eltrob

Okay, so this is somewhat of a long story.

I have a 2009 RX 350. Sometimes, in the morning, the car will billow large thick amounts of white smoke from the exhaust. Sometimes it is not clouds of thick white smoke but thin smaller clouds of smoke with a somewhat grayish color and a fuel, burnt gas smell. Once, the smoke had a sweet smell. The mpg was at 17.5 average.

Last week, I changed the spark plugs (front and rear). I changed the intake manifold gaskets and the throttle body gasket. I replaced the PCV valve and cleaned the throttle body.

After starting the car, I noticed that when I turn off the car, I can hear (but not see) puffs of pressurized air coming out from somewhere in the engine bay. It sounds like it comes from the hoses sometimes, sometimes it sounds like it comes from the intake manifold. Sometimes it sounds like it comes from either the PCV valve or the hose connecting the PCV valve to the intake manifold. The car did not make these noises before, so I am not sure what it is or how to fix it.

The mpg has gone down to 15.25 average, which is terrible. I was expecting the spark plug change to get me to 19 mpg average.

The car is still billowing white smoke (which goes away after driving for a while; it is just at startup).

I checked the coolant and saw that about 1-2 cups (a relatively small amount, but a noticeable amount nonetheless) had been used up from the last time I had topped it off, which was about 2 months ago. So coolant seems to be disappearing at a very slow rate.

I removed the intake manifold and put it back on to make sure there was no intake manifold leak (the gaskets are new), but it does sound like air noises, puffs are coming from the manifold sometimes.

So what is responsible for all of this? Could cleaning the throttle body have thrown off the sensors and it needs to be recalibrated? Are the gaskets of the intake manifold, which are new, not making a tight seal? Is there some other leak in the intake manifold? Is the PCV valve leaking or the hose to the PCV valve and intake manifold leaking? Why does it sound like air is leaking/being sucked in from my hoses or intake manifold? What is causing the coolant to slowly disappear? What is causing the white smoke? Why did the mpg drop after spark plug change instead of increase?

I should mention that I have checked everything: spark plugs seem fine, I put the intake manifold on tight with new gaskets, hoses on tight, cleaned throttle body carefully, pcv valve tight, but not too tight. Only thing I can think of is coolant leaking into engine causing white smoke and low mpg. Is it worth it to just use a small amount of stop leak, like bar's on it? Car has 150k + miles, so maybe worth it. But then why are the hoses or intake manifold or pcv valve or something in the bay making that pressurized air puff noise when turning off engine. Even if that is harmless, it didn't do that before, so how to fix it?

Thanks,
Robert E.

fabchef

Hey, maybe change the pcv valve? But...from what i’ve heard in the past... white smoke+sweet smell+coolant loss= possible head gasket leaking. You can have it checked out... gluck.

eltrob

Maybe my original post is too long.

These are the main two problems:

1) I replaced the front three spark plugs and mpg was good. I replaced the rear three spark plugs, and then mpg went down 25% instead of increasing even more. What could cause this?
2) There were no noises from the engine bay before I changed the rear three spark plugs. Afterwards, after turning off my car, I hear puffs of pressurized air noises from what seem to be the hoses or somewhere behind or near the intake manifold. I can't pinpoint it and it only last for about two seconds after turning off the engine and then they stop. Even if this is nothing to worry about, the car wasn't doing this before, so what happened. I have double checked the hoses, I replaced the intake manifold with brand new gaskets, what could be the problem? How do I get rid of these noises?

Any help would be appreciated.

fabchef

Audiqv8

Any DTC codes? What chemical was used and how did you clean the throttle body? Throttle body has coolant going through it and a leak could allow coolant to enter the intake manifold. Do you have access to a code reader with real-time data? You need to determine short-term fuel trim (STFT) and long-term fuel trim (LTFT). Without the proper tools, you're just guessing.

If you're near Staten Island you can contact "New Level Auto" Keith DeFazio posts to youtube or if you're further west you can contact Eric O at South Main Auto in Avoca New York, Both posts on Youtube.

thomas1

The key is you said you changed the intake manifold gasket, is it possible it is not in correct or has a break or tear? This could certainly cause your problem. The intake manifold on the older RX300 engine also had water passages. I cant say whether the RX350 Engine is the same. You may have water creeping into the air intake of the manifold. I would possibly take manifold back off and check that gasket. On my old RX I actually had a leaking of coolant from that gasket.

eltrob

Thanks for the replies.

It might be the spark plugs not being tightened enough, but I am pretty sure I did a good job. Re-checking will be a huge pain, as the rear spark plugs are hard to reach, but I guess I will have to try.

I used CRC throttle body cleaner on the throttle body. I made sure not to move the plate, as I know that moving the plate may throw off the sensor which would then require having the throttle body recalibrated. It is possible that I might have messed it up and the throttle body needs recalibrating, but I was as careful as I could be. I guess I would need to take it to the dealer for recalibration if that is the case.

