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[bigpaul]

Hi guys sorry work has kept me busy this week so first chance to get here was today.

Light seems to come on rough estimate every 7 days.

I have just re-set again thanks as always Entwood

so maybe a more accurate eye on the situation is called for so re-set at 09.30 on Saturday 26th November.

She ran a bit rough to begin with interesting enough the decoder that Entwood gave me clearly states on re-set that this is likely to happen as everything adjusts itself obviously this is in laymans terms cos im thick 

My friend the spanner man was interested that it seemed to take 7 days before the light came on again and suggested i put it to you guys the professionals as he is not an Omega man.

I may work alot of hours but the price of replacing this MAF is a little rich for me the cheaper ones that I have seen ie not Bosch will they still be up for the job I wonder ?

Your thoughts guys as always much appreciated

[bigpaul]

so now a further development  started her up at 10.55 to see how she was running like a pig gets it said

sat there for a while then on comes the light again.

Got out the trusty decoder expecting the same as usual but no

statement is  "random misfire" series of codes 300

not sure what to do gone out on a limb and re-set again but not convinced its doing the car any good will report back if anything else occurs

[feeutfo]

Fit Entwoods Maf to confirm.

If he doesnt mind of course.

[bigpaul]

ok hopefully he will see these posts and add comment

[feeutfo]

It's a two minute job tbh. Sorry E

[bigpaul]

New update 12.15 start her up again yes running like a pig again

Walk away to get a coffee come back running like a pig orange manaement light back on even uneducated me can hear the misfires.

Try to run her around the car park at work but limited space as Entwood knows

Shes going nowhere fast no power chug chug chug

ok little bit of rev well alot actually and i hear her come back to me and she becomes responsive off we go

Take a risk run her up the road she settles down misfires stop orange light goes out

What the hell is happening now ??

Going to have a bite to it then start her up again

[Lazydocker]

You need to check the plug wells for oil/water... It sounds like there is more than one issue here

[bigpaul]

ok the trouble is why has this other problem just recently occurred this morning just after th re-set its far too much of a coincidence for me 

She has never run this bad and now after starting her up yet again 12.50 hes runs like a pig this time management light flashes as i driver her around the car park this then stops engine starts running normally

I parked her up and left her on tick over for 5 minutes no problem at all

Seems this re-set has done her no favours at all you think ?

[Andy H]

What is happening is that your ECU is being fed duff readings.

Immediately after you reset the trims the ECU uses duff readings to produce duff results (result being it runs like a bag of spanners)

The ECU is smart though. Once the engine is warmed up and the ECU is running 'closed loop' it looks at the lambda readings to check that the air/fuel mixture is correct. If the mixture isn't right then the ECU makes changes to the trims to compensate.

If the numbers in the fuel trims get too big then the ECU is programmed to flag up a fault to tell you that it is being fed duff information. That was taking 7 days but is now taking less time which points to the problem getting worse.

The good news is that if the duff information is getting worse then it should be easier to recognise the faulty component using the live data 

[bigpaul]

Update 13.35 fired her up straight into normal tick over running smooth so maybe shes had a word with herself.

not sure that the problem is getting worse as the management light came an hour later after the re-set for the random misfires codes not the fuel trim

once the engine started running smooth the light went off so I believe that the second group of misfire codes were created by the original reset this morning.

That being said she took a long time to sort herself maybe its because shes old like me it often takes me ages to get things to work 

[Andy H]

Oops, reread the thread after I posted and realised that you hadn't said it was getting worse

I think it is running OK now because it has changed the trims a little (or maybe a lot).

Agree that the warning light was because of the misfire codes.

I do think that the problem is sensor related and that the ECU is applying more and more trim in an attempt to compensate until it eventually gives up and brings on the warning light.

(that said.. I made my earlier comment about spark plugs because a misfire results in air and unburned fuel disappearing down the exhaust. The lambda sensors are only measuring oxygen (they can't measure unburned fuel) so the ECU would think the mixture was too lean. I don't know if the ECU would try to change the trims (it shouldn't if it already knows about a misfire) but I imagine an intermittent misfire could cause some odd trims)

[bigpaul]

I think you definately have something there the more you listen the more you hear and there does seem to be something going on like she isnt running quite right almost a little hiccup going on from time to time if that makes sense.

[bigpaul]

can you believe it 26th December the light came back on so it was off officially for now thats close on a month it was off for makes no sense so now the trials and tribulations start again ? 

My spanner spoke spoke to a guy he knows who owns a local garage his statement was the decoder I have is a handy DIY bit of kit but constant re-setting will cause the car to shut down altogether 

To be honest not sure if thats the case but worried about doing it again in case he is right seems to be so many conflicting opinions over the potential cause