I just did a swap on my 99 accord ex same engine H23A4. This car runs fine before my swap except the knocking in the bottom end thats why I did my swap.

But now I have an annoying problem, the surges up and down. Giving me P0122 and P0505 codes. I read a lot of threads about it seems like its a problem of honda. But did it end up like that well in fact it was just fine before the swap nothing modified or change...

 

the dreaded honda idle problem. i have a surging problem too. only once its warmed up to operating temp

 

Your IACV is acting up

 

Yah the IACV is not that cheap to replace too. I tried to clean it but still the same...it throws me code P0122 the throttle valve too....

 

If cleaning doesnt help then you gotta replace it. no other way around

 

I have a surgin idle problem right now. 2001 Accord EX V6 coupe - 191K miles. A friend and I took apart the manifold to do the infamous EGR valve port cleaning, as the car was throwing the code for it. Once it was all back together (with new gaskets) the idle wasn't right. It surges up and down between 750-2000 rpms...otherwise, it'll just run a high idle until it's warm....then it surges.

Now it's throwing the P0122 code with the new idle surge. This is a mystery, as we just took apart the manifold/trottle body, cleaned the port, then put it back together. I had to go out of town, so my friend had the code read, saw TPS, and went ahead and replaced the TPS with an aftermarket for $45. Problem is, it's still throwing the same code. Took it to a shop who wanted to replace the throttle body. I declined and thanked him for the free advice. Any ideas what is going on here? Would it possibly be the IACV? I heard that the TPSs rarely go bad. Wouldn't it then give me a code for the IACV if that was the issue?

Any help is appreciated!!

 

I have a 1994 civic and it doesn't idle surge unless its cold and on the second start of the day. Once it warms up it goes to 1000 rpms and there's no problems with it. But when its cold its urges from 1 to 2000 what problem could I be dealing with