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| smiley235 |
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My uncle brought over his EL falcon I6 and its been misfiring. When idling, you can here a burble in the exhaust and when you rev it, you can hear it missing a bit and feel it in the throttle. I'm kinda stumped, what are the common problems associated with this and what kind of tests can I do.
_________________ 178.3 rwkw
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| joolz |
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Could be a number of things: plugs, leads and injectors or maybe all of these depending on when they were last replaced.
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| smiley235 |
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hmm, while the engine is running, is it safe to pull off a lead, put a screwdriver in it and put it near the head to see if its sparking?
_________________ 178.3 rwkw
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| Brett3158 |
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You'll soon find out how good the coil is, but probably not worth the pain. Dissconnect leads with the motor not running.
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| concorde |
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i had exactly that problem, changed the leads and all was good.
_________________ 2nd Place Summernats19 SQ Comp, Street Pro 0-600 Class
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| smiley235 |
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hmm, leads can be rather expensive and I wouldn't want to be changing them unless i'm sure they're no good. Whats a safe way to test to make sure each one has spark. If I remove a certain relay to stop the car from starting but still allow it to turn over, will I be able to use the screwdriver trick? and if so, which relay would this be?
_________________ 178.3 rwkw
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| bigbell351 |
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test the leads off the car with an ohm metre even a stuffed lead will allow a spark through, probe each end of the lead, the resistance should be less than 7000 ohms per foot of lead, if the lead is broken inside you will get no resistance or spark, but if you have a high resistance you will get spark but also a miss.
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| snap0964 |
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smiley235 wrote: hmm, while the engine is running, is it safe to pull off a lead, put a screwdriver in it and put it near the head to see if its sparking? Be safer and easier to put a timing light on, and move the inductive pickup from lead to lead - check if you're getting a consistent flash while the engine's running.
Run the engine at night and see if you can notice any crossfire between leads or between leads and the engine. Pull the leads and give them a good clean, give the dizzy cap a good clean inside and out.
_________________ 96 XH Longreach 'S': LPG, Alarm, 3.23:1 LSD, Cruise, Trip Comp, ABS, Power Windows, Mid Series Dome Lt, Climate Ctrl |
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| smiley235 |
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sweet, i'll try those things next time I see him. In the meantime, i've told him to run a bottle of injector cleaner through a tank incase the injectors were dirty.
Thanks all!
_________________ 178.3 rwkw
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| ELV8 |
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If the inductive pickup is placed on a lead and the timing light doesnt have a consistent flash, wouldn't this just mean that the length of lead from the dizzy to the pickup is buggered? Or could it also mean that the spark plug/spark plug boot on the lead is buggered?
In other words, for the timing light to flash does the individual spark circuit have to be completed? |
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| snap0964 |
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ELV8 wrote: In other words, for the timing light to flash does the individual spark circuit have to be completed? Yeah I understand what you're saying - there needs to be a spark fired for the inductive pickup to measure it. This is only employed to figure out which lead is having a problem - the fault could be anywhere, tracking inside the dizzy cap, crossfiring from the spark plug boot to the head, etc. The lead itself may not be the problem.
Because there are so many possible causes, you need to employ a number of methods to try and find it. And this is only the ignition side. Injectors are still a possibility - pull the vaccy lead (and plug it) off the fuel reg and see if your idle improves - if it does, the injectors will be dirty. Rev it and see if the misfire improves also.
_________________ 96 XH Longreach 'S': LPG, Alarm, 3.23:1 LSD, Cruise, Trip Comp, ABS, Power Windows, Mid Series Dome Lt, Climate Ctrl |
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| EL__Fairmont |
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just replace the dizzy cap, rotor button, leads and plugs and then check the timing.
_________________ 97 EL Fairmont 4l OHC .Silver. |
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| smiley235 |
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Ok, its been a while since this post but my uncle has been into hospital and out since, (but hes ok now). In the meantime, i've gotten him to run the injector cleaner over 2 tanks of petrol and he says the misfire has noticeably improved however is still evident. So injectors may have been 1 problem, i'm gonna try what snap said now with the timing light. Just 1 embarrassing question, I don't even know how to use the timing light, if I pick one up from repco, will it come with instructions?
_________________ 178.3 rwkw
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| P100 Ute |
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With the Timing light. it'll come with a longish wire with a clamp on the end.. this connects to Cyl 1 lead. then u shine the light towards the Harmonic balancer (most people use whiteout to mark the timing point) and theyre is a couple of marks above the harmonic balancer that you look at. when the light is shinning on it you should see a constant mark sitting on one of those marks.
if the mark is jumping around and not staying on 1 spot then theyre is a timing issue. which could quite easily be due to leads wearing away. if u have a multimeter then pull the lead off one by one and check for resistance (put the multimeter probes 1 in each end of the lead and see the reading on the multimeter.) *Edit* Took some pix coz i got a spare engine in the shed and also a timing light i only needed to use once that was in sight. Timing Light.. (shows the clamp) 
Timing Light with clamp connected and pointing @ the timing marks. (DONT leave the wire in the fan as shown in the pic.) 
Timing Marks as shown neer the Harmonic Balancer 
Closeup of marks (bad qual due to taken with camera fone and lighting isnt that good) Marks Shown = TDC, 3, 6, 10, 14 
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| smiley235 |
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oh, thanks so much p100, appreciate the trouble you've taken and makes alot better sense now.
Cheers again, i'll let you all know how I go.
_________________ 178.3 rwkw
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