Sigh. This saga never ends.

I have the sad misfortune of living in CA, so I have to pass the sniffer every two years. Two years ago, when I BOUGHT this car, (1988 350 IROC TPI) I found that the guy before me had cored the cat, and so I had to replace that to get past smog. Some bucks, but at least I had two years. (Can't find the old numbers, btw, or I'd post them...)

Well, I didn't put a whole lot of miles on it (about 5000 - for lots of reasons, not the least of which was that the US Navy called me up for a bit!!) SO now I'm due for the next smog. I have done a TON of work getting the car ready for this - new fuel pump, new computer, new distributor, new ignition module, new alternator, new EGR, and new EGR solenoid. (BTW - the passages, although they have a little soot in them, appear to be widely open...)

Passing HC and CO without problems, but my NO runs in the mid 1400's, and allowable is less than 767 at 15 mph, and less than 706 at 25 mph. IN fact - all the numbers are as follows...

15 MPH
RPM 1347
C02 14.14
%02 1.10
HC (max) 108
HC (ave) 31
HC (meas) 30
CO (%) (max) 0.71
CO (%) (ave) 0.10
CO (%) (meas) 0.00
NO (PPM) (max) 767
NO (PPM) (ave) 237
NO (PPM) (meas) 1381

25 MPH
RPM 1348
C02 14.20
%02 1.09
HC (max) 83
HC (ave) 20
HC (meas) 24
CO (%) (max) 0.58
CO (%) (ave) 0.09
CO (%) (meas) 0.00
NO (PPM) (max) 706
NO (PPM) (ave) 199
NO (PPM) (meas) 1211

My smog guy is TOTALLY cool. I had mentioned that I had lame (but mileage friendly) 2.77's in the rear, so he tried a bunch of things to help me along - higher drive gear, emergency bake, full manifold pressure on the EGR. Nothing helped substantially - at least not enough to get me even close to passing. Finally, out of frustration he drilled a hole in front of the cat and another behind and took measurements in both places.

Front Behind
HC 143 40
CO .59 0.01
NO 1090 1070

So his final recommendation to me was, despite the few miles on the cat, to replace it, as it did NOT seem to be doing it's job properly. (This is a GM replacement, 3-way cat).

So here I am - gonna have to replace the cat, but now I have two options - do I go with the single exhaust that is currently on the car (don't forget that this is a 1988, and the single cat was the only option that year) or upgrade into the dual cat setup that I have sitting in the garage (still have to buy new cats, whichever way I go, but I have the piping...)?

Is it LEGAL (and I do want to stay legal) to upgrade my exhaust to a dual cat system, as it came off of a later year car (1989?) Is it worth the expense? Should I just go for a single 3" setup with a good low restriction after market catalytic converter?

I suppose this is as good a time as any to get those 2055's, and do the whole job, too...

BTW - one other issue - my car (typical GM) has about 125,000 miles on it and blows a big puff of white smoke when it first starts - bad valve seals, I think. But do you think I trashed my former cat by not addressing them sooner? (I have new seals and will make a point of doing them, but if the rings turn out to be shot this motor's coming out for a rebuild!)

Thanks for any help.

Jonathan

 

The valve seals would affect HCs more than NO. In fact, higher HC tends to lower NO.

I'm not sure I agree with the cat not working part (although newer high-flow cats can actually work better than factory replacement cats). I think you may have another issue.

Were's your timing set? What PROM are you using? Base timing set too far advanced, or too aggressive an advance curve can raise NO. Also, what gas are you using? I never failed in CA when I used Arco premium (although it's been almost 10 years since I tried...).

Can't hurt to check the EGR passages. Bad seals can clog them up, and it only takes one point along any of the route being restricted to make the EGR inop.

Going dual cats may bring you other "issues" that you don't need right now. You should be able to pass it as a later model that offered dual cats, I would think (might be MAF/SD issues there, though).

And, thanks for your service to our country.

 

Have you tried the emissions reducers that you add to the gas tank?

A small bottle of denatured alchol added to a full tank of 93 octane might do the trick.

 

Homer don't go tellin' him about that yet, it's too early in the game.

Check your timing and ignition curve as mentioned. I passed NJ inspection this week in my truck after it failed NOx at 1444 with the timing at +4* so I retarded it to -2* and my NOx went to 900, which was 400 below the max for 1989 in NJ. The only other difference was that I got the 900 after the truck had been running all day. And that is a 350ci with 223,000 miles on the engine AND the cat. Use your stock chip, retard your timing and have at least a 180* thermostat and make sure the car is nice and hot. If all else fails once you've got it running as clean as can be, the alcohol will work, but I wouldn't use it with a full tank, I'd want it out of my system asap. Run the car till it's on E and add the booze somewhere on the way to the dmv, pass inspection, then get your *** to a gas station for a fill up. It's essentially going to do the same as using most brands of dry gas.

 

My timing's dead on at 6 degrees, 180 thermostat (brand new), premium unleaded fuel, and ran two tanks of the top-end cleaner through it. I have NOT tried using alcohol or Coleman fuel yet, and to be honest, would really rather do so only as a last resort - I'm perfectly happy to get the thing legal, I just feel I must be overlooking something somewhere. I'm NOT sure that I'm getting enough vacuum to the EGR - I would like to play with that. They have definitely checked my timing - I'm not so sure they'd let me get away with 4 degrees instead of six (but I MAY try it!) Oh yeah - and stock PROM, too. (No real mods yet - just trying to get the damn thing running, first!)

Can anyone else post their NO numbers so I can get an idea where these things seem to be running?

Given the amount of money I've thrown at the thing, you can imagine my frustraion - oh, and none of it counts towards the monetary limit, either (all has to be spent/done by the smog repair station - what a freaking RACKET!!!)