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where'd that nice idle go?

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peeeot

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I've been trying to pin down the best fast idle screw position and choke spring tension, and have met with a minimum of success. I wanted to make sure the choke was opening fully on its own at the present adjustment, so I tried to take the car for a brief spin to get it warmed up the rest of the way. It kept trying to cut out at idle. I brought it back home, and the idle (still) wasn't so good. I saw the tach was down close to 500, not sure how it managed to get that low, so I turned it up to 900-1000. The quality improved not one bit. I played with the mixture, and got it to run worse, but not better.

Last time I adjusted the carb I had altered the float setting slightly in order to eliminate a small fuel drip at idle. The fuel appears to be atomizing properly since the adjustment, as there is no longer any fuel visible down the barrels. After making the adjustment, I tuned according to some baseline settings and instructions I found online for my carburetor (Weber DGV). It was idling very smoothly, even as low as 550 rpm or so.

What could have gone wrong? I haven't messed with anything but choke and fast idle screws since, and they shouldn't be at issue when the engine is warmed up, which it was.
 
what kind of choke? electric or water?

mark
 
been thinking about this , my weber has a manual choke, so it has no choke screw. no offense intended but have you checked the ignition circut and checked spark on all cyls? perhaps you may have loosened a jostled a connection somwhere? also make sure you idle jet hasnt become clogged with anything. as well as you floats. lets figure this out.

mark
 
Haha, funny you should mention the ignition circuit... today was the first opportunity I had to get serious about addressing this. I pulled out a timing light, and sure enough, #3 wasn't doing anything. I figured a cleaning would take care of it, but it didn't, initially. I cleaned it a couple times, took the cap off, cleaned up under there, swapped plugs around to ensure that the plug was at fault, etc. Ultimately, I got action out of all 4 cylinders again, but I think I'm going to be needing a new cap and rotor, as #3 remains a little hit-and-miss. Holding the timing light on at an idle, on wire #3, sometimes it will flash 9/10 times; other times it will flash closer to 6/10 times, in spurts. All the other cylinders are quite consistent. I've returned the plugs to their original locations, so I suppose it could still be at fault, but it seems more likely a distributor issue when it's sporadically hit-and-miss. It's running much more smoothly now. I had the car running for a long while this evening, and drove it around some, and it was very smooth at idle and through the range. I didn't take the timing light to it again but I would guess that during that time it was working consistently, as a misfire should have been pretty evident.
 
peeeot, check that wire, or just replace, if it is a carbon wire you could have a break in it. Wayne
 
When you look at a raw end it will be black in the center with no wire showing just little stands of fiber around the center. Wayne
 
My wires say "7mm Hi-Temp Suppressed Ignition Cable" on them, and looking at the end, I see thick rubber insulation wrapping around a single solid metal-looking wire that is bent back to the outside of the wire where it is pressed up against the part that clamps on the plug or in the cap. I'm guessing that means it's not carbon. If so, does that mean the wire is likely not at fault?
 
peeeot, I would give that wire sticking out a little tug, because a lot of people put a short peice of wire up inside the carbon and bend if over to make contact with the plug metal as carbon would surely brake and the Hi-Temp Suppressed gives it away. Wayne
 
I tried to give the wire a tug, but couldn't really get to it. At any rate, I was running the car again and it behaved very well the whole time I ran it. Very smooth even up around 5000 rpm. A timing light test on all the plugs indicated a steady and consistent rate of firing. I'll take it /ubbthreads/images/graemlins/smile.gif
 
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