Watson Posted April 10, 2014 Share Posted April 10, 2014 (edited) Every once in a while I can get the car to idle but only at 200 rpm, and if I give it any gas or let off, it dies. The ideal TPS ADC seems to be 38 for it to even somewhat idle. Any more or any less and it dies. I've tried so many different settings it hurts. I'll attach my current tune.Specs: N42 Block/Head Stock L28ET turbo and injectors S13 240SX TPS Innovate MTX-L wideband O2 sensor MS1V3 running MSnS-E on code version 029y3 MS controlling Crane Cams Fireball LX91 coil firing NGK BPR7ES plugs gapped ~ 32 Crane Cams optical sensor and trigger wheel although I ended up tearing it apart and making my own working optical sensor. At least the RPM readings are steady and accurate. I think that's the pertinent stuff. With my current static spark settings I'm reading 10 degrees BTDC according to my timing light while cranking. I'm definitely getting fuel as I can really smell it and I've fouled out some plugs. It cranks and kicks like it wants to start but it just wont get going. Any help would be greatly appreciated. Watson.zip Edited April 10, 2014 by Watson Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 10, 2014 Share Posted April 10, 2014 I'm not positive but I think that 200 RPM is about impossible unless you have a massive flywheel to keep things spinning. If the engine runs but shows 200 RPM, I would think that there's a problem with your tach signal or a setting is wrong. Is the 200 on the car's tach or Megasquirt's and do they match? Do you have some other way to measure RPM? Might be a clue. Just a guess. I can't imagine a stock L6 idling at 200 RPM, but I could be wrong. Quote Link to comment Share on other sites More sharing options...
Watson Posted April 10, 2014 Author Share Posted April 10, 2014 (edited) Hmmm, interesting. I don't have a tach other than the megasquirt's display. I'm beginning to question the quality of my optical trigger. You see, I constructed it with just an LED, a resistor (can't remember the value), and a phototransistor. In theory it should work but I wonder if it is up to the task of rapid changes in light value (or lumens if that's how it's measured. Ultimately its just a resistor though). I think I will go ahead and order a new optical trigger. Any other suggestions? How does the tune look for at least getting running? Edited April 11, 2014 by Watson Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 11, 2014 Share Posted April 11, 2014 I know little about tuning Megasquirt, the 200 RPM just jumped out at me. By the way, I think that only people with Megasquirt or the right program can read your file. Might be limiting your audience. I don't have a program for MSQ files. I saw your thread on the new trigger. Pretty ingenious, I did something similar with an LED and a BA9 light socket (not really so difficult) . But the common cheap LEDs may not hold up to automotive use, even if yours is reading correctly now. I fried one with a nine volt battery and no resistor, it smelled like melted plastic. The lens was made of epoxy. The diode material is one piece of the package, the lens material is another. Quote Link to comment Share on other sites More sharing options...
Watson Posted April 11, 2014 Author Share Posted April 11, 2014 (edited) Software to view the tune is free by the way. Either MegaTune or the unregistered version of TunerStudio can be used to at least view a tune FWIW. Of course you would need to limit the voltage going to your resistor based on your application, which I have done, but I feel the issue lies with the phototransistor. I noticed that Crane Cams uses a sort of diode as opposed to just a phototransistor so now I wonder what the difference is between their diode and my phototransistor. They also don't have a resistor inline with the signal-generating diode so clearly there are multiple factors different between my setup and theirs. Tomorrow I will find out if that does in fact make a difference. If this post ever comes up in a Google search in the future (I hate unfinished forum threads) please locate my build thread. Google "Watson the Datsun" and I'm sure you will find it somewhere on the internet. Here or elsewhere. Edited April 11, 2014 by Watson Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted April 11, 2014 Share Posted April 11, 2014 Can you also upload a data log of the idle issue? This will give me more to go on. Didn't see much obvious in the log other than that on these cars, you'll usually want to use time based cranking instead of trigger return. Quote Link to comment Share on other sites More sharing options...
Watson Posted April 11, 2014 Author Share Posted April 11, 2014 Problem solved. A phototransistor just couldn't cut the mustard. An IR receiver and IR LED combo worked perfectly. Interesting... 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.