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After winter my car has reseted by itself (battery disconnected) and long term fuel trims both are +20. It takes like couple tanks to draw them down to like +15 and there they stay. I haven't looked in to why. But car works completely fine with no error codes so I have not kept any hurry. I know this is not how it should be.
It seems you went through a quite methodic way of replacing, so I might state the obvious below with a list of components and issues along the intake and firing line. However, for good order of this thread I list them anyway (did I miss one?).
Functioning of most sensors can be checked directly (OBD reader).
Once eliminated those, you should be able to see in the OBD live monitoring what is happening if you replicate the stuttering.
SHARED:
Air filter
Mass Air Flow sensor / Intake Air Temperature (+ connector of MAF)
The 2things I am wondering about till now:
- The very large difference between the LTFT (-7 & -15) and STFT (~ +20), but I have no idea if this is momentary or structural
I am just thinking about an old thread, some years ago.
The guy had crazy fuel trims, also after a mayor rebuilt (I think with engine out).
What happened was that the mechanic crossed the wires from the O2 sensors (I think the upper ones) during re-installation.
It obvious that the Short and Long term trim corrections will fight each other like crazy.
Maybe???
Hello Eric, that ambient temp sensor doesn’t ring a bell... I’ll look into it. all the rest was double checked. About the O2 sensors wires being crossed i thought of it but the wiring is really obvious as the bank 1 loom is much shorter than bank 2. Also, at some point my new right bank o2 failed (after 10k km) and code poped up. I replaced it and code went away. So that means wiring is good. I’ll have the new air filter Wednesday and I’ll do the readings then as if that filter of mine is clogged it might be it. Thank you for picking your brain on my issue !!!!! For now I use my wife’s car as the idle is really bad. It shakes in a scary way. Very annoying.
Hello Eric, that ambient temp sensor doesn’t ring a bell...
I forgot if the x308 has one, temp or pressure, maybe only the S/C on the manifold (too many car types ....)
I can set you up with some basic values of the various sensors, maybe starting at idle.
As mentioned before, I use the Torque Pro app, which is surprisingly handy.
It allows to log a sensor, but I never used that.
Instead, I use gauges which do not only show the live data, but also record the highest and lowest value over a test.
That saves me from continuous looking at the gauge, still helps me with the diagnose afterwards.
You might want to buy a ELM327 if you run an Android phone, they cost hardly anything.
I enclose some screen shots (not connected to car) and the ELM327 dongle.
LAST QUESTION: did the car ever run smooth after rebuild?
Interesting... I’m on IPhone but I’ll see if I can install that. After rebuilt I had other issues but idle was perfect and fuel trims were within the +/- 5%. Issues I had were TB related. I changed the TPS and the air assist control valve and that was it on the engine side. By the way: the air assist valve (also called idle air control valve) turned out to be the same as the one on Toyota Corolla... that’s a valuable info for the next guy as everyone told me it can’t be purchased separately. About the ambient air control: it’s part of the MAF I believe...
I don't think the Torque app works on an IPhone, and you will need an other type of dongle (EML works through wifi, I think IPhone works through Bluetooth).
I am sure there are apps available which do the kind of same, give live values plus maximums.
I turned on the car today to check something I haven’t checked before: smell from the exhaust fumes. It turns out I have a strong smell from the RH side. So that right bank rich condition might be related to that. I cleaned both catalytic converters a couple of month ago so I’m guessing the right cat might be failing. Plain and simple. That would explain all right?
I know that copious amounts of fuel can kill/melt a catalytic converter. For example, a customer came in with a engine misfire and they drove it for a month or better until they could bring it in. No surprise that after we fixed the misfire and they came back a few days later for another check engine light on that a catalytic converter efficiency code was set. Maybe this is what happened to your cats?
To clean the cat you remove the upstream O2 sensor and inject foam. It's a special foam to clean catalytic converters. Ideal is to inject little by little to ensure it really reaches the bottom of the honeycomb. That's it !!! Then you drive to heat it up.
Hello all, I haven' reported back for a while... So: what I did is install a new cat on the right bank. What a difference it made !!! Finally smooth idle and better acceleration. I fitted a BM catalysts. Perfect fit. So I'll change the other side right away so both are identical. As a result P0420 vanished but I now have a P1646 code. To see if it's the sensor or the loom and inverted with bank 2. It resulted in a P1647. So Sensor is good and issue must be on the loom. I checked the wires very carefully: nothing. I unplugged the ECM and cleaned the connector (that were bright as new) and changed the relay related to O2 sensors. It did nothing.... P1646 is still here right when I start. Any ideas? That bad wiring must be what ruined my original cat at first... When I check the OBD reading I see B1S1 amperage remains still. While B2S1 amperage is alive.
Humm oki: I’ll fit in a new one and see what happens. The current one is only 1 year old but it makes sense it was toasted by the clogged converter… Chain of events
