Download the helm manual already! You are asking very basic questions and the answers are in the pdf. You've got broadband, don't you?
I will read this thread for a while longer because I enjoy the entertainment. You newbies (and you should know who you are) don't seem to have a clue how to work on a car and shouldn't be doing so in the first place. There, I said it. I feel better now.
Sorry, but this is the truth.
I went from knowing nothing about Hondas a little over 5 years ago, to now being able to do a motor swap in under a few hours.... I read the Honda paper manual I had all the way through, and read countless online ones just to get a basic knowledge I needed before even touching the cars. (And cars are just a hobby and part-time job for me, not a career.) This is a first step you really must take or you will be consistently ripped-off by every mechanic you go to. Owning an older car and not being car-smart is a bad bad bad idea....even if it is a Honda.
On the never-ending quest for better gas mileage...
I have six cars. If I took them all to a mechanic, I wouldn't be able to afford keeping/maintaining and modding them.
ECU is pretty much plug and play. If you are mechanically inclined, I don't think you will have a problem removing and installing a new ECU. The hardest part is probably pulling the connectors from the ECU as they are locked.
If you don't have the right tools, simple removal and install of components end up being a major task. Through the years, I've bought so many tools I'd say I spent a few grands... everytime I work on my car, I usually have the right tools and it's such a satisfying feeling to be able to fix your own car and save hundreds (if not thousands) of dollar. I even make money doing this on the side. A friend told me Lexus was going to charge her close to $2k to change the timing belt and a few other things. I told her I'll do it for half and made a few hundred bucks. I'm so car crazy I even bought a four post car lift! My family think I'm a bit overboard ...
When I bought the VX, they really thought I went crazy, but after gas went over $3.50 (this is CA) gallon last year, they realize I'm not crazy afterall.
Curious, why did you buy an ECU for your car in the first place?
It is advertised as an L1H1, but right below it says "L1H1 Equivalent". Perhaps I should just bite the bullet and buy a genuine L1H1 sensor. If I'm
going to do this CA to 49-state VX conversion, I won't want to be debugging
O2 sensor issues.
I got a new ECU because the mechanic said that was probably the cause of the fast idle. He said when he hooked up his fancy $7000 computer to my ECU, my engine RPMs weren't being read by his computer, and so that led him to think the ECU was faulty. My tachometer works just fine tho, so I dunno.
Umm... what are the right tools for removing the ECU then? I have 10mm socket, which I believe is needed to remove the bolts. But what about connectors?
Another development with my Check engine light. Soo... I started the car up this brisk morning, and the CEL came on about one minute later. I then did an engine off coast about eight or nine minutes later. Bump start, and CEL didn't come back on. But, then I stopped at the bank. When I came back to my car about five minutes later, I started it up and the CEL did NOT come back on. I drove to school with no CEL. I did one more EOC toward the end of my commute about 30 minutes later, something I have confirmed causes the CEL to turn off.
Another thing. In the Haynes manual, it says that the 48 code has to do with the heat sensor of the o2 sensor, or something like that. So maybe once the car is warm the CEL does not come on? But why, then, doesn't it turn off once the car is warmed up? It only turns off if I turn the car off and then start it again. If I don't turn the car off, the CEL will stay on. If I turn the car off and then 5 minutes later turn it on again via key start, or moments later (no more than say two minutes) then it doesn't come back on. I have a feeling this has nothing to do with whether I'm bump starting or not, but whether the engine has cooled sufficiently for the CEL to come on, which then makes me ask, why is the CEL only coming on when the engine is cool? If I turn the car off, eat dinner and come back 20-30 minutes later, then it comes on a couple minutes after I start the car. Anyway, I will attempt the ECU replacement today. Should I reset the ECU before I change it? Might this take care of the CEL?
What does anyone think about my CEL behavior?
Also, the commute this morning, the idle wasn't nearly as high as it has been the last couple days with the new o2 sensor. The first day it was pretty high - around 1300 maybe even 1400. Yesterday it seemed maybe slightly lower (probably because I bump started, which tends to keep the idle from going as high once that is done) Also, last two days it's been bouncing from 1000 to 1250 or so. Today it just kinda stayed at 1000-900 the whole trip. Maybe 1050, or max 1100 for very short period. Mostly only about 1000. So I thought that was kind of peculiar. Anyway, I'm still hoping my o2 sensor isn't bad and maybe a new ECU or resetting the ECU will fix the problem. I'll be sure to keep ya all updated. Thanks again to everyone for all the info and advice.
The Helm's manual is $20 to purchase online. Someone on Ebay is selling it for $6 on CD. So I may buy that. But I have to wait for some money to get back in to my bank account first.
Hey J! Why buy, it's free online! It's a great manual - the bible for our cars.
If you want, I can try to find the link for you so you can download it.
About the CEL light. It looks like during the initial startup, ecu senses something not
right and sets a flag which is only reset when ignition is off. Once you turn it on again, ecu again checks o2 sensor but by then everything is ok (o2 warmed up).
So once on, o2 sensor light will not turn off unless ignition is off. Just a guess.
Perhaps ecu is checking the resistance of the heater circuit when cold. When cold the resistance is different than when the heater is HOT. The cold value of the heater is different than the OEM. When heater is hot, it checks out ok. Might want to check this out.
If something is wrong with the heater for the o2 sensor, it is the same thing as the o2 sensor being bad, since the heater is incorporated as part of the o2 sensor.
The CEL coming on in the cluster doesn't really matter though, and is only there to remind you to check the code stored in the ecu. The ecu should store the code until you reset the ecu (by pulling the fuse or the battery terminal).
It might seem promising that the light isnt on all the time and that the idle is one way or the other, but in reality, that is normal even if the problem still exists (which it still does when the cel is not on, it just isnt telling you then).
The reality is that something is probably wrong.
To be sure if something is wrong, first reset the ecu to maybe clear a code that was left from the last sensor. Do this by pulling the fuse under the hood for the ecu, or by pulling the negative battery terminal.
If the CEL comes back, then troubleshoot the problem.
On the never-ending quest for better gas mileage...