What is the best way to adjust the idle rpm of this engine? What is the recommended idle rpm??

Thanks.

 

Anyone?

 

Don't touch the idle screw, it was set at the factory at that point for a reason. If you have a high or surging idle fix that first.
We usually idle around 750rpm.

 

I would like a higher idle rpm to reduce my hydrocarbons at low speed.

 

Not passing emissions?

 

I have been passing, but only by a hair. I want some distance from the cutoff point. It is only low speed HCs that is a problem. High speed - no problem. If my idle were higher, then it would solve the emission test problem. I wish that I knew how to solve the problem otherwise.

 

How about replacing you cat if it's fairly old.

 

Yes, it may be the original cat converter. I would change it in a minute if I knew that it would solve the problem. Otherwise, the car seems to be running fine.

 

What is the ignition timing set at? If you have excessive hydrocarbons, the ignition timing may be out of spec causing an incomplete burn.

 

I am not sure what the timing is set at - but if it were not set right, wouldn't the high rpm produce high HC as well?

Here are the latest numbers:

RPM @2613
HC = 81 (200 is limit)
CO = .35 (1.2 is limit)
CO2 = 14
O2 = .62

RPM @910
HC + 192 (200 is limit)
CO =.18 (1.2 is limit)
CO2 = 14
O2 = .72

-----------------------------
Two years ago, right after an engine rebuild, I got the following:

RPM @2444
HC = 79 (200 is limit)
CO = .55 (1.2 is limit)
CO2 = 14.2

RPM @1005
HC + 100 (200 is limit)
CO =.17 (1.2 is limit)
CO2 = 14.9
---------------------------------
I was expecting after a rebuilt motor to have excellent results. But the high HC at low rpm was a surprise. Before rebuild I had similar numbers. If rpm here is lower (e.g. 925), then the number is much worse.