When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I have a 2001 XK8, 4.0 engine, 130,000 miles. The only work I've had done was to replace the throttle body last fall because the coil spring was broken. I've had no problems until last week.
I would like some advice on next steps or how to trouble-shoot. I recently began getting a CEL and periodic "restricted performance" warning, along with these codes: P0101 Mass Air Flow Sensor Circuit Range/Performance P0172 System too rich Bank 1 P0175 System too rich Bank 2 P0507 Idle Control System RPM higher than expected.
First advice was to replace the MAFS which I did (pics of old & new attached). I also disconnected the battery for several hours before starting with the new MAFS. Now, upon starting, the RMS's race to 3000 then settle back down at 1800 on idle. I can put the car in drive and coast along the highway at 45 mph without my foot ever touching the gas pedal.
The only code now is P0507, with the occasional CEL & "restricted performance" warning.
What should my next steps be, or what other information can I provide? Thanks very much.
Last edited by ludlowbaylive; Sep 6, 2023 at 11:49 AM.
Reason: add info
Thanks for the suggestion. If you mean setting the position by putting the pedal to the floor a couple of times, then idling in park and then drive, I did that, to no avail.
Thanks for the suggestion. If you mean setting the position by putting the pedal to the floor a couple of times, then idling in park and then drive, I did that, to no avail.
Have you looked at the live data over OBD to see what percentage the throttle position is reading? You can adjust the cable to get as close as possible to the full 0-100% range.
The car is designed to rev higher at start up, then drop down after a few seconds to normal idle speed - 3000 RPM is obviously way higher than it should be.
@dibbit - I will try this tonight when I get off work. Should the engine be running for this throttle position reading, or just have the key in the "ON" position? Thank you.
Last edited by ludlowbaylive; Sep 9, 2023 at 04:47 PM.
@dibbit - I will try this tonight when I get off work. Should the engine be running for this throttle position reading, or just have the key in the "ON" position? Thank you.
Key On and engine either on or off should show the live data.
For reference, on my 2001 XKR 10% throttle in neutral gives 2800 rpm, at idle my throttle shows 3.5% - maybe mine needs adjusting also.
Excessive RPM's
