Octavarium454 Posted October 22, 2009 Report Share Posted October 22, 2009 I have installed all new plug wires, changed the coil, and changed the plug, all to no avail. I definitely got spark though, I was shocked taking off the plug wire by the spark plug. The thing is though this thing is stupid fast an hauls balls, something which I would not think a car missing a cylinder could do. You can however hear the miss at idle though. Now my vacuum lines are also slightly screwed up, as when I got the car they were cut, and I probably installed some wrong. I'm holding the vacuum lines I have questions on in the pictures below. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 22, 2009 Report Share Posted October 22, 2009 That one looks like an auxillary one for cruise and/ or HVAC controls. Even with a small one like that, it shouldn't make the engine run too adversely (I know, I had near exact one broken on my '92 for some time) Even then, it shouldn't single out one cylinder. It would be all or nothing. Quote Link to comment Share on other sites More sharing options...
tunerlover3 Posted October 22, 2009 Report Share Posted October 22, 2009 Did you have a misfire before you did the tune up? Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 22, 2009 Author Report Share Posted October 22, 2009 Yes I did, it was the reason I did the tune up. When I first did the tuneup it was fine until I took it around the block and warmed it up, then it started missing at idle again, but no power was lost when I got on it. In fact it has more power now after that tune up, as when I went to remove two of the old plug wires they actually pulled apart . I guess I will try seeing if the injector is bad, and run a compression check, but when its not idling it has plenty of power, which confuses me. Quote Link to comment Share on other sites More sharing options...
4door Intl Posted October 22, 2009 Report Share Posted October 22, 2009 Missing at idle + full power when you punch it = vacuum leak. A bad TB to plenum gasket is what made my car run like crap for months. I thought it was this..then that...even pulled six injectors from a wrecker and instaled them only to find out...car idled like it had H1N1 x 9/11 when i fired it up (i must've made the gasket worse while getting to the injectors). Then i found the little defect in that gasket. I swapped a new one in and my 493,000 km beast again runs like a top. Check all the vacuum lines and intake gaskets. The missing is caused by too much "unmetered air" being sucked in at idle which prevents detonation repeatedly hence the misfire. Once the throttle is hammered so much air is sucked in that the extra getting in via the vacuum leak no longer makes a difference. Check this article out, of course i found it after the months of shit running and gasket replacement. When i read the symptoms i was like "Well son of a bitch" http://www.aa1car.com/library/vacleak.htm Quote Link to comment Share on other sites More sharing options...
9lumina6 Posted October 22, 2009 Report Share Posted October 22, 2009 Missing at idle + full power when you punch it = vacuum leak. A bad TB to plenum gasket is what made my car run like crap for months. I thought it was this..then that...even pulled six injectors from a wrecker and instaled them only to find out...car idled like it had H1N1 x 9/11 when i fired it up (i must've made the gasket worse while getting to the injectors). Then i found the little defect in that gasket. I swapped a new one in and my 493,000 km beast again runs like a top. Check all the vacuum lines and intake gaskets. The missing is caused by too much "unmetered air" being sucked in at idle which prevents detonation repeatedly hence the misfire. Once the throttle is hammered so much air is sucked in that the extra getting in via the vacuum leak no longer makes a difference. Check this article out, of course i found it after the months of shit running and gasket replacement. When i read the symptoms i was like "Well son of a bitch" http://www.aa1car.com/library/vacleak.htm You are correct about that.........but he is having a misfire in only 1 cylender..... that type of situation I would think would not result in a misfire in only 1 cylender. What I think it might be since you already replaced the plug/ wire/coil is a vacuum leak in the Cyl #2 injector. The injector o-ring is possibly all dry rotted or possibly not seated right. First... check the 10MM nut on the back left corner of the fuel rails....since that's the closest to Cyl 2.....if thats tight....you might have to pop it off and just to be safe replace all 6 of the injector o-rings (not hard to do at all). It could also be a cloggged injector that will not perform correctly at idle... but may not be clogged enough to affect performance when on the throttle. Just a thought. Also........by looking at the 1st picture, that looks to me like the vac. line that comes out of the MAP sensor. If that is.....it's supposed to go down to where the little nipple coming out of the LIM under the S/C snout There should be a "T" down there where that will slip into..and out of the other side of the T it should go up to the fuel pressure regulator. Ad then from there on over to the Boost Bypass Valve (BBV) Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 22, 2009 Author Report Share Posted October 22, 2009 Yeah I don't even have a T down by the LIM, lol. Oh I'm going to have fun getting this deal done right, but what you are describing is exactly what the vacuum diagram is saying, so I'll get on it tonight. And the fuel injector has to be it, I noticed that the fuel rail had a couple new injectors (not on cylinder 2 though) and the receipts I have showed they installed these back in July, so I'm thinking maybe it was having some problems with other cylinders and now the fuel injector for cylinder 2 is on its way out. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted October 22, 2009 Report Share Posted October 22, 2009 do an OHM check on all injectors. you might have a sick but not dead injector on cylinder 2. Quote Link to comment Share on other sites More sharing options...
