No it doesn't. The engine management system gets input from several sources, and uses it to decide what directions to send to several components. Not all input is used to calculate all directions, only what's pertinent.

Pertinent to both engine speed and spark plug firing is one sensor. Typically a crankshaft position sensor or a camshaft position sensor. Computer uses that sensor to measure engine speed and determines when to fire spark plugs. How does a manifold vacuum sensor, throttle position sensor, air temperature sensor, Oxygen sensor, EGR position sensor, fuel pressure sensor, coolant temperature sensor, load sensor, or battery voltage measure engine speed?

Spark timing is a variable calculated on a shitload of conditions, and may or may not be correct depending on the information fed to the engine management system.

Hey xoB

A war of words here is battling on his turf. Here are some pictures that might help.

I've been following along, silently :facepalm:. I see a bit of :banghead: which will naturally progress to :brikwall: and :rollanim: . That's great if you want to descend to his :blah: level. Personally, I think this is :crazy:. All the :bitching: in the world won't transform a :confused: :dunce: into :idea: :thumb2:. Old and busted--:bonk:. New hotness--:mock:

Just my :2cents:

I :heartpump our favorite :robot: so :stop: :worm:ing him. Go :fish:elsewhere or :chill: and kick back with a nice cold :guinness:

I'll buy the first round. ;)

Yeah, so anyway, I've got a 4 day weekend coming. I should have some time in there to tinker a little.

My plan is to double check the engine mounts using a mirror and flashlight to really examine them. I had done the "see if the engine moves around under load" test, and ruled them out, but they are the most obvious culprit so I'm going to try to really get a good look at them.

Then I'm going to spray a bunch of carb cleaner on the vacuum hoses to check for a leak, since that's probably the next most likely culprit.

And then I'm going to look for anything that's touching the frame/body that shouldn't be.

Wish I had some jack stands. I asked for some for Christmas, so can't go out and buy any yet. It would be a lot easier to examine this car if I could raise it a bit and get under it safely.

glatt, when the car's all warmed up or whatever conditions are needed for this rough idle symptom to appear, would the roughness disappear if you gave it a tiny amount of gas? Like just enough to raise the idle, as if the idle were, say 100 rpm greater?

im, you crack me up too. not like Ron White or anything, but your own special smart funny. :thumbsup:

Puh. I got pieces of Ron White in my stool.

:lol:

Not sure if only 100 extra rpm makes it go away, but a couple hundred more do make it go away. If it goes from 700 to around 1000, the vibrations go away.

hm.

1000 rpm is a high idle. Does the roughness diminish in a linear fashion from 700 to 1000? What's the lowest rpm that is acceptable? Maybe you have a tach, maybe not.

What I'm thinking is how low can you go to get the idle to be smooth? I don't really care about the number, I guess. If it was my car, I'd do the stuff you're doing. But if I could not find anything, I'd rig some way to get the throttle to stay in a position that let it idle smoothly. If that meant using the adjustment screw on the throttle linkage, ok. If that meant bending a bracket to accomplish the same thing, ok. If that meant putting some kind of washer/spacer in the linkage, ok. Pressing eversolightly on the gas pedal while stopped would not be ok. Something like that.

Not to worry, I'm aware. I've made my suggestion and don't intend to pursue it, as I'm sure tw will have a solution.

I watched the engine for a while today. Can't find anything wrong. Motor mounts are fine. I used a flashlight and small mirror to look at all 4 of them very closely. Can't find any vacuum leaks. Don't see anything touching that would transmit vibrations. I listened to the injectors with a plastic pipe, and can hear them all clicking at the same speed and strength.

It sounds a little louder near the belts, and it's a throaty exhaust sound, but I can't find anything wrong with the exhaust other than a pinhole leak in the muffler that drips water. The hangers are fine.

Does this O2 sensor look right? This is a highway trip from about a month ago. I've got 4 charts from the trip.

Speed:

Attachment 41795

RPMs:

Attachment 41796

I think this is the O2 sensor up by the engine:

Attachment 41797

And I think this is the O2 sensor after the catalyst:

Attachment 41798

Shouldn't this second O2 sensor be pretty much flat? It's fluctuating almost as much as the first one.

There are no codes, and the check engine light is off.

That is about the point where an engine changes from its idle mode operation to normal mode operation. More accurately, point centers closer to 1200 RPM. Its not a sharp transistion. But at 1000 RPM, idle mode parameters are changing to normal operation mode.

