I just bought a 95' Millenia S with 134k miles today with the understanding something was wrong under the hood (either a head or the supercharger). I'm trying to diagnose the issue so i can dig in and get it fixed. I've been reading through this forum and it sounds like oil leaks are pretty common in these cars when the supercharger is bad/going bad which it does have a small oil leak under the engine bay(i havent yet narrowed down specificaly where its coming from). When I start the car at idle the motor has a tick/quiet knock which quickly goes away about 1500-1800rpm + and completely smooths out past that. The other thing i found interesting is that when driving if i give alot of throttle it seems to really hesitate but when i ease into throttle it's really smooth and i can feel the boost that would come from forced induction. I've never driven a supercharged Millenia before only an N/A model. But to me all of these syptoms seem to equal the supercharger being bad (based on mechanical experience and reading through this forum The people i just purchased this from said they were told it was the supercharger which they say they purchased a used one with 90k miles on it and had it replacedand the problem did not change. I find this a little funny now after reading that the chargers life expectancy is only 90k miles.. Any insight or thoughts on this issue are much appreciated!!!

Thanks

 

the oil leak in the compressor would be internal. external is more likely valve cover gaskets, cam/crank seal, or oil pressure switch. under boost, it would smoke like heck if the compressor was bad. you should start with basics, one of the problems i have seen is the spark plugs. the rear bank is labor intensive, so unless the owner is doing the job, shops will give up and only change the front bank. the rear plugs could be original. also, the wells tend to fill with oil, esp. #'s 5 and 6. oil in the wells will make the coils die early. since the rear bank gets way more heat than the front, i usually switch them front to rear. another part neglected is the fuel filter. that lives on top of the fuel tank. if you remove the carpet in the trunk, you will see a circular metal plate, under that is where it lives. one way to check the compressor is to remove the plastic cover that says miller cycle. you will see a rectangular plate, the throttle cable runs right over it. take off the 4 bolts, and you then can see the rotors of the compressor. they should be dry, or just a very light film of oil. they will be a light brown color. if they are full of oil, then the seals are starting to go.

the use of the compressor on the mc motor is a bit different than a conventional one. under normal running conditions, the compressor keeps the intake under pressure, because the inlet cam has very late timing, and the valves close very late. so, because the inlet valves stay open longer, on a conventional motor, some of the intake charge would be forced back out. the compressor on the mc motor keeps the charge where it needs to be, this enables the motor to run such high compression. however, this system is not efficient at high rpm's. the mc motor is designed to be a small displacement motor with high torque. great power, and good fuel economy, and it does it quite well.

imho, the compressor gets blamed for a lot of things. one of the reasons is the lack of knowledge/experience on this car/motor. most shops, including the dealer, have not seen this car. with the car out of warranty, and dealer pricing being much higher, owners tend to take the car to the cheapest place they can find. what ends up happening, is then the owner pays the shop to learn about their car. there is a huge difference between shops that can diagnose, and those that are just parts changers. guess which one costs less?

 

the rear plugs could be original. also, the wells tend to fill with oil, esp. #'s 5 and 6. oil in the wells will make the coils die early. since the rear bank gets way more heat than the front, i usually switch them front to rear. another part neglected is the fuel filter. that lives on top of the fuel tank. if you remove the carpet in the trunk, you will see a circular metal plate, under that is where it lives. one way to check the compressor is to remove the plastic cover that says miller cycle.

when you say that you usually switch them front to rear are you referring to the coils or the spark plugs? I really appreciate your reply and just to add a few more things... the motor doesnt smoke at all and after i drove the car home from buying it the other day i havent seen a single drop of oil (like i saw below it where it had been parked for 6 months) do you think bad spark plugs/coils could be the culprit to the low idle 1800 or less idle noise that i'm hearing? tick tick tick tick tick ....... I've rebuilt motors in the past on Mitsubishi's and have knowlege when it come's to forced induction this is just a whole new style motor thati'm used to dealing with... i know how much of a difference bad spark plugs or wires could hinder performance on those cars i'm just trying to relay it over to this style motor. Thanks again for your input!

 

the coils. never switch the plugs, just change them. normal maintenance is replace at 60k. i always use the factory recommended PZFR5F, dont go wierd on plugs, like iridiums. be aware the gap is small, same as the mitsu 4G63T motor. unlike the mitsu, the motor is non interference. the timing belt is like iron, it will go forever. ticking might be valve lash, unlike the mitsu, or the 2.5, the lifters are solid. to get to them is a real bear. then, you will have to measure each puck, and order the correct size. i had a 91 galant vr4, evo 16g, denso 660's, hks cams, vpc, fidanza, full noltec, rre pipes/fmic, water injection, keydiver chip, yada, yada. that was a fun car.