ok. I have been reading thru a ton of post and cant seem to find the answer im looking for. About a year ago I bought a 99 civic ex with 145000 miles. Once I got home I started actually run it alil bit and it would fall on its face at like 5k rpms. So I guted the cat and everything has been fine for the last 10k miles. Noe all of a sudden its idle is up and down between 1k-2k, and sometimes it stays at 2k. Ive cleaned and then changed the iacv but that hasnt helpd. I was recently told a gutted cat could mess up the o2 and cause this. Can anybody confirm this. Could the downstream o2 cause the up an down idle Thanks

 

What CEL is being thrown?

 

I had advance auto check it but he didnt tell me the code. I didnt know there was so many different o2sensor codes. I know it was o2 malfunction bank 1 sensor 2 but not the code number. But ive had that code for a year, ever since I gutted the cat. I cant figure out why all of a sudden the idle is going crazy.

 

How To Retrieve Check Engine Light (CEL) Codes/List of OBD1 CEL Codes

 

Absolutely not

 

^+2.... Upstream O2 sensors are the only thing that effect A/F (the ones before the cat), downstream O2s are 100% solely for telling the computer if your cat is working correctly, and obviously you gutted yours, hence the Bank 1 Sensor 2 malfunction code.

 

Thats what I was think. That the 2nd o2 was just for the cat. I have a friend with the same year car that is lettin me try some parts to try to find the problem. We switched iacv and map sensors and that didnt help. I wana try switching tps sensors next. But if I put it off his car and switch to mine will it need to be recalibrated. Im not sure how to do that if its needed. if it needs to be done can some post a link to a how to. Ever how to I find the pics dont work anymore.

 

Switch over the whole throttle body. To take off a Honda TPS, you have to unbolt the TB anyway. No need to recalibrate with the whole TB unit swap.

Also, retrieve your own code(s) and find out what's wrong instead of blindly throwing parts at it. Also, have you checked coolant level? The IAC and other things rely on a steady stream of coolant. Air bubbles cause funny idles.

You do need to pull codes, though, to make sure the secondary O2 sensor one is the only code because like other people said...downstream O2 sensors are just there as monitors for cat operation.

 

ok. I will try to get the codes later on today. When checking the codes with the check engine light how do you check if its more than one code. Also can i swap throttle bodies without having to buy us both new gaskets. Thanks

 

Read the CEL sticky at the top.

 

Don't be silly. You will need new gaskets as they will likely rip apart when TB is removed.