Hi,

Still trying to find my fault here so today I had a look at the spark plugs and generally they are clogged up with white deposits and on one the gap was not even visible. Should replacing these be my first port of call. I understand that the white deposit can be caused by a bad fuel mix so coul that then follow on to lead to the MAF and/or Lambda sensor.

Also the wells we pretty clear, a tiny bit of oil in one and two but only a drip.

After swapping the plugs around the car really struggled to start

I just don't want to throw money at parts that I may not need so was really looking for some expert advice on what my first port of call should be. Plugs a good start? Could they be the first culprit

Thanks

 

Still got P0300 and P0301, if it was a MAF or Lambda sensor problem wouldn't all cylinders be effected.. I.e. Get the P0302, P 0303 and P0304?

Thanks
Alli

 

From the condition of your plugs it seem that they will need to be replaced befor you can confirm the diagnosis.

White plugs would indicate a lean mixture so once you've changed the plugs, try the following one at a time:

If you're using something like Multiecuscan, look at a plot of the lambda voltages, a good sensor should look something like this: Fuel contamination problem in South East England - Silicone coating Oxygen Sensors :: Gendan Automotive Products

Disconnect the wireing from the MAF, the car may stall at idle and you will get the engine management light on but if it drives better then this would indicate a faulty MAF.

Check for air leaks between MAF and throttle body.

If P0301 comes back, swap coil pack to another cylinder and see if fault moves with it.

Good luck!

 

From the condition of your plugs it seem that they will need to be replaced befor you can confirm the diagnosis. White plugs would indicate a lean mixture so once you've changed the plugs, try the following one at a time: If you're using something like Multiecuscan, look at a plot of the lambda voltages, a good sensor should look something like this: Fuel contamination problem in South East England - Silicone coating Oxygen Sensors :: Gendan Automotive Products Disconnect the wireing from the MAF, the car may stall at idle and you will get the engine management light on but if it drives better then this would indicate a faulty MAF. Check for air leaks between MAF and throttle body. If P0301 comes back, swap coil pack to another cylinder and see if fault moves with it. Good luck!

How to swap coil if alfa 159 coil comes one line coil built in.??

 

Cheers, that's a great help, I'll order some plugs and take it from there. I'll report back soon. And yes using multiscan so will have a look at the links you posted.

Cheers
Alli

 

OK - Finally got a chance to have a look at the car - replaced all 8 spark plugs with ngk - Still got the issue and same fault codes.

Have looked at the lambda 1st sensor pre cat but wasn't sure on whether i should just be idle or revving. Attached is the voltage reading while idle. Bit hard to see what voltage that is at and i snapped the laptop charger.. doh, so will have to fix that and try to get a better image tomorrow if i can.

Should i just be taking the reading while idle??

Also i swapped coils over and still get the exact same faults. P0300 and P0301 so can rule out coil pack.

Cheers

 

Ok - fixed the laptop cable and got a much better screenshot of the graph.

This was while idle and the car was warm (running for a good 10-15mins). It doesnt look as neat as the example so does this look like it could be faulty?

Also the status of the Lambda was open loop?

Another observation is that the idle doesnt wander - its is around and just below the 1000rpm which is where its always sat - but its just real lumpy and bumpy.

Any ideas on the lambda graph would be great - Cheers

 

OK - Just been for a Spin with MAF unplugged.

I cleared the P0300/P0301 faults first - then unplugged MAF and went for a drive.

I suppose it felt better but as the problem is with pulling away 1000-2000rpm i guess with the MAF unplugged you get that hesitation anyhow...but

..after reading the codes again once i returned i only get P0100 (MAF) and P0110 (AIR TEMP SENSOR) NOT the misfiring P0300/P0301 Codes!

So, does that mean that the MAF is causing the Misfire codes and therefore its not working properly???

 

With the MAF unplugged, you will get P0100 and P0110, your Lambda graph does look a bit grim, certainly not what I'd expect from a good one.

 

I'm having the same issues with 2.0 GTV I hope someone come up with the answer...

 

Yeah those were the faults i got - but the P0300 and P0301 faults did not occur with MAF unplugged on a 10 min drive up and down the dual carriageway, and do occur again as soon as MAF is Plugged in??? So is the MAF causing the misfire faults and therefore is it buggered.

When i first read the codes after the initial problem back on NYE there was a MAF fault code stored and the P0300 and P0301 were 'light on - fatal' as they are now with MAF connected

Also i will run the car a bit longer tonight until Lambda goes to Closed loop and then look at the graph as i understand that will give a true reading.

 

The fact that the fault codes failed to occur when the MAF was unplugged would strongly suggest that's where the fault is.

 

Cool - that's what i was thinking - ill check the Lambda again tonight anyhow once it goes closed loop so then i can cancel that out for sure.

 

I would have thought you wont get those codes as the engine is running on A default map and not using the lambda

 

So as the default map is adding default values and the misfires are not occuring the problem is likely bad readings from either lambda or MAF which is in turn causing the misfires?

So... if i can eliminate the Lambda - see new graph attached once it was closed loop which looks much more like the healthy example in an earlier post...

... And that with the MAF unplugged it runs so much better and doesn't return the P0300/P0301 codes..

...Can i think that the MAF is giving bad readings thats causing the problem??

If it was an injector problem wouldn't that still occur with and without MAF and bring up the P0300/P0301 codes that seem to be the problem??

 

That is a bad graph.
Should be well defined troughs and peaks.
Read here
Lambda sensors / exhaust oxygen sensors

As to the P0300/P0301 codes, try swapping no1 cylinder coil pack to another cylinder and see if the code changes to P030* depending on which cylinder you moved it to.
If it moves, thats your problem. Coil pack breaking down

 

I already swapped coils from 1 to 2 and the error hasn't jumped so figured I can rule out coils. If without MAF things are better, what's that telling me? MAF is bad... Lambda coils also be bad as it's not using data from that?

 

OK - after not having time to do anything for a while i have defiantly found that cylinder 1 is not working. Simple test of pulling off the coil pack wire connection with engine running and nothing happens (engine drops when other cylinders connections are pulled)... Also have tested wire with volt meter and i think there is power there - had a mechanic have a look but was a bit tricky to get a reading - but he seemed confident power was there... Anyone got advice on double checking the voltage - and what reading i should get. (the mechanics just made a small as possible hole in the wire insulation tubing and then took a reading - is this the normal way.

Also - i take it my next step is a compression test on Cylinder one or is there anything else that i can look at before that?

Cheers
Alli

 

Compression Test

Is £35 to get a mechanic to come do a compression test worth it...

or should i buy a tester from screwfix for £20 and do it myself?

Is the £35 worth it for the bit of (hopefully) expert advice he may be able give me on the readings, as for a DIY'er who is comfortable knee deep in alfa... this starting to get up to my goolies...

If i did it my self...
- Do i just test on the 14mm spark of each cylinder leaving the 10mm in place.
- And is the trick of squirting a bit of oil in and retesting the done thing to indicate worn pistons/rings if the pressure is higher?

Thanks for your advice