What exactly is that point? Decelerate while not touching the accelerator. It begins entering idel mode when fuel injectors go from no operation (no fuel into the engine) to providing fuel for idle mode.

Idle for most cars is 800. But again, what determines that idle? Its computer times the engine by monitoring only the crankshaft or camshaft sensor. Computer only reads that sensor to adjust fuel for 700 (or 800 on most cars) RPM once the engine is warm.

Asking if 700 is too low is a valid question. Sometimes that spec number is on a label glued under the hood or attached to the door pillar (that label covered when the door closes). I have never seen a shop manual not provide that number even when no adjustment is possible. Since a wrong number could be symptoms of a specific problem.

Anything you might do to change idle will be compensated for by the computer. So if idle should be 800, well that would imply a master clock problem in the computer. And therefore might explain roughness only at idle only because the computer wants an idle that is too low.

Well, touch the accelerator to raise RPMs up to 800 may or may not report something useful. Says little by itself. But in combination with other facts, may imply a suspect.

An engine is constantly adjusting (ie short term fuel trim, timing advance) for changes you may not even realiize exist. View how stable your foot is by monitoring the throttle position with Carchip. Also see how much an engine changes with throttle and load variations (ie monitor manifold vacuum, timing advance). Simply approaching another vehicle means those parameters must vary significantly with less air flow resistance. An O2 sensor must detect changes so tiny that you do not even realize they exist. Those same changes would also appear after the catalytic converter.

O2 sensor is important during normal operation. Install a defective O2 sensor and see little to no idle mode change. Your gas mileage implies everything necessary for proper normal mode operaation (engine timing, spark advance, manifold air pressure, EGR valve operation, O2 sensor) is ideal. Concern is something different during idle mode.

For example, an EGR valve must open and adjust position during normal mode. Same EGR valve must be completely closed during idle. Same EGR valve acts completely different in the two operation modes. EGR valve could be leaking (defect during idle mode). But performs as a completely different device (100% functional during normal mode). IOW the same part has two completely different operation modes.

Your EGR tests said the EGR valve in both operation modes was OK.

O2 sensor says little during idle mode operation. O2 sensor is mostly about detecting minor changes in normal mode operation to cause minor adjustments to fuel injector fuel trim. Your mileage suggests fuel trim is just fine because an O2 sensor is accurately detecting minor changes such as your foot on the accelerator, minor change in road grade, air resistance due to the vehicle in front, etc.

How much must parameters change when you think everything is constant? Use CarChip to monitor thottle position, manifold vacuum, ignition timing advance, and short term fuel trim. Notice how much your engine changes when you think everything is constant. The O2 sensor, as Carchip shows, also reflects those variations.

Sensor readings and control adjustments vary much during normal mode operation. Those same sensors are typically irrelvant when in idle mode operation. During idle mode, a computer monitor a crank or cam sensor to measure engine speed. Then makes adjustments to the Idle Control Valve to maintain RPMs. Other sensors and control functions change little or are ignored. When entering idle mode, a part that does not operate or change during normal mode operation (Idle Control Valve) goes from doing nothing to doing the most.

Again, exhaust noise suggests no missing cylinders. A vacuum gauge would probably confirm that. 700 RPMs, although low for most cars, may or may not be too low for your engine.

We have avoided the Idle Control Valve. Nothing at this point suggests a problem exists there. However manually testing it for smooth operation (with fingers) might discover a minor problem. I seriously doubt it. But really, we are running out of suspect. And the 700 RPM number is slowly sounding relevant.

A most complicated operations occur during normal mode operation. What we have seen and what gas mileage confirms implies all those functions are OK. Idle roughness only at 700 RPMs involves many fewer sensors and parameters. O2 sensor typically is not on a list of idle mode suspects. An O2 sensor defect would be more apparent in normal mode operation. But everything we have seen implies the O2 sensor is just fine.

Don't remember if an answer was provided. Are the voltage limits for that O2 within specs defined by the shop manual? At one point I wondered if your O2 voltage variation was too much. If remembering correctly, you said it was OK.

When I checked the EGR valve, I could open and close it by sucking on the hose that goes to the diaphragm, but I couldn't see inside the valve to see if it was sealing properly when it slapped shut. Maybe there's a little grit keeping it from closing. I sprayed A LOT of carb cleaner in there so I think it's clean, but I can't know for sure. I suppose I could have tried somehow blowing through the exhaust channel to see if it was blocked. Even after cleaning, there's no way I'd want to press my lips against that surface.

