duragg Posted September 4, 2011 Share Posted September 4, 2011 After driving for 30 minutes or hard charging I get mis-firing and studdering under load at higher throttle and RPM. If I keep my foot out of it the problem mostly goes away. Newly built L28 with Triples, Fresh engine with maybe 50 miles on it. Has Wideband and Knocksense. Engine L28 / F54 / N42 / 210psi each / L490 cam / MSA Spring kit. Carbs DCOE 40-151 / 45F9 / 130main / 200 air / Synced and dialed in. 3psi currently with floats precisely set. Have 1/3 100LL and 2/3 91 pump gas in now. AFR on wideband very consistent in the 12.5 to 13.5 range. Have 3 layers of heat shields, header wraps, blankets, but still hot. Ignition Crane XR3000, recurved L24 dizzy with 8 initial and 28 by 3000. NGK BP8ES. Accel "can" ignition coil (chrome) <-- is that thing a POS and overheating? I am in Phoenix. It is INSANELY hot. AEM Wideband is quite consistent betweeen 12.5 and 13 even under load and when studdering. Something is failing when hot and worse under load. Fuel boiling in the carbs? Coil or Ignition module HOT and misfiring? Its either fuel or ignition I guess. Any way to tell which one? Its not like the AEM O2 sensor is showing too lean or too rich when misfiring although it is jumpy then due to the bad emissions. Quote Link to comment Share on other sites More sharing options...
Leon Posted September 4, 2011 Share Posted September 4, 2011 This is exactly what is happening in my Z (triple Webers and headers) when it's hot out. It can get bad enough for me to have to pull over for a little bit. I don't have a heat shield though and am planning to make one next week. I'm hoping that it will solve my problems, but I guess we'll see. I'm also using a stock fuel rail and was thinking of insulating it at the mounting points to limit conductive heat transfer. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 4, 2011 Share Posted September 4, 2011 (edited) When it happens, jump out, take your can of Radio-Shack FREEZ-IT and ****** the coil, jump back in and see if it goes away. <EDIT> My gawd, the German word for 'shower' is not acceptable to the censor-bot! O.K. "SPRAY" it, don't use the word also associated with feminine hygiene (or German for 'shower') because it's BAD! <EDIT> If it does, you have heat related issues with the coil. If not, then continue with the electronic components until you have eliminated all of them. Then it's something fuel related. If you think it's heat (insanely hot? What, like 53C at 1130AM and rising higher to a peak over 55C at somewhere between 3-5PM... ) then get a can of Freez-It and start cooling the components to see if that is what it is---this is how you do it with the ignitor module, it will work on virtually any electrical component to isolate heat-related issues. In the bad-old, pre Global Warming Scare days, I would have told you to shoot a freon horn at the component, or use R12 in a can since everybody had it laying around. But I can't say ****** it with your little can of R134 because that would be wrong today... Freezing bearing shafts with a 20# can of R22 and a gauge set hose is probably frowned upon these days as well... Edited September 4, 2011 by Tony D Quote Link to comment Share on other sites More sharing options...
duragg Posted September 4, 2011 Author Share Posted September 4, 2011 THanks All. I tried to cool things with spray but it seems at idle or after driving everything is performing OK and couldn't tell. More pronounced at higher RPM. Coil and Ignition box are HOT to the touch. It is 45c+ outside air temp and the air under hood is significanly higher. I was having hot idle misfire running NGK BP6ES plugs. Switched to BP8ES and that hasn't come back. Maybe a BP10ES is worth trying? That ACCEL coil is probably a POS even though it is new. Maybe I need to invest in a better coil regardless. I am not running a resistor. Plugs ceramic nipple thing is white. Shoulda taken a pic today. Maybe shoulda gone with less C/R. Quote Link to comment Share on other sites More sharing options...
