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I have a USA Toyota Echo 2003 Sedan (1.5L 4-cyl. 4-speed Automatic). It’s been extremely reliable, never had any major problems. I believe it’s at around 130,000 miles. I’ve kept up on the maintenance, oil changes, etc. I replaced the spark plugs a year ago. Not because of any symptoms, just because it was time. I’m not a mechanic, just enjoy learning new things and doing it myself, to the bitter end.
The car has been having problems with very rough idle, for about a week, no problems prior. The whole car shudders. When I put the car into neutral or park, it settles down. When I accelerate, it goes fast enough, just sounds slightly rough until it gets going. It has never failed to start, and has never stopped running.
The problem doesn’t consistently happen. When it’s ok, it’s all ok for the entire drive, no issues at all. And I have established a pattern. When the car has been sitting a while, it always starts fine. After that, it runs good, even for long distances. I can drive it all the way to work (16 miles) without any issues. The issue occurs when making a series of short trips. From home to the first stop is good. The issue begins when I start it back up, and happens all the way home.
So here’s what I’ve figured out so far:
When it first happened, I wanted to see what error it was trying to throw, so I took it to an auto parts store to read the OBD code. It had P0136. I researched that a bunch. That means the post-cat O2 sensor was reporting low voltage for a period of time.
I hooked up a multimeter to the O2 sensor. The O2 sensor has 4 wires. 2 black wires are for the heater element, and those showed exactly the resistance they should. I connected the positive lead to the sensor wire and negative lead to an exposed screw (vehicle ground). I did this by wrapping a thin wire around the male pin of the sensor wire and plugging it back in. So I am getting a voltage reading from the O2 sensor at the same time it’s connected to the car.
When the vehicle is acting GOOD, it has the usual voltage between 0.1 and 0.9. It does fluctuate a bit, especially at first. I understand it has to warm up. Seems stable after that, usually stays around 0.8. Every now and then it drops under 0.1 but vehicle still drives fine. After I parked and shutdown the engine I watched fascinated as the voltage slowly dropped from 0.8 down to 0.04, at a rate of around 0.01 volts per second. Like the exhaust gas was slowly dissipating.
When the vehicle is acting BAD, I have found the voltage stays at anywhere from -0.02 to +0.04. It never rises any higher than that.
I have read in various places that the post-cat O2 sensor is only to monitor the catalytic converter and has no influence on the running engine. So if the sensor is just going bad, why would the car have any other symptoms? What other problem could cause the O2 sensor to bottom out like that? I found http://www.bimmerforums.com/forum/showthread.php?1519895-Do-post-cat-o2-sensors-affect-fuel-trim which does indicate it could have an impact.
Based on this, I’m planning to replace the O2 sensor asap. Seems doable. Just wanted to seek some input. I’m concerned it could be something else.
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Fascinating. There is no 12V on the heater wires. Thank you!! I think we’re getting somewhere.
I said the wires were black, they’re actually white. In the interest of documentation for the world at large, the two top-most white wires are for the heater element. On mine the O2 sensor showed 14.4 ohms. It should be between 11 and 16 ohms to be good. The one black wire is signal, and the one gray wire is ground.
I checked my connections. The same connections where I just checked the resistance, I checked voltage (of course with everything plugged back in and car started) and no voltage.
This makes sense. Correct me if I’m wrong. When you first start the car, the sensor gets ignored because the computer knows it needs time to heat up. After a while the computer figures it’s heated up long enough and starts using it to trim the engine fuel mix. With short trips the sensor doesn’t get enough heat from the exhaust to start working, but on the highway there’s plenty of heat so it doesn’t matter.
So maybe it just doesn’t turn on the voltage right away, so I’ll monitor it on the way to work. If still no voltage, I’ll jiggle some wires. Maybe I could jump the o2 sensor into the cigarette lighter, at least temporarily? Taking any and all risks of electrocution and/or permanent catastrophic damage into my own hands of course.
