luckygti
Posted a lot
I need to try harder!
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Jul 24, 2010 17:57:35 GMT
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So, the van (VW DoKa, 2.1 fuel injected beast  ) broke down last week, did a trip of about an hour, and then it started misfiring, couple of backfires and died. The coil felt really hot to the touch, so left it for 10 minutes, tried it, broom broom, and off we go. For another 5 minutes  and same again. Did this a couple of times, until I eventually gave in and called out the AA. This weekend I've renewed the coil, the leads and the plugs, 20 minutes up the road, yep, same again  The coil feels exactly the same, so is this a problem, or is it likely to be someting else? Opinions all appreciated, have a pic  |
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CIH
Posted a lot
Posts: 1,466
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Jul 24, 2010 18:01:47 GMT
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maybe a short or bad earth somewhere ? my old 1.8 manta had some bad wiring around the coil and you could actually see it arcing when it misfired.
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luckygti
Posted a lot
I need to try harder!
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Jul 24, 2010 18:19:12 GMT
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Cool, I'll have a poke around but wouldn't that make it run badly all the time, not just intermitantly?
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Jul 24, 2010 19:17:22 GMT
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Coils do get hot. Not sure what the ignition set-up is on your Vee Dub, but sounds similar to condenser failure. That can self-cure temporarily. Does it have one?
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1986 Citroen 2CV Dolly Other things. Check out my Blog for the latest! www.hubnut.org |
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Jul 24, 2010 19:49:14 GMT
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This is a pretty common problem (particularly on pugs 309/205 iirc), where the ignition amp/coil gets too hot and can't heatsink to anything. This causes spark breakdown as you are experiencing.
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- '80 Mk1 Vauxhall Cavalier Saloon, 3.0l 12v... in progress with some special plans ahead
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luckygti
Posted a lot
I need to try harder!
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Jul 24, 2010 20:21:41 GMT
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Dollywobbler, not sure that it has a condenser, (electronic ignition) but i'll have a dig around, Jasonb, it does have an amp, but having trouble tracking it down at the moment! I'm going to attack it again in the morning. Cheers chaps  |
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mrj
Posted a lot
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Jul 24, 2010 21:21:36 GMT
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no, it doesn't have a condenser, if it is a 2,1 l ... check if the fuel pump is running; when you turn the ignition on, it should run for a few seconds; it then runs again as soon as the engine is started again . I would rather check the temp sensor for the injection; if it is running too rich when hot, it stalls ... you could check the coil if you cool it down (ice spray, wet towel etc.) when the engine dies. Also, next to the coils is a little black box with two relais; one is for the idle stabiliser, the other one is for the fuel pump .... check those , too ....often the relais/wiring is tired, don't ask me, how i found out ;D
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- 1971 VW 1600 TL Fastback
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luckygti
Posted a lot
I need to try harder!
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Jul 24, 2010 21:42:20 GMT
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Will do mrj, Had a quick look at the relays, and I'm pretty sure the fuel pump is working ok, but I'll check all of that as well! Ahh, the joys of chasing faults around |
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30psi
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Jul 25, 2010 10:54:57 GMT
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Maybe it's a ballast coil on a non-ballast car?
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1962 Ford Thunderbird 6.4L
1981 Datsun Bluebird SSS CA18DET
1981 Datsun Bluebird SSS SR20DE
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CIH
Posted a lot
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Jul 25, 2010 11:45:00 GMT
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Cool, I'll have a poke around but wouldn't that make it run badly all the time, not just intermitantly? It would miss-fire around 2.5k revs then clear not long after. |
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Lopez
East Midlands
Posts: 867
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Jul 25, 2010 15:06:13 GMT
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As dollywobbler said, a coil should not get hot - if it does, something is wrong.
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30psi
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Jul 25, 2010 15:48:39 GMT
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Coils do get warm/hot. If you leave the ignition switch on, the coil is continually earthed out unless the points are open and it will get quite warm. Measure the resistance of the coil if you have a multimeter. Also measure the voltage going to the coil. Then you will be able to tell if you have a balast resistor and choose the correct coil appropriately.
If its a balast coil on a full 12V system it will get hotter. A ballast coil is typically rated at running 6-9V. When cranking the engine the balast resistor is bypassed and the coil gets 12V for a better spark. The balast resistance reduces with load so when on a blast the coil also gets a bit more power but would normally supply 9V to the coil.
Also check the connectors. curse word connections can lead to the electrics getting hotter.
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1962 Ford Thunderbird 6.4L
1981 Datsun Bluebird SSS CA18DET
1981 Datsun Bluebird SSS SR20DE
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ChasR
RR Helper
motivation
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How hot should a coil get?ChasR
@chasr
Club Retro Rides Member 170
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Jul 25, 2010 17:47:41 GMT
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I'd check the coil out to see if it should be ballasted or not. What is ohm rating on both of the coils and what do they measure?
Finally, do you have a spare rotor arm? Get yourself a very small bit of wire (or a coat hanger), cut a very small piece and solder it onto one of your rotor arms so that you bypass your suppressor in the rotor arm. In many German applications, I have found that these have broken down.
Other solution to rule out the arm is to buy either a German made BERU arm or a genuine VW part (or one that has been proven to work fine on another car).
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luckygti
Posted a lot
I need to try harder!
Posts: 4,912
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Jul 26, 2010 19:32:52 GMT
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Cheers guys for the input. Vans back at home now (and I'm not ) so I'm getting my local garage (run by my neighbour ) to have a butchers. I really want it sorted for the gathering, (otherwise I'll be in my wifes 10 plate Merc.......... and that would look bad  ) So fingers crossed he can figure it out. |
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) broke down last week, did a trip of about an hour, and then it started misfiring, couple of backfires and died. The coil felt really hot to the touch, so left it for 10 minutes, tried it, broom broom, and off we go. For another 5 minutes 
and same again. Did this a couple of times, until I eventually gave in and called out the AA.
) So fingers crossed he can figure it out.