timing has jumped a tooth or 2

Reasonably easy to check if they know what they are doing ?

[virtuoso23 10]

I would note, mine sounded like a tractor for around 200-300 miles before eventual timing death.

 

Might be unrelated but who knows.

[vw rule 19]

Yes as above possibly vacuum leak somewhere,

also have the fuel pressure checked just in case. Also the fuel pressure regulator when they fail, the car normally won't start up at all, but if it does it'll run like a bag of poor.

 

Timing chains do stretch over time especially over 100,000 miles, the engine will sound like a bag of nails when you go on & off the throttle, on a well used warn engine like that those chains could be 1/2 a tooth or close to 3/4 of a tooth out, but for most cars it'll still run.

 

But for an engine to run rough the sprockets would have to be close to 1-1/2 to 2 teeth out as mentioned above by Harrier.

 

I'd firstly get the engine timed up and check everything is in alinement, because to get the timing chains replaced your looking at £1200 if not more depending who does it.

Also get a compression test done on all six cylinders, and like I say get the fuel pressure checked.

 

Crank sensor normally tells the coil pack when to fire.

 

Cam sensor normally tells the injectors when to fire.

 

You've mentioned that the Lambda sensor has been replaced, also the coolant temp switch, air flow sensor and coil pack.

 

Could be a wiring fault somewhere or fault with the ECU, but you'd normally have a fault or error code for that.

 

Si

[Macdaddy 10]

Thanks all, waiting a call back so I can ask what they've actually checked up to now.

 

I'm dubious about it being the chain.

[Dox 22]

Blocked cat or exhaust from remnants from the cat?

[Macdaddy 10]

Blocked cat or exhaust from remnants from the cat?

 

It's got a decat, worth a mention re objects in the exhaust though.

[Macdaddy 10]

Just as an update, after some fault finding back at home as the garage were claiming a £4500 engine rebuild it turned out the MAF I’d replaced was also faulty.

 

Now runs better than it has in years!

[Keyo 47]

Was it a JP MAF that was faulty?

[Macdaddy 10]

Refurbished BOSCH, apparently....

[Keyo 47]

Is it a VR you own and which brand did you fit?

 

Thanks

[Macdaddy 10]

Yes it’s a VR, ordered the “TwoWinds” from Amazon.

 

It was about £69 and seems ok for the money