BIL Posted December 21, 2009 Report Share Posted December 21, 2009 I know this is kind of basic and maybe a little dumb, but what is the spark plug gap? I had to move to an 8 series NGK and gap them at .030-.032. Link to comment Share on other sites More sharing options...
BOHO Posted December 21, 2009 Author Report Share Posted December 21, 2009 (edited) I've got 7's gapped at 37...Why did you have to move up Bill?. This isn't just a little hiccup....its missing pretty bad under load. but free rev it doesn't miss at all. I tried to add fuel and change AE but didn't really seem to change. Edited December 21, 2009 by BOHO Link to comment Share on other sites More sharing options...
Chad Posted December 22, 2009 Report Share Posted December 22, 2009 I've got 7's gapped at 37...Why did you have to move up Bill?. This isn't just a little hiccup....its missing pretty bad under load. but free rev it doesn't miss at all. I tried to add fuel and change AE but didn't really seem to change. I've tried from stock 6's all the way to 9's and have come back to 7's at .032". The colder plugs don't seem to do much for detonation (the whole purpose) and they tend to foul easier on my build. Same with gap, when I got under .030" it flooded way too easily on cold starts, and didn't see any spark blow out even at .040". I use the SDS coil pack which is a modified GM coil pack setup, but my spark energy is the same as most any other. 8's worked OK, but the 7's seem to work just as well for me, and are easier to get. Link to comment Share on other sites More sharing options...
BOHO Posted December 22, 2009 Author Report Share Posted December 22, 2009 I'll close the gap up a little and see if it helps...Does this sound like most of my issues is probably in my tune Chad? No boost leaks...good idle and free revs nice. This car hasn't seen the road with this ecu or MPI so I'm kinda lost right now. Link to comment Share on other sites More sharing options...
Chad Posted December 22, 2009 Report Share Posted December 22, 2009 Yah, probalby your boost map in perticular. If it revs fine but not under load, that's usualy the manifld pressure settings. When you free-rev, you are deep in the negitive pressure range, but under loat, you are much closer to 0 PSI, even before you spool the turbo. Can you log the AF ratios yet? Perhaps just watch the WB gage while it's happening will tell you what you need to know, most are responsive enough to register a sudden lean or rich condition while it's breaking up. Just to be sure, you should throw a timing light on there and rev it in neutral to see the timing move (advance) correctly. On some designs, breakup can be noise getting into the pickup too. When cylinder pressurs increase, so does the electrical resistance at the plug gap. That causes the plug wires to emit more noise. Link to comment Share on other sites More sharing options...
BOHO Posted December 22, 2009 Author Report Share Posted December 22, 2009 I can't log right now. I don't have a laptop that will datalog right now. I will look into the other stuff you were talking about. hopefully its not the noise in the ignition signal. I'll try to keep a closer eye on A/F ratio's and shorten the gap on the plugs. Link to comment Share on other sites More sharing options...
Chad Posted December 22, 2009 Report Share Posted December 22, 2009 I'd way .037" is fine, stock is .039 - .041", you don't need short gaps till you start seeing high cylinder pressures (lots of boost). Below 10 PSI, you want a wide gap anyway. If you are tuning, you want to run low boost till you are positive you are on the right track with all the other settings. I'd say leave it where it is till you turn up the boost. Link to comment Share on other sites More sharing options...
BOHO Posted December 22, 2009 Author Report Share Posted December 22, 2009 I've still got smoke, missing badly under load, and I don't know what to do. It does have lean spikes when the motor is under load but no amount of fuel will fix it..I guess I'm going to pull the head and see if I can find anything. Don't know what else to do at this point. Link to comment Share on other sites More sharing options...
jisleyjr Posted December 22, 2009 Report Share Posted December 22, 2009 The WB will spike lean if you are mis-firing. Adding more fuel won't make it better, perhaps you are too rich. Link to comment Share on other sites More sharing options...
franco101 Posted December 23, 2009 Report Share Posted December 23, 2009 What are your compression numbers before you pull the head Franco Link to comment Share on other sites More sharing options...
BOHO Posted December 23, 2009 Author Report Share Posted December 23, 2009 between 146 and 149 on all 4 Link to comment Share on other sites More sharing options...
