Killin skeeters

My 97 recently started blowing smoke when I get on the throttle more than about 50%.

I pulled the plugs and they looked like they were a little worn so I replaced them and the plug wires with NGKs. This seemed to reduce the size of the cloud, but I'm still killin skeeters when I get on the gas.

I tested the resistance on the coil packs and they checked out fine.

I did replace the exhaust manifold with a header shortly before this started happening, but it was a couple of weeks between the time the header was installed and the smoke started appearing.

I have always had a little black stuff around the exhaust on the rear bumper, but since it has started this it is worse than ever.

Yeah, but is it black or is it blue smoke?

In other words, is it running way rich or is it burning oil?

RJ

My money's on an O2 sensor if it's black smoke...

Or is it white smoke?

I never really paid much attention to the color. BRB :twisted:

First off I would like to say to the guy in the Suburban "I hope that you don't have any permenant lung damage, but you really don't need to be that close to my rear bumper." :lol:

The car has been sitting in the parking lot since about 7:30 this morning, and when I first took off there was a cloud of grey smoke. On the way back to the office, however it was the black cloud that I am accustomed to seeing.

Black smoke? Take TC's advice & change out the O2 sensor... see what color the smoke is after that.

Are you throwing a CEL? And are you sure if you aren't? (maybe someone just disconnected the bulb or it burned out - Do you see the light on when you turn the key but haven't started the car?)

RJ

It's not throwing a CEL while running, but I do see the light when I first put the key in the ignition.

I'll stop on the way home and get an O2.

I learned two things tonight.

1. Posi-lock connectors were invented by a guy named Loki, who is probably still laughing.
2. Even if you put newspaper down first you will still get yelled at if you work on car parts on the breakfast table.

Well the ugly black cloud is gone, but it starts blowing white smoke at around 5500 at full throttle. I had not noticed it doing this before, but I have also been taking it really easy on the car while driving it.

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Originally Posted by brock

it starts blowing white smoke at around 5500 at full throttle. I had not noticed it doing this before, but I have also been taking it really easy on the car while driving it.

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White like steam or blue like oil :?:

Just checked and coolant is full. I changed the oil about 500 miles ago and it is about half way between full and add on the dipstick. The engine has never done this in the past 70K+ miles. http://instagiber.net/smiliesdotcom/otn/sad/mecry.gif

I am beginning to suspect either the rings or the valves. Is there some way, short of taking it apart, to tell if either of these is the problem?

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Originally Posted by brock

I am beginning to suspect either the rings or the valves. Is there some way, short of taking it apart, to tell if either of these is the problem?

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See this thread if you havent already. It looks like Majik is dealing with the same issues.

Not related, but what was your impression of the header after you installed it? I think I got the same header but haven't installed it yet.

Good luck with your car.

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Originally Posted by bigDstars

Not related, but what was your impression of the header after you installed it? I think I got the same header but haven't installed it yet.

Good luck with your car.

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It's great. The final fit and finish is really good. I have heard horror stories about headers rubbing on either the transmission or the trans tunnel, but it fits with a lot of room to spare.

The EGR tube during install is another matter in itself. I ended up having to remove the coolant line from the heater core to the engine and route the EGR tube under it. There is also a mounting bracket that had to be removed on the back of the engine in order for the EGR tube to be coaxed into position to attach to the header. I tried heating the tube with a propane torch and bending it , but this was worthless.

I'm still killin skeeters and using about 1qt of oil per week. I just ran a compression test and vacuum test.

The vacuum seems normal at idle with a steady 19in/lb hg. With the engine running at a steady 2500 RPMs it bounces around from 17-22 in/lb hg. :scratch: Could this point to valve spring problems or a burnt valve?

Here are the results of the compression test after warming the engine up to operating temp and disconnecting the injectors / coil packs.

#1 = 160 psi
#2 = 158 psi
#3 = 160 psi
#4 = 160 psi

Here is what they read at the tech day on Aug 22, 2004

#1 = 190 psi
#2 = 185 psi
#3 = 190 psi
#4 = 195 psi

Is it time for a new engine?

http://www.seriesrover.com/series_te...uum_gauge.html

With the combination of the pulsing vacuum and losing oil. I would bet valve problem. Easy enough to pull the head and have it reworked. They come off in about 2-3 hours...

While it might be valves, I'm betting on rings, and blow by. Never the less, you have to pull the head on the way to replacing the rings, so there is no harm in checking the head. :?

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Originally Posted by brock

Here are the results of the compression test after warming the engine up to operating temp and disconnecting the injectors / coil packs.

#1 = 160 psi
#2 = 158 psi
#3 = 160 psi
#4 = 160 psi

Here is what they read at the tech day on Aug 22, 2004

#1 = 190 psi
#2 = 185 psi
#3 = 190 psi
#4 = 195 psi

Is it time for a new engine?

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Quick question did you use the same gauge for both tests? You will get some variation in readings gauge to gauge. Also did you have the throttle at WOT for the test?

My secretary had the throttle to the floor with the injector and coil pack harnesses unplugged. I let the engine idle for about 15 minutes before pulling the plugs and taking the readings.

I just picked up a gauge last night. I wonder if Mark52 would be willing to let me borrow his to do a quick comparison. I believe that it was his gauge that was used at that tech day.

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Originally Posted by brock

My secretary had the throttle to the floor...

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Is that in her job description!? ;-)

AT 70K miles you should not be having mechanical problems on a normally aspirated car. I would consider other things other than valve or ring issues. From your description everything was fine until you installed the header. You also described a change to the EGR tube.

Loosing a quart of oil in a short amount of time is not normal for a Miata either.
You also said you had changed the oil about 500 miles ago. (have to ask)... Is it the correct filter?

There are ways to check for head gasket problems. I can think of a few but I will let the real mechanics speak up on the procedures best for Miata's.

I will be optimistic and say the motor is still good.

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Originally Posted by general default

AT 70K miles you should not be having mechanical problems on a normally aspirated car.

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It actually has 113k but I have had it for the last 70k, and cannot speak for the previous owner's experience.

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Originally Posted by general default

From your description everything was fine until you installed the header. You also described a change to the EGR tube.

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This could be a possibility, as I first tried putting the header on the studs with the EGR tube installed. I was going to have to use too much force it on, so I decided to remove the EGR and install it after the header was mounted on the studs.

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Originally Posted by general default

Loosing a quart of oil in a short amount of time is not normal for a Miata either. You also said you had changed the oil about 500 miles ago. (have to ask)... Is it the correct filter?

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The filter is the same one that I always use. I've been buying them 6 at a time, and I still have 2 more at the house. I have also been checking the driveway every morning and there are not any spots at all under the car.

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Originally Posted by general default

There are ways to check for head gasket problems. I can think of a few but I will let the real mechanics speak up on the procedures best for Miata's.

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Please do enlighten.