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#1
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How to test ignition coils?
I'm experiencing what I think is a misfire in my Buick that's killing my gas mileage (~20 MPG, mostly highway ). I feel it most definitely when the car is at a stop -- uneven and rough pulsing through the steering wheel -- and also sometimes smell a twinge of unburnt gas after highway rides (but not on local rides, even when they last at least as long as the highway ones).
I guess my first question is to ask if you guys agree with my misfire diagnosis or not and if you think the unburnt gas smell is related to the misfire or not. My second question, assuming that you would agree that I have a misfire, is: How should I test the coils? I've already replaced the spark plugs and am just going to replace the plug wires, since they are 20 years old and NAPA wires are $35 for a set, but I'd like to try testing the coils so that I don't spend $100 buying three new coils when I am assuming I don't have to.
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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes 1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod 2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die." |
#2
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How to test ignition coils?
Obd2 should throw a code for a bad coil, but check the spark at each plug. If one of the could went it will misfire every 3 ignitions, since each one has 2 plugs correct ?
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#3
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Also which iteration of the engine is it? I know at least on the 2.8s they had fuel pump/pressure problems (had it go on my celebrity too). I'm not sure about the 3.1/3.4 which are essentially the same
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#4
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Mine is a 1994 -- first year for the 3.1 L. It's OBD-I,and although there are ways to read OBD-I codes, I thought it would be more interesting to try to diagnose it myself.
__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes 1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod 2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die." |
#5
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Easy way to test the coils is to pull the plugs one by one and visually check the spark. You'll probably want to unplug the fuel pump or something so it doesn't start up on you, unless you're ok holding it while the engine misfires. Also if you do this make sure you are NOT the ground, those things kick. It's simple and crude but works.
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#6
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Don't allow the misfire to persist for too long, as you might be sending some unburned fuel down the exhaust system and overheating the cat.
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#7
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Ooh, good point.
__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes 1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod 2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die." |
#8
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A fuel leak would do those things for you as well.
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#9
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Yeah you would smell it though. Also the car would more likely misfire at higher rpm than low. I wouldn't count. Out the alternator either, at low rpms it might now be giving enough electricity. Jooseppi try turning on and off some accessories when the car is doing it, see if there is any difference. Might not be enough to illuminate the battery ought. Sent from my iPhone using Tapatalk
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TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#10
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Quote:
Quote:
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#11
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I interpreted that as cat smell Sent from my iPhone using Tapatalk
__________________
TC Current stable: - 2004 Mazda RALLYWANKEL - 2007 Saturn sky redline - 2004 Explorer...under surgery. Past: 135i, GTI, 300E, 300SD, 300SD, Stealth |
#12
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And that's prolly a good thing ...
I never met a cat that smelt like gasoline.
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#13
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Pulling the wire off of each plug , in turn, of a running engine, is one way to check for spark
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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags |
#14
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Quote:
Quote:
I did this many years ago when first screwing around with the engine on our lawnmower. YOW!
__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes 1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod 2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die." |
#15
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First off, I would run the car in a dark garage at night. Spray a fine mist of water around and see if the plug wires are leaking.
If not, turn on the lights and pull out one wire at a time and plug it into a spark plug tester to see if the flame is steady and blue. All of this is with the engine running.
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01 Ford Excursion Powerstroke 99 E300 Turbodiesel 91 Vette with 383 motor 05 Polaris Sportsman 800 EFI 06 Polaris Sportsman 500 EFI 03 SeaDoo GTX SC Red 03 SeaDoo GTX SC Yellow 04 Tailgator 21 ft Toy Hauler 11 Harley Davidson 883 SuperLow |
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