Chad Posted December 23, 2009 Report Share Posted December 23, 2009 What is your timing in neutral at say 3500 RPM? It will break up if it's not timed proppery. It can read rich too if it's up to full temperature, as the unburnt fuel hits the hot turbine wheel, it can ignite which will read rich or lean, depending on how much fuel is in there. It is black smoke when it breaks up? May be too much fuel in the upper ranges of the manifold pressure map. I don't know how your ECU shows your maps, but on the SDS you have to draw it out on graph paper, it runs best when the line is fairly straight as that represents the flow of the turbo. Turbo flow is fairly linear, it's the cam profile characteristics that are non-linear, and those are tuned in different areas of your map. Link to comment Share on other sites More sharing options...
BIL Posted December 23, 2009 Report Share Posted December 23, 2009 Chad, when you say neutral at 3500 rpms, what do you mean? Are you saying 0 degrees? I have not heard this before and would like to be enlightened. Link to comment Share on other sites More sharing options...
Chad Posted December 23, 2009 Report Share Posted December 23, 2009 put the car in neutral, and with a timing light on, rev the motor to 3500, what is the timing at this RPM? Shoud be arround 30* advanced. If not, you'll have fuel burn issues. Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 I'll put the light back on it tomorrow..I got a new one today..I don't even know what the dial and stuff is for...lol. I guess I need to read the instructions..my stupid actron stopped working on me... Link to comment Share on other sites More sharing options...
MoneyMakerTsi Posted December 24, 2009 Report Share Posted December 24, 2009 I had this same problem with my car. Under load i had really really bad miss fires. It ended up being my spark was not advancing under load. Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 I had this same problem with my car. Under load i had really really bad miss fires. It ended up being my spark was not advancing under load. Were you on a distributor or EDIS? Just curious. Link to comment Share on other sites More sharing options...
MoneyMakerTsi Posted December 24, 2009 Report Share Posted December 24, 2009 I have a distributor but wouldn't the concept be the same if it wasn't electronically advancing (i figure you have a EDIS) Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 No you are correct...I just had the same problem with EDIS though. Everything worked right except it would not control timing. It ran in limp mode all the time. I JUST put a distributor back on the car. I'm only skeptical because the distributor is supposed to be controlling timing with vac advance. Its not locked or anything. I will check it out today post up. Thanks for the help. Braden Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 OK!!!!.....wt......!!!.....lol....I put my new timing light on and can not find my timing mark....knowing that I must be off a tooth or something I pull the plugs...find TDC with screwdriver in #1 check timing mark...sure enough crank timing is on....pull the distributor cap...And its dead on #1 plug.....Now I'm even more confused...put it all back together and try to find timing again....Well...I found it....If the distributor is all the way to the right....Bolt all the way on the bottom....The car is idling at about 23-25degrees BTDC....So I must be off a tooth......which way would I have to go...Does this seem like I'm on the right track? Thanks guys. Link to comment Share on other sites More sharing options...
Chad Posted December 24, 2009 Report Share Posted December 24, 2009 re-stab the distributor atelast 1 tooth counter-clockwise from where it is now sounds like you are off 2 teeth, but ry just one tooth at a time. Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 Well....Even though the car was off by about 20degrees...It's still breaking up...But not nearly as bad...I can clearly see lean spikes when I get close to true "zero" psi. I'm going to go over accel enrichments and lookover the VE table again....I still havn't seen boost but with the timing being that far advanced and the white smoke...which seems a little better now...I'm still worried about the headgasket. Link to comment Share on other sites More sharing options...
BOHO Posted December 24, 2009 Author Report Share Posted December 24, 2009 Chad you are right...It was 2 teeth. Link to comment Share on other sites More sharing options...
pure_insanity Posted December 26, 2009 Report Share Posted December 26, 2009 so how did it act after you moved it the 2 teeth? i had this happen to me a while back on another project. somehow i had stabbed it wrong and even when i checked the timing physically, i still had problems but thought it was right. then somehow i figured out i had been an idiot. set timing and it was all good. Link to comment Share on other sites More sharing options...
jahjah Posted December 26, 2009 Report Share Posted December 26, 2009 OK!!!!.....wt......!!!.....lol....I put my new timing light on and can not find my timing mark....knowing that I must be off a tooth or something I pull the plugs...find TDC with screwdriver in #1 check timing mark...sure enough crank timing is on....pull the distributor cap...And its dead on #1 plug.....Now I'm even more confused...put it all back together and try to find timing again....Well...I found it....If the distributor is all the way to the right....Bolt all the way on the bottom....The car is idling at about 23-25degrees BTDC....So I must be off a tooth......which way would I have to go...Does this seem like I'm on the right track? Thanks guys.well thats definitely way off.... I would mess with it till your idle is where its supposed to be Link to comment Share on other sites More sharing options...
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