pinking has gone after using super unleaded

[Ady]

i decided to check my plugs condition the other day and noticed the ceramic insulator has yellow deposits on all 4 plugs,is this a lean mixture? which is why it's pinking with normal unleaded,i decided to try super unleaded from texaco yesterday and now the pinking has 99.9% gone,so now i'm even more confused,why is the diagnostic not throwing any error codes up when clearly going of the plug condition the car is running lean? why is it running lean? the 1st garage suggested the air flow meter is faulty so tried another one from a breakers and it didn't have no affect,so what else could cause a lean condition?

 

[Tom]

Super has a higher octane which burns slower. Thats why it seems to have sorted your prob. Its nothing to do with mixture.

A lean mix usuaully leaves a glazed plug or a very clean plug. Sometimes you see the nose has burnt away. Dunno about yellow bits though.

 

[Ady]

hmmm

what i can't understand is that the car from new has always ran on norm 95 ron,and now it's gone with super surely indicates air/fuel ratio has gone to pot?

 

[Tom]

Re: hmmm

Nope, pinking can be caused by a lean mix but more usually by over advanced ignition.

Super u/l still requires the same amount of fuel for a correct mix but as it burns slower, the ignition can be more advanced than for normal and it won'r pink.

 

[Ady]

i see

and according to my local garage the ecu on my bravo 1.8hlx does not have the ability to adjust the timing as it's set from the ecu? i wonder of theres a software update for the ecu from fiat?

 

[Tom]

Re: i see

Did they bother checking that the cam and crank sensors are in the right place? Its easy as pie to change the ignition by moving them.

 

[Ady]

no they haven't

they haven't checked,apart from the diagnostic check which showed all sensors passed

 

[Tom]

Re: no they haven't

It could be one of those has slipped, most likely the crank sensor as the cam sensor just tells it which part of the 4 stroke cycle its in.

 

[Ady]

heres some data

i got from the diagnostic he did

errors,
168 drive away protection code not recieved
40 drive away protection unknown code

then he suggested using the spare new key...

131 air mass meter open circuit/earth short

and heres some readings

coolant temp 94c ok
mixture 1.007 ok
lambda switch (mhz) ok
timing (idle no load) 8.0 ca ok
air mass (may 1st+2nd) should be 400 read 350 kg/h
inj pulse 11ms should be 14ms min

going of that i can see why he suggested air flow meter but since trying a good working replacement and then cleaned my original and both attempts had no affect whatsoever,i am pretty sure it's nothing to do with the air mass.ah well i'll continue to use super till i get it sorted.

 

[Tom]

Re: heres some data

Has anyone put a timing light on it? I know its a bit old hat but....

If its pinking and higher octane petrol sorts it is HAS to be ignition. No questions asked. No amount of diagnostics will tell you the sensor is in the right place as it has no way of knowing.