rxgxmdx

I have a 99 RX300 with over 122K. Could you guys help me with these problems?

The first is the heating system. I have to turn the temperature very high to get heat, otherwise the A/C will kick in. Say I started the car with temperature set at 70F. The hot air blew for a while then turned into cool air. I then had to set the temperature to 75F, then 78F, then 80F to prevent it from blowing cool air. Sometimes when driving in a big snow I had to set to MAX HOT AIR. This problem has been going on for about 2 seasons. Recently the water pump broke down. I told the mechanic about the heating problem, and he said it should go away with a new pump installed. Well, it was better in the first couple of weeks but the same problem has returned. BTW, the cooling function in summer has never had a problem.

The second problem occurred this morning. When I drove at a very low speed or when I was braking to a stop, the front part of the car started to shake. It felt as if the driver's seat was rocking back and forth. The shaking disappears when the speed picks up or after the car comes to a full stop. The thing is, I replaced all tires just before the New Year and had the wheels balanced and aligned. And there is no visible vibration under the hood. Oh, the Check Engine light started to flash this morning too (Yep, flashing ... not steadily on). I had the O2 and MAF sensors replaced about 14 months ago. So what could this be?

Thanks a lot!!

Lexmex

On part 2, you need to go to an AutoZone or somewhere you can read the codes so that I can tell you what is up.

On part 1, I have to defer to the rest of our fine members as I rarely if ever use my a/c or heater nor encounter a problem.

lxtauto

first problem possible air pocket in in the cooling system. second problem engine light flasing means cylinder missfire. possible air fuel ratio sensor,ign coil

rxgxmdx

All these sound foreign to me :-), and the missfire and ign coil part also sound serious. Would this be a big repair job? I hoped to drive the car to the end of its life. But since it sailed past 100K miles 2 years ago, I have been spending ~1500 annually in repair and replacement. Maybe I should re-consider.

Thanks.

Lexmex

Misfire is pretty easy, but about $125 USD a coil to fix (you can DIY, I can show you). You would notice it, because it feels as if you lost some power and it feels like it is lagging every time you step on the gas. Any AutoZone can read the code for you, which I highly advise before you spend $$$ on anything.

I would do this pretty quickly in case it is a misfire, as you are just wasting gas (a lot) and also possibly damaging emissions control components with excess gas going through the system.

If you get the code, I can tell you.

rxgxmdx

I don't think I felt the loss of power ... yeah, I will try it out again and stop by auto zone.

Thanks.

Lexmex

I wish I could be there each and every time someone has an engine problem.

thomas1

Yea, You have a heart of gold. For the folks out there that get gouged, knowledge is the fix. At least they are on this site trying. Lex, I wish I could have taught my daughters about cars, but neither was interested, but boy who do they come to when they break. That is life. Yet some of the women on this and the other site are awsome. I just read a post on the other site of some young lady who had changed her timing belt on a LS400. That is like too cool. She gave a point by point of how she did it. Hey that could be a great post question, how many women on this site wrench on their own cars?

Lexmex

Whether I have a daughter(s) or a son(s) in the future, I will certainly be teaching them the tricks of the trade, though I am sure by the time they are my age, vehicles will be so very advanced.

thomas1

The other solution is make them rich, and let somebody else wrench them. By the way if you get codes p0301 through p0306 that is a missfire. By swapping coils you can see if the code changes. if so, bad coil pack..... Say you get a p0301 which is cylinder 1 and you move that coil to cylinder 3 and you get a p0303 then the coil you moved to cylinder 3 is the culprit. Easy. Except getting to the back coil packs (ones closest to the firewall)

lxtauto

check the codes and make sure the air fuel ratio sensors are working. If you need more info see ****************** to contact me.

rxgxmdx

auto zone read out the code this morning: P0305 .. cylinder 5 miss fires. i still drove the car to work today which seems to be a bad idea. i will drop my car tonight to have a mechanic check out ign coil and air fuel ratio sensor.

thanks to all who kindly replied.

rxgxmdx

i checked out your site ... too bad you are too far south ... otherwise i will drive straight to your garage :-)

thanks again

thomas1

P0305, cylinder 5 missfire, unfortunately located on the back side of the engine. From right side of vehicle to left it would be 1, 3, 5 and the front of the engine would be 2,4, and 6 which would be the left side of vehicle. switching 5 with 6 would tell you whether you have a bad coil pack if the code becomes p0306 after switching

rxgxmdx

Are there DIY instructions on this site about switching coils?