Rough running when cold

[mikester]

Okay, I had the Cat reinstalled for my smog check and intended to leave it on because that's the way I am. With the bypass in the car ran great - with the cat - when the engine is cold I get a lot of backfiring.

5 minutes of running and it's normal but in that 5 minutes - it's really running crappy between idle and 2k rpm.

I don't think it should be this bad - Alex at P-tech tuned if for the CAT and said it might backfire a little but this is more than a little.

Dare I ask - it this normal?

Thanks

[ischmitz]

Hm,
is your cold-start enrichment working? There is a microswitch on the throttle body that needs to engage in idle. With the engine off you'll hear a click whenever you move the throttle off idle. That's the switch.

I don't see why one would adjust CIS different for a cat or no cat. And besides that backfiring is burning fuel in the exhaust. That should be more pronounced (louder) with the bypass and muffled out with the cat in place. But hey, I am by no means a specialist when it comes to CIS.

Ingo

[mikester]

Well, I'll tell you what. I was having a problem with the pop off valve popping out because the glue wasn't holding it in. So - I reglued it this afternoon. The wife and I went for a little drive up and down the beach just now and it didn't backfire when I started it up at all. It had been sitting for a few hours and was quite cool too. I wonder if sealing up that valve helped out some.

I had hypothesized that it might to myself....Anyway - I'll try it cold again in the morning and listen for that "click" as well.

Thanks!