Well, I failed emissions yesterday. Mods are in sig, but the ignition stuff was installed AFTER I got back from the emissions testing (I probably should have installed it first, but oh well). I had burned a chip the night before with 4* less timing and less fuel and my car was running okay with that all the way there (had some trouble starting though). When I got there and had to shut my car off and turn it back on, it wouldn't start again. I think my problem is because I just keep pulling chips in and out and they might not always make contact. I should invest in a ZIF. Anyways, I ended up putting my stock chip back in, and it ran fine, but with the check engine light. I realized as soon as I connected the pins to check codes, the CEL would go out. Well, when I turned my car off for them to do the gas cap test, and turned it back on, the CEL light was on again, but I didn't want to make it appear that I was messing with the computer at all, so I didn't bother to clear it. Ran the test with that on the whole time..

Anyways, my readings were...

So anyways, I'm obviously running very rich, which was quite odd for the stock chip. I remember when I was first datalogging that the car would run lean with the stock chip. After emissions, when I was on my way out to pick up the ignition stuff in a trade, I noticed my BLMs were around 127-130 which, like I said, was odd for the stock chip.

I don't have a FP guage or an AFPR. I'm holding off on the AFPR until I get the LT1 stuff installed (different AFPRs)

I have no idea how old the cat is on my car. I'm going to assume very close to original (the car was an IN car and I don't believe it had to pass emissions) because the heat shield on the bottom has practically rusted off, so I'm sure a new cat will help tremendously. My thing is, I want to get one without AIR connections because I'm going to remove the AIR system as soon as I pass emissions. I'll get one with an AIR port on it though if it won't clog with the AIR port capped off.

I'm assuming a new catalytic converter should help a lot. I also replaced the stock 7mm wires yesterday with 8.5mm wires and re-gapped all of the spark plugs. For the effort I put into all of that, I should've just bought new spark plugs, but I'm an idiot so I didn't. Re-gapped them all to .035-.036" though. Most of them were up around .045" and some closer to .040". I think I used to have a miss from time to time and can't hear that anymore, but I doubt that would have raised my HC and CO so much.

When I go back, I'd like to make sure I pass. A new 3" cat will be ordered (AIR or no AIR tube?). I was hoping to be able to wait until I put headers and a new Y-pipe on before I had to put another cat on :/ Another chip (what should I change...32B or 6E?). I'll try some of that dry gas stuff as well. NOx readings aren't even measured, so basically I just have to get my car as lean as possible without missing or pinging. What octane gas should I run? I had 89 in the car. The Accel supercoil was already in there. Operating temp was right at 189.5*F, based on my datalogging. My stock t-stat should be 195*F, but I realize they can be inaccurate sometimes.

No vacuum leaks, I replaced ALL of the vacuum lines a month or two ago. My car also has bad valveseals and I have new valveseals sitting right here on my desk for it. I was also hoping to save these for the new heads, but they are cheap enough it doesn't matter I guess. On some of the spark plugs, it looked like there were some small carbon deposits too..

 

Sorry for the long post above.

This is probably the order I should do things?
-Replace valveseals (they are cheap viton positive seals)
-New O2 sensor (hasn't been changed since I've owned the car...probably original)
-New sparkplugs? (needed?) Which AC Delcos?
-New 3" hi-flow cat


I could probably do the first 3 of those today with the money I have. Then burn a new chip and buy a new cat?

EDIT: Oh, something else I noticed on the form for my emissions, it shows my vehicle weight as 3206lbs. Doesn't that seem extremely light for an '88 Trans Am with just the back seats and AC removed (that's just under 60lbs removed)?

 

^bump^ any other ideas/tips/hints?

 

FIRST - if you just swapped the chip and didn't clear the computer's memory by disconnecting the battery cable for a few minutes, it was trying to run with the old fuel tables learned values. Hence I'm not surprised it wasn't running very good. Especially with the reduced timing and the heavy fueling.

Also - it the check engine light was on what code is it reporting? Need to see what it's talking about before going any further.

WIth small carbon deposits on the plugs, you don't sound all the rich for the majoruty of the time. Doing the tuneup stuff should help a bunch for the next test.

Still check for a vacuum leak with some brake cleaner, just spray it around the manifolds and air/fuel system joints. If the engine speeds up at any point you just found a vacuum leak.

High HC and CO often point to a bad cat, but can also point to way too much fuel. Since you know yours is old and rusting out, I'd definitely replace it before the next test attempt.

The .035" plug gap was standard on my 305 HO TPI, so I'd say you were correct in that. New plugs might have been nice, but since your's sounded like they were okay I wouldn't worry about that.

You might check the air filter and change the oil before the next test as well. Both can help.

So will the new O2 sensor, it could be on the way out.

If it were me, I would NOT do the valve seals. That usually only manifests itself as a problem on startup (the old blue puff of smoke after sitting all night.

What all are you changing in your chip? From the looks of your mods, the factory chip should work fine. Unless you've got something I missed, I'd use it and see what code it's reporting for your CEL.

And yeah, they sound too light on the vehicle weight, but I doubt that would matter much.

Hope this helps a little bit. Good Luck!!!


- Vern

 

Thanks for the reply. As for the vehicle weight, I know it has nothing to do with the testing, I was just curious as to whether my car really was that light..

Anyways, the CEL was on, but that's because the PROM wasn't working well. Since then, I've fixed any issues with PROMs not working 100% of the time (installed a ZIF and soldered in a switch, etc.). Now its much easier to swap chips and its a lot more reliable.

I actually think I ran the test in limp-home mode...which would make sense for the high HC/CO numbers because of the heavier fueling under limp-home.

I've also decided against fixing the valveseals for the test. I'll save them for the new heads.

With the new wires and the re-gapped spark plugs, I noticed a big difference in performance as well, so I'm sure that's helping to get a more complete combustion. I shouldn't need to replace the spark plugs since I just re-gapped them. I'll replace them when I do the head swap.

Air filter has less than 3k miles on it (stock STP filter) and as for the oil... well I just put 2 new quarts in it the other day and now it looks clean again I had no idea my car was eating oil that much...about 2 quarts in just about 3k miles. Looks like my oil pressure sender is leaking a bit, and of course the valve seals on startup.

I'll probably go buy a new O2 sensor tonight and install that.

As for the chip burning in the first place, yes the stock chip works fine for me. However, I figure you can always get a bit more out of a car with the correct tune. Heck, 3.8 Trans Am got 225RWHP on a mostly stock L98'd GTA. Only mod was a 3" SLP cat-back.. So chip burning could help even a stock car. I wanted to get into it early before the head/intake/cam/header swap...except now it looks like I'll probably be switching to SD at the same time.

Anyways, I'm pretty sure a new cat and O2 sensor will pass me along with a slightly leaned out chip. I'll take a bit more time on the chip tuning this time. For the emissions chip, it was something I spent about 5 minutes on the night before, and that was before I soldered the bin switcher and ZIF into the memcal.