That's why you kiss the ERG valve and just blow (or suck). Didn't they make a movie about that?

I have another car question. Yay!

This one is about a 2001 Toyota Camry.

We bought this car used about a year ago, and so don't know its history or what "normal" is for it. No idea if all proper maintenance had been performed because maintenance records are incomplete, but the car has fairly low miles (65k) still and it appears to be in pretty good shape.

Sometimes when driving on a highway at steady speed, I would notice a very very slight fluctuation in engine power. Kind of like a stuttering. But so minor, that I thought it might perhaps be my imagination. Except I was sure it was actually there. This has been going on for the past 3-4 months very intermittently. We buy brand name gas. This stuttering was not a big deal, because is was barely noticeable, and others in the car didn't even notice it.

Last weekend, after driving on highways for about 2 hours on our way to the beach, we got to a surface street and had to stop for a light. When it was time to go again, the car wouldn't move. And the check engine light was on! After a moment of panic, I realized the car had stalled, but I hadn't heard the engine stop because the radio was so loud. The check engine and a couple other lights were on, but went off when I restarted the car. It started fine. We continued on our way.

We had about 15 more miles to travel to our hotel, and the car was sputtering intermittently the entire way. It stalled two more times, in spite of my efforts shifting into neutral and giving it some gas as we stopped at lights. The last time it stalled, it started back up again and behaved perfectly normally for the last mile or so to the hotel.

Driving it the next few days at the beach, it behaved perfectly normally.

On the 3 hour drive back home, it behaved perfectly normally.

I tinkered with it in the driveway at home and it behaved perfectly normally the entire time.

the clues:
-There is no check engine light on, and no diagnostic codes. I assume this means the spark plugs are firing, because I think the computer would report no spark.

-It behaved a lot like a lawn mower running out of gas. Except the tank was 3/4 full when it stalled.

-The repair manual says that when you turn the ignition key to the "on" position, you should hear the fuel pump whirring for about two seconds, and then it will turn off. When I turn the key to the "on" position, the fuel pump does not run. The fuel pump doesn't begin running until I turn it to "start."

-I checked the fuses and relays that the manual said I should check, and they appear to be fine. One relay check was only a partial check though, but I swapped it with an identical relay for the horn and the horn still worked and the pump still didn't.

-I pulled out the back seat and checked the voltage at the connector to the gas pump when the key was turned to "on." It had battery voltage at one conductor and 5 volts at another. The manual didn't say what it should have.

-I saw a creepy little spider crawling around on top of the gas tank when I opened the hatch under the back seat to look at the fuel pump connector. How long had that guy been there?


So do I just go ahead and replace the fuel pump? They cost like $200 for the part, and there's also some whirlygig contraption next to them that controls them and I don't know what they cost, but they look expensive and complicated.

I also noticed that there is no little metal flap on the gas tank opening on this car. Every other car I've had has one of those little flaps under the gas cap. Could that flap have fallen into the tank and blocked something? Or didn't this car have one?

Possible. Next time it does this, slam on the brakes good and hard, if that's the problem, it should clear up, for a while.

I'd start a fuel pump/fuel filter replacement fund, anyway.

Also, you might go to an Autozone, and have them check your ignition coil(s). My local Autozone does this for free. They might can tell you what those voltages you spoke of at the tank are supposed to read, too.

Also, too, FWIW Momdigr's LeSabre did not show a 'check engine' or 'something's f'ed up' light with a dead miss/no fire at the plug.

Voltage to the pump typically should be 12 volts. No reason to put an expensive 12 volt to 5 volt regulator on pump power. So why is it only 5 volts?

I saw this once on another car. One transistor would not properly conduct in rare cases when it got warm. So the car would not start until that transistor cooled. Then works fine. Later I heard of a service bulletin for this problem.

That is but one example. Many reasons could explain this. But only 5 volts on what should be 12 volts is enough to concentrate on that symptom. To go further or say more requires electrical diagrams. Generally $40 from the only company that sells these books (Amazon apparently is not permitted to compete.)

All cars start same. When a switch is first placed on, then the fuel pump operates for a few seconds. You must be in a quiet area to hear it. In your case, it probably works most of the time but maybe does not work when something is too warm or has some other environmental change after long operation.

Moving on to other symptoms. For your problem to create a check engine light, you may have to aggravate the problem on multiple and consecutive restarts. For example, after each restart and when the engine is hot, floor it. Find some place (ie steep hill) to do this so that the engine demands full fuel. You may not feel a problem. But the check engine computer does. If you restart the engine only once without doing this, then you must repeat this test all over again.

