264/272 cams and high hydrocarbons

[jpolizo]

I put HKS 264/272 cams in my 2G and was hopeful that it would pass smog as long as I showed up with an innocent looking face. The car actually runs very well with just a bit of a lope. When they put it on the smog machine, though, it was blowing 1000 on the hydrocarbon test which is out of range.

Are the cams doing this or is something else screwed up? I've searched around and found varying opinions on cams blowing smog but the 264/272 seemed conservative enough to make it. I haven't found anything specific that says a 272 exhaust cam will raise hydrocarbons that high.

Any suggestions?

 

[CPHunter]

try checking for a weak spark, check timing. losts of things throw it off. HC emissions from a vehicle are basically unburned fuel. High levels of HC emissions indicate incomplete fuel combustion, either the result of a misfire or of low engine compression.

 

[Spln_Hrd]

try checking for a weak spark, check timing. losts of things throw it off. HC emissions from a vehicle are basically unburned fuel. High levels of HC emissions indicate incomplete fuel combustion, either the result of a misfire or of low engine compression.

He is right, I would like to add that it can indicate rich a/f mixtures as well.

 

[jpolizo]

Interesting. This is kind of what I was wondering about; I hate to go around chasing wild geese. I can switch back to the stock cam but it's a pain if that's not the problem.

Sounds like back to basics; make sure all the simple things work.

Good advice!

Many thanks!

 

[jpolizo]

I went through everything again and found that the plugs I used (Iridium) were fouled with what looked like a bit of oil on the two outboard cylinders (1 and 4). So I threw those out and went back to good old NGK copper plugs, put in a new set of Magnecor wires and replaced the coils in the coil pack.

So, I go in to get smogged and they do a pretest. HC is down to 68 which is way better than the 1000 it was the first time. Then, they run the real test and the stupid thing pops up to 397 and I get nailed as a "gross polluter". The smog guy was totally blown away and said he'd never seen that before. He asked "did somebody put cams in that or something, the idle is kind of weird". Everything else, like CO, CO2, and O2 is fine and it checks out perfectly at 2500rpm; it's just the low rpm that it fails.

I'm coming to the conclusion that this must be the cams but I really don't want to replace them if that's not the problem because it is a pain in the behind as we all know.

Any ideas? I am getting a bit discouraged.

 

[95AWD_TSI_TALON]

I know this is old but for $hits an grins you should just bump your idle up a tid bit for going through. If the idle is a bit high, might fix the problem and will also take away the slight lope sound that the would hear. Just a thought.
Matt