duragg Posted September 4, 2011 Author Share Posted September 4, 2011 (edited) I think I will just buy a real coil and start from there. Maybe even new wires again. A few areas I know I am weak: Coil, Fuel pump and delivery hoses no fuel return. But with this heat thing I am just suspecting some kind of ignition situation. Leon: Email me and I will send you pics of how I made Po-boy heat shields. ******. < hehe, i said ****** too..> Edited September 4, 2011 by duragg Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 4, 2011 Share Posted September 4, 2011 I don't think you understand what is being said: spray the component when the misfire is happening. Spray it to coooooool it down to the core. This will take literally seconds. Then RESUME high load,high rpm running. If it goes away, then you have isolated it. Jumping around throwing parts at it won't solve your problem with any degree of certitude on what exactly was wrong. The Freez-It works, if you say the above conditions had no effect, then HEAT is not your problem with the component. Remember a coil only processes the on-off signals it receives. My Vair would 'go nuts' with random short-like firing of the coil at elevated temperatures. LOOKED like a bad coil breaking down. But repeated flooding with compounds not to be mentioned now(this was testing on the Palm Springs grade at 110F+ in the early 90's) had no effect. Dumbfounded that it WAS NOT the coil, in desperation I started flooding EACH COMPONENT in turn which was either in the engine bay, or in some way connected to the coil. It ended up being the Spearco Water Injection Controller. Somehow when it got hot, it did something to the negative side of the coil (where it took a tach input...but apparently could backfeed and screw up the coil) which made it randomly fire at crazy intervals or simply ground out completely and die. I suspect a diode in the input circuit of the board going bad...but I disconnected it and the problem never came back... I would never have thought it was the Water Injection Controller in a million years unless I'd flooded it with 'quick evaporating coolant' and the thing stopped misfiring and acting up RIGHT THEN AND THERE! So try again if you haven't, and go straight back to High RPM / High Load after cold-soaking the coil or other suspect components. If it stops, you have it. My assumption is this doesn't happen when the engine is cold... BTW, 45C is not 'insane hot' not by a longshot! Those numbers I gave started at 33C at just before sunup, with humidity so high a thick fog blankets the area. It's miserable hot, and by noon, when it's 50+ you thank your stars the humidity has 'evaporated'! Wrap a water-soaked rag over your face to get humidity to breathe into your lungs... As for 45C, add 98% humidity to it and you realize 45C in Phoenix ain't that hot at all. It rarely exceeds 120F there anyway, it's not THAT hot! There are places around the world where it's hotter, or just as hot but with oppressive humidity that just goes away to nothing during the day! Nah, Phoenix is a 'vacation mecca' comparatively. Very mild climate... Quote Link to comment Share on other sites More sharing options...
duragg Posted September 4, 2011 Author Share Posted September 4, 2011 You are saying to pull over spray and hammer down? Can do that. Good idea. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 4, 2011 Share Posted September 4, 2011 How else will you determine it? That is what you have to do! Quote Link to comment Share on other sites More sharing options...
duragg Posted September 4, 2011 Author Share Posted September 4, 2011 Visa. THats the only other method. An excuse to replace all the "marginal" components with new stuff. But my budget for old "R.O.P.O.S" is drying up and my old Benz 560SEC wants new springs and brakes so your surgical strike method is probably smarter. Quote Link to comment Share on other sites More sharing options...
duragg Posted September 21, 2011 Author Share Posted September 21, 2011 Changed the coil to an MSD BLaster2 and WOW. What an unbelievabe difference. The old coil was an ACCEL that was only a year old. But my alternator was overcharging for a while and maybe it got fried. Them triples start right up and don't miss a single beat in any regime now. MAJOR difference. TJ Quote Link to comment Share on other sites More sharing options...
Leon Posted September 21, 2011 Share Posted September 21, 2011 Funny, I have a Blaster 2 and was considering going back to stock! Glad you found your problem, now I need to fix mine! Quote Link to comment Share on other sites More sharing options...
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