Sy229
Move with Purpose
The hot idle on my Sy began getting erratic recently, missing and going lean to the point of near stall on occasion. We had changed the distributor out a month ago to fix a no-start problem, and the truck had been running ok until now. I finished the tune up yesterday with new plugs and wires hoping it would cure the idle issue, but it seemed to make the problem worse – I could now hear misses and feel the stumble.
I dusted off my Windows 98 Dell laptop and collected Datamaster idle runs on the Sy and Ty (which has always idled great). When I compared the two, the only significant difference was the spark advance – significantly higher on the Sy. Everything else looked normal, O2 and IAC cycles, vacuum. So I unplugged the brown wire and the timing light showed the mark to be way off !? Turns out the distributor had worked its way loose out from under the hold down. I fiddled around with that for quite a while until I was finally able to get the hold down in the proper place, the bolt snug but still loose enough to move the distributor around some, and the wrench in position to tighten it once I found the sweet spot.
The truck idled like crap with the timing mark in the ‘right’ spot, so I assumed the indicator had slipped out of position. I tossed the timing light aside, plugged the brown wire back in, and just let the truck tell me where it wanted the distributor. Locked it down and now it idles considerably better. It’s still hunting a little bit (the computer is probably still needing to learn the new setup; spark plugs and timing). And there’s a bit of hesitation when I romp on it, so I suspect the timing is a little off (retarded ?) but that beats the hard miss I was getting before.
I guess next thing is to search for the procedure to find TDC, and go from there.
I dusted off my Windows 98 Dell laptop and collected Datamaster idle runs on the Sy and Ty (which has always idled great). When I compared the two, the only significant difference was the spark advance – significantly higher on the Sy. Everything else looked normal, O2 and IAC cycles, vacuum. So I unplugged the brown wire and the timing light showed the mark to be way off !? Turns out the distributor had worked its way loose out from under the hold down. I fiddled around with that for quite a while until I was finally able to get the hold down in the proper place, the bolt snug but still loose enough to move the distributor around some, and the wrench in position to tighten it once I found the sweet spot.
The truck idled like crap with the timing mark in the ‘right’ spot, so I assumed the indicator had slipped out of position. I tossed the timing light aside, plugged the brown wire back in, and just let the truck tell me where it wanted the distributor. Locked it down and now it idles considerably better. It’s still hunting a little bit (the computer is probably still needing to learn the new setup; spark plugs and timing). And there’s a bit of hesitation when I romp on it, so I suspect the timing is a little off (retarded ?) but that beats the hard miss I was getting before.
I guess next thing is to search for the procedure to find TDC, and go from there.
