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And is also the same (not all but quite a few) for the TPS electrical connector.
I would certainly replace the MAF connector and short harness. The question rises if the harness is failing right at the MAF or where it joins with the rest of the main harness under the valve cover. Think about how many times we’ve had our intake pipes off either for access to something else or just checking the air filter.
My XJR row does the same too. But this car does not have CEl on ever. My long term trims arent -20% when engine is hot. But when cold, they are. Car is German model so it does not have map or fuel pressure sensor. It would be nice to measure pressure. Just before I drove the car to the garage for the winter. I looked in to the trims. At highway speeds long terms were -12% and -9%. At that load cell. Those wil vary as we know. Shorts were good always. So the ecm has found the sweet spot. I would have sent injetors to be serviced. But that job is not so nice..
Sometimes, mine will stumble at low rpm's. And when it does, it always throws the rich bank 1&2 codes. I guess that is when the MAF harness shakes and briefly loses contact. If it didn't do that, i'd just keep on boosting, lol.
That said, I did see something on the MAF harness. My dad has an 03 xjr r1, and a 99 vdp parts car. Neither of those have what I saw on my MAF harness. Pics to follow later.
Last edited by Z07Brandon; Oct 4, 2020 at 06:14 AM.
First two pics are from my car. Last one is from my dad's 03 xjr. Notice how on my car, where I have the red arrow pointing, is like some kind of crimp. I looked at all the sensor harness' in the engine bay. The MAF harness is the only one to have something like that. Who knows if a previous owner had this problem in the past. But it is worth noting that the MAF harness is the only one to have it on my car. And looking at my dad's two x308's, those car's MAF's don't have the ceimped looking wire.
So now, the car is running lean. At WOT, the AFR was 14.64
Shouldn't these cars be11:1 at WOT?
Even at part throttle, fuel trims are 16-17. Not throwing any codes, but those aren't good. Especially on a S/C engine.
I verified fuel pressures again. They are perfect.
I was just curious about my fuel trims and AFR's, and all of a sudden they are lean.
In closed loop, should bank 1&2 oxygen sensors read fast or slow at idle?
Ah, and with the car now lean, I wiggled the MAF harness several times. It didn't change engine RPM at all.
Last edited by Z07Brandon; Oct 7, 2020 at 07:58 PM.
Key on, engine off: 40psi
Running: 39psi
Vacuum line pulled off the FPR: 48-50psi
WOT in the Park/Neutral: 48-50psi
AFR's are the same, whether going WOT at idle, or flooring it on a drive.
As of late April of this year, the car has two new fuel pumps and new fuel filter.
Last edited by Z07Brandon; Oct 7, 2020 at 08:09 PM.
1st screenshot is idle.
2nd is with a steady throttle input.
Oddly, the long term fuel trims show rich at part throttle. Yet the AFR is lean.
Also, I can't read o2 sensor 1(both banks) in Volts. Only in mA. So I'm trying to figure out how to understand if my o2 sensor mA readings are good or not.
Last edited by Z07Brandon; Oct 7, 2020 at 08:17 PM.
I did some research on how to understand o2 sensor mA readings. Since this is how my upstream sensors read. Hope this helps someone out in the future. So, with a warm engine, at idle, you should see it at zero. Example, 0.023
If you hold the RPM steady, at any rpm, it should also be at zero.
If not at zero, much higher, or lower, then you have a bad oxygen sensor(s). Under the idle and steady RPM scenarios.
Tapping the gas pedal(like doing quick revs) will make the number go above 1. That is ok, sensor is acting as it should.
I was thinking my upstream sensors were the issue. But no, they are doing what they should be doing.
To add to the madness, the long term fuel trims are now going rich. And I didn't touch anything. What a **** show.
The number reported in the long-term fuel trim is the direction the mixture Has to go in order to be correct. So if your air fuel ratio is showing lean, The PCM will give it more gas So your short term fuel trims should go rich and over time it will make an adjustment to your long-term fuel trimsIn the same direction
I learned while at this some years ago, that it really needed a long distance driving (talking 50-100km), this due to the various maps involved.
