proxlamus© Posted October 4, 2008 Share Posted October 4, 2008 Im having problems with Megasquirt.. or my car I can't figure it out yet. The car has good fuel pressure.. 38psi at idle.. and all of the settings in Megasquirt seem fine.. the symptoms I'm having is the car will start and run for a few seconds and then my tachometer bounces from 1000 RPM to 0 RPM a few times. Then the tachometer reads 0 RPM and the car continues to run for about 2-3 seconds then the car dies. When I have Megatune running it shows a fairly constant RPM... So the cars tachometer reads 0 RPM but Megatune shows 900 RPM until the car dies after 2-3 seconds. I attached a LOG of the event.. On Megasquirts "Tuning your Megasquirt" in the instruction manual states If the engine starts and runs for more than 20 seconds or so, then stalls, you need to adjust your warm-up enrichment bins. As you adjust your warm-up bins, you may need to re-adjust the afterstart, since these interact (i.e., a larger warm-up value may require a shorter or smaller afterstart enrichment). Now I have tried numerous settings on the Warm-up enrichment bins. I don't know why all of a sudden I am having this issue. The car ran great for over 3 years now with the SAME settings!! The only thing on the car I have changed was the transmission!! By the way the car runs fine and pulls hard.. I'm only having issues at IDLE! Quote Link to comment Share on other sites More sharing options...
Careless Posted October 4, 2008 Share Posted October 4, 2008 have you tried holding the clutch pedal to release the connection between the trans and the car to make sure it's not the transmission that's got some crud in it that's making it spin slower than it should? just an idea, but hey, it might be worth a shot! Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 4, 2008 Author Share Posted October 4, 2008 LoL.. tried that too =) Quote Link to comment Share on other sites More sharing options...
Careless Posted October 4, 2008 Share Posted October 4, 2008 lol, gaht dangit. ummm.... remove and reinstall the TPS? replug it? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 4, 2008 Author Share Posted October 4, 2008 judging by the LOG .. the TPS value is steady .. so I dont think it's the TPS at all. if I had erratic TPS values I would start looking at it.. hmm Quote Link to comment Share on other sites More sharing options...
Forrest Posted October 4, 2008 Share Posted October 4, 2008 Are you using a distributor? Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 4, 2008 Author Share Posted October 4, 2008 the problem is getting worse!! I can drive the car in any gear untill I pop the car in nuetral and let it idle! it dies almost immediatly now!! The car was able to run for almost 2 min before it died... and the problem is getting worse and now barely running for a few seconds. I am running a '83 distributer.. HEI ignition and MS1 extra 021u (old i know). The fuel pressure at the rail stil reads 38psi!! I was assuming it was a clogged filter or pump or something.. ah! what the devil is going on!! Quote Link to comment Share on other sites More sharing options...
Forrest Posted October 4, 2008 Share Posted October 4, 2008 Check the distributor shaft play against factory spec. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 5, 2008 Author Share Posted October 5, 2008 Forrest... Since I last drove the car the only issue was the clutch/transmission which I have changed. I will check the play in the dizzy.. i'm just confused how all of a sudden the play in the dizzy would play a factor. Quote Link to comment Share on other sites More sharing options...
Forrest Posted October 5, 2008 Share Posted October 5, 2008 It's not really "all of the sudden" - the wear increases over time until it has crossed the threshold where it starts causing the car to die. I can't guarantee that it is your problem, but excessive distributor shaft play causes exactly the symptoms you are describing. It's very easy to rule out (especially if you have a spare distributor) so you might as well do so. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 5, 2008 Share Posted October 5, 2008 Wow that's almost exactly what happened to me about two months ago. I now have EDIS-6. I was told that the dizzy's pickup electronics tend to fail as they get hot and then work again after they cool off. That's a sign that it is failing. You can get a new dizzy for about $250. My tach would start swinging around like nuts while driving and shortly afterwards the car would just shut down for 20 minutes or so. While trying to restart, the tach would go bonkers until it cooled off. It happend to me twice in three years. I decided to get away from the dizzy and so far so good. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 5, 2008 Author Share Posted October 5, 2008 thank you for the suggestions guys.. I wonder if there is a way to test the dizzy other then the shaft play? I dont have a spare '83 dizzy so I will look around on ebay and the junk yards.. its very very strange this is happening.. and such a gradual event I also think its bizarre it only happens at idle!! The car pulls like crazy in every gear!! Quote Link to comment Share on other sites More sharing options...
mobythevan Posted October 5, 2008 Share Posted October 5, 2008 I didn't look at the log you attached, but are both coolant sensors reading OK? I had my IAT go bad and the car ran good but had idle problems because it was making it too rich. Not related to tach problems, but just in case. Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 5, 2008 Author Share Posted October 5, 2008 according to the logs and what Megatune shows.. the intake and coolant sensors are reading like normal.. no spikes.. The AFR's are also normal.. the car idles around 13.5 AFR ... then the tachometer shows wild readings.. the AFR still shows 13.5 AFR.. then its like the fuel/spark both get cut off at once.. so the AFR goes to 20.1/O2 which is the calibrated O2 value without the engine running. Im considering going to EDIS now lol Quote Link to comment Share on other sites More sharing options...
Zmanco Posted October 6, 2008 Share Posted October 6, 2008 Ryan, a few additional thoughts beyond what others have posted: - Is the tach getting its signal from MS or the coil? If it's the coil, then it's very interesting that the tach goes dead shortly before the engine dies. That would suggest to me that the spark is fading and the tach loses the signal followed shortly afterwards by the engine dying. Culprits could include the driver on the MS board, the HEI module, or possibly even the coil. I'd start with the HEI module mainly because it's easy to swap and cheap. - I suppose too much play in the dizzy might contribute too. I have a spare '80 zx dizzy that you're welcome to borrow if you want to try a swap. But unless there's a lot of play I doubt this is it. - I noticed that your MAP reading is 73 before the engine starts. At my home (elevation ~6300 ft) I typically see ~80 so that might be a clue that something is off with your MAP sensor unless you were up at the ski resorts. But I can't imagine how that would cause this given the datalog doesn't show anything abnormal. I wouldn't suggest going to EDIS until you know what the issue here is. Adding more unknowns is only going to make it harder to trouble shoot if it doesn't just "go away". Quote Link to comment Share on other sites More sharing options...
proxlamus© Posted October 8, 2008 Author Share Posted October 8, 2008 Problem solved!! I should of guessed it.. BAD HEI! its the 3rd one since January!! but another bad GM HEI ignition module. Good thing I have a lifetime warranty lol Quote Link to comment Share on other sites More sharing options...
midnightzxt Posted October 13, 2008 Share Posted October 13, 2008 Problem solved!! I should of guessed it.. BAD HEI! its the 3rd one since January!! but another bad GM HEI ignition module. Good thing I have a lifetime warranty lol I've been having the same problems with the HEI. Be sure of a couple of things: 1. Make sure the HEI is mounted in a cool spot with lots of heat sink. Typically the killer is overheating the module. (Obviously, next to the turbo on the strut wall is not a good idea like I did) 2. Make sure that you don't turn the MS on and leave it on with the HEI module plugged in. This has also killed them for me. 3. Buy the EXPENSIVE brand. Don't go for the $7 HEI, get the $36 one. It makes a HUGE difference. 4. Last resort, get a different ignition setup... HEI has been nothing but trouble for me, and I need something more reliable. Quote Link to comment Share on other sites More sharing options...
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