Checked for leaks first thing all manifolds are tight did the old intake mani carb cleaner test too nothing obvious. No audible leaks from exhaust got under the trucks wheel well with tire off to check.
Maf reading is about 7 grams per min at idle...
So the fuel trims being 5-7% different is ok?
Will check fuel pressure but I can't imagine one bank being lean and not the other if that's the case.
Also would point out it runs smooth....gas mileage is spot on.....
Im starting to lean towards bad ecm if this continues...but I need more info on the sensor. If the voltages are within spec at idle, then the ECM should not be throwing a code, and seeing a lower voltage.
You can pretty much forget what's happening at idle. The ecu is seeing the a/f go out of range for a pre-determined length of time, probably as you drive. The voltage for this type of sensor can go well above one 1 volt, but somewhere around .5 is ideal.
My truck routinely runs about .45 for B1 and .80 for B2. The fuel trims also reflect that, but I have no code or leaks.
Did the maf reset then ecu reset per the manual...
At idle vs driving at 50mph there is not that much difference in the voltage readings per 0bd2
Where is the ECU getting its voltage reading for the scanner though? 4 signal wires all hanging out around 2-3 volts. Its NOT data, its voltage, but which wire? And how does that translate to .29v? The ECU must take the information from all 4, then make up its voltage we see on the obd2. if I knew the formula its using to calculate the A/F from this sensor then I can a least rule out the ECU being the problem.
I just want to see if what is seeing actually is accurate per the sensor.
Good ol 4 wire o2 sensors are easy, one signal wire.
Did do a reset last night, I must of did something out of sequence because it was misfiring afterwards on cyl 3...reset again and it cleared up.
still have 2 more tests to do...
fuel pressure and im going to rig up a pressure tester for the intake mani. After that im stumped.
I love the OBD1 on my 3000gt, I can turn off injectors individually, etc, makes troubleshooting a snap. Too damn many sensors and chicken dances on modern vehicles
At this point if it continues I may just have to get a waiver for emissions. Any repairs that are over $450 to get it to pass we get a 2 year waiver if we cant solve it.
How about freeze frame data.
U coukd use uprev to record fuel trims while driving to see if it jumps out of range. Ecu is unlikely. Have you reset kam .
Reset kam? Sorry enlighten me what that is abbreviated for
I realized after this post that the fronts are wideband sensors so voltage readings are pretty much useless at the sensor. However I could probably hook up my AUTOMETER wideband gauge to it from my car to it since it's the same sensor and see what the actual schitz ratio is.
Getting a p1148 code now after doing the maf reset and relearn last night. Closed loop malfunction
Kam = keep alive memory.
Basically it is a resetable memory that can be cleared after a repair is done.
You may be able to disconect battery. Touch both cables together for a minute. Sone cars kam must be cleared with a scanner. Im actually a ford master tech (or was a few years ago) nissans are not really my specialty. I will research this product and chime in .
Plus one to a bad electrical connection . Loose pin in a harness. Sonewhere?
I'm pretty sure it's the maf...I had a shop check it out too and it seems to be getting leaned out regardless of what the sensor sees...and the maf was dirty prior to all of this. It's clean now but they noted that it's giving an airflow reading when it's off.
I didn't know it had multiple airflow sensors I'm used to dealing with single wire maf sensors......
2nd maf no change. I'm gonna pull off the intake manifold and replace the gaskets and clean it out really good. I bet we have a small air leak somewhere. If that doesn't fix it then it has to be a fuel issue. Wish I had a smoker
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