bdoggie22

I need help figuring out what this part is so I can replace it. I've gone through detailed manuals but I'm not able to find a specific answer. There appears to be a part missing and a hose is hanging down in the middle front undercarriage. The pictures show the broken or missing area which is beneath the radiator. The last picture is the hose that appears to have been connected to something...perhaps the missing piece. Any help is appreciated

johnnyg66

Last pic looks like drain **** to rad and the holes to me probably where the undercover was screwed on.

bdoggie22

what do you think the piece is that's broken? There is carbon buildup around it and my gas mileage has depreciated to about 5-7mpg

LScowboyLS

you photos are not clear enough to ascertain exactly what is broken, if anything, but in any case, I cannot think of any piece on the car, on the underside, that if broken, would cause gas mileage to go down to 5-7 mpg

you need to dump the codes using this procedure

if you are getting 5-7 mpg and you have no codes, then the problem is very likely failing ECU capacitors, which is common for 92-97 models

bdoggie22

Thank you. Very helpful answer.

dc893

Bad distributor caps, rotors, plugs, wires, and air filter can drop MPG significantly. If your maintenance is not up to date that is where I would start looking. My MPG had gone from about 400 miles per tank to 330 a tank. Replacing a bad distributor cap brought it back up to normal.

bdoggie22

yeah, I'm going to start with the basics and hopefully I won't have to work my way up. This is my first Lexus, I bought it for 1200.00 from a mechanic. It has well over 300,000.00 miles on it and before this incident it was running great. I've been getting regular oil changes but that's about it. This car has made me a Lexus fan. Sorry about the pics I know they're crappy but it was late and I had been working under the car when I saw that.

LScowboyLS

be sure to use the real Toyota (Nippon Denso) caps and rotors - you can find them discounted online by many Lexus dealerships for aroud 25-28% off full parts department price. This is not an area where I would buy aftermarket from your local auto parts store. However, on plug wires and plugs, the auto parts store is fine, as long as your stick with Denso or NGK brands only.

also don't forget the two other items that often kill fuel mileage, the thermostat and the engine coolant temperature sensor - both of these need to come from a discounting online Lexus dealership as well.

some of the online Lexus dealership with a good discount are Sewell Lexus, Park Place Lexus, Lexus of South Atlanta, and Lexus Parts Now.

once you have replaced all of this, if mileage hasn't returned, then it is likely time to look at those ECU capacitors!

Unclebob9

My 92 LS400 had a lack of power and the MPG dropped by 3 to 4. I tried several things over at least 6 months. Finally I started hearing a rattle and a hissing noise that appeared to be coming from the dash vents.
What had happened is the rear Catalytic convertor was plugged up and the pressure caused a pin hole exhaust leak which resonated up through the dash vents.
Replaced the Cat and hissing stopped, power restorred, they said it should also improve my MPG which I firmly believe (just replaced it yesterday).

Another common problem, which drove me nuts trying to find, was the car would die for no reason. this turned out to be the Fuel Pump Relay Resistor, which is located under the fuel pump relay which is right behind the air cleaner. it is about 1.5" x 3", silver with cooling fins.
This can be bypassed by un plugging and connecting the wires together.

Bob