A check engine light for this particular fault only lights when the same problem has been seen at least two or more times consecutively (after each restart). This problem would only be seen by a check engine light when the pump is taxed (full flow). If you restart the engine once and do not tax that pump, then the check engine light zeros its counter.

!2 volts to power the pump, 5 volts to operate the gage, ground to chassis.

Makes sense.

The pump not running for two seconds when the ignition key is turned to "on" is an actual observed problem. But I don't know if it's the same problem that caused the car to stall. If I track down the pump running problem and fix it, I have to wonder if that will also keep it from stalling.

I think I may need to research the ignition switch and test that next. I wonder if a problem with the switch is causing the pump to not run for those two seconds.

Meanwhile, the car runs fine on errands around town.

The couple of seconds of pump action is to bring the fuel pressure up to the range the fuel injection needs, before it even bothers to turn the engine. If it thinks it has pressure it won't start the pump.

Depends. Only some vehicles monitor pump pressure. Often a two second (on some longer) pump action is only by a time delay relay or something equivalent. Without those schematics, nobody can say anything more.

If problems exist as suspected, then the 'floor it with each restart' test is essential so that the check engine system (light) can report what is defective and intermittent.

I don't see lots of other important facts such as amount of gas in the tank, engine temperature, battery voltages (ie lights changing intensity, a check of all battery cables for a loose connection, etc)

Of course you can call into Car Talk on NPR every Saturday and Sunday. They may even sell you a voodoo doll on the shameless commerce division of Cartalk.com to keep away evil spirits. That sometimes works.

When it stalled, the tank was at 3/4, and the engine was hot from driving two hours. The battery terminals are clean, and look tight, but I didn't try to move them or tighten them more. That's another thing to double check. I don't remember the battery voltage. A little under 12 volts, I think, but the engine was turned off then. The voltage would probably be higher with the alternator running.

This car's computer does not report fuel pressure. I tried checking it with my CarChip pro data logger but there was nothing to record. It has no dashboard fuel pressure gauge either. I wish it did.

I'm going to take another look at it this weekend when I get some time. Meanwhile, it's driving normally.

Voltage must be above 13 volts when running; over 12 volts when engine is not. CarChip can report this voltage.

However that voltage would not explain your problems. A loose battery connector would explain problems. Better mechanics always disconnect the battery when doing work. Sometimes attach the cable but forget to tighten it. So high temperatures longer (ie 2 hours) means the connection is not as firm.

Wouldn't the radio have cut out if the battery cable was loose? And it stalled at a traffic light while the car was perfectly still. Doesn't matter. It's an easy thing to double check.

I wouldn't associate any of that with your problem(s).

I'd focus on the fuel system.

Just sayin'.

**********************

Remember the seventies? :rolleyes: If your car didn't work right, it was a fuel/air/fire issue.

Nowadays, if it don't go, it could literally be one, or more, of 75-100 different things.

it is still about fuel/air/fire, as long as we're talking about internal combustion engines.

...

however...

when the fire is sent, when the fuel is sent, how much fuel is sent, the control of the air (via variable valve timing), those kinds of things are MUCH MORE strictly controlled, and affected by MANY, MANY MORE factors that didn't used to be considered. Those factors are evaluated by VASTLY MORE sensors, and that means lots and lots and lots more points of failure.

Yeah there's about twelve dozen electronic fuck-ups that can leave ya hoofin.

No for at least three reasons. Current required to maintain engine operation means voltage can drop too low to maintain the engine. Current required to keep the radio running would be so small as to not cause the same voltage drop. Radio will also operate for a short period of no power without interruption.

Of course that means the cable is loose only to the point that is it disconnecting (partially) with higher temperatures. However, by the time this question was posted, that suspect could have been identified or eliminated. This suspect only discussed to demonstrate how many more reasons could create your symptoms.

Suspects are not limited to fuel. Also as likely are problems with the ignition system. Or with a MAP. Significant number of suspects quickly diminish if the problem trips a check engine light. If you cannot, that also diminishes the number of suspects.

What's the resistance value for "continuity" in a relay? The manual says to check for continuity, but the meter reads 0.9 ohms when I test the meter by touching its leads, and reads 118 ohms when testing the relay's prongs. When I apply battery power to those same prongs, I hear the relay click, and the other set of relay prongs go from no continuity to 0.9 ohms. Seems like it's working, but I'd expect "continuity" to have a far lower value.

