Engine runs fine after ECU reset, poorly shorty after

[Zachccccc]

This all started when I pulled off the highway and noticed the brakes surging. The cause being the engine revving to what can be guessed as 900-1300 RPM. Pulled into my apartment, and stopped the car put it in Park. Noticed that the car revved high still, turned the engine off and restarted it. Upon restart it idled pretty rough, but was idling low.
Went to advanced auto and got them to run codes, threw a
P0301, 302, 303, 304. Misfire on all 4 cylinders ! In addition to a a VVT code that got thrown.
So I opted to replace my plugs in hopes that was the issue. Replaced the plugs, with the battery disconnected to do an ECU reset. Started up and everything seemed to run normal. No rough idle no random revving.
Drove 3.2 miles to get food for my roommate who helped me replace the plugs, stopped the car at the Taco Bell car ran fine no revving or rough idle. Started fine as well drove back to my apartment 3.4 miles.
Ran fine until I got into my parking lot and the revving came back in addition to the rough idle.

So it's not a mechanical issue as it ran fine on the reset ECU, it's a sensor issue making the ECU 'learn' improperly.
What do you all think ? I'm leaning toward MAF sensor but I dunno the VVT code seems to make me think it could be the VVT solenoid ? But would a VVT solenoid effect the learning and make me misfire across all 4?
I'm in a 2001 Echo so the 1nz-fe

[tmontague]

was the drive belt changed recently? Usually the vvt solenoid never dies unless it is physically damaged (commonly by leveraging against it when changing the drive belt).

That being said I'm not aware of a bad vvt solenoid causing a misfire. It's not likely that it is the coil packs since it's all 4. Not too sure what else it could be other than a bad/dirty maf or bad vacuum leak (that said it would've thrown a lean code if it was a vacuum leak).

Can you check fuel trims using a obd reader?

[Zachccccc]

was the drive belt changed recently? Usually the vvt solenoid never dies unless it is physically damaged (commonly by leveraging against it when changing the drive belt).

That being said I'm not aware of a bad vvt solenoid causing a misfire. It's not likely that it is the coil packs since it's all 4. Not too sure what else it could be other than a bad/dirty maf or bad vacuum leak (that said it would've thrown a lean code if it was a vacuum leak).

Can you check fuel trims using a obd reader?
Nah the drive belt wasn't changed. I think the VVT code was secondary to the actual issue. Maybe the faulty something goofed up the VVT ? But I dunno.

I'm going to try and clean the MAF tonight and see if that doesn't fix the problem. If not the next step will be buying a new MAF :frown:

I don't personally own an obd reader, so I can't check unfortunately.
Any other checks for a vacuum leak ?

[tmontague]

I wouldn't go spending money on a new MAF if you aren't sure it's the problem. They're costly and a waste if that isn't the issue. That cash is better spent on a code reader.

The other way to check for a vacuum leak is to light a stick of incense and with you car running and in an area with no wind (open garage works) move the stick around the intake manifold and vacuum hoses. You are looking if the smoke that comes off of the incense stick is being pulled into any of the intake plumbing.

I find this way a bit more sensitive than spraying carb cleaner on the enigne and hearing for a higher idle.

[Bluevitz-rs]

I would check your O2 sensor first. On that old of a car, it's possible that it's not reading full range an causing the car to run rich.

Has your millage been degrading at all?

[tmontague]

^this. I never thought about the O2 sensors but that's definitely a good point. You can use fuel trims (read from a code reader) to see if your running rich

[Zachccccc]

How would I go about checking the o2?
Just the fuel trim ?
I have noticed a slight decrease in mileage. But this issue seems to have come out of the blue it wasn't gradual.

[Bluevitz-rs]

You can check it with a volt meter back-probing the wire on the computer under the dash. Just stick a sewing needle into the back side of the pin as your probe.

a good O2 will sweep back and forth from roughly .050V-.900V holding the RPMs at about 2000.

[Zachccccc]

What pins should I check ? Is there a pinout somewhere ?

[Bluevitz-rs]

Actually you there should be a pin on the OBD connector you can use. I think it's a white wire.

[Zachccccc]

Alright well when I get back to my apartment I'm going to attempt to read the o2 with my voltmeter. If that is functioning properly test the vacuum using the incense method. If there doesn't seem to be any leaking get some MAF cleaner and see if cleaning fixes the issue.

