03-02-2016, 01:16 PM
(03-01-2016, 11:10 PM)fixkick Wrote: welcome bad from road trip..
-25% means the ECU is removing 25% fuel from a gross over rich mixture.
if it misfires, at all at idle, this sends, excess oxygen air slugs to the exhaust ports, and 02 sees that as lean , oxy lean. and goes huge Plus percent to correct it.
same with exhaust leaks near 02. huge oxy (air 20%) land there and huge + percent LTFT.
so what on earth causes -25%
too high fuel pressure tops my list
leaking injectors. (1 or more)
MAF stuck high,(but under the DTC error stuck high point, nah)
not clogged injectors as LTFT goes +25% to compensate.
its nice having scan tool data, no?
see whats going on with fuel trim... is a very good thing.
so you have zero DTC errors.
Yes so another day driving home from work I monitored some PIDs.
Today it started running properly much more quickly than the previous trip. Idle still started out shaky but it started running fine almost as soon as it warmed up. No DTCs present. STFT and LTFT were both a lot more normal today (0-6%).
I didn't change anything from yesterday to today. When I parked it, it was running perfectly normal. Strange beast this is. I considered a leaking injector, but that wouldn't fix itself after 20min of driving. Brand new FPR although I haven't actually put a gauge on it. I'm going to continue driving it and see if the problem continues to clear up (wouldn't that be nice).
I'm trying to think of what would cause horrible idle when cold with hesitation, and wouldn't cause a problem when warm. Dark and rainy out tonight so I'm not pulling the plugs just yet, but I will do it sometime this week. I still have my suspicions about the EGR valve aybe sometime being sticky. That should make it read lean, but maybe when it misfires, the raw fuel gets dumped and burned one the next ignition event (in the exhaust manifold). Possible?
I really need to get a proper datalogging software so I can datalog when it's running weird.