You know what’s weird that I just thought of. Years ago the lighting on the gear shift went out. That’s the same area where the o2 sensor connection is at. For a while I could punch it and it’d come back on, but that stopped working and it’s been just out for a few years. I wonder if this could be related.
Apparently the 12V doesn’t start until you actually start driving. It was about 13V all the way to work. So it’s time to get dirty and in the zone tomorrow.
[quote=”casualcoder” post=178059]Apparently the 12V doesn’t start until you actually start driving. It was about 13V all the way to work. So it’s time to get dirty and in the zone tomorrow.[/quote]
Your either losing connection or the heater element is going bad. Hopefully its the o2 and not the wiring.
Even though you ohmed the heater in the o2 and it checks out the element/ heater may not be staying
at the right temp.The heater inside could be hanging on by a thread and the ohms will still read correct.
Keep us posted on your progress.Here’s how it went down today. I would call it good fun.
I had autozone read the OBD again just because I was wondering if the same code would be there. It had P0302 this time, which is too many misfires on cylinder 2. I suppose I’ll start with the O2 sensor assuming that was the root cause, disconnect the battery to reset when done, but definitely appreciate any input. When I replaced the spark plugs a year ago, I did not replace the ignition coils. Might be time to do that?
The O2 sensor was pretty difficult to get off, but with the help of a piece of dry ice and a proper wrench it relented. I had to read the numbers from it because there were two options. I have the right one sitting here now. I’ll put it on tomorrow. After reading a few debates about crimp vs solder, I have decided to crimp even though it doesn’t actually make scientific sense to me. I’ll crimp, then smother it in shrink wrap, lol.
When I was looking closely at the old O2 sensor, I noticed wedged into one of the gaps was a chip of something. So I’m also concerned about the catalytic converter.
Successful day. I wired up and installed the new O2 sensor. I noticed the old one had no crimping at all. It was four pristine wires from sensor to connector. The crimping doctrine looks more dubious now but I crimped anyway.
The voltage looked like it should. It stayed at greater than 0.8 most of the time. Does that probably mean the catalytic converter is ok?
I took it for a drive and it ran fine. It’s too soon to say for sure since I only stopped and started one time, but it idles ok so far. It did shudder for a few moments driving down the road, so I think I might just get some ignition coils, online.
There are a few simple ways to test the catalytic converter. Is there a rotting egg smell? Raise the car safely after its cooled off. Knock on the cat firmly, as in knocking on the door. Did you hear a rattling inside it? If so, the cat is definitely bad.
Thank you. I did tap the cat a few times with a rubber mallet, and it said, “dong, dong”. No rattling. So it’s probably good. I thought I might have smelled rotten eggs but it’s gone now.
I still have the CEL on, even after I reset. It came back on during the drive to work. So I removed the coils. I tested resistance, they all have the same ohms. I removed the second spark plug to check it (assuming they’re numbered left to right, the internet told me). It was a little caked with a thin layer of white substance. I cleaned it off with alcohol and blew compressed air at it, to see if it helps. And put it back in with some fresh anti-seize. I also swapped coils 1 and 2 for troubleshooting purposes.
The engine is caked with the goop of 130,000 miles, so there’s some cleaning I’ll going to (carefully) do.
The rough idling is definitely fixed by replacing the O2 sensor. I think I still need to keep at it and consider what could be going wrong upstream that may have messed it up. Thank you everyone for the help.
The code that was read was P0302. That is a misfire on cylinder 2. I swapped 1 and 2 ignition coils so that if it does happen again I’ll see if it jumps cylinders. However, I was just assuming that it was the same code when the CEL came back on. Silly, but I didn’t actually have it re-checked. I ordered a bluetooth ODB2 reader. I had no idea something so awesome could be only $20. Not here yet.
