Another regular Restricted Performance issue.
#1
Another regular Restricted Performance issue.
Lately, seemingly when I am at or near idle with a warm engine, I get a pretty frequent Restructed Performance. Car has new plugs and I replaced one coil pack when the car was having issues earlier. It throws a P0172 and P0175, both banks running rich. Do you think I have more bad coil packs and should replace the other 7? Possible dirty MAF sensor? Vacuum leak? Any suggestions?
#4
If you can measure the fuel trims you might try this to narrow it down,
Diagnostic Tip:
For a suspected vacuum leak, note the fuel trims at idle and increase engine speed to 2500 RPM and hold. If the STFT immediately decreases and moves to acceptable levels and the LTFT slowly starts to come back down, you have a vacuum leak. After the repair, reset the KAM and start the vehicle. Monitor the fuel trims to make sure they are within the normal ranges. It could take up to 10 miles of driving for an accurate LTFT reading.
ps, op supplied codes
Diagnostic Tip:
For a suspected vacuum leak, note the fuel trims at idle and increase engine speed to 2500 RPM and hold. If the STFT immediately decreases and moves to acceptable levels and the LTFT slowly starts to come back down, you have a vacuum leak. After the repair, reset the KAM and start the vehicle. Monitor the fuel trims to make sure they are within the normal ranges. It could take up to 10 miles of driving for an accurate LTFT reading.
ps, op supplied codes
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Are you an XK8 or XKR? I had a similar situation on my R (simultaneous onset of 172 & 175 codes) and found it to be a disconnected little vacuum(?) hose that ran from the top right side of the s/c to what looked like a pressure regulator on the front of the right fuel rail. Reconnected the hose and the problems went away instantly. Good Luck!
Last edited by scardini1; 10-08-2014 at 06:57 PM.
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#9
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+1 from me at 90k miles on original 02 sensors on at least checking them!
They may not necessarily throw any codes but even a failing 02 sensor will cause all sorts of trouble.
Rough uneven idling / hesitation / surging / increased fuel usage and others
They may not necessarily throw any codes but even a failing 02 sensor will cause all sorts of trouble.
Rough uneven idling / hesitation / surging / increased fuel usage and others
#10
So far I've checked the intake tube and it looks perfect . I cleaned the MAF sensor while I changed oil today and it seems good so far, but I'm not sure it can be that simple since it looked very clean to start, but I guess we shall see
O2 sensors are probably the next thing to look at. I haven't looked, do these cars have 2 or 4?
O2 sensors are probably the next thing to look at. I haven't looked, do these cars have 2 or 4?
Last edited by K.Westra; 10-09-2014 at 10:40 AM.
#11
So far I've checked the intake tube and it looks perfect . I cleaned the MAF sensor while I changed oil today and it seems good so far, but I'm not sure it can be that simple since it looked very clean to start, but I guess we shall see
O2 sensors are probably the next thing to look at. I haven't looked, do these cars have 2 or 4?
O2 sensors are probably the next thing to look at. I haven't looked, do these cars have 2 or 4?
#13
Day 2, about 75 trouble free miles with MAF and MAF connector cleaned, so we will see if my luck holds.
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JimC64 (10-09-2014)
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Well today I was chasing TPS issues and replaced the gold contacts (with no luck ) so I had the hold intake elbow off. I had looked over it before, but today I noticed one little bad spot. Could this be enough to cause issues? Right now the Restricted Performance takes a back seat to the failsafe engine, but it does make me curious.
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