Hi folks,
First off, mustang67408 -thanks for taking the time to maintain such a great wealth of information. it is people like you who are willing to share information which makes the Internet a fantastic tool.
I have used this site to fix my problem and wanted to reply indicating my symptoms and build to what is already here so that perhaps it will help other people even more.
I have 2001 Echo, 65,000kms, 2nd owner, automatic. Car gave consistent 41mpg with mix of city/hwy (mostly hwy) for the last 10,000kms I have owned it. About 4 weeks ago gas mileage dropped to 35Mpg and I noticed a bit of sluggishness when leaving a stop light or when getting onto the highway on an on ramp with moderate to hard accelerator depression. Then a check engine code got set on a rainy night as soon as I got on the highway above 80kms. The check engine then went off by itself after about 2 weeks. then 1 day it started stalling when you leave a stop light. sometimes when it wouldn't stall, it would bog so badly you thought it had stalled. as a test a few times I pushed the gas to the floor and the car barely moved. it was like it was only firing on 1 cylinder or running out of gas. it would start and idle fine even during this period. I found your site and read about the MAF sensor requiring a cleaning. I took mine out and I thought the heat sensor (2 wires that have a bulb at the end which joins them) was what you were talking about. My heat sensor was so dirty there was a dirt bridge from the sensor to the housing. I cleaned it and reassembled. took it out on the highway and at highway speed it almost felt like the transmission was shifting funny (rougher, wrong gear). This was not noticed before the heat sensor was cleaned. Also, the check engine light returned as soon as I got on the highway and exceeded 80km/h. I borrowed a code reader and found a P code lean O2 sensor (thought I wrote down the code but can't find any record-> think it was a P171 but can't remember -> although I am 100% certain it was a lean O2 code). My code reader (Auto Enginuity ScanTool) could not clear the code so I pulled the battery terminal for about 10 mins. That cleared the check engine light. I drove it back on the highway again, still worked strange and stalled/bogged from a stop but check engine did not reset. Checked the Idle air control (IAC) valve using this process:
• Key off (unenergized), the valve was 1/3 open
• Coolant temp sensor disconnected from wiring harness, key on, the valve was 2/3 open and vibrating (could only sense the vibration when I would touch a very fine screw driver to the valve and I could hear it vibrating against the screwdriver)
I didn't know if this was expected for the IAC... so I came back on this forum and re-read a bunch of posts. they all talk about the "2 wires" of the MAF and some posts say how fragile they are... well... from what I recalled, I had already cleaned 2 wires but they did not seem fragile to me. so I checked other sites and found one (
Sorensonbrian) that shows the MAF sensor is not easily visible unless you know where to look and have a flashlight. I checked again and sure enough I did have some fuzz on these wires - and they are VERY fragile. I cleaned them with electronic parts cleaner and reassembled. I cleared the computer again and then took for a test drive - perfect. After 1 full tank, back to 41.5MPG!
For the sake of completeness, the only other problem that I have had (4 months ago) is a P440 code related to the charcoal canister that got set when I thought I would put in more gas after the pump clicked off the first time when filling it up. These cars DO NOT want you to fill up the whole filler tube or I think gas leaks into the canister. The code got set and eventually went out on its own after 5 months. Funny enough, it went out after the car was idling for 20 mins when we were digging it out of a snow bank. I never idle my car except at stop lights so perhaps there is something during an extended idle cycle that causes it to recheck that circuit or perhaps you need to idle a long time to draw the extra gas out of the canister. I am not sure if the fuel in the canister (my assumption of the problem) just eventually evaporated but this is my assumption.
Again, thanks for all your efforts and I hope the long novel I wrote has added more information to assist others.