New to the boards so please don't eat me.

I got a '91 Accord that I just rebuilt the head on after the timing belt broke. Ran great for about a month afterwards then it started to surge and carry on when it idles. It's really bad when it's cold out.

I think it's either a vaccum leak or the timing is still out a few degrees. I was wondering if anyone might have an idea for something that is a common problem.

 

I haven't had experience with this luckily, but I would say it's a vacuum leak. Start with the PCV valve and run your finger over the hose to see you can find any areas that have a suction on them. That's all I know to do at the moment.

 

I would agree with it being an intake leak. Many hondas that have an intake leak, will surge from about 1,000 rpm to about 2,000 rpms or more, and do this about once every 3 seconds or so. Since your cylider head was recently replaced, check around closely to see if any vacuum lines are loose or cracked. If no lines are damaged or loose, its possible an intake gasket may have developed a leak and will require further inspection. It is definatly a common problem, and I have had this problem with my 91 accord a few times after working under the hood, and forgetting to reconnect a vacuum line.

 

Check the coolant level in the radiator (not the overflow bottle).

 

x2 On checking your coolant and bleeding it if necessary.

Then read the Accord FAQ's and look for a post on IACV and FITV cleaning. It sounds like if your not dealing with a vacuum leak or low coolant. then it is more than likely your Fast Idle Thermal Valve (FIT).

Vacuum leaks, air bubbles in your coolant, the FITV & IACV are all well known causes for a hunting/surging idle.

 

x3
also check the coolant in the radiator as Targa250R said

 

Wow, didn't expect this many response this soon.

Replaced the IACV and FITV when it first started surging. Never would have thought to check the coolant level though.