Rough Running is driving me mad !

[TheCod]

Ok, have had a problem for a little while now and its starting to drive me mad £1100 later and still not fixed....
The problem is when starting up the S2 whether the engine is hot or cold it struggles to start and sounds like it is running on 3 cylinders, I have changed Plugs, Leads, Distributor cap and arm, all temp sensors, and still no joy.


Am now at a loss when its up and running it purrs like a kitten and goes like stink,,, anyone any idea what causes bad starting on these, would it be crank case sensore related?? ??

Any Help appreciated.

Steve

[andyg plym]

maf?

[TheCod]

maf?

Good point, but wouldnt iit run rough all the time not just when starting up ??

[Jamo]

could be the hall sensor in the dizzy itself

[220bhp]

Sounds as if it could be head gasket starting to fail,or head corrosion/crack.
Coolant enters one or more cylinders when engine is turned of and contaminates plug.
When you start up the engine it wont fire on all five until the moisture clears,then it runs on all five with no problem. BTDT

[TheCod]

Starting still an issue

Ok, have had a problem for a little while now and its starting to drive me mad £1100 later and still not fixed....
The problem is when starting up the S2 whether the engine is hot or cold it struggles to start and sounds like it is running on 3 cylinders, I have changed Plugs, Leads, Distributor cap and arm, all temp sensors, and still no joy.


Am now at a loss when its up and running it purrs like a kitten and goes like stink,,, anyone any idea what causes bad starting on these, would it be crank case sensore related?? ??

Any Help appreciated.


Steve

still having the starting problem, if it does not start on the first turn of the key, then it will not start for about 20 - 30 mins,, it stinks of petrol if you miss getting it started on the first turn.

Could it be overfuelling causing it to choke and make it reluctant to start, What sensors/units control petrol flow to the injector rail,,, ???


Any help appreciated

Steve

[spink]

as always 1st thing to do is check the codes,good chance it will tell you straight off what the issue is

[TheCod]

as always 1st thing to do is check the codes,good chance it will tell you straight off what the issue is

O yes forgot to say had codes read and matey at the garage diagnosed as defective water sensor down on the back of the block, he changed all three X1 big and pricey and another 2 a bit cheaper were also changed.

[spink]

O yes forgot to say had codes read and matey at the garage diagnosed as defective water sensor down on the back of the block, he changed all three X1 big and pricey and another 2 a bit cheaper were also changed.

ok so have the codes gone now? (were they cleared?)

[TheCod]

yes all codes are now gone,,,

steve

[Rusty]

When you say it doesn't start, does this mean that it'll turn over for 10 mins without firing or that it coughs and splutters and tries to fire but can't?

If it's the former then it's the crank or cam position sensors or wiring -BTDT, as have most long time S2 owners.

MAF will somtimes throw a code for mixture adaptation if it's knackered - I've jsut replaced mine because of this. Won't tick over very well but runs pretty much OK, if a little rough when coming on boost.

Replacing sensors left right and centre is not the way to do things really, unless you have deep pockets, better off connecting it to VAG com and working out what's wrong.

Head gasket sounds feasible, the plugs might highlight that one (colour / oil etc.)

At least when it's all working, it'll all be new

Has it got the correct injectors and chip in it?

[TheCod]

When you say it doesn't start, does this mean that it'll turn over for 10 mins without firing or that it coughs and splutters and tries to fire but can't?

If it's the former then it's the crank or cam position sensors or wiring -BTDT, as have most long time S2 owners.

MAF will somtimes throw a code for mixture adaptation if it's knackered - I've jsut replaced mine because of this. Won't tick over very well but runs pretty much OK, if a little rough when coming on boost.

Replacing sensors left right and centre is not the way to do things really, unless you have deep pockets, better off connecting it to VAG com and working out what's wrong.

Head gasket sounds feasible, the plugs might highlight that one (colour / oil etc.)

At least when it's all working, it'll all be new

Has it got the correct injectors and chip in it?

Thanks for your response, the car is factory fresh and apart from sound system and is un modified, when turning the car over it tries to start but doesnt quite make it, when it does eventually start it appears to be running on 3 cylinders and need the throttle dipping to get it to run on all 5..

Steve

[Rusty]

Right, unlikely to be the cam/crank sensors then.

On an ABY I'd suggest looking at the ignition modulels at the back of the engine bay but the 3B has a coil

Any smoke when you start the enigne, blue/white etc.? That would indicate something being in the cylinder / exhaust when it was started.

The flooding is a strange one. It indicates that there's no spark so I'd stick with that area for now. I'd pull the plugs and see what state they're in, any rust or oil and it's looking more like HG, stem seals, rings etc. A compression test is a good way to go to test these.

Just throwing ideas about as, without seeing the car, it's difficult to get the whole picture.

[S2central.net]

Go back to basics...

Step 1 - compression test from cold - unplug the camshaft sensor and cold crank each cylinder with the throttle wide open... look to see what range of values you get across all 5 cylinders... cheap and cheerful compresion testers can be easily acquired

[TheCod]

Right, unlikely to be the cam/crank sensors then.

On an ABY I'd suggest looking at the ignition modulels at the back of the engine bay but the 3B has a coil

Any smoke when you start the enigne, blue/white etc.? That would indicate something being in the cylinder / exhaust when it was started.

The flooding is a strange one. It indicates that there's no spark so I'd stick with that area for now. I'd pull the plugs and see what state they're in, any rust or oil and it's looking more like HG, stem seals, rings etc. A compression test is a good way to go to test these.

Just throwing ideas about as, without seeing the car, it's difficult to get the whole picture.

Dont think i have said before but the engine is a 3B, there is some white smoke but it clears after a few mins, just by chance i took of the expansion tank cap and there is a petrol like smell when you sniff it..... smells expensive !!!

Steve