ADD Posted May 9, 2010 Share Posted May 9, 2010 Hello all, my supra has started acting strange, if i travel more than 20'ish miles it starts to missfire (regular and hard driving) but if i stick to short journeys ie under 20 miles it doesnt play up. Has anybody got any ideas what this could possibly be? i have error code 14 stored but i have replaced all connectors,coil pack and plugs 5 months (400miles) ago! ta Ad Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 9, 2010 Share Posted May 9, 2010 Replaced all the coil packs or the ignitor unit? Did you use second hand coils? Does sound to me like its a duff coil, the hotter it gets the more the resistance goes up. Code 14 also points to it. Quote Link to comment Share on other sites More sharing options...
ADD Posted May 9, 2010 Author Share Posted May 9, 2010 cheers swampy, they were all brand new mate yes. Just have to jump on it when its occuring and play with the connections. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 9, 2010 Share Posted May 9, 2010 No probs, if they were all brand new coils its bad luck if one is biffed. Quote Link to comment Share on other sites More sharing options...
ADD Posted May 11, 2010 Author Share Posted May 11, 2010 Do you know Of any way I can test each coil pack? Maybe a resistance Reading or something? Ad Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 11, 2010 Share Posted May 11, 2010 You can resistance check them no worries, although Im not sure on the figures. Test them all and see if 1 is significantly higher than the others? Quote Link to comment Share on other sites More sharing options...
jagman Posted May 11, 2010 Share Posted May 11, 2010 The coil packs have the insulation break down, the hotter they get the the lower the insulation resistance - misfire The outer case of the coil packs get brittle and over time /temp they get tiny hairline stress cracks , It is here the insulation resistance breaks down ,also if you fit them tightening too hard they can crack . to measure them you need to measure the insulation resistance using a megga , measuring the coil connections might not tell you much at all take them out carefully one by one and closely inspect them for tiny cracks , and try spraying a clear lacquer over them , or coating in RTV (not pretty) to add insulation to them. or just get new ones (one ) Also make sure the LT side connector is nicely connected and undamaged Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 11, 2010 Share Posted May 11, 2010 His are brand new dude Quote Link to comment Share on other sites More sharing options...
ADD Posted May 11, 2010 Author Share Posted May 11, 2010 Hank u chaps great help as always Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted May 11, 2010 Share Posted May 11, 2010 No probs, hipe you get it sorted. Where in Hampshire are you? if you want a loan set of coils to try Ive got 2 spare sets Quote Link to comment Share on other sites More sharing options...
jagman Posted May 12, 2010 Share Posted May 12, 2010 http://www.virtualvillage.co.uk/gun-style-infrared-thermometer-003920-045.html One of the above type temp guns is an essential for your tool box ,they are sooo useful -get one with a higher range if you can start engine and run till it misfires - then point the laser at each exhaust manifold branch and record the temp - the coldest one is your misfire cylinder -thats the coil pack or plug thats knackered They really are useful in all sorts of things ,a must on any tuned engine so you can "see" whats happening around the engine , nicely set up each cylinder should have even temps - You can get 1 cylinder running say hotter than the others all the time and fit a colder plug in that 1 cylinder cos thats the plug that will fail -lose its tip and cost you £££££ -forewarned is for armed , a big build cost down the tubes for the sake of a £50 temp gun Good to check on cars that you are going to buy too "nice car mate but your rads knacked " hard to argue with too Quote Link to comment Share on other sites More sharing options...
ADD Posted May 12, 2010 Author Share Posted May 12, 2010 Jagman thank you, I have one of those at work so that's a result! Prob is it only missfires under load (drive) as soon as I put it in P or N the miss fire goes. But I'll just get someone to sit in the car with it in drive. Thanks Quote Link to comment Share on other sites More sharing options...
jagman Posted May 12, 2010 Share Posted May 12, 2010 If it misfires under load ,it misfires without load but you cant detect it -still should have a temp difference just not as large as under load so still a valid check and may help you Quote Link to comment Share on other sites More sharing options...
absz Posted May 12, 2010 Share Posted May 12, 2010 I had a similar problem with mine some time ago it was one of the coilpack wires just before the connector, the wiring insulation was fine but the wire itself was broken inside causing a misfire when on load due to bad contact. very hard to find had to use a scope and some live data recordings to find the fault. Quote Link to comment Share on other sites More sharing options...
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