jacob80 Posted May 10, 2010 Share Posted May 10, 2010 Hey guys, Well tonight I was giving my brother a ride in my 240z with an L28ET and had a little mishap. My tune isn't 100% and theres a spot where it cuts out, but at any rate, at some point, I think I hit that point and then a small backfire IIRC and then it died. That was odd, but I started it and it started just fine, but when I went to rev it, the O2 gauge just went completely lean and died. I started the car again and it idles fine, but when I touch the gas, it hates me. This scared me, but I was hoping it was just a fouled plug. We proceeded to push the car 1/2 mile back home to do some diagnosis. Came home, and pulled the plugs. I was scared that I either A) Blew a head gasket, Blew a hole in the piston or C) blew a valve stem seal, if that is possible. I cleaned the plugs and compression checked 3 out of the 6 cylinders, and they all checked out fie (~140 PSI). I also checked to see if any of my vacuum lines or intercooler piping blew off, but a I saw nothing. Went ahead and tried it again and the same symptoms occurred. Right now I am absolutely distraught and am regretting driving the car without a 100% reliable tune. I know I shouldn't have, but what is done is done. What is the next step? I plan on going back and confirming that all cylinders are up to ~140 PSI, but then what? I hear no knocking or anything terminal of that sort, just doesn't want to rev. Thanks for your help guys!! Quote Link to comment Share on other sites More sharing options...
frank280zx Posted May 10, 2010 Share Posted May 10, 2010 (edited) Hey guys, Well tonight I was giving my brother a ride in my 240z with an L28ET and had a little mishap. My tune isn't 100% and theres a spot where it cuts out, but at any rate, at some point, I think I hit that point and then a small backfire IIRC and then it died. That was odd, but I started it and it started just fine, but when I went to rev it, the O2 gauge just went completely lean and died. I started the car again and it idles fine, but when I touch the gas, it hates me. This scared me, but I was hoping it was just a fouled plug. We proceeded to push the car 1/2 mile back home to do some diagnosis. Came home, and pulled the plugs. I was scared that I either A) Blew a head gasket, Blew a hole in the piston or C) blew a valve stem seal, if that is possible. I cleaned the plugs and compression checked 3 out of the 6 cylinders, and they all checked out fie (~140 PSI). I also checked to see if any of my vacuum lines or intercooler piping blew off, but a I saw nothing. Went ahead and tried it again and the same symptoms occurred. Right now I am absolutely distraught and am regretting driving the car without a 100% reliable tune. I know I shouldn't have, but what is done is done. What is the next step? I plan on going back and confirming that all cylinders are up to ~140 PSI, but then what? I hear no knocking or anything terminal of that sort, just doesn't want to rev. Thanks for your help guys!! -If you blew a HG you will smoke white and overheat -To be sure CHECK ALL cylinders and do a leakdown on it -If you blew a hole in piston you will smoke BLUE (i.e. Oil) and your vents will bollow smoke -It sounds like an electrical issue What are you running in the car engine management whise? MsS i think (from your sig) i think you fried something else in the MsS Edited May 10, 2010 by frank280zx Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 10, 2010 Author Share Posted May 10, 2010 -If you blew a HG you will smoke white and overheat -To be sure CHECK ALL cylinders and do a leakdown on it -If you blew a hole in piston you will smoke BLUE (i.e. Oil) and your vents will bollow smoke -It sounds like an electrical issue What are you running in the car engine management whise? MsS i think (from your sig) i think you fried something else in the MsS Yeah I'll definitly do a compression check of all cylinders this evening. This morning, I went ot and tried to start it again, which it sid, but it just doesn't want to stay running. I've experienced no smoke so that's a good sign. Yes, I am running megasquirt and spark, but what could I have fried? It almost seems like I have a really bad vacuum leak, but j checked my lines and none appear as though they've popped off, but who knows. It very well seems like an electrical issue, but I'm not sure where to start. What could I have potentially screwed up? Perhaps I popped a fuse? Thanks for your help! Quote Link to comment Share on other sites More sharing options...
