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 18 2016, 12:00 PM
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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, did more work on the car today, and I am completely puzzled. Things I did:
a) Cleaned up all four spark plugs as best I could with a wire brush, and reinstalled them. b) Checked that all 4 injectors "click" when grounding the corresponding pin of the ECU wiring harness. c) Tried to start it -- started with great difficulty, ran very unevenly (as if firing only on 2-3 cylinders) and got to 2-3000 RPM only with great coaxing and pressing a lot on the throttle. Lots of foul smelling smoke came out of the tailpipe, looking like a haze (smells like burning oil). d) Pulled a plug immediately after running it, and it was again black, but the sooty thing on it seemed a bit more like oil than like dried carbon deposit (what I had before). e) Pushed car onto ramps, and drained the oil. Oil looks good to my uninformed opinion, no metal observed in the oil. (But I did not run it through a strainer.) There was more oil than I remember draining out at other times -- almost exactly a full gallon. Smelling it there is somewhat a smell of gasoline, but not sure. I have not yet pulled the oil filter, but will do that later this afternoon (after I buy new oil and a new filter). Several questions: a) I assume the oil smoke I see from the tailpipe suggests that oil is getting into the cylinders. How could this be happening? Could it be that having a higher oil level than the high mark on the gauge could somehow be allowing oil to slowly leak into the cylinders while the car is stopped? b) If I do a compression check with the engine stone cold, will it tell me anything useful? I can't see how I could warm the engine enough to do a proper compression check with the engine running so badly. I don't dare run it more than 30 seconds, what with all the bad smoke coming out and the uneven way it runs. c) Could the timing be terribly off and cause it to behave the way it does? Should I try to fiddle with the timing, or at this point I should leave it as it is? At this point (or at least after I put the new oil in and change the filter), I am at a loss which way to go forward. If someone could tell me what would be the best steps forward it would be very helpful. Thanks. |
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