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Papa Indy 61 position 12 White / Green wire , PI61 is usually a white connector but can be black or the other way around
33 circle double hash is the fuse # X , the current is allowed to pass by the timed ( start duty time or maybe back on at idle as cooled down exhaust gases ) grounds provided by the ECU ( red lines )
Last edited by Parker 7; Jan 25, 2026 at 05:38 PM.
The correct titania O2 sensor develops a resistance that modifies a reference voltage ( exactly 5.0 volts ) that is returned to the ECU
The more common sensor develops it's own voltage from O ground as one of the wires and in older O2 sensors from the ground through the mounting threads
The difference between the 2 off top of head is titania 3 5 volts DC and the other 1.7 abouts . I can certainly be wrong on these numbers
You can see this with a ELM - 327 live data reader or common meter on the return signal
Old receipts for current sensors ?
Last edited by Parker 7; Jan 26, 2026 at 10:05 AM.
There’s really no reason to believe the wrong type of sensor was installed. The car should be undriveable. I’m sure the ECU would throw all
sorts of lights up on the dash.
The question is whether failing oxygen sensors could cause this kind of issue. I don’t really see how it would, not without throwing a code. A failing sensor could lock the fueling into a max fueling situation, I suppose, flat lining on positive fuel without swinging back down, but that would be a stretch.
The sensor has been replaced, old one was pretty shot. I dont have a way to read it unfortunately
the reason i was asking is because the intake air temp is relevant to the supercharger cooling circuit. I have the 4.2 supercharged. Different of course and have no experience with the 4.0. I once had my supercharger cooling pump go out and the intake temps went sky high. It smelled like gas when it did that. Intake air too thin and hot to burn all the fuel i guess until trims stabilized as best they could. It also threw a intake air temp code. When your car gets to the hot flooded type condition maybe check the temp of the intercoolers by touch. Be careful. If all is working right they should be warm to the touch. If not they will be quite hot. Best i can think of being that i have zero knowledge of the 4.0 system
Interestingly, I did suspect the intercooler pump had died as the SC body and covers were quite hot. I replaced it with and AMG unit and you're right, its warm to the touch now but not hot, while the engine is hot as expected.
Update time. The issue is still there. FPR replaced. Old one was leaking. So now I'm running out of ideas. Next I will be pulling all the injectors and having them serviced. I don't see this as the culprit, as all plugs are equally sooty and black. I wouldn't think all injectors would fail together, and therefore see differing levels of soot on the plugs.
I have also ordered a replacement MAF, again, don't see this as the over fuelling gremlin.
Just to confirm the issue:
The car starts fine and runs fine until it reaches temp. The fans cut in and out as they should about 4 to 6 times, which is well past operating temp. Car revs fine, no black. But can smell fuel. After this time the car will begin to sputter, revs will start dropping off and it will die. After this the car will not start. If left for a couple of hours, it will fire up as if nothing happened, then soon enough do it all over again.
The car has plenty of power, sounds fine, no backfires, doesn't miss, no engine shake. if the car is driven and I don't stop anywhere for more than 30 seconds, it keeps running.
You certainly appear to have covered most points; however, have you checked your fuel pressure hot, a failing fuel pump may reveal its condition only when hot.
You are most likely unaware that you drive around with a spare fuel pump available,
I have attached details of my small modification which does allow you to switch over to the second pump for normal running. It could be wired up on a temporary basis just to do a check of the number 1 pump which does normally operate at all times.
I have also attached details of installing a fuel pressure gauge.
You also mention a lingering fuel smell, that is not normal.
Would a failing fuel pump cause over fueling and flooding?
Not past the FPR it shouldn't. I don't see how it could. That's the whole job of the FPR.
The injector service is worthwhile, and it certainly could be the problem. If the FPR was bad, then I could see the injectors getting damaged over time as they have been overpressurized for awhile? Its a theory...
If you had an OBD2 reader, you would be able to see what the ECU is seeing. This would be a helpful tool in realizing whether something like the MAF is indeed at fault, or maybe just a wire harness issue. The OBD2 reader gives you a window to what the car sees, not just what is being transmitted by the sensor itself.
In your recent post you stated -
"I have also ordered a replacement MAF, again, don't see this as the over fueling gremlin"
Where did you order it from, the MAF to suit your XJR is unique and is part Number LNA1620AA, not LHE1620AA which only suits the normally aspirated engine. You have done extremely well if you have managed to order a LNA1620AA MAF, they are extremely rare, new ones unavailable and secondhand ones just about the same.
You don't by chance already have a LHE1620AA fitted do you, they are completely unsuitable for the XJR and will cause your XJR to run excessively rich. A faulty MAF may also cause over fueling.