4door Intl Posted October 22, 2009 Report Share Posted October 22, 2009 Ah i missed the "2" in the title and thought it was just a misfire condition. But wait, aside from the obvious: a bad sparkplug, wouldn't it have to be a bad injector in the cylinder? I mean what else is there?? rofl What does an engine gunned on five cylinders sound like by the way? I would've figured it would be clearly different than one firing on all six but i've never pulled a plug wire to find out. Quote Link to comment Share on other sites More sharing options...
9lumina6 Posted October 22, 2009 Report Share Posted October 22, 2009 Yeah I don't even have a T down by the LIM, lol. Oh I'm going to have fun getting this deal done right, but what you are describing is exactly what the vacuum diagram is saying, so I'll get on it tonight. And the fuel injector has to be it, I noticed that the fuel rail had a couple new injectors (not on cylinder 2 though) and the receipts I have showed they installed these back in July, so I'm thinking maybe it was having some problems with other cylinders and now the fuel injector for cylinder 2 is on its way out. It's most likely injector #2........if it wasnt replaced... i doubt they put a new O-ring on it....and it was all dry rotted......and that will cause a vacuum leak/misfire under idle. It also is very likely the injector is stuck. I would just replace the ones that wernt replaced with some low mileage used ones.....and put new O-Rings on all 6 and try that. And re-route that Vacuum line and I think you will be all set. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted October 22, 2009 Report Share Posted October 22, 2009 Those are the most common reasons...but low compression in a cylinder, or a burned valve could also set a misfire code. Not nearly as common as vacuum leaks, or injectors, but they happen sometimes.. Ah i missed the "2" in the title and thought it was just a misfire condition. But wait, aside from the obvious: a bad sparkplug, wouldn't it have to be a bad injector in the cylinder? I mean what else is there?? rofl What does an engine gunned on five cylinders sound like by the way? I would've figured it would be clearly different than one firing on all six but i've never pulled a plug wire to find out. Quote Link to comment Share on other sites More sharing options...
9lumina6 Posted October 22, 2009 Report Share Posted October 22, 2009 Those are the most common reasons...but low compression in a cylinder, or a burned valve could also set a misfire code. Not nearly as common as vacuum leaks, or injectors, but they happen sometimes.. True...........i think he mensioned that it pulls nicely when he gets on it and runs fine. If it were low compression on that Cyl or a burned valve it would not be running any better when getting on the throttle. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted October 22, 2009 Report Share Posted October 22, 2009 to sum it up; probable causes: Bad spark due to bad plug, bad wire, bad coil, or bad ICM Worn out injector, or clogged injector. poor compression. vacuum leak any of these issues COULD be responsible for an uneven idle, which may not be as noticeable at a higher RPM. last but not least... DO YOU HAVE THE METAL HEAT SHIELDS ON THE PLUG WIRES??????? Those alone have been known to cause misfires. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted October 22, 2009 Report Share Posted October 22, 2009 I wasn't aware of that...the metal shields can cause misfires? You may just have helped me solve an issue on my wife's '93 Buick Century. to sum it up; probable causes: Bad spark due to bad plug, bad wire, bad coil, or bad ICM Worn out injector, or clogged injector. poor compression. vacuum leak any of these issues COULD be responsible for an uneven idle, which may not be as noticeable at a higher RPM. last but not least... DO YOU HAVE THE METAL HEAT SHIELDS ON THE PLUG WIRES??????? Those alone have been known to cause misfires. Quote Link to comment Share on other sites More sharing options...
carkhz316 Posted October 22, 2009 Report Share Posted October 22, 2009 I rock the metal heat shields on my L36 with no problems. If the plug wires are good, the shields should be no issue. Quote Link to comment Share on other sites More sharing options...
