Any Toyota techs in the house? 2000 echo stubborn misfire codes

I was helping my friend with a problem on his wife's 2000 echo yesterday and ran into a problem that's confusing me. It has 140k miles and less than great maintenance. We couldn't get straight answer from her about how long it's running badly or when the CEL came on.

It ran like poo and had several fault codes, a couple for evap related stuff, that I think was caused by a cracked hose near the purge solenoid (easy fix) a several misfire and fuel trim codes. I should have written them all down, but didn't. they were lost due to having the battery out to clean up corroded terminals.

We changed the plugs, all were dark and kind of sooty, #1 was really nasty.

The new plugs made barely any difference at all.

Now it's giving a p0300 (general misfire) and p0301 (cyl 1 misfire) idles awful and bogs until at about 2000 RPM. Swapping coils made no difference, and all seem to be working. The injectors seem to be working, each cyl drops out as that injector is disconnected.

Using the Torque(light) app, I can see that both O2 sensors are giving output, the MAF sensor, coolant temp and TPS all seem OK. The rubber duct from the MAF to the TB is not cracked or loose.

My gut is telling me it is too lean, but the new plugs were a bit wet and clearly smelled of unburnt gas when pulled back out.

I didn't have all my stuff, so I wasn't able to get a compression test.

I've heard that VVTI Toyota's can have all sorts of drivability issues and fault codes when the solenoid fails, but can they fail and not trip a VVTI code?

There were not catalytic converter codes, but could it still have a plugged cat? The fact that it runs better at high RPM makes me doubt a clogged cat, along with lack of p0420 code.

What else should I be looking at on this? Thanks.

Dirty air cleaner/critter nest in air box?

In reply to outasite:

None of the above

Black plugs mean the computer is seeing a lean running engine. It's dumping fuel to bring it back inline to "normal".

I have no idea how Toyota vtec works but it seems like a likely place to start.

I run it like its stolen and see if it clears up. I suspect stuck rings if it's been running that rich for possibly that long...

Idle air control valve/motor?

What is the MAF reading at idle? In grams/second.

It should be higher than 3.

Toyota MAFs are bad for getting gunky and respond well to a good cleaning.

I'm unfamilar with the Echo's engine, if it is coil on plug then swap the #1 coil and see if the fault moves. Did you inspect the old spark plugs' porcelain (on the outside) for carbon tracking? If a plug has carbon tracks, you need to put new wires/boots on since the spark will still arc down the boot. Probably wreck the new plug, too.

Try pulling the codes again. It does kinda sound like the VVTi may be having "issues." It runs fine way up on top, right? Just down low it runs like crap? If the mechanism was all gunked up and stuck, I think that might do it. Don't know how to check for that. The computer is only going to throw a code for that if the valve itself is disconnected electrically. You might try disconnecting the valve and seeing if there is any difference in the way it drives.

What does the LTT (long term trim, it will be in the live data) number look like? I bet it's positive (correction in the rich direction) and pretty high. I'd suspect a relevant sensor fault (O2, airflow, temperature) somewhere falsely screaming that things are lean.

Knurled wrote: What is the MAF reading at idle? In grams/second. It should be higher than 3. I'm unfamilar with the Echo's engine, if it is coil on plug then swap the #1 coil and see if the fault moves. Did you inspect the old spark plugs' porcelain (on the outside) for carbon tracking? If a plug has carbon tracks, you need to put new wires/boots on since the spark will still arc down the boot. Probably wreck the new plug, too.

IIRC, the MAF reading was 2. something. A lower number means it's under measuring air mass, right?

That would result in a rich condition.

It does have COP ignition, I did swap coils around and nothing changed. I did not check for carbon tracking, I'll have to add that to my check lust for the future .

In reply to BrokenYugo:

Yes, I want to change the O2 sensors anyway, just because they are old, still factory parts.

Leaky injectors?

Our GS300 was running rough at idle and wanting to bog down and stall at low RPMs. It turned out to be a bad VVTi oil control valve. The valve was sticky and the oil filter for it (small stainless mesh screen) was plugged. Cleaning the filter helped but then it got worse again. Replacing the valve fixed it 100%.

It was throwing a VVTi solenoid code, though. I don't know if it's possible for it to be bad and not throw a code. You can try unplugging the solenoid to see if it makes a difference. If there's no difference, then your solenoid is stuck.

I've also seen where people will tap on them with a hammer and the idle will smooth out. Didn't work on mine - mine must have been really stuck.

You can bench test the solenoid (remove it and apply 12vdc on your workbench to see if it moves), but mine passed that test despite definitely being bad.

In reply to HappyAndy:

You do a quick and dirty diag for a whacky upstream O2 by unplugging it, resetting the computer(disconnect battery), and going for a drive. They'll gradually start to read lean after 100k or so, but I've seen one go full batE36 M3 crazy before at like 120k and make the car useless with it plugged in.

HappyAndy wrote:

Knurled wrote: What is the MAF reading at idle? In grams/second. It should be higher than 3. I'm unfamilar with the Echo's engine, if it is coil on plug then swap the #1 coil and see if the fault moves. Did you inspect the old spark plugs' porcelain (on the outside) for carbon tracking? If a plug has carbon tracks, you need to put new wires/boots on since the spark will still arc down the boot. Probably wreck the new plug, too.

IIRC, the MAF reading was 2. something. A lower number means it's under measuring air mass, right? That would result in a rich condition. It does have COP ignition, I did swap coils around and nothing changed. I did not check for carbon tracking, I'll have to add that to my check lust for the future .

A lower number than it should be means it is measuring low flow. Either due to a dirty MAF, or a vacuum leak/false air. It could also be due to cam timing being way off but IME the idle mechanism will crank up the airflow to compensate. It takes a given amount of air to idle, generally in the 3.5-6.0g/s range depending on engine size and idle speed.

