A&Q about 350Z
Q:
Is there a way to test a coil to see if its breaking down?
I dont have any real means to measure the output but i do have a portable scope and was thinking about making a pickup coil type arrangment around the main cable from the coil. Should be able to see a spike each time it fires, though not calibrated it might enable me to see something happening.
I might get one from the scappy just to try..
A:
...I might get one from the scappy just to try..
Be very careful! If you make a test installation where you can get a direct shock from a HT wire you can end up in a bad way... Most shocks when working on cars are indirect.
A:
ive had a shok from a ht lead before. i thought my friend kicked me in the back
A:
My mate was once leaning over his engine trying to hear which plug wasn't firing, he touched an HT lead with his hand, got a belt off of it and headbutted the rocker cover.
I have never came so close to p*ssing my pants as that before
A:
Cheers for your concern guys
I wasnt going to try and get the coil going out side of the car! (though some HV experiments might happen for something completey differant)
Ive got the up most respect for electricty as im an electronics engineer by trade. I also used to (still do..) wire up 200A 3 phase and the like, im used to dangerous electrical things...
My idea was to try and measure the HT indirectly from the HT lead by means of a pickup coil, so theres no direct connection with the HT itself.
Same idea as strobe timing lights, sun engine analysers get the idea?
The voltage induced into the coil ( not many turns) would be a lot lower than the HT voltage itself.
As long as the HT lead insulation isn't breaking down i shouldnt get a shock, but i wasnt intending to get near the HT leads while it was running anyway!
I think l'll just get another one to try from the scrappy and stick it in the car to see what happens.
No other ideas on how to suspect the coil by how the engines running?
A:
Cheers for your concern guys
I wasnt going to try and get the coil going out side of the car! (though some HV experiments might happen for something completey differant)
Ive got the up most respect for electricty as im an electronics engineer by trade. I also used to (still do..) wire up 200A 3 phase and the like, im used to dangerous electrical things...
My idea was to try and measure the HT indirectly from the HT lead by means of a pickup coil, so theres no direct connection with the HT itself.
Same idea as strobe timing lights, sun engine analysers get the idea?
The voltage induced into the coil ( not many turns) would be a lot lower than the HT voltage itself.
As long as the HT lead insulation isn't breaking down i shouldnt get a shock, but i wasnt intending to get near the HT leads while it was running anyway!
I think l'll just get another one to try from the scrappy and stick it in the car to see what happens.
No other ideas on how to suspect the coil by how the engines running?
The problem is the HT will find/make a fault by beaking down the weakest insulation, so testing is hard. One thing is to gap the plugs 0.1 mm bigger than recommended and see if that produces problems. If all's good, you know the HT system has a bit in hand. Otherwise the scope is good to check the hall sender signal and the ignition amp output (schmitt triggered, constant energy) is good, there are good waveforms on the net for comparision, or the haynes electronic book gives a few general examples (mostly vauxhaullll). Measuring the HT inderictly is a bit worthless as it depends on so many variables inside the combustion chamber...
A:
a 'scope is also useful to see waveforms on the earth, if there's a high resistance there.
A:
...I might get one from the scappy just to try..
Be very careful! If you make a test installation where you can get a direct shock from a HT wire you can end up in a bad way... Most shocks when working on cars are indirect.
Years ago you used to be able to buy a coil tester but after a few fatal incidents they stopped selling them.
A:
...Years ago you used to be able to buy a coil tester but after a few fatal incidents they stopped selling them.
Yeah, a lot of people get a bolt of a HT system and assume they got the full beans and it isn't that dangerous, but a few mm of air has such high resistance it's protecting them beyond their imagination. Those yellow HT warning stickers scince the '80's aren't evidence of a nanny state, they're nessesary, it's a shame (for whatever reason) people treat them with such complaceny...
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..One thing is to gap the plugs 0.1 mm bigger than recommended and see if that produces problems. If all's good, you know the HT system has a bit in hand.
Otherwise the scope is good to check the hall sender signal and the ignition amp output (schmitt triggered, constant energy) is good, there are good waveforms on the net for comparision, or the haynes electronic book gives a few general examples (mostly vauxhaullll). Measuring the HT inderictly is a bit worthless as it depends on so many variables inside the combustion chamber...
Good idea with the gap, i guess if things go a lot down hill from there the HT could be low or probelm with the coil. Guess there should be 12v up around one of those 3 wires on the coil? Ive not metered around there yet.
Was that HT tester like a spark jump tester, where you have a scale in KV as you open the gap? Not suprised there were some casualties from that one..
See what your saying about measuring the HT, proberly wont tell me anything doing it the way i was thinking. Just trying to make use of stuff ive got around
The cars still miss firing and lacking power, ive not been able to get hold of another coil yet to try.
Ive cleaned the earth on the coil and gone all over the wiring and cleaned where it looked like it needed it. The earth strap was a bit loose on the rocker cover but it hasnt made any differance.
Im thinking maybe fuel problem as well.
I was going to do a compression test today but its not happened, next week i hope...
Can any of the relays cause this kind of probelm? (thinking the ECU one or X relief)
What was that quote about owning a VW?? be prepared to spend 12% of your life under the bonnet!!
Cheers Guys
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describing the car (golf 3 by any chance??) and the missing symptoms hot/cold/after a long run, etc might help us to help you...
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Sorry i didnt mention that as the thread started off about testing a coil..
Well yes you've guess it its a mk3 GTI, 92' 2E engine, digifant (doomed i know)
Cars always been a bit lumpy even after a service of the usual stuff.
The cars started to miss-fire and feels like powers down.
Doesnt seem tempreture related, will playup from the off. seems lower rev range were the miss fires are but im sure its doing it at higher revs as well.
I had a problem with the 02 sensor (that i repaired the dodgy wiring..)
The car ran great for a week or so then more problems..
I still have a suspicion that its not 100% but it is switching hi / lo but gets a bit lazy. I need to just get a single reading to determine wether its the data link being slow with the pc.. (maybe use the scope..)
Just cleaned out the ISV (lots of crap in there..) / throttle body and checked all the coil wiring. This has helped the idle no end, but still the miss fire.
I changed the plugs back for the NGK's that were in there and it miss fires less and runs smoother.
Ive also changed back to the original main HT lead from the coil.
Could do with somemore ideas..
The car used run great, loads of power there under your foot but its gone.
Im wary now of it missing so im driving like an old git..
(I know its a heavy lump and slow in many peoples view, but its a nice car)