By the way, I checked the battery cable, and it felt secure, but I was able to tighten it up considerable. There's a little rubber gasket between the two sides of the clamp, and it barely squeezed before. I tightened it up until the gasket was bulging a bit.

Tried to get the check engine light to come on by driving hard, including up a hill. But it's still off.

The only thing I've found wrong is the fuel pump doesn't come on for two seconds when key turned to "on."

Less than .9 ohms. :eek: A fingerprint will give you .9 ohms, that's nothing. Sounds like the relay is cool.

Homeland security saw you were speeding and punished you by sending a signal on skynet for your car to hiccup, you know, just to scare you a little. ;)

Sounds like at this point, without throwing a ton of money at it, or making it a possibly fruitless quest, you'll have to wait for a solid failure, or at least less intermittent symptoms.

As far as the pump not giving you that two seconds, it doesn't matter as long as it's starting right up when asked.

Not the right thread, but maybe the car guru's can help me...

Each year I spray our metal heat register covers with a "refresh" coat of black paint.
This year, I used a can from last year.

The problem:
The paint on two covers are still sticky after overnight "drying" in the house.
The paint does not transfer to my hand or paper, but I'm concerned that
walking on the register may end up tracking paint onto the floors.

Any suggestions for hardening the paint now instead of later ?

Hair dryer? Coat o' clear?

Will it fit in the oven? A gas oven can be moist at low temps, but an electric would be good. Set it for 175

Thanks Griff and Glatt.
I tried the oven thing overnight and things are much improved
... still a little tacky, but it looks like it will be OK after the house heat has been on for a while.

Same issue with the car today for about 10 minutes. Then it got better.



Never stalled, but almost did.

Fuel.

It's so bizarre that it's intermittent. It's running perfectly now. If I took it to a mechanic, I wouldn't be able to show them the problem.

My first thought was a dirty fuel filter, but I wouldn't expect that to get better.

You could show someone familiar with that type of car the video clip. They may have previous experience with that syndrome, or at least a clue where to look.

Pfffft. Fuel filter could easily be intermittent. Do you think the crud the filter collects is uniformly fine and uniformly distributed? Unlikely. It could easily be mostly crapped up, but still have a small passage for the fuel. Then with the vibration of the engine shake loose some crud opening a wider path for the fuel.

Seriously, why not just SHOTGUN the situation and replace the fuel filter? (you're welcome tw). Worst case, you have a new filter and twenty fewer bucks. Or, it could fix or ameliorate the symptoms.

Plus tw will berate you.

Ok. I have obtained a fuel filter. And I should have time tomorrow afternoon to install it. We need an oil change too, so I'll do that at the same time.

He is gonna blow his top.

Quick, put on your safety glasses.

If a fuel filter is clogged, the problem is easily identified so that an intermittent no longer exists. Simply remove the filter and blow through it. Flow would be obvious restricted. Or backwash the filter with a solvent. Either means you know if a problem was or was not solved. Since you have a new filter, then blowing through the old and new filter will make any restriction obvious.

Shotgunning did not find the problem. Leaving you unsure if anything was fixed.

Or the entire fuel system could be tested without replacing or buying anything. Shop manuals may state how many pints a fuel pump will pump in a specific time. Then the pump, intake filter (inside the gas tank), pipe, check valves, and in-line filter are all verified as a complete system. IOW a problem is known solved because the problem was first seen before corrected.

Concept was taught in CSI: "Follow the evidence".

If I go through the hassle of taking off the old filter (it's buried behind a lot of stuff) then I'm definitely going to replace it with the new one. The filter is cheap.

This car has 60k miles on it. The manual says filters should be changed every 30k. It should be on its 3rd filter by now. I don't know if it's ever been changed, but I doubt the previous owner changed it just before unloading it.

Glatt, was the vehicle doing that 'surging' thing by itself, or was someone moving the throttle? Assuming it was happening without throttle input, could the throttle position sensor cause such a thing?

It was doing it by itself. It would almost stall, and then the computer would give it more gas to prevent the stall. And then it would stop giving it more gas, and the cycle would repeat.

I just finished installing the fuel filter. And now it's idling a bit fast. Haven't driven it around yet, so that might just be the cold start, fast idle mode. It was a bit of a pain. Had to remove the air cleaner assembly and half a dozen vacuum hoses and sensor cables to get at the thing. Frankly, I'm pretty proud that I got it all back together and working with no leftover parts.