rags Posted May 10, 2010 Share Posted May 10, 2010 Make sure you have fuel pressure before going crazy with the tune. Setting up a tune with a clogged fuel filter of fuel lines will spell disaster later on. Not to mention you will pull your hair out trying to figure out why the AFR's won't settle. joe Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 10, 2010 Author Share Posted May 10, 2010 (edited) Make sure you have fuel pressure before going crazy with the tune. Setting up a tune with a clogged fuel filter of fuel lines will spell disaster later on. Not to mention you will pull your hair out trying to figure out why the AFR's won't settle. joe Definitely! That is something I was looking at last night and the gauge on the rail is measuring a normal 37 PSI, but of course I'm second guessing myself. My brother once had issues with his 240sx running like absolute ****...then he realized he was out of gas! Just to make me feel better, if I don't hear any knocking, see any plooms of smoke, or have any oil on my spark plugs, and my compression is good on all cylinders, could I almost conclude that I have sustained no terminal damage? If I had some serious damage, wouldn't I hear a knock or something of the sort? I'm really hoping its just a bad fuse or fouled plug or SOMETHING. I'm just driving myself nuts today thinking about it, just hope someone has a good idea of what it could be. When I get home I'm going to check my compression on all cylinders, like I said. I'm also going to bring all the pistons up and shine a light through the spark plug hole and see if I see any damage or oil on the pistons. Then, I'll check all my vacuum lines and intake manifold in general and see if when it back fired it just didn't pop something off. This has happened to me before when I went to start the car, there was some sort of back fire through the intake and some smoke came out and blew my vacuum lines off! Very odd. Hopefully this ends up to be something silly because I plan on attending the Branson Z Fest in about a month (as many of you probably already know). Once again, thanks for all your help guys, I don't know where I would be without ya! Edited May 10, 2010 by jacob80 Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 10, 2010 Author Share Posted May 10, 2010 Ok guys, major update, ...it runs! Very odd circumstances with this one. I tossed and turned for two hours last night beside myself about driving the car without a 100% tune! When I got home, I popped my radiator cap off and it was green as grass, good sign! Next, I checked my plugs again, compression, and timing. All looked good! This was very odd I thought, but I'll go with it. Hopped in the car and tried to start it, did the same thing. Crap. Went over to the computer, reflashed my MSQ and tried it again. Same thing happened. At this point, I wasn't sure what to do. I grabbed my video camera and made this video: Self explanitory I'm just thanking god that I didn't grenade the motor, ahhh so relieving!!!!!!!!!!!!!!!!!!!!! And yes, I did say I was checking the oil and popping off the radiator cap, ahahahahaha! Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 11, 2010 Share Posted May 11, 2010 Ok guys, major update, ...it runs! Very odd circumstances with this one. I tossed and turned for two hours last night beside myself about driving the car without a 100% tune! When I got home, I popped my radiator cap off and it was green as grass, good sign! Next, I checked my plugs again, compression, and timing. All looked good! This was very odd I thought, but I'll go with it. Hopped in the car and tried to start it, did the same thing. Crap. Went over to the computer, reflashed my MSQ and tried it again. Same thing happened. At this point, I wasn't sure what to do. I grabbed my video camera and made this video: Self explanitory I'm just thanking god that I didn't grenade the motor, ahhh so relieving!!!!!!!!!!!!!!!!!!!!! And yes, I did say I was checking the oil and popping off the radiator cap, ahahahahaha! Check all of you intake connections. When it wasn't running right it sounded like a intake leak. I doesn't sound all that good. I am assuming it's a stock cam right? It should pur like a kitten. Did you calibrate your timing? I'd set you idle timing to 30 deg or so, it will smooth the idle right out. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 11, 2010 Author Share Posted May 11, 2010 Check all of you intake connections. When it wasn't running right it sounded like a intake leak. I doesn't sound all that good. I am assuming it's a stock cam right? It should pur like a kitten. Did you calibrate your timing? I'd set you idle timing to 30 deg or so, it will smooth the idle right out. 30 degrees? Really? Maybe I'll try that! I'm at like...15 now, is that bad? What is stock advance? 30 just seems pretty extreme for idle, but maybe not. Thanks! Quote Link to comment Share on other sites More sharing options...
