Badly fouled spark plugs |
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Badly fouled spark plugs |
andreic |
Sep 15 2016, 08:43 AM
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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. |
andreic |
Sep 22 2016, 08:30 AM
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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 |
Before I start messing up with the AFM (something I am afraid to do) I would like to get to the bottom of the problem with the blue smoke from the tailpipe. That is what's worrying me the most. I tried starting the car this morning, and it seemed to be running somewhat better -- it is not hard to get it to rev up to 4000 and 5000 RPM by quickly pressing the gas pedal. It still does not idle (shuts down if you take foot off the gas pedal) and at lower RPM's it runs somewhat rough, but there's some improvement (could be from moving the timing forward, something I did a couple of days ago).
But my concern is the bluish smoke coming out of the tailpipe -- there's still loads of it, does not seem to go away at all. Everybody says this is from oil getting into the cylinders. (If this is the case, it might also explain the perhaps overly rich mixture: if there is oil getting in, burning the oil uses up some of the oxygen that would normally be used to burn gasoline, making the mixture too rich.) One potential cause for the oil smoke, if I understand correctly, could be some oil rings not seated well. I did drive it quite hard for the 600 miles since the rebuild (while it ran well) -- I kept it below 4500 RPM for the first 300 miles, but then I would occasionally go to 5000-5500. Anyway, I suppose I could try to jerry rig something about the idle and go for a drive with it again one of these days, revving it hard, in the hope of getting whatever oil ring is messed up to seat again. Is this a reasonable idea? Other suggestions I heard from someone in my neighborhood was to try to use Seafoam to clean up the cylinder walls (in case they got glazed, I suppose). Is this something you guys would recommend? Would I put the Seafoam in the gas tank, or directly into the cylinders? Any other home remedies you guys can think of for oil leaks? Or should I give up and try to take it to a garage for a leak-down test to see if indeed I have an oil ring leak? Would a leak-down test show an oil-ring problem? Wouldn't that be futile, given that the regular compression test I did at home seemed to be fine? |
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