I picked up a beautiful Silver EX sedan 5mt last month, one owner and dealer maintained. 228,xxx miles. Runs perfect and looks nearly perfect. I noticed a rusted out air duct clamp where it connects to throttle body. Clamp was rusted through and broken. So I disconnect two electrical connectors and pull off air duct. I spray brake clean on a rag and wipe out throttle body while I'm in there. I reinstall duct and snap connectors back in place. Start my car and it starts surging. 1000-2000 over and over. What could I possibly have done? I also own a 97 Ex 5 spd that I had a surge problem earlier this year and fixed that with a new gasket so I have been through this before. I'm pulling my freaking hair out because of this. Idle relearn procedure? Thanks in advance

 

I have had this happen due to a small vacuum leak. Check if you have knocked loose any small hoses near where you were working. If not you can also try spraying TB cleaner around the area to see if you can produce a change in idle indicating a vacuum leak. Only try spraying on a cold engine.

 

Thank you for the reply. I picked up a IACV gasket from Honda today and will do a thorough search for missing vacuum lines before taking IAC off and cleaning.

 

Well, not that anyone but sona1111 is interested, I pulled the IACV and cleaned with Simple Green and brake clean. Finished it off with compressed air and reinstalled with new Honda gasket. No change. Still bouncing between 1000-2000 rpm. Does anybody have a good test for IACV before I pay $188 at Honda for a new one? I don't know what else it could be.

 

Oh and I bled coolant by opening radiator cap and overflow cap until fans came on which took nearly twenty minutes to come on.

 

I had a 2003 and while it never had the surging problem, I do remember from the shop manual that you cannot "reboot" the idle control system by pulling the battery or a fuse. It uses non-volatile memory where earlier cars could be reset by pulling a fuse.

 

Hi jaxflex,

(anyone correct me if I am wrong, I have only worked on older hondas so this may not be the correct method anymore)

With the cleaner your goal is not to clean, you are looking for vacuum leak which could be caused by a loose / cracked hose which is very hard to see. Basically you start the engine (when it is fully cold, for safety) and just spray the cleaner all around the wide area where you worked. all over the vacuum hose connections etc. What you are looking for is a place where you spray it, and the idle drops (or raises). This is an easy way to find a small vacuum leak which in my experience has caused surges like this. (though for me it was usually between TB and manifold gasket somewhere)

Let me know if you have tried this.

 

Sorry sona, yes this was the first thing I tried after it happened. I might not have said it, my mistake. This is so mind blowing because Last year I put a reman head, did timing belt and water pump and all related vtech and leaking gaskets on my 97 with great success. To replace a hose clamp and cause an issue is deflating to say the least.

 

Did you unplug any of the sensors in that picture?

 

Yes I did. To remove air duct I removed electrical connector from air duct and what I believe is the TPS on the side of throttle body. Once I put on new clamp I reconnected both connectors. Surging started immediately after doing this work. Next day I sprayed brake cleaner on vacuum connections and any openings on air duct and throttle body with no changes in rpm. 48 hrs ago I removed and cleaned IAC with Simple green, then brake cleaner and blew out with compressed air. Installed new IAC gasket from Honda dealer. No change. Would an idle relearn procedure fix a problem like this. I'm talking about the hold at 3000 rpm for 5 mins procedure after starting. Also I did not remove negative battery cable before I initially unplugged connectors and changed clamp. Are there any good ways to test IAC? I dont want to throw parts at it but changing the IAC is the only thing I can think to do. Thanks