Hello i just want to poke peoples brains about fuel trims!

Now at motorway cruise my LTFT is around -6% and STFT is around 0% (seems ok?)

As soon as I pull up to a idle my STFT plummets to -17% and my LTFT drop to -12%

Can you guys tell me if i could have a problem? The MAP is reading good, as is the coolant temp and intake temp, although my intake temp does reach 60deg at idle as the car is ap1 with the sensor in the intake manifold.

My car did run lean at a rolling road so I dont really want the LTFT leaning out at WOT.

Thanks Rob

 

I personally think that is fairly normal to see, the reason it is leaning out on the trims is because the ecm feels that the car is running rich. I have not been able to check my fuel trims on this car but seeing them leaned out is not abnormal.

What were your air-fuel readings on the rolling road (dyno) ?, that would be helpful to know if you obtained that info.

 

Ok thanks Jfusion. Here is my AFR, he did say they may seem alittle off due to the tail pipe sniffer



Here is injector duty to

 

yeah they do seem very lean from 3500-7500, particularly since our cars tend to run overly rich. Many tail pipe sniffers just aren't that good at measuring air fuel ratios as you are measuring them too far away from the motor and after-catalytic converters. I'd say it is more machine error but hard to say for sure.

 

Ok thank you, i may buy a AFR gear to moniter from the de-cat pipe.

I had some lean run issues when the tech had to stop the run half way though. Here is my topic if you get chance to have a look that would be great!

https://www.s2ki.com/s2000/topic/989...#entry22140334

 

I don't know if this is your issue or not but I would check your valve clearance.

what other symptom do you have?

how does your map reading at idle? if you have a way to post it up, it would help to determine your issue.

 

I have recently adjusted my valves. All to the tight side of the spec if you think that could have a effect?

I will take a photo of my map readings at idle and post tomorrow. Let me know if there's any more info you need!

 

Here are my fuel trims at idle after a motorway run to work


Fuel trims while cruising on the motorway at 70mph

 

i'm not sure if the intake reading is the MAP reading. It is showing kPA which is vacuum. If that is the case then your map reading is normal. So its something else.

did you get any CEL light? Running the rich in LTFT and STFT, if you go up to -25, it will pop up a CEL of a PO172.

if your car is a 00-05 then I would clean your IAVC. Another thing would be a leak in your intake manifold possibly...what was the last thing that was done on your car?

 

Yes that is the MAP, at WOT it is like 100 or something. No cel light yet. My car is a 2001.

Here is my engine bay, i have removed and cleaned IAVC (i think thats what i cleaned, ill check) fitted K&N, new radiator, adjusted valves, refurbished valve cover, spark plugs, new aux belt, decat and exhaust.

The dyno guy was messing with the TPS because the car was playing up running lean when hot on the dyno?! Could it need setting lower than 6.3% at idle?