Need4Speed Posted August 26, 2010 Share Posted August 26, 2010 I've been through old threads and come up with a blank. I've got yet another misfire (sometimes but more often than not) at low to mid (up to 2nd turbo) revs with anything but gentle throttle. At high revs and with boost up everything is sweet. The plugs are new and I've changed the front oxygen sensor for a new one. My gut feeling is it's a fueling issue, but what else controls the fueling that might cause this sort of problem? There are no apparent leaks or smoke or anything obvious. The car's a UK Auto BPU spec. with about 60,000 miles covered. Link to comment Share on other sites More sharing options...
Nic Posted August 26, 2010 Share Posted August 26, 2010 If you've recently changed the plugs then it could be broken coil pack connectors or faulty coil pack. What plugs did you fit? Link to comment Share on other sites More sharing options...
TT Paul Posted August 26, 2010 Share Posted August 26, 2010 i would agree with nic as mine done this, replace coilpack plugs easy to do and check coilpacks for hairline cracks, Link to comment Share on other sites More sharing options...
Need4Speed Posted August 26, 2010 Author Share Posted August 26, 2010 Sorry, I forgot to mention the new coilpack connectors I fitted. Link to comment Share on other sites More sharing options...
TT Paul Posted August 26, 2010 Share Posted August 26, 2010 maybe injector try unpluging one by one on tick over does eng run the same or change and check coilpacks unpluging one by one the same way but not together Link to comment Share on other sites More sharing options...
Need4Speed Posted August 26, 2010 Author Share Posted August 26, 2010 maybe injector try unpluging one by one on tick over does eng run the same or change and check coilpacks unpluging one by one the same way but not togetherIt's not that severe a missfire. It idles smoothly and usually runs smoothly. I've had it running on only 5 coils and that was 100 times worse than the current problem. And as I said earlier it's fine at top revs and WOT. Link to comment Share on other sites More sharing options...
Nic Posted August 26, 2010 Share Posted August 26, 2010 Is the miss intermittent or does it always do it under certain conditions? Link to comment Share on other sites More sharing options...
Need4Speed Posted August 26, 2010 Author Share Posted August 26, 2010 Nic, it's the sort of missfire that I can drive round and then again I can make it miss. It's in the middle of the driving spectrum - thrash it and it's fine and drive like your granny and it's fine... in the middle it missfires. I hope that's a clear explanation? Link to comment Share on other sites More sharing options...
Rinus Posted August 27, 2010 Share Posted August 27, 2010 Maybe stupid thought, but if an injector is broken, maybe it sprays to much fuel in the middle of the revs, or isn't this possible? Link to comment Share on other sites More sharing options...
Need4Speed Posted August 27, 2010 Author Share Posted August 27, 2010 After dismantling and rechecking all my coil-pack connectors, it appears to have been a dirty electrical contact at the ignitor pack. I unplugged and plugged it back in again and it's pretty-well perfect. I found this suggestion via a post from somebody with a miss-firing single. ps, does anybody know the French for "miss-fire"? Link to comment Share on other sites More sharing options...
Dnk Posted August 27, 2010 Share Posted August 27, 2010 I just put miss fire into Babel fish and thats the result le feu de coup manqué Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 le feu de coup manqué That's translation software for you! Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 After a 50 mile drive all was still apparently fine; then it started missing and progressively got worse. After another 200 miles it's missing, popping and all sorts, particularly on medium throttle. The weather here has been warm (38ºC) but the car's not overheating. Link to comment Share on other sites More sharing options...
jevansio Posted August 29, 2010 Share Posted August 29, 2010 After a 50 mile drive all was still apparently fine; then it started missing and progressively got worse. After another 200 miles it's missing, popping and all sorts, particularly on medium throttle. The weather here has been warm (38ºC) but the car's not overheating. My last missfire of those symptoms was the ignitor Link to comment Share on other sites More sharing options...
hogmaw Posted August 29, 2010 Share Posted August 29, 2010 Do you have stock or aftermarket ECU? Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 My last missfire of those symptoms was the ignitorDid you change it or was it a connection problem? Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 Do you have stock or aftermarket ECU?Stock Link to comment Share on other sites More sharing options...
jevansio Posted August 29, 2010 Share Posted August 29, 2010 Did you change it or was it a connection problem? Changed it, IMHO when tracking down missfires I'd be swapping things that you know work from other cars to elliminate stuff. The fact you can drive 50 miles to me points on something breaking down as it heats up Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 ...the fact you can drive 50 miles to me points on something breaking down as it heats upThat's where my train of thought was heading. I'll try the car this morning while the air is cool. The problem here is that I've never seen another Supra mkiv - and neither has any Toyota dealer I've spoken to. They are very rare. Having looked at the Toyota service manual it appears there is no diagnostic facility on the igniter pack - they just say "try another". Finding another is the main problem. I guess they're not cheap! Link to comment Share on other sites More sharing options...
jevansio Posted August 29, 2010 Share Posted August 29, 2010 That's where my train of thought was heading. I'll try the car this morning while the air is cool. The problem here is that I've never seen another Supra mkiv - and neither has any Toyota dealer I've spoken to. They are very rare. Having looked at the Toyota service manual it appears there is no diagnostic facility on the igniter pack - they just say "try another". Finding another is the main problem. I guess they're not cheap! No they're not, you can pick them up 2nd hand for £80 to £100 on here & SF.com Link to comment Share on other sites More sharing options...
Need4Speed Posted August 29, 2010 Author Share Posted August 29, 2010 (edited) No they're not, you can pick them up 2nd hand for £80 to £100 on here & SF.comThat's not too bad then - thanks for the help, I'll give it a try. Am I right in thinking that the igniter pack performs the equivalent function of a mechanical distributor? Edited August 29, 2010 by Need4Speed Added the question. (see edit history) Link to comment Share on other sites More sharing options...
Need4Speed Posted August 30, 2010 Author Share Posted August 30, 2010 At least two coil packs are showing higher than normal primary resistance - 1.2ohms hot compared to a new coil pack at 0.8ohms. More expense... Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now