Pulled the left bank spark plugs yesterday, Champion #7's & insulators were pretty white....figured it was a heat range issue. Pulled the right bank plugs today, insulators were dark....I'm now figuring it's a fuel richness matter. Replaced w/NGK-BR8EIX Iridiums. How many of you check the distributor advance curve (1000rpm -5000rpm) first before using the gas analyzer? Can I just tweak the fuel distributors for now and do the fully blown out tune later? Anybody use Colortune to tweak each cylinder? Image Unavailable, Please Login
The K-Jet fuel distributors really can't be tweaked on an individual cylinder basis by the end user -- if it/they need it, it/they should/must be disassembled/cleaned/rebuilt/recalibrated. No harm (or procedure error) by tweaking the fuel distributor mixtures at a given point in time (however, if you think the advance isn't working you'd at least need to eyeball it with a timing light). The CIS models in this category using K-Jet without Lambda essentially have an analog computer, the warm-up regulator, running things, so it's not some sort of "unchanging" digital control gizmo -- it can "age"/"change" over time so "never touch mixture screw forever" isn't assured. Since you are showing a clear bank-to-bank difference, it probably could use a tweak even if it's running OKish. What year/model/version? Are you have any runability trouble?
'84 400i series II. Runs great, not sluggish at all, have just read that pulling CO measurements with analyzer is the last thing you do after full ignition tune-up.
Sure like to know what CO you guys have. The factory calls for a range of 1 to 2% which is 4 times higher than the state allows.
The factory CO range is for "without catalytic converter treatment" -- i.e., the exhaust gas that leaves the cylinder. Unfortunately, if your state emission requirement is "CO less than 0.5% at the tailpipe", this can really only be achieved by having a working cat system (and maybe hitting the low end of the factory spec if the cat isn't real "fresh").
What they are trying to convey here is that it doesn't make sense to do a mixture tweak unless the ignition is working OK -- so the mixture tweaking always follows the ignition tweaking/checking in the F service documentation. Having the plug appearance equal within each bank is a good sign that your ignition is pretty healthy (even if your advance behavior is yet unknown since both banks share the same advance mechanism) -- so poor advance can't be causing the difference, and it must be mixture differences (although the uniform plug appearance in each bank is also a good sign that your FDs are still well-balanced internally). However, if your only problem is the plug appearance and you weren't fouling those standard electrode spark plugs too quickly, no need for immmediate action (especially if you don't have cats to overheat).
I know and understand all that you said above but it doesn't answer my question. So back to my original question, "What CO levels are you all running?"
My bad if I misunderstood your intent (although I don't understand what the "state level" has to do with it then).
Yep, I probably didn't write that state part very well. Let me try again. Texas requires some CO level like .5, or .7, something like that. Most 400's won't meet that demand unless they have working cats installed and are tweeked really well. The factory specs call for a range of 1 to 2%. In order to meet the Texas inspection, just before I roll onto the rack I really lean out one side. Once I pass I go back to spec. What CO levels do you guys run without cats? How about with cats? How many have NO idea?
The attached photo shows difference between banks, but all plugs on the Dx bank match #1, all plugs on Sx bank match #12. No fouling on any, only a very subtle difference in shades between the front 1 or 2 to the back 4 or 5 (that being the front a tad lighter which is to be expected).I'll first insure gap @ butterflies are @ .003". I need a balancer to check air intakes though before sniffin, should I get the STE SK 'snail' synchrometer? Is it best to T into the vac. line between the WUR (warm up regulator) and the induction manifold or sync. @ air filter inlets?
Interesting that you can run that lean and get by -- usually lean mis-fires start to occur often enough that it raises the HC level, but, if it works, why not!
No, you'll need a vacuum gauge (or 2), not the STE device. "Balancing" on the 12-cyl CIS-equipped F is about setting equal absolute pressures inside the intake plenums downstream of the throttle plate. Don't know the details of your model well enough to recommend where would be best, but tapping the vacuum measurement off the hose between the intake plenum and the WUR on each bank would be fine.
Dave When I got my car the CO was 4 and 6% on the two banks. I adjusted to 1.5 +/- 0.2%. No comment on passing the emission test, you never know who might be 'watching'. (My 69 Lotus with a Cosworth BDR and 45 Delorttos actually passes emissions test (<500 ppm HC's)even thought it is not required.) I adjusted AFTER setting the timing which was way off at 1000 RPM but my advance mechanism is right on. Not for Dave, If your banks are different with a single distributor, it is okay to tweak one side or the other if you have no reason to believe the timing is not right. If you later adjust the timing you will need to recheck the CO. Ken
No, not really. I bought a couple of AutoMeter brand dash gauges, but their readings didn't match very well (when measuring the same vacuum source) so I had to make up a little "correction" chart -- and lately, I've just been using one gauge and (quickly) moving it from one bank to the other so as not to use the "correction".