No CEL. I do not have a code reader. I guess I could get one. What would the fuel trim tell me? What should I look out for?

What about the puffs of air coming from somewhere from my engine bay for 2 seconds after turning off the engine? Where could that be coming from? How to get rid of it?

Audiqv8

A positive STFT lean condition (computer is adding fuel) could be caused by a vacuum leak. If you have an android phone or tablet you can purchase Torque Pro on the Play Store. You will also need a Bluetooth OBDII dongle from Amazon. The program Torque Pro is under $10 and the Bluetooth OBDII dongle is around $20 or less. Torque Pro is also a code reader and can read existing and pending codes. Spark plugs are not tightened to crazy torque. They are tightened to between 15-20 FT LBS.

eltrob

OK,
So I did as Audiqv8 said. I bought a obd dongle and got Torque Pro app.

Here is what stuck out:

LTFT1: 3.4
LTFT2: 2.6
STFT1: switched between -1.56, .78, -.78, -2.5, 2.5 at idle, hit 0 only rarely and did not stay at 0 for long; driving it ranged from -12 to 12, but usually -6 to 6. It only hit 0 and stayed there after reaching high speed and then taking my foot completely off pedal and coasting.
STFT2: basically same as STFT1

The air to fuel ratio was about 14.1:1 at idle, and would go from 10 to 15 during driving, but usually stayed within the narrower window of 13.7 to 14.4 while driving, again with average 14.1.

The throttle position was at 14.9% idle and went up to 45% when hit the gas, while the absolute throttle body was at 45.9% and went to 56% when hit the gas.

RPM was about 660 idle.

O2 1x2 voltage: 0 at idle, .7 when hit gas, but then stayed at .6-.7 did not drop to 0 for a while; did not seem to go higher than .7 when hit the gas, but can't say for certain as my eyes weren't on it while driving
O2 2x2 voltage: same as above

The vacuum was 25.7 in Hg at idle, and went down quickly to 14ish upon acceleration but then quickly rebounded to about 22.

So I think the fuel trims are off but I am not sure. I think they should be at 0. What could cause this, and how can it be fixed? Does this explain the low mpg?
The air fuel ratio seems off. Shouldn't it be exactly or very nearly 14.7, not 14.1? Could this explain the low mpg?
The throttle positions seem off. Maybe it needs to be recalibrated after I cleaned it?
Oxygen sensor voltage: not sure how to interpret.
The vacuum seems fine, so it seems to suggest there is no vacuum leak/intake manifold leak/loose hoses, etc.

I tried to add a PID for misfires, but apparently there are no Toyota/Lexus PIDs in the Torque Pro app. I wanted these to check if the spark plugs I installed were installed correctly and working. Is there a way to use Torque Pro to check the health of the spark plugs?

Other than those, everything else seemed to be fine. No fault codes, no warnings or failed tests or red lights. But I can't be sure to have checked everything. Is there something else I could check to help diagnose the problems?

tomr51

just a thought, were they the correct plugs, and also were they pre gapped?

Htony

Cooling system pressure test.

eltrob

Spark plugs were OEM and pre-gapped. The only possible issue is by some small, small chance I did not install them tight enough because the rear plugs are so hard to reach. Is there some easy way to test spark plug performance with Torque Pro or some other method, without actually opening the entire thing back up and physically removing the plugs?

I will try to do the cooling system pressure test soon and report the results.

Are the fuel trims considered off or within operating range? What about the air fuel ratio?

Audiqv8

A misfire(s) will indicate a problem with a cylinder(s). Since you do not have any DTC for misfire (P0300) code I would not worry about the plugs or taking apart the intake manifold to inspect. I would just run the car for a couple of weeks and see if the gas mileage improve. My guess is that the throttle body didn't like the cleaning that you gave it. Here is an image of my engine at idle and at operating temperature. BTW my City/Highway driving is usually about 22mpg, but with the winter weather, it has gone down to 20 mpg.

eltrob

My AFR is 14.1 vs your more normal 14.7. My LTFT1 and 2 are similar to yours, just both positive. My STFT1 and 2 go to 1.56 sometimes at idle, but like yours usually are at .78. My RPM is just slightly higher, 630 up to 670. My vacuum at 25.7 seems stronger than the 18-22 found in most vehicles. My throttle sensor reads 14.9, which I think is supposed to be normal, unless cleaning messed with the sensor. Is there a way to recalibrate it manually, without taking the TB apart?

I think I have a very very small coolant leak which is getting burned and coming out as smoke in exhaust at start-up only, and after about 2 miles driving stops. This probably means a blown head gasket, which could be the reason my AFR is lower than yours. I will try the pressure test and go from there.

Audiqv8

A little amount of white smoke can be expected in the winter months. Water will condensate inside the muffler. Yes your AFR number would indicate a rich condition. Might be time to replace the air/fuel mixture sensor, there are two and they are costly. Many people mistaken the Bank1 or Bank2 sensor 1 as an oxygen sensor.

Here is how you test for a blown head gasket.