This on a 1991 LS400 w/156K miles, of the first four fillups I've gotten 14.5 MPG, 13.7 MPG, 15.7, MPG, and I'm working on the forth tank now.

I've got new plugs (Denso Iridium), new wires, new airfilter to install. I'll buy the new CPS but wanted to get a little feedback on what else may be causing poor fuel economy but not throwing a code.

Thought about changing the O2's just for grins but they would presumably throw a code if they weren't working properly, right?

I'll also probably clean up the throttle plate, and maybe wash/soak the intake with seafoam... runnig the seafoam into the intake, kill it and let it soak for 15 minutes fire it up outside...

Any other ideas are very much appreciated.

Thanks,
Plat0

 

Also, go ahead and clean the MAF sensor...