92 Es300 Smoking

[cws42680]

I have a 92 ES300. Recently, it started with greyish white smoke. Occasionally, it would puff out a bit for a half-second at startup if the car had sat for more than a couple of days. However, it began acting differently. No smoke, ran great for about 5-10 minutes (depending on if it was surface streets or highway. Ran a little better longer on the highway). After a period of time, it would consistently smoke. It also was throwing the code for the left main bank 02 sensor.

I knew that the car was burning a tiny bit of oil. About a quart every 3 months or so. So, I took it to an independent shop, and they wanted to do headgaskets, timing, rebuild the head....almost a complete rebuild. Finally got the vehicle back, and for the first day (I only drove it breifly around the neighborhood, and on the interstate for about a mile), it ran great.

This morning, it started doing the same identical thing. Ran fine for a few minutes, and then started smoking exactly the way it was before. It's used 1/4 a tank of gas for about 40 miles of driving (it got poor mileage previously also).

I realize that yes, I will need to take it back to the shop (which I am). I just want to go armed with information about what they need to be checking. Is this possibly a bad 02 sensor (a byproduct of burning a bit of oil all the time)? The CEL is no longer on, but I haven't tried to pull any codes yet to see if something is still present.

[George_Jetson]

That is some 1/4 for 40 miles is real poor mileage. Are you sure the smoke is not black? Can you smell any gas when you stand behind the car? If you had a code for the O2 sensor, I would recomend replacing it, while you are at it, I would strongly suggest replacing the right hand O2 sensor also.

You also want to check the vac hoses for splits,, MAKE SURE to closely inspect the vac hose to the fuel pressure regulator. When the engine vac is low, the fuel pressure regulator increases the fuel pressure so that more fuel will be injected (low vac, hard accleration).

The other most likely possibility is the water temp sensor. When the engine is cold, the ECM runs the car rich. Does the temp gauge read app in the middle of the range? If it reads cold, then you need to fix that. If it reads in the normal range you could still have a sensor problem, because the ECM uses a separate sensor to determine the engine temp.

As far was the head gaskets, are you loosing any coolant? How does the oil look? I am a little skeptical that the gaskets are a problem. If you had a blown gasket it would not run well for a while, then bad, and back to well. It would be bad, then worse.

[cws42680]

That is some 1/4 for 40 miles is real poor mileage. Are you sure the smoke is not black? Can you smell any gas when you stand behind the car? If you had a code for the O2 sensor, I would recomend replacing it, while you are at it, I would strongly suggest replacing the right hand O2 sensor also.

You also want to check the vac hoses for splits,, MAKE SURE to closely inspect the vac hose to the fuel pressure regulator. When the engine vac is low, the fuel pressure regulator increases the fuel pressure so that more fuel will be injected (low vac, hard accleration).

The other most likely possibility is the water temp sensor. When the engine is cold, the ECM runs the car rich. Does the temp gauge read app in the middle of the range? If it reads cold, then you need to fix that. If it reads in the normal range you could still have a sensor problem, because the ECM uses a separate sensor to determine the engine temp.

As far was the head gaskets, are you loosing any coolant? How does the oil look? I am a little skeptical that the gaskets are a problem. If you had a blown gasket it would not run well for a while, then bad, and back to well. It would be bad, then worse.

I wasn't losing any coolant that I could tell (before or now). Like I said, the heads have been rebuilt, so it's got all new headgaskets, new fluids, etc.

Temperate range is normal, smack dab in the middle once it's up to operating temperature (which is when is seems to start smoking). The longer it takes to get up to operating temperature, the longer it takes before it starts smoking.

Yes, I'm quite sure it's not black smoke. I've had that issue. It's not as white as coolant, but definitely on the lighter side of middle gray. I have smelled gas once, but the problem wasn't happening, and I didn't smell it today when I got out of the car. It also doesn't have that sweet smell that coolant smoke does. I'll check the vacuum hoses at lunch, though I gave them a look over when the problem started happening initially and couldn't see anything amiss.

[George_Jetson]

I was a little confused, When you said that the shop wanted to rebuild the heads, and replace the gasket I assumed that they had not done that yet.

So the next step would be checking the hoses, and then replacing the O2 sensors. I would strongly recomend replacing both sensors at the same time.

[branshew]

I agree w/ George Jetson. If it was white smoke, I could understand the head work as it would indicate coolant being burned off, but that doesn't sound like your problem so I'm unsure why the head work was done. Burning oil typically isn't a head problem. Gray smoke is typically oil burning or possibly excess fuel being burned (running rich) or fuel being pushed into the cat and being burned off there. As GJ mentioned, I would check the FPR vac lines. It is possible that you have oil slipping past worn piston rings.

[George_Jetson]

One other question, how many miles do you have on the car? Your car is OBDI which doesn't have O2 sensor heaters or some of the other checks that OBDII has.

Was there any coolant lose before the rebuilt the heads? If so it would be easy to see one of the O2 sensors being contaminated (they are sensitive to contamination). The last thing to check would be the MAF, these years use a lo-tech (but much more adj, for the tuner) vane sensor. You need to use carb cleaner to clean out the build up in the sensor, and make sure that the vane moves freely, with no sticking at all.

[cws42680]

One other question, how many miles do you have on the car? Your car is OBDI which doesn't have O2 sensor heaters or some of the other checks that OBDII has.

Was there any coolant lose before the rebuilt the heads? If so it would be easy to see one of the O2 sensors being contaminated (they are sensitive to contamination). The last thing to check would be the MAF, these years use a lo-tech (but much more adj, for the tuner) vane sensor. You need to use carb cleaner to clean out the build up in the sensor, and make sure that the vane moves freely, with no sticking at all.

176K miles. Before the rebuild, there was no coolant loss.

[Lucky13]

Is ther PS pump leaking?

[cws42680]

Is ther PS pump leaking?

No.

I'm beginning to suspect the fuel pressure regulator. I was checking (again) for loose/disconnected vacuum lines, and tapped on the FPR. Immediately after, it ran great, and then after a while, began running poorly again. The blatent smoking is much less, but still crops up for 10-15 seconds at a stoplight about 25% of the time.