I would change gas filters, air filters, PCV valve, and spark plugs as recommended. Eventually learned that was mostly unnecessary. But again, if a filter is the problem then blowing through it would make the problem obvious.

Eventually I stopped replacing spark plugs, washed the PCV valve in a solvent, banged the air filter on asphalt to clean it, and never replaced a fuel filter.

Generally, idle is not controlled by the throttle (as that picture shows). An IAV does idle air adjustments (a problem discussed with Cloud? when a Honda that mechanics refused to solve it until another mechanic was used). To say more requires facts from the shop manual.

How to eliminate fuel as a suspect was defined. Air leaks might be found by using vice grips to restrict any hose the manifold. Learning how to examine the EGR valve as a suspect would be useful. Just a few of so many suspects (maybe 50) can create an unstable idle; best identified rather than replacing (shot gunning).

I have long forgotten what is the car, what all symptoms are, what was tried, etc. However you have learned from reading the shop manual how many suspects are on the perp list. A list so long that shotgunning can get expensive.

Pictures are always fun.

This is what it looks like when I start to replace the fuel filter. You can't even see the damn thing, but it's down there.
Attachment 45855

When I lean in a little closer, you can see the banjo bolt at the top of the guy under there. There is no way I can get my hand in there, even from below, to remove the thing. Well, maybe from below, but the last thing I want is a face full of dripping gasoline when I open the fuel lines.

So here's the filter, and what I need to remove to get to it.
Attachment 45856

Here it is, with the entire air assembly removed, and half a dozen hoses and cables detached to be able to get to it. Notice I put blue masking tape on everything and numbered them so I could keep track of where it all goes when I put it back.
Attachment 45857

And look at all the room I have to work with now! I actually had to halfway remove the bracket holding the thing so that I could get the lower (rigid) fuel line to align with the new filter.

Attachment 45858

It was all pretty straightforward, but took about two hours, including getting all the tools out and putting everything away again.

We're waiting for the denouement.. did you fix it ?

Beats me. I replaced the fuel filter. Didn't take a picture of the new one. The pictures were for reassembly reference and not so much for sharing on the Cellar. That was just a bonus.

It was an intermittent problem that went almost exactly a month between showing up the last two times. We'll see if it happens again between now and Thanksgiving.

You've neglected to mention, but, uh, ahem - is this car a female, by any chance?:eyebrow:

An answer is simple and immediate. Blow through the old filter. Is it restricted? If not, then it did not solve the problem.

Oh, yeah. There was more resistance blowing through the old filter, but it wasn't dramatic.

So a new fuel filter did not solve anything. An original and still 'wet with fuel' filter might explain a slight restriction. It would not explain fuel restrictions during idle.

Imagine what happens when the car was actually demanding much fuel. Idle demands little. Heavy acceleration requires plenty of fuel. The engine would obviously stumble and almost stall on acceleration if that filter had any relevant obstruction (was dirty).

An intermittent problem can be created by many things that exist constantly. For example, if a fuel pump pressure was slightly low, then the car would work normally almost all the time; only have intermittent stumbling.

The EGR valve would not move smoothly. But the car would work normally almost every time - just not in the rare time when the EGR valve intermittently stuck. Move the valve by hand to feel the restriction that only rarely gets stuck. Unfortunately intermittents not reported by the computer can be this difficult to locate.

Distributor vacuum advance and retard motion can also be intermittent. In one case, I discovered that intermittent was created by grease on those moving parts that had become sticky with age. It always existed. And was located by physically moving the part by hand. The sticky grease always existed. But the resulting bad performance only occurred rarely and without any one common action making it happen. Intermittents are that nasty to find when computer diagnostics do not report them.

As you recall, shop manual provides a list of suspects that are numerous.

BTW, the engine is almost two completely different engines when in idle and when moving the car. Many parts do completely different operations in those two modes. Another way to eliminate suspects from that list. That was the case in cloud's IAV failure. Only the 'idle' engine was failing. The 'moving the car' engine worked just fine.

Two months without a problem. Convinced the fuel filter fixed it. Then it was doing the same sputtering today that it was doing before. No time to trouble shoot or look at it. Got to my destination. Shut it off for about 5 minutes, and it's been working fine since then. Such a weird intermittent problem. But it's fine now, so *shrug*.

I guess I know now why the previous owner parted with this used car.

Try writing down all the conditions/details you can come up with each time it happens.

-how long you have been driving it
-distance
-time of day
-amount of fuel
-engine temp
-ambient temp

Maybe you'll see a pattern that hasn't emerged just yet.