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Misfiring Vauxhall Astra - Al860

My 2001 Astra has been misfiring on cylinder 3 intermittantly for a while now. I have taken the car to a vauxhall garage who connected it to a tech 2 plus whatever else they felt like doing before advising me that the cylinder head was probably coked up and a head off decoke was required. I later took it to an independant garage for a decoke quote who told me that it didn't need one the problem lies elsewhere.

Since then I have change the spark plugs, HT leads and used numerous tankfulls of redex and the like, cleaned the injector inlet using injector cleaner, poured redex into the cylinder and leaving it for a whilst. After all of this the car is running better but still has an intermittant misfire on cylinder 3. The car is producing fault codes 300 (multiple cylinder misfire) and 303 (cylinder 3 misfire) but not all the time, it has also thrown up a 136 fault code (O2 sensor) since cleaning the cylinder with redex but I think that may be because the exhaust still had some in it..

The possible solutions that I can think of are:
1. Remove the cylinder head and give it a good cleaning.
2. Remove the injector and give it a good clean.
3. Something electrical.

Some question I have are:
1. If I remove the injector or cylinder head would the car need attaching to a tech 2?
2. Is there a lot of grief involved in removing & refitting the cylinder head?

Also if anyone has any hints or advice it would be much appreciated.

Many Thanks

Misfiring Vauxhall Astra - bell boy
and a compression test shows?
Misfiring Vauxhall Astra - elekie&a/c doctor
before you do any major strip down ,I would suggest an engine oil flush and refil with a good quality fully synthetic oil. (use the GM oil).I have seen a lot of Astras with erratic misfires/running faults cured by this procedure.hth
Misfiring Vauxhall Astra - yorkiebar
I think the engine strip down is a real red herring at this stage.

Compression test first?

Misfiring Vauxhall Astra - antuk
i have/had a simlar problem with my vauxhall carlton .
after spending a small fortune trying different various parts it turned out to be the amplifier a little black box just behind the coil 5 pounds from a local breaker try this it might cure it it might not but at a fiver its no lose if it dont .
Misfiring Vauxhall Astra - Number_Cruncher
>>a little black box just behind the coil

Glad to hear that your problem has been fixed. Well done for finding one for a fiver - I dread to think how much they are from a Vauxhall garage!

However, Astras since about 1992 don't have an external final stage like your Carlton - so, in this case, it can't be that!

Misfiring Vauxhall Astra - Number_Cruncher
I agree with everyone who is saying that you shouldn't rush to get the engine apart. As well as the wise suggestions of a compression test, I would also connect a vacuum gauge to the inlet manifold, and see what it does when the engine misbehaves.

Which size of engine is it? 8v or 16v?

Do you feel the misfires? Under what conditions do they happen?


Misfiring Vauxhall Astra - Dynamic Dave
I'm curious as to how the OP managed to change the HT leads. Could be wrong, but I thought a 2001 Astra had coil packs that connected directly onto the plugs?
Misfiring Vauxhall Astra - yorkiebar
If it has then a suspect coil pack has to be a good suspect?

How good a check did dealer do if so?
Misfiring Vauxhall Astra - Number_Cruncher
I think the 8v engines do have plug leads DD - If I were more on the ball, the existence of plug leads would have answered my 8v or 16v question.

Misfiring Vauxhall Astra - djchewmacca
I've got an 02 reg Astra and I have been having the same problems with it mis-firing. It tends to be fine for the first minute of starting it up and then it loses power, it sometimes stalls when I come to a junction.

I've had mine into a Vauhall dealer 3 times and had the following work done to it... Replaced 4 new spark plugs as they were completely pitted, new coil pack fitted and only recently had my ECU replaced as they assured me that was where all the problems have stemmed from. The car has only been running for 2 weeks and I'm back where I started with it mis-firing. I've contacted the Vauxhall dealer and pretty much gave them a piece of my mind. I've spent close to £900 in the past 3 months trying to get it sorted.

I may have to count my losses and get rid of my car. Unfortunately I still owe £4000 on it.
Misfiring Vauxhall Astra - SpamCan61 {P}
I agree with yorkiebar, the OP's problem sounds like coil pack to me, as the HT leads have already been changed.

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