letitsnow Posted May 11, 2010 Share Posted May 11, 2010 Under low load/high vacuum conditions engines like a lot of timing. I'm only running 19 or 20 deg at idle though. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 11, 2010 Author Share Posted May 11, 2010 Well here is my current spark map: Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 11, 2010 Author Share Posted May 11, 2010 Well here is my current spark map: Quote Link to comment Share on other sites More sharing options...
letitsnow Posted May 11, 2010 Share Posted May 11, 2010 (edited) Under low load/high vacuum conditions engines like a lot of timing. I'm only running 19 or 20 deg at idle though. Edit: whoops Edited May 11, 2010 by letitsnow Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 12, 2010 Share Posted May 12, 2010 Again, did you calibrate your timing so that the actual timing (as seen with a timing light) matches what you see in Megatune? If you haven't done this, then your timing table means nothing, and your timing is probably way off. At no load (idle), you can run a lot of timing. Doesn't hurt, just gives it a nice idle. How much boost will you run? 250kPa (150kPa above atmospheric) = 21psi. Do you really want to run 21psi? Your timing at 15psi will be 21 deg according to your table. But if your calibration is off, who knows what it will be. Best to verify your timing calibration before doing anything else. I would also suggest spending a few hours on a dyno to get the tune close. Pete Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 12, 2010 Author Share Posted May 12, 2010 Yes, my timing does line up. I set it to 10 degrees advance while cranking and that is what it is showing. I am running the stock 7 PSI for boost right now, so I do not need that high of a kpa scale, but I have yet to find a good timing map that maxes out at 7 PSI kPa equivalent. Perhaps someone could throw one my way? Thanks! Quote Link to comment Share on other sites More sharing options...
wigenOut-S30 Posted May 12, 2010 Share Posted May 12, 2010 (edited) I noticed in the vid the wide band at idle was like 10.8-11.0 and you stated that it is lean.That is actually super rich. You should shoot for a idle AFR around 14.7. Edited May 12, 2010 by wigenOut-S30 Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 12, 2010 Author Share Posted May 12, 2010 I noticed in the vid the wide band at idle was like 10.8-11.0 and you stated that it is lean.That is actually super rich. You should shoot for a idle AFR around 14.7. Yeah, I said some silly things in this video. What I meant was that as of right now, it does idle at that and it wasn't unusual. Yes, it is extremely rich and I hate it! I did lean it out the other day and it idled decently around 13 AFR but after some stop and go driving, it idled like absolute crap and wandered like no other. What could be causing this? Perhaps I should increase my timing advance? Quote Link to comment Share on other sites More sharing options...
z-ya Posted May 12, 2010 Share Posted May 12, 2010 Yes, my timing does line up. I set it to 10 degrees advance while cranking and that is what it is showing. I am running the stock 7 PSI for boost right now, so I do not need that high of a kpa scale, but I have yet to find a good timing map that maxes out at 7 PSI kPa equivalent. Perhaps someone could throw one my way? Thanks! +7psi=150kPa. 27 deg is probably safe with 93 octane. Yes, you can change the scale to get more VE and timing bins in the engines operating range. You need to know what you plan on running for max boost and set the VE and timing table scales accordingly. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 12, 2010 Author Share Posted May 12, 2010 +7psi=150kPa. 27 deg is probably safe with 93 octane. Yes, you can change the scale to get more VE and timing bins in the engines operating range. You need to know what you plan on running for max boost and set the VE and timing table scales accordingly. Max Boost: 7 PSI (stock, for now) I'm getting a really bad stutter around 3k RPMs while under no load, for instance when I'm cruising at ~60 mph and slowly increase throttle it'll just cut out like its about to back fire, or sometimes it will stutter. I guess thats a whole different can of worms. Its a work in progress I suppose Quote Link to comment Share on other sites More sharing options...
FlatBlack Posted May 12, 2010 Share Posted May 12, 2010 What spark plug wires are you running? I've heard alot of people ahve issues that are solved with Magnecor KV85s. I just bought some for my car aboout a month ago. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted May 12, 2010 Author Share Posted May 12, 2010 They are, indeed, Magnecors. Quote Link to comment Share on other sites More sharing options...
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