'98 XK8 Emission System

Hello all,
on my '98 convertible I lately experienced a problem with emissions. The exhaust tips are black and it smells like in the good old days when we used to drive cars without catalysts. Checked spark-plugs and air-intake system for any obvious cracks or damage. I tried to read out any DTC’s but nothing shows up. The car is running ok however I experienced a rough idle a day ago and after disconnecting the battery (reset) everything went back to normal except still black exhaust tips and the smell. Average fuel consumption hasn’t changed much.I suspect the MAF or any of the throttle sensors. I have a donor car (also a '98 model) from which I could swap parts). Any advice would be highly appreciated. Thanks!

Without more info, it’s a shot in the dark, but a leak in the intake tubing, or a dirty MAF, could cause the ECM to believe the engine is lean, and be turning up the fuel. Could also be faulty O2 sensors, or a myriad of other things. Use something like Torque Pro app and an OBDII reader to look at fuel trims. You can also use a scan gauge like the Autell X60 to get that info.

If you just want a shot in the dark fix, try cleaning the MAF sensor ( use MAF Cleaner- be careful).

1 Like

thanks Mike and yes I agree it is a shot in the dark… I just downloaded software called “Movi-Pro”
and ordered a bluetooth interface to connect to my macbook
Hopefully it will give me a more precise approach. In the meantime I will get the MAF out and clean it. Not long ago I installed a K&N air filter and I am wondering whether this might be an issue in regards to contaminating the MAF.

Just an update: Did some research on K&N air filters in regards to contaminating the MAF. There are lots of pros & cons however I exchanged the MAF from my donor car and it seems like the excessive exhaust fumes are gone and average fuel consumption also came down.
Does anybody have experience with K&N air filters running in the XK8 in regards to contaminating or troubling the MAF. Any inputs would be appreciated. Thanks!

If the K&N is one that has oil applied to it, then it will mess up the MAF over time. Additionally, if it is open to the engine compartment, then you are sucking in hot air vs cooler outside air, so your performance will take a hit. They sound good, but IMHO they do more harm than good.

1 Like

It is the filter cartridge as a direct replacement to the OEM filter element not the open version however it has the oil application. I suggested to go back to the stock paper-filter element not to get a chance to mess-up the MAF.
Thanks Mike for your input.