After taking on a contract some distance away and handing my hire car back last week, the Z has been pressed into service for some serious miles over the next 8 weeks.

 

140miles a day, 3 days a week.

 

After hopefully sorting my smoking exhausts out (oil weep from sump plug washer) I've got a new one, the Cat overheat light.

 

Problem is the car doesn't appear to be missing and seems to be running fine, although it does feel a little lumpy at idle, but never when driving. I've had this issue before but before I could track it down it went again.

 

Car is returning an average of about 23-24mpg so fuel economy isn't horrific but I'd hoped for better sitting on the motorway.

 

I'll connect the conzult tomorrow and drop off the coil packs individually and see what happens.

 

Any idea's on where to start? I'll get it on the ramps to check the condition of the sensor wiring as I'm thinking false alarm at present.

 

Cheers

Pretty sure cat overheat light is down to fuel igniting in the exhaust. Make sure your PTU, coilpacks and CAS connections are nice and clean. Also take a look at your O2 sensors in case it's over fueling

I've been out for a nice little drive.....with my laptop in logging mode and found the following.

 

[ATTACH]62333[/ATTACH]

 

I think my LH O2 sensor is lazy, it seems to take it twice as long to come up with similar figures to the RH one.

 

Right now the coil pack wiring is so brittle and dodgy I daren't disturb it until I get some more connectors and replace it all but I've checked using the balance test on the diag that all 6 cylinders are firing fine.

 

Could a lazy O2 sensor cause the issues I'm getting? Unfortunately the fried CAT light only ever comes on after a sustained motorway run, something I've been unable to replicate today.

 

I have the log from the OBD Scan Tech (Nissan) software if anyone has the software and can have a better look at the data for me.

 

Thanks

You sure you're testing the O2 right? IIRC you hold the revs at 2k (once warmed up) and look for the O2 to bounce between lean and rich.

Didn't realise there was a procedure. :confused1: All I've done is set the laptop into logging mode and driven around allowing enough time for it to warm up, then done some straight roads, cruise control on to allow the engine to settle itself for a bit.

 

I've then looked at the logs in the house to see what was going on.