Original message:
https://www.thirdgen.org/techbb2/sho...hreadid=177258

For those that have been following today's episode of "As My Car Sucks", I pulled the plenum and rigged up a tool contraption that allowed me to get the bolts out of the EGR valve without pulling the runners. I tested the EGR valve and it seems to be seating 100%. I couldn't blow through it at all. Instead of putting it back on, I installed a block-off plate just to see what happens. Before I put the car back together I'm going to cut a hole in the passenger side valve cover and reinstall the air line between the throttle body and the valve cover (right now I'm running a breather).

Since I know this isn't going to solve my problem, where do I look next?

 

TTT, hoping for some ideas.

 

I put the plenum back on and the car started right up. I needed to nurse it to keep it idling until it warmed up, but a lot less than I usually need to. Once it warmed up it idled smooth at 900 rpm. The car seems to be a tad rich now. At idle the crosscounts don't move up very much, and my o2 sensor voltage seems to stay between .620 and .670. Block learn was around 116 when I shut it off, but it seemed to drift between 108 and 121 while I was driving. While cruising the o2 stayed between .620 and .670, but my crosscounts were adding up quickly, and for a while the rich/lean flag toggled back and forth like it should. On decel, it goes lean, right down to .004 volts one time. I tried to watch it at WOT, but between the dark and my inabilities to watch the scanner while I was driving, it was hard to tell. I think it stayed rich during WOT.
Any opinions?

 

Sounds just a tad rich, which I would rather have than lean! Remember that the scan tool value is updating maybe about 1/10 as fast as the O2 sensor is actually changing. The .004 v means that the injectors shut off for fuel cut as they should on decel, not a bad thing as long as it picks back up. the 116 block learn isn't terrible, it just means the computer is trying to take away some fuel as it should with the O2 staying above and average of .450. Proper O2 conditions would be switching between .2 and .8 volts. I wouldn't be alarmaed by the 116 block learn, but the 108 would be something to fix. Figure out where you're getting more fuel than you should. Do you have a AFPR and have it set too high?

Just thought I'd offer a little theory and ideas!

 

I've got an AFPR but I've got it backed off. I think I'm right around stock pressure. Maybe I'll try backing off on my injector constant, but I want to make sure that I'm staying rich over the whole RPM range first.

What bugs me is that in the fall before I put the car away, my block learn sat smack dab at 128.

 

Ah, I forgot that you had your own prom in it, therefore you know about what I was talking about at least as well as I do! Much more than stock applications, my experience falls off like a rock! Although, I know how things should work!

Also, since it had sat over the winter, have you run a tank or 2 of gas through it yet?

 

I filled it up once since I got it out of storage. Once I gain enough confidence, I'll start driving it to work to get some miles on it.

 

If you had a lean condition, (which it doesn't look like it now!) I would be more likely to blame the fuel, or deposits, or varnish from the old fuel, but that doesn't seem to be it. I like your idea of driving it a little bit before doing anything. Especially after sitting for a while, it may just need some run time on it! I wish they all just needed that, would make my job easier, and somewhat funner! LOL

 

Jim,

I may have missed it in the earlier thread, but I didn't see the part about the PCV system before. You were running a breather on a MAF setup? You never want to do that, since the PCV air becomes part of the mixture, and needs to be metered by the MAF. That's why there is a CCV tube from the throttle body to the rocker cover. It's good that you got it back the way it should be, but now you may have to do a little more PROM tuning since you have a more accurate air intake measurement.

With a stock EPROM, that extra air would surely make you lean. Search for "Code 34" and PCV, and you might have some interesting results.

 

Actually, I haven't fixed the PCV system yet. I can't find the stock tube from my old 305, and I'm too lazy to crawl all over the junk in my garage to get the valve cover elbow. I'm going to have to go fishing at the parts store and come up with my own setup. I don't think the stock tube will fit terribly well between my SLP runners & GM valve covers.