I should do a hard reset, then take the wife and go for a nice ride with various driving.
Only after that you will be able to judge the long term trims.
At my end, i've done everything I can. @xalty my AFR's are the same whether I am revving/going foot to floor in Park, or driving the car on the road. So since my fuel pressure is fine in Park, I doubt watching the fuel pressure gauge while driving the car will show different numbers.
The car will sometimes go very rich, or lean at idle. Everytime the car goes rich on both banks, the MAF g/s are like 7-9. While it should be 4-5 at the normal idle speed. When it was rich, I wiggled the harness. Engine ran rough for a second or two. And MAF g/s were brought back to 4-5.
Autoscope(highly rated Euro shop in Dallas)didn't want to work on my car. They said due to the year.
The car runs fine, except for when it occasionally stumbles at parking lot speeds. When that happens, it is rich.
My wot AFR is 14.7. I like to drive my cars hard. But lately I've been driving it like a lowrider. Not trying to put a hole in a piston.
There are really only 3 things I can do on my own at this point.
1. Check for vacuum leaks. I'll get a smoke test done.
2. Do as Eric said and bend the MAF pins.
3. Replace the MAF connector.
Truthfully, I'm not very confident those will solve my issue. But worth a shot.
On 9/7/20 you reported that you replaced old maf with a new oem maf and the fuel trims are the same.
On 9/8/20 you reported doing a hard reset and that it didn’t do anything to remedy your overly rich condition.
On 10/7/20 you reported running lean condition.
Between 9/8 & 10/7, excluding fuel pressure check and wiggling the maf wiring harness, did you do anything else to the car to try and remedy the situation?
If not, I would get your old maf and gently twist the pins to where it’s slightly askew from the untouched pins next to it. Perform another hard reset and go from there. Report back after this was done and drive it a few days. The key is to follow through by erasing the fuel trims after you change something especially for driveability.
I am not sure anymore, but I remember that you mentioned it was starting bad? Right?
Did you consider the fuel pressure regulator?
I did read of x308 owners who had problems with them, so it's not unimaginable on our cars.
And I bought an absolutely amzing Honda HRC VTR1000 very very cheap, as it hardly started, and once it ran, sometimes good, then all of a sudden very very bad.
A new, 30 dollar pressure regulator solved it all, best buy ever...
Maybe you are in the triangle of the MAF sometimes working, sometimes disconnecting and car going back into default (rich), and a regulator acting up in the background.
Just thinking out loud for you.
On 9/7/20 you reported that you replaced old maf with a new oem maf and the fuel trims are the same. Correct, I did do buy a new oem MAF.
On 9/8/20 you reported doing a hard reset and that it didn’t do anything to remedy your overly rich condition. Sadly, it didn't improve.
On 10/7/20 you reported running lean condition. Yes and it threw me by surprise.
Between 9/8 & 10/7, excluding fuel pressure check and wiggling the maf wiring harness, did you do anything else to the car to try and remedy the situation? Nothing else. Just went lean all of a sudden.
If not, I would get your old maf and gently twist the pins to where it’s slightly askew from the untouched pins next to it. Perform another hard reset and go from there. Report back after this was done and drive it a few days. The key is to follow through by erasing the fuel trims after you change something especially for driveability.
I am not sure anymore, but I remember that you mentioned it was starting bad? Right?
Did you consider the fuel pressure regulator?
I did read of x308 owners who had problems with them, so it's not unimaginable on our cars.
And I bought an absolutely amzing Honda HRC VTR1000 very very cheap, as it hardly started, and once it ran, sometimes good, then all of a sudden very very bad.
A new, 30 dollar pressure regulator solved it all, best buy ever...
Maybe you are in the triangle of the MAF sometimes working, sometimes disconnecting and car going back into default (rich), and a regulator acting up in the background.
Just thinking out loud for you.
It was hard starting, but the new fuel pumps and fuel filter took that away.