9lumina6 Posted October 22, 2009 Report Share Posted October 22, 2009 Those metal shields were giving me misfires on heavy throttle.........not idle...took em off at the Dayton meet and car was fine WOT Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 22, 2009 Author Report Share Posted October 22, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? Quote Link to comment Share on other sites More sharing options...
Crazy K Posted October 22, 2009 Report Share Posted October 22, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? maybe. do a VISIBLE spark check on each coil point to ground. as in stick a phillips screwdriver in the spark plug end of each wire and lay it on the intake or body or wherever. Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 23, 2009 Author Report Share Posted October 23, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? maybe. do a VISIBLE spark check on each coil point to ground. as in stick a phillips screwdriver in the spark plug end of each wire and lay it on the intake or body or wherever. Did that, and everything works fucking fantastic, I didn't even need the screwdriver, instead my hand seemed to work just fine. Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted October 23, 2009 Report Share Posted October 23, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? maybe. do a VISIBLE spark check on each coil point to ground. as in stick a phillips screwdriver in the spark plug end of each wire and lay it on the intake or body or wherever. Did that, and everything works fucking fantastic, I didn't even need the screwdriver, instead my hand seemed to work just fine. :lol: Quote Link to comment Share on other sites More sharing options...
Crazy K Posted October 23, 2009 Report Share Posted October 23, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? maybe. do a VISIBLE spark check on each coil point to ground. as in stick a phillips screwdriver in the spark plug end of each wire and lay it on the intake or body or wherever. Did that, and everything works fucking fantastic, I didn't even need the screwdriver, instead my hand seemed to work just fine. no... you need to see if the spark is an even color with each plug. a weak spark might show as orange instead of the typical blue. You're a conductor, not a voltmeter. you will not be able to tell the difference with an electric experience. Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 24, 2009 Author Report Share Posted October 24, 2009 Well guys it is not the injector, so what could that leave then. I guess I should run the compression check quick, but that will probably show up fine too. Could a bad ICM cause only 1 cylinder to misfire? maybe. do a VISIBLE spark check on each coil point to ground. as in stick a phillips screwdriver in the spark plug end of each wire and lay it on the intake or body or wherever. Did that, and everything works fucking fantastic, I didn't even need the screwdriver, instead my hand seemed to work just fine. no... you need to see if the spark is an even color with each plug. a weak spark might show as orange instead of the typical blue. You're a conductor, not a voltmeter. you will not be able to tell the difference with an electric experience. Trust me, its all good. The spark is blue in all 6 cylinders. Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 27, 2009 Author Report Share Posted October 27, 2009 So instead of just changing the one injector, I swapped the whole rail with a spare I had laying around when I did this about a week ago. Who would of thought that the other rail would of had the same cylinder injector on it bad. I just changed the single one tonight with one I knew was good and no more codes pop and it purrs at idle. Still, those vacuum lines are going to be fun. I wouldn't worry about it if I wasn't running the car without any lines going to the MAP sensor, lol. Quote Link to comment Share on other sites More sharing options...
Octavarium454 Posted October 27, 2009 Author Report Share Posted October 27, 2009 Ok so I went to back it out of the garage this morning and for the first minute it was fine. Then it popped the Check Engine Light and who would of thought, it is a misfire in cylinder 2. Could the connector to the injector be dirty or bad? I'll hit it with some electronics cleaner otherwise I got a spare connector I could splice on. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted October 27, 2009 Report Share Posted October 27, 2009 Have you actually OHM tested the injectors? DO A NOID TEST. all you need is a 12 volt bulb to do this. grab a flat blade style bulb (like the glovebox or trunk often use) and bend the metal tabs out. insert it in the injector harness connector and start the car. See how the flashing looks, and compare it to several other injector connectors. Quote Link to comment Share on other sites More sharing options...
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