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andreic |
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#1
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Member ![]() ![]() Group: Members Posts: 172 Joined: 21-December 15 From: Madison, WI Member No.: 19,479 Region Association: Upper MidWest ![]() |
Hello,
I have a problem on my newly rebuilt 1.8L engine, with L-Jet. Yesterday as I was driving home the car simply quit about 5 blocks away from home. Until this point it was running very well. I had to have it towed home and now I started trying to diagnose it. So far I've checked that the fuel pump operates when opening the flap in the AFM, so I suspect I got fuel pressure right. The starter spins the engine well. I have strong spark on the main distributor cap wire (coming from the coil), and putting a brand new spark plug into one of the spark plug wires I have spark at that too. (Originally I was too lazy to pull an actual plug from the engine.) But this morning I tried pulling a spark plug from the engine, and it is completely black and covered in carbon. Not wet, just covered in a thick layer of solid black material. I can't check right now whether the spark plug from the engine is fouled badly enough to not give a spark at all, or if it still is OK. (I need to wait for my son to come back in the afternoon to help me, this is a 2-person job.) But assuming the spark plugs are the problem, can somebody offer a guess as to what could have caused the engine to foul the spark plugs so badly and so quickly as to stop the engine while driving? Before that there was no indication something was wrong. Other slightly strange things. a) I've noticed the car burns a lot of gas. I barely get 20 mpg in mixed city/highway driving. b) I have about 600 miles since the rebuild, engine ran well all along. c) The only other issue with the car is that I can not get the idle right: it seems to idle at 1800 rpm most of the time, but if the engine is well warmed up (after about 1/2 hour of driving) or if I hold off the clutch as I come to a stop until the rpm's come down to 900, it'll idle at 900. I've tried two different throttle bodies, thinking it may be the throttle that sticks, but it behaves the same way with both. I started to suspect that the distributor is sticky and does not retard the idle sometimes. Any suggestions, highly appreciated. Thanks, Andrei. |
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andreic |
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#2
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Member ![]() ![]() Group: Members Posts: 172 Joined: 21-December 15 From: Madison, WI Member No.: 19,479 Region Association: Upper MidWest ![]() |
OK, I am now officially stumped. Here are the latest developments, and if someone could suggest where to go from here, I'd highly appreciate it.
a) I did a cold compression check on all 4 cylinders. (Throttle wide open, fuel injection disabled, all 4 plugs out, crank it with gauge tight in each hole in turn.) I have 125 PSI all around with very little variation from cylinder to cylinder. b) Cleaned spark plugs again, this time with brake cleaner. As far as I can tell they are good to go. Changed timing slightly (advanced it). Tried starting it. Started almost right away, but again runs very rough, will not idle at all (dies if I take foot off throttle) and lots of blue-ish smoke billowing out of the tailpipe. c) Took spark plugs out again. They seemed to have a fine layer of dusty soot, but also some wet spots, which I could not tell if they were gasoline or oil. The spark plugs looked roughly all the same, maybe the one on cylinder 1 was slightly dirtier but not much worse. At this point I have two things I can think of that may have gone wrong: either I run way too rich, or I get oil somehow in the cylinders. In favor of the oil contamination hypothesis is the fact that I blow out blue smoke. But if I had bad rings on one cylinder wouldn't I be seeing a loss of compression in that cylinder? I can't quite believe that all 4 have gone bad at the same time... Remember that the car had been running just fine before it stopped suddenly. In favor of the "running too rich" hypothesis I guess I have the dusty residue on the spark plugs. But could running pig-rich cause me to smoke badly, with blue-ish smoke? I could certainly imagine some scenarios where some electrical connection for the L-Jet has gone bad and is causing it to put way too much fuel, but would that be causing rough running? I changed the throttle body about a week before this all started, and in the process I fiddled with the WOT switch and the AFM plug. Please help... I feel like I'm losing my mind. |
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