Well, I just flunked smog for the 5th time and am running out of ideas. I'm close to passing but not quite there. CO and HC's at 2500 rpm are fine, I'm blowing clean, at Idle is where the problem is. I'm 2 to 3 time the normal limit on CO and a little over on HC's. I've swapped out my 72# injectors for the stock 24#er's and it cleaned up my 2500 rpm tests but did not help the idle. I used a BLM locker and set A/F at idle to 16:1 and it actually made it blow a little worse at idle.
I was thinking of retarding the timing at idle about 6* to see if that cleans it up, Any other ideas would be appreciated.
I have no vacuum leaks and the O'2's are fairly new, Car runs great except for this smog problem.

 

You check the cats yet? Pull off the exhaust and check 'em.

For a cat converter to work effectively, the air fuel must be at or near 14.7:1

 

Ed, I have a new cat on it and am going to take out the blm locker at idle because that made it worse and try retarding the timing, Whats strange is I've passed before with a not so smog friendly cam.

 

What cam you got in it?

Did you give the computer time to "learn" after swapping in the 24 pound injectors?

 

I had the cam ground to 228/236 510/525 113 LSA with 1.5 RR. I have run the car some with the 24# injectors, But maybe not enough. I'm taking it back in monday to try again, I just went over my programing and noticed I had the settings right for the BLM locker at idle for 16:1 A/F but it wasn't turned on so I'm going to try with the BLM locker on as it should work I hope.

 

Hey, good luck passing.

Post some smog numbers.

I'm not so crazy about running the car with a 16:1 ratio, that's seems too lean. It should be able to pass in closed loop, 14.7:1 or close to it.

One final thought, does that cam have a lot of overlap? If so, that is not beneficial to passing smog. I know the blower cam I just stuck in has only 2 deg of overlap.

 

We have figured out that the engine ( and headers ) need to be hot to lower HC. I have acheived a 59, 69 and 159 with stock fan settings and about 1/2 gallon of gas line dryer in the tank. Actually the 159 was with the fans sset at 230, it was way too hot, I think the temp guage read 245 at one point, stock seems best. We have retarded it to 8 or 10 but it was still logging around 13 at idle. I am up again for the sniffer next month. I am gonna try to pass with just the stock fan settings. BTW I have a gutted cat, no air, no egr.

 

where do you live? in bakersfield we only do a 2 speed test. not an idle test.

im kinda worried. ive never smogged since doing the hot cam with RR and the vortech SC. also, colder plugs, 160 stat, and fans programmed to kick on earlier.

ive heard about a product called "sure pass" or something like that. put it in the gas tank and it helps emissions. never seen it my self though.

jeremy

 

Well I just flunked smog again. I'm in the San Luis Obispo area , They don't put it on a dyno but I do have to pass at idle and at 2500 rpm HC's and CO. At 2500 it blows super clean Co and HC's. At idle I'm about 3 times over the limit, If I can just lean this POS at idle and get the CO down I think the HC's will come down with it. I'm not worried at running 16:1 at idle cause there isn't much happening at idle, But after locking the BLMs at idle I'm still running rich and the coolant temp was at 220*. As far as having the blower thats actually a plus when it comes to passing smog. I logged a run with datamaster and the O2's indicate rich at idle, there at about 600 to 700. I think I will try cleaning the MAF and do some more program changes, This is getting old, I gotta pass sooner or later i hope.

 

Lets get back to the basics for a second. Oil been changed lately? Plugs and wires in good shape? Check that the plugs are tight and wires arent burnt.

Adding alchol to the gas will get rid of some HC, try raising the temp a little higher. I have never had a problem with CO, so I am not sure what you are doing wrong, on my bros car, 83 olds cutty 350 plus cats, I created two small vacuum leaks that sent the CO from 5-6 to 0. Not sure how to do that on an LT1 though.

The granuteed to pass isn't really worth it. Any form of alchol will work just fine and its ALOT cheaper.

 

P.S. The only car locally that I havn't seen past is a 383 with a cam on a 106 or 108.

 

you can just add isopropal rubbing alcohol? how much?

 

Just changed oil 50 miles ago, Fairly new plug wires with protective kevlar boots. It has no miss, Car runs fine. As far as the alcholol, How much do you need to put in per gallon of gas? I've thought about creating a vacuum leak, But as I've said before this car should pass cause I've passed before with old motor with a less friendly smog cam with more overlap. I've had the engine temp up to 245* on one smog attempt with no luck.

 

I tried the CNC "Guaranteed to Pass" fluid and it brought my number from 49 up to 52. They won't double my money cause i have modified the cats/engine.

I am curious about the alcohol thing. How much alcohol do you put in the tank?

 

The gaps on your plugs are very important for clean burn at idle. Make sure it is in the vicinity of .050. Too small of a gap will cause to not combust completely.