rollex Member 682 Member For: 9y 10m 10d Gender: Male Location: Australia Posted 07/12/16 02:44 AM Share Posted 07/12/16 02:44 AM (edited) My BF XR6T is dropping a cylinder at idle and low loads when hot. Especially worse when in peak hour traffic. First presented 6 months ago. Changed the plugs and it went away. Now about 5000kms later and it is back. Changed the plugs and no improvement, the plugs looked fine as well. When cold, Ac is on the miss goes away. Same if you go above 2k rpm. Under high load and boost there is no missing or lack of power. Only low load and rpm. I thought if it was coil packs it would affect under load not idle. Does this sound like coils? Edited 07/12/16 02:48 AM by rollex Link to comment Share on other sites More sharing options...
BAXRTUTE Gold Donating Members 2,639 Member For: 8y Posted 07/12/16 03:01 AM Share Posted 07/12/16 03:01 AM Coils could def be the issue, though what plugs are u using and gapping? And is it tuned? Link to comment Share on other sites More sharing options...
rollex Member 682 Member For: 9y 10m 10d Gender: Male Location: Australia Posted 07/12/16 03:07 AM Author Share Posted 07/12/16 03:07 AM Bosch 0.9mm platinum ones. I previously used cheap copper ngk. Both drive identically. Car is tuned however this issue is new. I retuned it myself and fuel trims at idle were within 5% Now it goes lean at idle indicating a miss fire. Woudlnt coils get worse at revs/load as the spark will get weaker and have more fuel to ignite? The do have repetitive spark below 1500 rpm (sparks twice) but it doesn't stop missing into closer to 2k. Anything above 2k feels fine though it might be interested simply can't detect the misfire. What coils do people recommend using? If they are cheap I might just do it anyway as it has 205k on the dial now. Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,291 Member For: 16y 9d Gender: Male Location: Melbourne Posted 07/12/16 03:10 AM Share Posted 07/12/16 03:10 AM stock coils FTW! Link to comment Share on other sites More sharing options...
skidxr6t skids Donating Members 2,754 Member For: 11y 3m 21d Gender: Not Telling Posted 07/12/16 03:12 AM Share Posted 07/12/16 03:12 AM (edited) I would go down to your local shop that sells batterys for a free battery test. one where they get you to start the car while it's attached to show what the battery is doing under load. Maybe the alternator is struggling or something else electrical. Could definitely be coils too, I had cracked coils that weren't causing a miss but the transmission would go into neutral when I booted it. no coil related fault codes either. I whacked VDO coils in and no issues, stever ran vdos for ages too. if you can afford genuine I would go for them but VDO seem fine. Edited 07/12/16 03:12 AM by skidxr6t Link to comment Share on other sites More sharing options...
rollex Member 682 Member For: 9y 10m 10d Gender: Male Location: Australia Posted 07/12/16 03:13 AM Author Share Posted 07/12/16 03:13 AM I did actually have an issue previously with starting however I replaced the alternator and battery and it has a rock solid voltage now. I'll price up some coils anyway. Link to comment Share on other sites More sharing options...
skidxr6t skids Donating Members 2,754 Member For: 11y 3m 21d Gender: Not Telling Posted 07/12/16 03:25 AM Share Posted 07/12/16 03:25 AM (edited) sounds like coils then! After doing coils, I would still check the cables between battery/alternator as for example my negative lead had excessive resistance due to corrosion and I had to upgrade it upon installing a sound system. Edited 07/12/16 03:25 AM by skidxr6t 1 Link to comment Share on other sites More sharing options...
rollex Member 682 Member For: 9y 10m 10d Gender: Male Location: Australia Posted 07/12/16 03:26 AM Author Share Posted 07/12/16 03:26 AM Anyway to test them? Eg how accurate is measuring resistance to confirm if they are breaking down internally? Link to comment Share on other sites More sharing options...
k31th less WHY; more WOT Site Developer 28,291 Member For: 16y 9d Gender: Male Location: Melbourne Posted 07/12/16 03:29 AM Share Posted 07/12/16 03:29 AM 3 minutes ago, skidxr6t said: I had to upgrade it upon installing a sound system. That's probably why you don't have any stereo whine Link to comment Share on other sites More sharing options...
skidxr6t skids Donating Members 2,754 Member For: 11y 3m 21d Gender: Not Telling Posted 07/12/16 03:32 AM Share Posted 07/12/16 03:32 AM (edited) Good point man, the issue is it only measures between where the tip of the multimeter contacts the cable/terminal. so it is possible to see high resistance when the cable is fine. I use a fancy digital multimeter so maybe just google how to test resistance of a wire. believe you can also test the coil with multimeter too but a visual inspection must be performed too. Just now, k31th said: That's probably why you don't have any stereo whine yeah just girlfriend whine whenever I apply the accelerator! Edited 07/12/16 03:34 AM by skidxr6t 1 Link to comment Share on other sites More sharing options...
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