280zedx Posted September 18, 2004 Share Posted September 18, 2004 i'm ready to snap! My megasquirt supercharger project is so close!!!! The tach signal is still jumping around especially between 2500 and 3200 RPM. You can see it on the tuning page and it is really evident on the datalog table. This i'm sure is causing the bad sputter it has everytime i drive around those rpms. I'm fairly confident i have the fuel mapping in the ballpark, as i'm also using the LM-1 wideband. I can't fine tune it till i fix my tach signal. So far i've: replaced the coil replaced the signal wire with a direct shielded wire. tried a couple different Ed caps (.01 &.1mf) and the latest- installed the Dave cap (22mf) no difference, it even seems the sputtering is worse since i got it on the road. Outside these tach areas the car runs and hookups great. Tonight i'll try a couple of different resisters in-line with the tach wire itself. If no luck then i'll try wiring a HEI module in. It's a bit of a pain as it needs to run parrallel and connect directly to the VR sensor itself (not the ignition module). Question: has ANYBODY had these type of tach problems with a non-turbo setup? or has anyone even successfully got the megasquirt working on a 81-83 non turbo? other info- it runs the exact same with the supercharger unbelted. Sparkplugs look good. Wideband readings are often "perfect" when it sputters (12 - 14 AFR). other wierd tidbits- i couldn't get the MS tuning page to work properly, it appeared to be backwards with the "ball" off the table. I eventually tried setting up my VE table backwards (high kpa at the top, low kpa at the bottom) and the car ran the same and now the tuning page works right! also- the datalog after the Dave cap was installed shows the rpm incorrectly. the rpm numbers seem to be 1/100 of the actual. (idles at 8-9 and when its in the 20s it jumps around like 50, 80 100 etc. This is probably right where it sputters like before. what gives. I know this a lot to take in but i'm so close i can taste it.....argghhhhh p.s. i'll be posting this on the MS forum as well. thanks, Mike 1983 supercharged ZX Quote Link to comment Share on other sites More sharing options...
jkube Posted September 18, 2004 Share Posted September 18, 2004 By any chance did you take the 12 volt switched power from any line close to the alternator. I did this with my setup and the symptoms were similar to yours. It seems there is quite a dirty signal coming back through the alternator which affects the RPM and injector pulses. Mine would idle fine but as soon as I gave some gas (RPMs) the engine would run like crap. Oddly enough there were times it would run fine. If you are suspicious that this might the reason, then find a switched line close to the fuse box. Jeff Quote Link to comment Share on other sites More sharing options...
280zedx Posted September 18, 2004 Author Share Posted September 18, 2004 which 12volt are you talking about? The MS relay board's switched 12v is under the dash connected right near the ignition. the coil's 12v is the factory wire (untouched). I do have a fan relay tapped off the coil 12v and i noticed the fan ground is grounded at the alternator. Could that cause a weird loop signal? sidenote: couldn't get a resistor in this small town so the other mods will have to wait. I couldn't. i figured it sputters less the faster you go through the gears so.....i did some wot runs (with Bernardd's zx egging me on ) The wideband readings are almost perfect and the supercharger launches it out of the hole with an evil whine and killer torque Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 18, 2004 Share Posted September 18, 2004 take a look in the megasquirt files site at yahoo. perry harrington devised a circuit that will isolate all the ignition noise on the input section for the board altogehter. he will make the circuit and install it on your board for $50, but the parts are far cheaper than that, and installation is fairly easy. remember I had a problem that was traced to my LAPTOP and the way it handled the com. Who knows why, but it did. I haven't tuned yet, due to similar jumping, but as long as I just download a program into it, and don't hook up my laptop, it runs fine. The minute I hook it up, it starts doing crazy things. I'm sure you read my travails in the turbo forum under the MS sticky. But the resistor may solve the interference. One thing I did was install a stereo power filter on the input power line, taken directly from the battery positive connection, as well as on the switched power input line (yeah, I wass reachin'...) and while it did not solve MY problem, it DID make the power traces on the O-Scope MUCH cleaner. I used the big black box rated at like 20A from Radio Shack... Good Luck! Quote Link to comment Share on other sites More sharing options...
Guest 305240 Posted September 18, 2004 Share Posted September 18, 2004 When reading this post, a thought accured to me. While I was reading some fan installation tips from a ford forum, I run across an interesting tidbit. When using a perminate magnet fan, such as the taurus, it will free wheel backwards when not in use. This starts putting juice backwards into the electrical system. He used a diode to stop this. Here is the link. It's pretty informative. Possably this might help? http://www.fordmuscle.com/archives/2003/02/electricfan/index.shtml Quote Link to comment Share on other sites More sharing options...
280zedx Posted September 18, 2004 Author Share Posted September 18, 2004 thanks, it should also be an easy test to determine. I'll just disconnect the fan (and keep an eye on the temp) and see if it acts up still. very information link- Mike Quote Link to comment Share on other sites More sharing options...
280zedx Posted September 22, 2004 Author Share Posted September 22, 2004 Eureka! Finally running sweet! the moment i put a 22k resister in line the problem was solved. after about ten minutes of driving i got a few tach flicks on the high end. a 33k had a rare flicker and a 47k was perfect! the fuel map is definately in the ball park and the blower is working awesome but it's killing me that the car is finally running sweet and it's almost time to park it here in canada. Quote Link to comment Share on other sites More sharing options...
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