Today I cleaned the MAF sensor (with MAF cleaner), the throttle body (with throttle body cleaner), and the PCV valve (throttle body cleaner). Before I cleaned it, the throttle body did scrape slightly when I turned it. Now it’s smooth. No symptoms or CEL yet, but it’s too soon to tell. All of it was really filthy. I’m pretty sure it’s never been cleaned. I am also planning to carefully clean the rest of the engine later. And I got some Auto-rx, not here yet.
The throttle body cleaning I just sprayed up in there and wiped out with a rag. There’s a video online where someone removes it and the idle air control and washes it in a bucket. Not doing that, kinda scary and probably not necessary.
The filthiest part of the engine is this area around the “camshaft timing oil control valve”. It’s caked with oil. No telling when that happened because it’s never been cleaned. Is this goopy mess evidence of something to be concerned about, like a leak? I noticed that the oil is at half full. It needs an oil change anyway, will be doing that asap.
I got the OBDII reader today. Good tool to have. And the code that keeps coming back is……
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P0037 – They Are All Gonna Laugh At You.
Actually, it means HO2S Heater Control Circuit Low. Because I forgot to plug in the sensor connector. 😳
No other codes so I think it’s fine. It runs perfectly now. I just changed the oil and put in the Autorx sludge cleaner. Still going to carefully clean the crap off the outside of the engine later. Thanks everyone for the help. I think case closed.
That was a pleasure to read 🙂 Just for the record, I’ve had good results with the Gumout multi-system tune up. Not a monthly additive, but seemed to condition some relatively small issues I was having with my engine before an oil change. Glad you got your problem solved. And by the way, I forgot about the Toyota Echo! The Nissan Versa is probably happy Toyota pulled that from their line, woot woot :cheer:
I wanted to post an update, to provide closure, document for the internet, etc.
It started doing the same thing again. It would drive fine after sitting for a long time, then after warmed up and stopped/started it would drive rough. The code that kept coming back was P0302, misfire on cylinder 2. I did clean the engine (so much easier to see stuff now). And added fuel injection cleaner.
Then one day it wouldn’t start back up after I drove a short way and parked. It turned over and felt like it might start but never got past the hump. So I replaced spark plugs on the spot after letting it cool. It drove like it was new again. It felt like a race car, really. I think over time I had become accustomed to the slowly decreasing performance and it felt normal.
However, when I parked and started it again, it was back to misfiring exactly as before. Weird!! So I got to thinking, it has something to do with heat. I had tried to “reset” the problem by unplugging battery, and that made no difference, so definitely related to temperature. So I turned my attention to the fuel injectors. Cylinders 1, 3, and 4 tested exactly 13 ohms. Cylinder 2 was at about 200 ohms! When you add heat to a circuit, the resistance tends to increase.
So I replaced that fuel injector and cleaned up the others with brake parts cleaner. Those 13 year old o-rings disintegrated like they were made of olives. It was briefly, um, stimulating, seeing fuel gush from the engine. No harm done. Always replace any rubber/plastic parts when doing anything, I have learned. That repair went really well after getting new o-rings on. I lubricated the o-rings with new engine oil and ensured the area around the hole that leads into the cylinder was free of debris.
Replacing the #2 fuel injector has definitely solved all issues. It’s been driving in racecar-vroom-vroom mode for days. Short trips, long trips, hot, cold, this engine tears it up and just doesn’t give a shit. It starts instantly compared to what I had become used to.
I’m pretty sure that replacing the post-cat O2 sensor did something for the rough idle / misfire on short trips problem, because it did appear to be 100% solved for at least 2 weeks. I’m still not sure if there were two problems or just one problem that I misdiagnosed.
[quote=”casualcoder” post=180808]It’s been driving in racecar-vroom-vroom mode for days. Short trips, long trips, hot, cold, this engine tears it up and just doesn’t give a shit. It starts instantly compared to what I had become used to.[/quote]
Yeah, those Echos were surprisingly fun and competent little cars to drive. Glad you got yours sorted out.
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