So am I correct in thinking if it were a vacuum leak the engine would idle poorly even with a reset ECU ? I mean to say, the vacuum leak would occur and affect performance instantly because it is a mechanical fault. Where as my failure seems to be a sensor/ computer one, because the engine ran fine (idle was OK, started quickly, et cetera) for about 6 miles ~15 minutes then started to foul up.

[tmontague]

if this was a vacuum leak issue that was that bad to cause multiple misfires (don't even know if that can cause this) I would expect it to run bad even with a newly re set ecu. That being said moderate vacuum leaks in my experience (one that was about 15-18% and just under triggering a CEL) did not idle rough until the ecu completely reset after about 100km or so.

[Zachccccc]

Hmm. Hopefully its not a vacuum leak, those seem like a pain to find/diagnose. But I'm leaning toward MAF or O2 just because this issue seems to 'pop up' and not get gradually worse. I'm guessing the ECU is building a poor map after receiving faulty o2 readings. But then again, this is all guessing on my part. I appreciate your guy's help ! :biggrin:

[Zachccccc]

Quick question about the o2 sensor, isn't there just one that sits in the exhaust? (pre-cat) and you can see the connector under the shift linkage trim ?

Shown here
Toyota Nation - How to replace o2 sensor (http://www.toyotanation.com/forum/26-yaris-scion-ia-vitz-echo-forum/474769-toyota-echo-oxygen-sensor-change-diy-due-po141.html)

Another question about testing
http://farm9.staticflickr.com/8105/8522264193_32a451e01c_z.jpg

It says the o2 should be heated to 68F if it's ~40F here how would I achieve 68F on the sensor ?


My bad on the double post, should have edited !

[tmontague]

The pre cat O2 sensor is an AFR sensor (wideband), the post cat is a typical short band O2 sensor.

I believe Blue vits is referring to the primary AFR sensor, but you may as well check both.

[Zachccccc]

Where is the primary located ?
What I linked is the post cat correct?


*Edit http://ww2.justanswer.com/uploads/Dr/drivefast1971/2013-02-21_180131_3.gif
Nevermind those two questions


I also threw a 420 code, but that's just an emissions thing. That wouldn't cause the mis-fires would it ?
I'm full of questions
http://media4.popsugar-assets.com/files/2014/04/23/212/n/4852708/8cf80ccc92488109_28-smiling-face-with-open-mouth-and-cold-sweat.xxxlarge/i/We-think-Happy-inexplicably-sweaty.jpg

[Bluevitz-rs]

The pre cat O2 sensor is an AFR sensor (wideband), the post cat is a typical short band O2 sensor.

I believe Blue vits is referring to the primary AFR sensor, but you may as well check both.

The primary is NOT an AFR on an Echo. It is an O2 sensor.



And yes the post Cat O2 Sensor will influence the long term fuel trim.

The primary is before that Cat. It is connected in the engine bay. The connector is mounted to the rear engine mount and is a PITA to disconnect. The secondary O2 is the one connected under the shifter.

[tmontague]

^thanks for the correction, forgot the op had an'01 Echo

[Bluevitz-rs]

Where is the primary located ?
What I linked is the post cat correct?


*Edit http://ww2.justanswer.com/uploads/Dr/drivefast1971/2013-02-21_180131_3.gif
Nevermind those two questions


I also threw a 420 code, but that's just an emissions thing. That wouldn't cause the mis-fires would it ?
I'm full of questions
http://media4.popsugar-assets.com/files/2014/04/23/212/n/4852708/8cf80ccc92488109_28-smiling-face-with-open-mouth-and-cold-sweat.xxxlarge/i/We-think-Happy-inexplicably-sweaty.jpg


Actually the misfire is probably what caused the 420 code.

It's actually crazy how far out the readings on the sensors can be screwing with other components and not set a code.

[Zachccccc]

The primary is NOT an AFR on an Echo. It is an O2 sensor.



And yes the post Cat O2 Sensor will influence the long term fuel trim.

The primary is before that Cat. It is connected in the engine bay. The connector is mounted to the rear engine mount and is a PITA to disconnect. The secondary O2 is the one connected under the shifter.

So to test the Primary do the voltmeter pin check and it should oscillate from .4-.9v ?
I'm still not certain which pin to test the white one on the OBD ?

How would one go about replacing that sensor if it is bad, any tips/tricks ?

Also, are there tests that can be done to diagnose a bad MAF?

Actually the misfire is probably what caused the 420 code.
It's actually crazy how far out the readings on the sensors can be screwing with other components and not set a code.
Oh, ok gotcha !

