trwebb26 Posted August 27, 2006 Share Posted August 27, 2006 I've been fighting my megasquirt for a couple of months now. I just can't figure out what is going on. About my setup: 78' 280z MS v3.0 board MS&SE 83' turbo optical dizzy Using (-)D14 to trigger an MSD6a to an MSD blaster 2 coil. As you'll see in the video - everything runs great when I first start the car. Then the timing will go to hell. It seems to be heat related somehow. Here is the movie: EDIT: http://www.fileden.com/files/2006/8/28/191641/Megasquirt_problem_small.wmvFree file hosting from File Den! Here is my MSQ (remove the .txt from the file name) http://www.geocities.com/trwebb26/280z_problems.msq.txt And here is a datalog of a similar time that this happend. You can see that it is fine at the beginning - then the MAP will change, but the RPMS stay put. http://www.geocities.com/trwebb26/datalog200608271842.xls The tach signal for the guage in the video comes out of the MSD box. I took video of it to show that the problem is either in the megasquirt or the MSD. I think that is pretty sure-fire evidence that the coil is not at fault. I've kind of run out of things to try... The only things I can think of are to send my megasquirt back to have it looked at - or replace my MSD box. Please help! Quote Link to comment Share on other sites More sharing options...
mobythevan Posted August 28, 2006 Share Posted August 28, 2006 Do you have anybody close that has another MSD to swap in? Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted August 28, 2006 Author Share Posted August 28, 2006 unfortunately not. Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted August 28, 2006 Author Share Posted August 28, 2006 If you were having trouble with the movie - I've changed the location to another server. Please try to download it again. http://www.fileden.com/files/2006/8/28/191641/Megasquirt_problem_small.wmvFree file hosting from File Den! Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted August 29, 2006 Author Share Posted August 29, 2006 Bump... bump... come on - nobody has any advice? Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 30, 2006 Share Posted August 30, 2006 Does it do it if you DON'T snap-throttle rev it? I had an issue with my timing offset and the high-map bins where on drop-throttle when the vacuum went high in the manifold, the spark would jump to the next terminal in sequence, and then STAY THERE until I shut the engine off and reset the box by turning the key of and back on. Underboost, I was cool, no drop throttle from boost above 2500rpms, I was cool, but hit any of those 40degree advance bins, and Braaap,Bang,Pop,Poof, BANG! Try taking all your high-vacuum bins to 30 degrees and see if it stops going nuts after you rev it. You may be jumping time one terminal ahead like I was doing! My WAG! LOL Good Luck Quote Link to comment Share on other sites More sharing options...
trippintl0 Posted September 2, 2006 Share Posted September 2, 2006 i know this might seem stupid - but is it possible that the ignition rotor in the distributor is like right on the edge of the terminal on the distributor cap, so that when it advances (or retards) enough, it jumps to the next spark plug wire? Quote Link to comment Share on other sites More sharing options...
Clifton Posted September 2, 2006 Share Posted September 2, 2006 And here is a datalog of a similar time that this happend. You can see that it is fine at the beginning - then the MAP will change' date=' but the RPMS stay put.http://www.geocities.com/trwebb26/datalog200608271842.xls I don't see in your datalog were the map changes and rpms stay the same. At idle it is pretty steady, around 38. If you tach is bouncing from 1-2k at what looked to be idle speed in the video but your log shows a steady idle speed. I would think it is an MSD issue or it should show up as bouncing on the log with a steady TPS (0%). Are you running solid core wires? Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted September 2, 2006 Share Posted September 2, 2006 It looks like you are dropping a lot of spark with that. My stock Ignition unit would do that and I replaced it with the bottom of the line MSD unit and the car ran better than it ever had. No sparks dropped at all. My setup is completely different though (N/A 2.6, SUs...). That is what makes me think your ignition unit needs replacing. Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 3, 2006 Author Share Posted September 3, 2006 I'm not running solid core wires (taylor spiral-cores) It seems like tony D may have the ticket. It seems to be advancing to the next terminal in the cap - advanced to around 68 degrees (10 degrees less than my trigger angle) Are you running an MSD too, Tony? Did you ever put a timing light on it when it started to go crazy on you? Like the movie shows - it stays right around the 68 degree mark, but seems to skip around for some reason. Can you export your timing map for me, Tony - so I can take a look. Meanwhile - I'll mess with the high vaccum bins. Clifton - look at the tail end of the log... I was opening the throttle (hence the loss of vacuum and increased MAP), but the RPM's were staying in one place - meaning that then engine stopped responding. olderthanme - what do you mean by "dropping spark"? Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 4, 2006 Author Share Posted September 4, 2006 So I decided to just set the RPM fixed at 30 RPM to test Tony D's theory about "dropped throttle". It seemed to run much better... the timing became a tad less eratic. So I decided to rev it up high and all of the sudden the timing skipped to the next trigger in the distributor and got a huge BANG... big backfire:malebitch . I now believe that my megasquirt and MSD box are fine - as they act perfectly ok when the timing is correct. I now blame the distributor for a crappy square wave signal at high RPMs. Anybody disagree? I borrowed a scope from work and I'll check to see what the square wave looks like on the input to megasquirt. Any reccomendations about maybe changning my pullup resistor to a different Ohm value to be less sensative at high RPM's? One more thing. When I ran the wires for the distributor - i cased them in the braided sleeve that RS-autosport sells. I grouned the steel sleeve at the megasquirt (not the distributor). I know that you aren't supposed to ground it at both places (ground loop)... but I'm not sure if the grounding should be reversed. Should I have grouned the shield at the distributor? Does it make a difference? I'm a mechanical engineer and the one or two circuits classes I took have long since been forgotten. Thanks... I feel like I'm getting a lot closer! Almost there! Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 8, 2006 Author Share Posted September 8, 2006 Can anybody help - or give some opinions? Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 9, 2006 Share Posted September 9, 2006 What was the result of you last tests? Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 10, 2006 Author Share Posted September 10, 2006 Well... The tach signal looks good. The output of the megasquirt looks good. The output of the MSD looks ok... but it is really tough to tell because of the frequency of the signal. It is just a pulse instead of a wave - so it is tough to tell what is going on. My latest guess is that the MSD is bad. I hate just buying parts to test stuff out, but I don't know that I've got much choice. Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 10, 2006 Share Posted September 10, 2006 Can you eliminate the MSD for now by using an HEI module to see for sure if it is the MSD? So just to reiterate, when you first start it, it runs fine whether the engine is hot or not. But after a minute or so, it starts missing badly. If you check the timing, it is now way off. Does it matter if the engine ishot or not (or does it never have a chance to actually warm up?)? If you shut the engine off, and restart it, it runs fine for a minute or so, and then shows the same problem, correct? It does sound hardware related, but it could also be firmware. The firmware version and the version set in MT match, right? Do you get any errors when you start MT with the MS powered up and connected to your computer? When I try to load your file in my MT that is set up for 029q, I get these 8 warnings: C:WINDOWSDesktop280z_problems.msq:Open WARNING(04): Constant "Stg2ndParmDlt" units mismatch, "KPa" in msq, expected "kPa" from ini. WARNING(04): Constant "Stg2ndParmKPA" units mismatch, "KPa" in msq, expected "kPa" from ini. WARNING(04): Constant "VEFixValue" units mismatch, "kPa" in msq, expected "kpa" from ini. WARNING(04): Constant "afrBins1" units mismatch, "AFR" in msq, expected "Volts" from ini. WARNING(04): Constant "afrBins2" units mismatch, "AFR" in msq, expected "Volts" from ini. WARNING(04): Constant "bcBins1" units mismatch, "kPa" in msq, expected "kpa" from ini. WARNING(04): Constant "bcBins3" units mismatch, "kPa" in msq, expected "kpa" from ini. WARNING(04): Constant "splitkpaBins" units mismatch, "kPa" in msq, expected "kpa" from ini. When I first started working with MSn'E, I had problems with firmware version mismatches. I suggest fixing any warning messages before trying to debug any hardware problems. Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 10, 2006 Author Share Posted September 10, 2006 My problem happens whether the car is hot or not. I can let it idle for a half an hour - with NO problems at all. Timing stays steady and everything does what it is supposed to. When I rev the engine up - something happens. The timing will stay steady, but the car won't rev up. Then if I open the throttle again... the timing will skip to around 60+ degrees and stay there for around 10 seconds and then start skipping all over the place. For giggles - I tried a new coil... It did the exact same thing. I don't have any errors when I start up megatune. Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 11, 2006 Share Posted September 11, 2006 Is the RPM always steady in MT when you are seeing the timing jump around? What does the wavform look like on the trigger input of the MS? It should be a pronouced +12V square wave. There should not be any glitches (narrow noise pulses). I if the RPM display in MT is always steady, then it is not an input problem, but an output problem to the MSD. Again, an HEI module will eliminate the MSD as the potential problem. Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 15, 2006 Author Share Posted September 15, 2006 So I bought a new MSD and installed it last night. Now the car does something different - but still not correct. As before - it starts and idles fine with the timing correct. The second you touch the throttle - the timing jumps to ~60 degrees. This happens even if you have the timing fixed at a certain degree. If you let off of the throttle - it goes back to the correct setting. I guess I'll send my Megasquirt in to be looked at? Quote Link to comment Share on other sites More sharing options...
z-ya Posted September 15, 2006 Share Posted September 15, 2006 Why do you have the dwell dettings to a fixed duty cycle of 50%? Also, why is your trim angle ony 50, shouldn'tit be closer to 70? Quote Link to comment Share on other sites More sharing options...
trwebb26 Posted September 16, 2006 Author Share Posted September 16, 2006 trim angle is set to 71. The dwell is set at 50% cuz i'm using an MSD. It is capacative discharge and is suposed to have a fixed dwell (from what I've read). Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.