Colin wrote:Careful that you do not assume that high HCs are too rich. They can be from a lean misfire just as easily.
I wasn't focussing on the high HC count, but rather was taking the combination of low NO (206 ppm), high CO (2.43%), high HC (138 ppm) and non-existent free oxygen (0.0%) as cumulative evidence of a too-rich mixture. I would have thought that at least
some O2 wuld have been measured if teh engine was running lean.
I'm also concerned that a the #4 spark plug is consistently showing sootier than the other three plugs. When you were here we noted that and theorized that the oil ring might have its gap at the bottom. I'll be pulling the plugs for another inspection today.
I was surprised to find that the BobD did better with fuel economy when I richened cruise, something about increased efficiency alowing me to back off the accelerator. I think you pivoted at 14.7 because it sounded theoretically right, when in fact it was causing crazy lean misfires.
I am concerned aout lean misfires, particularly with the stock points and coil. The engine does stumble at the crucial 2000 RPM speed when not fully warmed up, which I take to be a sign of misfiring. I will be looking at ignition upgrading options that I can definitivley defend to the referee with the Executive Order system.
I do have one of the California-emissions Hall-effect ignition systems that I was running on the van for awhile. It worked great, but it has the advance-retard vacuum can on it, which I'm sure he'd notice. The single-advance can doesn't bolt on to the Hall-effect dizzy, so I'd have to explain why I didn't have the retard side of the can hooked up.
Remember that retarding the mixture helps heat the exhaust manifolds, a good thing.
Retarding the mixture?? Sorry, haven't had coffee yet. Retarding = leaning?
Dealing with people who have to interact with rigid bureaucratic methodologies is an exercise in frustration no doubt. A little empathy with their plight goes a long way towards establishing a working relationship through the process.
Actually he was pretty flexible, within the bounds he has to operate in. When his official information source said that my car wasn't supposed to have an EGR valve, but was supposed to have an oxygen sensor, he was willing to accept the contrary evidence I showed him in the owners manual. I tried to joke that I wouldn't have gone to the trouble of adding an EGR system if it wasn't there to begin with. He's not a jocular type. 100% business-like, which I suppose he has to be.
I don't know if this is typical, but the referee station is at a local college, where they train more referees and automotive techs. They use students as inexpensive labour for the referee program. It has the feel of a high-school auto shop. There was a 914 perched on a hoist in the corner of the parking lot which is apparently the project of one of the instructors. I guesss the referee guy has the additional stress of needing to maintain his authoritative standing to his students, so he's not about to take much crap from some guy with a beat-up old VW.
To webwalker: didn't mean to thread-jack here. For what it's worth, I've strapped a CARB-certified 3-way cat to my Federal-spec engine. So far it doesn't seem to have helped emissions. At the same time, it doesn't seem to have hurt either. I noticed no change in performance when I bolted on the cat.
If you are truly interested in improving the emissions on your vehicle, and if it's permitted in your jurisdiction, then maybe look into implementing a Megasquirt solution. That should appeal to your engineering mind-set.