Running rich - advice please

[The Doc]

Well on sedate driving off boost the cars run lean ,that's how you get good fuel economy and off boost you could see lean figures on the AFR gauge I.e 14.7-1 maybe higher which is not dangerous.........most lads with mapped cars on a cruise can achieve over 35mpg off boost.

 

[grim_d]

Well out today for a run, hard to give it a thrashing close to my unit but here are the plugs after a few quite hard pulls, look ok to me?

Seems to be getting better the more it gets driven, high 11's on idle and less stumbling on startup.

It hasn't done much but idle while I tinkered with it for a while so changed the oil too as it did smell quite badly of fuel.

 

[The Doc]

Perfect

 

[grim_d]

Thanks for all the info and advice doc.

 

[grim_d]

Done about 250 miles since I got it back out, back and forward to work. 30 miles a day.

When I come to a standstill I have AFR's of about 13:1 and It idles fine but then steadily drops down to low 11's, seems unnecessary? I wonder If I have an IACV issue or something.

Oil a bit niffy of fuel but plugs look great, struggling to really stretch it's legs properly.

Would like to have my injectors cleaned and tested if anyone has any recommendations of a place to use?

 

[vss irvine]

Consider a terraclean?

 

[The Doc]

As above

 

[The Doc]

What's your oil tempreture?

 

[grim_d]

I would consider a terraclean, Scott does them doesn't he? It would clear out the air IACV and such wouldn't it?

Oil temp never gets above 90, even with a good bit of boosting, standard gauge and sender.

 

[The Doc]

Yes and good, is this a long time at idle and are you sure the gauge is not 1 point out on the lambada sensor......what have you had to compare the gauge too for calibration?, does the car foul the plugs up?

 

[grim_d]

Yes and good, is this a long time at idle and are you sure the gauge is not 1 point out on the lambada sensor......what have you had to compare the gauge too for calibration?, does the car foul the plugs up?

No huge amounts of idle other than stopping at lights, junctions etc, I can smell fuel if I have the window open when stopped.

I havnt compared the gauge to anything. My only indication of its accuracy is that on cruise it hovers around stoich, just a touch lean, which is about right?

Had the plugs out when I changed the oil and filter last week, looked fine, no fouling on the insulators.

Could a diff 02 sensor play a part?

 

[The Doc]

Depends if the sensor is ok, if it's the correct one, if it is set as closed loop in the ecu.......does it change if the sensor is unplugged and are you aware the ecu uses scatter timing at idle and what is actually means?

 

[grim_d]

Not tried unplugging, will try.

No idea what timing scatter is or how the ecu is tuned. It was done by ed.

 

[The Doc]

To maintain idle at tick over the ecu will advance and retard the timing automatically and adjust the fueling via the lamda sensor (be it only narrow band) hence why you will get the fueling riches up at tick over as it will not always burn completely as some will always not be burnt fully to keep the idle down, cams and loss of velocity thru the engine will also add to this effect and because of over lap you will end up with a rich fueling on the scale to stop the idle being very lumpy due to non completion of burn in the combustion chamber due to there not actually being enough fuel in there.....hence why tick over is set more by ear than by gauges that cannot measure what is actually going on in the combustion chamber.

 

[grim_d]

Unplugged the o2 sensor, made no change at all that I noticed.

Gave the car a good pasting on the way home, oil temperature didn't budge from about 85.

Understand what you are saying about the cams and how it needs to fuel etc but if this is the case then maybe I need to be considering changing the cams and having it mapped because clearly I can't get the oil to a temperature to evaporate the fuel which is only going to end in tears eventually as fuel is definitely getting into the oil.

 

[The Doc]

You might as well just put it all back to standard as a forged engine with cams and a gt30 turbo doesn't suit your needs as a daily driver.......or is it you are worrying needlessly and expecting something that is not going to happen?

 

[grim_d]

It doesn't, the long term plan was always to go with a smaller turbo/mild cams eventually but that's beside the point.

Maybe I am worrying too much but I would say fuel in the oil is a reasonable thing to be concerned about.