Either way, fuel trims are going to get cranked up way positive.

Now, the fun part is, you can't look at fuel trims if it is actively misfiring, because a dead cylinder will pump the exhaust full of oxygen and if the computer is running in closed loop, it will also start dumping all kinds of fuel for that reason. Fords have historically been really bad for this because they are really bad at misfire detection. A computer should kick out into open loop if a misfire is occurring.

try cleaning the MAF, when I first got my echo it ran poorly at low rpm also. I cleaned the MAF and changed the PCV and it ran great afterwards. also a common problem is the Oil control valve, which works the VVTi

Before you do anything else, pull the intake boot. Toyotas and Hondas were notorious for the rubber rotting and getting a big split in the bellows. Chances are its on the bottom of the boot near the engine end.

That causes almost all of what you describe. The vacuum leak means the MAF says its getting 2 lbs of air but the O2 sensors are reading 4 lbs worth coming out. At idle it makes misfires and wet plugs. When you open the throttle, the MAF is reading 6 lbs of air, but the engine is actually getting 12 lbs, hence the lean bog.

Knurled wrote:

HappyAndy wrote:

Knurled wrote: What is the MAF reading at idle? In grams/second. It should be higher than 3. I'm unfamilar with the Echo's engine, if it is coil on plug then swap the #1 coil and see if the fault moves. Did you inspect the old spark plugs' porcelain (on the outside) for carbon tracking? If a plug has carbon tracks, you need to put new wires/boots on since the spark will still arc down the boot. Probably wreck the new plug, too.

IIRC, the MAF reading was 2. something. A lower number means it's under measuring air mass, right? That would result in a rich condition. It does have COP ignition, I did swap coils around and nothing changed. I did not check for carbon tracking, I'll have to add that to my check lust for the future .

A lower number than it should be means it is measuring low flow. Either due to a dirty MAF, or a vacuum leak/false air. It could also be due to cam timing being way off but IME the idle mechanism will crank up the airflow to compensate. It takes a given amount of air to idle, generally in the 3.5-6.0g/s range depending on engine size and idle speed. Either way, fuel trims are going to get cranked up way positive. Now, the fun part is, you can't look at fuel trims if it is actively misfiring, because a dead cylinder will pump the exhaust full of oxygen and if the computer is running in closed loop, it will also start dumping all kinds of fuel for that reason. Fords have historically been really bad for this because they are really bad at misfire detection. A computer *should* kick out into open loop if a misfire is occurring.

MAF reading after cleaning the sensor is 3.5-3.8 G/S. The reading responds quicker to revving the engine too, but it still idles badly.

Double checked the air duct, no tears at all.

Removed the VVTI valve filter screen, it was dirty, by not what I would call plugged. The VVTI solenoid won't come out. So instead of risking breaking it, I'll wait till I get a new one and just replace it.

In the mean time I'll try disconnecting the upstream O2.

The MAF's idle reading is now sane. One problem down, at least one more to go.

Is it idling generally rough or is it a dead miss?

Now that the MAF is reading correctly, go on and re-clear the computer and see how it do. It probably will be running horribly rich until it can go into closed loop again and re-correct itself, otherwise. Do not disconnect the O2 as it will never go into closed loop (obviously) and it will just be going off of its learned long term fuel trims, which will be massively high due to the previously dirty MAF.

Hmm, after it warmed up the MAF reading dropped to 1.8 - 2.2 G/S.

I couldn't get the O2 sensor disconnected, and I found the springs on the exhaust pipe to manifold bolts were both broken. Doesn't sound like an exhaust leak, but it's one more thing that needs to be fixed.

Ooooh, you gotta fix that, too. Exhaust leaks upstream of or very close to an O2 sensor absolutely can and will wreak havoc...

I was back at it with this hoopdie this afternoon.

If fought me with everything that it had.

I decided to start with the VVTI solenoid because it was the easiest to get to.

The stupid thing snapped off as soon as I yanked on it. The valve body was absolutely stuck fast in the cyl head. I pulled the valve cover off to see if could push it out from the inside, and found that the small part of the valve that is visible was split open.

First I tried an easy-out to try to get the valve body to spin out, but it wouldn't spin, and thanks to the super soft aluminum that the body was made from, I think I made things worse.

I spent the next three hours cracking the valve body apart from the inside out with a sharp thin chisel. I don't yet know if I'm brilliant or a butcher. I'll go back tomorrow and clean out the crumbs. I managed not to gouge housing in the cyl head, so I have that going for me at least.

Since the valve had a crack in it, I'm hopeful that this will solve the problem, as long as i get all the metal chips out.

Sometimes we have to get through these repairs through force of will alone. Just remember the truth, "there is no spoon,"

Or, rather, remember it's supposed to be fun. ;)

Alright, VVTI seems to be operational, car still isn't quite right.

It was a whole lot happier (but not perfect) after the O2 sensors were replaced. The exhaust manifold to pipe mounts broke the rest of the way when I touched them, so it's definitely leaking and effecting the sensor reading now.

I'm going to tell my friend to have that fixed at an exhaust shop, ive already gone way above and beyond the call of a beer money repair.

Could a partially clogged oil filter cause a VVTI malfunction? The oil warning light wasn't coming on, but after an oil and filter change it's noticeably better. I know the idiot light is not the most accurate device, and before the oil change the engine the engine had run about 3-4 seconds to make the light go out from a cold start up, now with fresh oil& filter, it goes out before the engine lights off.

If it matters, the old filter was a generic jobber filter, new filter is a Denso. The old oil was looking pretty used up, but at the proper level.