[tmontague]

The P0420 code is a cta efficiency error, either your cta is clogged from the misfires or something else. I'm not sure if this could cause multiple misfires you're experiencing maybe Bluevitz can chime in on that

*EDIT, looks like he beat me to it :D

[Bluevitz-rs]

Ok, just checked and there's no O2 wire on your OBD port, it's only available on Conector C Pin 16 on the ECU. It is a white wire. Pin 13 is also white, but is the knock sensor.

The reading should oscillate from .050V - .900V

So in other words, within 1V. It should swing back and forth if you hold the revs at about 2000. If it's not going all the way up and all the way down, the sensor is shot.

Mine was reading 0.100-0.550V and no code we set but my millage was getting bad and I had a rougher idle. My fuel trims where shooting up to +23% at idle. Changed the sensor and started getting 100km more per tank and the idle smoothed out a bit.

edit: for reference, low voltage is a lean reading and high voltage is a rich reading on an O2 sensor. If the sensor is only showing the ECU half way up the scale it'll think its too lean and start increasing the fuel trims. It can get to the point that it's so rich it's flooding the engine and fouling up the cat. Another indicator can be a rotten egg smell from the exhaust.

[tmontague]

Ok, just checked and there's no O2 wire on your OBD port, it's only available on Conector C Pin 16 on the ECU. It is a white wire. Pin 13 is also white, but is the knock sensor.

The reading should oscillate from .050V - .900V

So in other words, within 1V. It should swing back and forth if you hold the revs at about 2000. If it's not going all the way up and all the way down, the sensor is shot.

Mine was reading 0.100-0.550V and no code we set but my millage was getting bad and I had a rougher idle. My fuel trims where shooting up to +23% at idle. Changed the sensor and started getting 100km more per tank and the idle smoothed out a bit.

edit: for reference, low voltage is a lean reading and high voltage is a rich reading on an O2 sensor. If the sensor is only showing the ECU half way up the scale it'll think its too lean and start increasing the fuel trims. It can get to the point that it's so rich it's flooding the engine and fouling up the cat. Another indicator can be a rotten egg smell from the exhaust.

Does the primary or secondary O2 sensor tend to wear out quicker?

[Bluevitz-rs]

Does the primary or secondary O2 sensor tend to wear out quicker?

One shouldn't be any more susceptible to wear than the other. With that said, the primary has a lot more influence on the AFR than the Sub, so it can be noticed easier than a failing Sub sensor. The Sub's main job is to monitor the Cat's efficiency.

[nortonfb]

An easy check for a air leak is to spray WD40. If your idle picks up you have a leak.
Check when you are having the problem, sometimes heat causes the expansion to cause the leak.

[tmontague]

^although it'll work it is messy as he'll, there's no way i'm spraying that on my baby!

[Zachccccc]

An easy check for a air leak is to spray WD40. If your idle picks up you have a leak.
Check when you are having the problem, sometimes heat causes the expansion to cause the leak.

The heat expansion is very true. Noticed that my car idled fine when I got home from work. Went to drive in circles with a friend to test heats effects. Turns out when it gets warm the issue arises. Let the engine cool in a parking lot and drove off issue cleared up. So the issue wasn't resolved by resetting the ecu as I originally thought; it was letting the engine cool.

So I'm thinking now its a leaking gasket somewhere, what do you all think ?

Also I will check my o2 tomorrow with the voltmeter thanks for the pin information and general o2 information bluevitz ! :)

[tmontague]

Check the O2 sensors to rule them out. And then invest in a scan tool that does readings as well. You'l thank yourself down the road and it'll easily pay for itself.

Use fuel trims to check for a vacuum leak. Just Google fuel trims or use the search function on the forum and info will pop up

[Zachccccc]

Turns out it was my VVT solenoid, it would keep the car in really advanced timing after heating up causing the issues.

[Bluevitz-rs]

Yeah that would do it. Was it clogged or something? I've never head of the solenoid failing other than it getter broken.

Did someone perform an active test on it to confirm.


Sent from my iPod Touch

[Zachccccc]

Yeah that would do it. Was it clogged or something? I've never head of the solenoid failing other than it getter broken.

Did someone perform an active test on it to confirm.


Sent from my iPod Touch
Apologies on the slow response,
Y'know I didn't really think to ask. I took it to a shop because uni was starting and I didn't have the time. My guess was it was gunked up because, admittedly, I was embarrassingly behind on my oil change. I should have asked for the old part back :x
But then again the car drives much much better, so it would seem the solenoid had been having issues beforehand.