Slightly warm exhaust on VX

[John Clements]

Hi everyone. Advice needed.

Travelling home after a brief outing ysterday my VX 2L injection suffered loss of power and began running very rough, to the extent that I had to pull over. On inspection the whole of the exhaust silencer unit was glowing bright red, with a 4 inch flame blowing from the pipe. Needless to say I could go no further and finished the journey hitched to the back of an AA van.

Having checked the distributor unit there were two good sparks and two weak, could this unit be at the root of the problem?

The car is a standard 1994 HPC with the original exhaust system complete with CAT.

Any advise as to where to start would be greatly appreciated. ☹️

[Bricol]

Failure of catalyst?

 

Had Mundano start to run rough, no power, inability to pull ant decent revs under load - catalyst had failed, blocking exhaust - which choked engine.

 

 

Bri

[stevefoster]

I had cat failure on our Daewoo. It had been rattling for a while. The latter half rattled loose, turned and blocked the exhaust gas outlet. The water temp climbed a bit and the engine would not pull and missfired. Pushing on at this state would have resulted in melted pistons or valves...

Thankfully the VX based lump in the car is fairy hardy.

I took the cat off (we were on hols in Sweden at the time) and broke up the duff cat bit and shook it out. It is still running on the other half of the cat and

passed the emissions.

 

Did the VX HPC have a cat? My 1997 carb HPC version obviously doesn't!

If no cat then I would investigate failure in the injectors or a mad ECU...

 

/Steve

 

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Hants (North) and Berkshire area club site

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Edited by - stevefoster on 10 Nov 2002 18:22:34

[John Clements]

Thanks for the replies, sounds like my first port of call is to get the catalytic converter tested, is there any way of doing this without having the car towed to a garage. It's not drivable. Or can anybody recommend anybody in the Ashford, Kent area who could have a look?

[John Howe]

John, if you have two weak sparks and two good ones... could it be that the weak sparks are sufficently feeble that they cannot fire two of your cylinders. Thus you will have only half your normal power with 50% of your fuel failing to ignite and will end up in the Cat. to be cooked and could the cooking of this unused fuel be the reason for flames and red hue?

 

JH

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[John Clements]

Thanks John,

 

Yes, this does sound quite likely. Not being particularly technical, where do you suggest I start the evaluation? My first thought was to change the distributor unit which I think costs around £50. Alternatively, get the car towed to a garage with the relevant testing gear, the local Vauxhall dealer for example.

I can change the distributor, or lump that replaces the distributor on a VX injection (not sure of the correct name for it), so maybe I should do that first.

 

Cheers,

[stevefoster]

You will have a crank sensor near the alternator and a coil pack at the upper rear of the engine that the plug leads come out off. All these things are pretty expensive so testing would be the best option.

 

Take the spark plug cover off and check the plug leads and most probably the crank sensor lead is run along that cover too. I removed my crank sensor lead as it got interfered with by the

sparks... this won't be your problem.

 

So you are sure you have a cat then? Do you normally have an emissions test?

If you have a kit car of before 1998 or so then you do not need an emissons test. Many MOT places do not know this...

 

whereabouts are you? I have a spare coil pack and leads sitting in my garage...

 

/Steve

 

My racing pics, 7 DIY, race prep. Updated often here

Hants (North) and Berkshire area club site

here

 

[StewartG]

Two good sparks and two weak ones leads me to ask if you have a distributor or a wasted spark system. With the wasted spark you get two coils and no conventional distributor. My eyebrows are also raised at a CAT on a 94 car.

 

Edited by - stewartg on 11 Nov 2002 08:30:32

[John Clements]

Steve

 

Yes, I am pretty sure that I have a Cat. I had an emissions test at the last MOT, carried out by a local garage. The exhaust unit has a welded seam approx 1/3 of the way along, as I understand it, this front section is where the Cat lives. I am in Ashford, Kent. Not exactly round the corner.

 

Stewart, It has the coil pack at the upper rear of the engine.

 

Cheers, John

[rjc]

If your VX is an injection - i.e. fuel injection then it is most likely to have a twin coil wasted spark ignition where the spark signals are generated by the engine management ECU. If you have dropped out one signal then only two cylinders fire and indeed the car is undrivable.

 

I lost ignition in this way and I needed a complete new ECU unit in the end. Is your car fitted with an engine management ECU unit ?. If so you may well end up having to get this checked out. That's a performance car specialist or the Vauxhall main dealer if its the original Vauxhall fuel injection system. Look for any markings on the box. The options for a fix depend on what type of system is fitted.

 

 

[16vastra]

i dont know the coilpack setup (far to modern for me ) but if you are still having problems (definately sounds like the pack tho as it fires in pairs) ask on www.migweb.co.uk as there are a few who do know it inside and out. they are not cheap to replace, but give autovaux a ring for cheaper than dealer prices on gm parts - www.autovaux.co.uk

[EFA]

John,

 

What John Howe has described is the true symtom.

 

Your car uses wasted spark and does have a cat.

 

The Bosch Motronic injection/ignition in your car is prone to ECU failures and is also prone to odd problems related to HT discharge. Check the ignition leads (if you need a spare set I have some you may borrow and I am only just over the Kent/W.Sussex border) and also change the spark plugs for new. The Motronic systems are known for trying to shut down half the coil pack when there is bad HT on one side.

 

I also have spare sensors etc if you need to use them to diagnose.

 

Finally, remove the crank sensor and check the disc it picks up on has not loosened on the crank - if it has it'll wobble in the front to back plane when you poke your finger in the hole. Crank sensor is under #4 exhasut primary.

 

Fat Arn

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[John Clements]

Thanks all of you who have replied so far, it's the first time that I have posted a question on the forum and I have to say the response has been great.

 

Having taken all of this on board, I think I will start with the HT leads and plugs and eliminate these first. The plugs are however fairly new as the car was serviced by Redline only about 800 miles ago and they did replace them.

 

If that's not successful, I will have a chat with the local Vauxhall dealer. the last time I had a problem (dirty mass air flow sensor), they were happy to diagnose with the Tech 1 system for no charge. That way I will hopefully be able to find out which more expensive component has failed. Maybe they will send out somebody with a hand held unit.

 

Arnie, If I could borrow the leads etc for an evening that would be great, I just need to know where to get them from. I will be at the club meeting at the Ringlestone arms tomorrow evening and I could always go the long way round to pick up first. You can e-mail me with details if it's convenient.

 

Thanks again

John C