DCZ

I'm going to try that the next time I get out there. The car is not ready to drive but at least if I can get the engine to fire it might motivate him to do all the other things that need to be done (I hope you're reading this Lee!). Then I'll look into the BIP373. We need another zt on the road in central NC

Thanks Metro. What you said makes perfect sense. In my case, I'm trying to help a friend complete an MS install that was started by someone else and the 7-pin HEI is already in the circuit. I have no information as to "why" things are set up as they are, so I am trying to figure out if using this module with this distributor is a good idea, or even possible. I think one of the biggest hurdles to a MS conversion is figuring out the "why". The "how" is pretty well documented, although spread out in multiple places with multiple MS versions, but rarely have I found good explainations of "why". When you are trying to decide which combination of bits to use for your specific build, understanding "why" you want to use a specific component (or MS version or firmware etc.) vs. another is extremely valuable. So in this case, I don't think there is a good reason why we should stick with the 7-pin HEI, other than the fact that we already have it. The reasons why not would be that 1) I still don't know if it will work, even if we bypass the VR input to the module, and 2) It seems unnecessarily complicated vs. direct coil control. I will have to check and see if he has the BIP373 on his board.

I'm doing some research on using a GM 7-pin HEI module with MS2 and have reached a dead end on one point -- can I (or does it make sense to) use the stock ZXT Optical distributor with the 7-pin HEI? The megamanual (http://www.megamanual.com/ms2/GM_7pinHEI.htm) shows the setup with a VR distributor and explains how the HEI module conditions the VR "AC" output into a "square wave" signal that MS can use as a trigger input on pin #24. Can the ZXT Optical distributor output, which is a "square wave" be used as an "AC" input to the HEI? Seems to me that would not work properly, if at all. Or could the Optical output signal be routed directly to MS pin#24, skipping the VR conditioning of the HEI module? In that case, is there any advantage to the 7-pin HEI over a 4-pin HEI? Whoops - one question turned into several. Any thoughts, conjectures, ACTUAL EXPERIENCE with this setup appreciated.

The tach on my 73 works fine with a stock L28ET swap and also after the switch to megasquirt, using the stock ignitor. I'm pretty sure it is a stock 73 tach. I don't remember exactly how I wired it but the key is to remember that the tach is driven by current, not simply voltage i.e. you can't just run a wire from the + terminal on the coil to the tach, unless that wire is actually the current feed for the coil. If that's not too confusing post back and I'll try to find my notes.

Where in NC are you? I have a stim board you can borrow in Durham.

Tony! Toni! Toné! Normally you are such a careful reader and a proponent of exact language usage, but I'm afraid you missed what I've written this time. I never said that. For the record, the pencil I used was much longer than 86mm. Until is wasn't. I DO understand that and appreciate it, but somehow they (we?) keep slipping in around the edges! To that end, I said The fact that the OP was asking about this procedure suggested to me that he is closer to the latter than the former. I was simply trying to pass on a bit of my limited but hard-earned experience. And lo and behold, the HybridZ community responded with several excellent tools and tips. Group Hug! But your point about the pencil being handy, cheap and readily available is well taken, and I have since successfully used it to determine TDC. I just make sure to introduce it to the cylinder at a point closer to TDC, so that the pencil does not get wedged in the cylinder and thereby snapped in two by my above mentioned ham-handedness, leading to "short pencil syndrome". A fate we all wish to avoid, no doubt

You can use the stock cylinder head temp sensor instead of a coolant sensor.

***WARNING! WARNING! DANGER WILL ROBINSON!*** If you are a good mechanic, or at least a careful and knowlegeable tinkerer, the above advise is fine. However, if you are a ham-handed tool torturer like yours truly, you might get caught up in turning your engine over and watching the timing mark so much that you hear a crunch and turn your head just in time to see half of your pencil fall to the ground while the other half falls into the #1 combustion chamber! Took me a while to fish that out of there while cursing the "cheap Chinese pencil" and otherwise casting blame elsewhere. You might want to use something less breakable, but not something that may scratch the piston top, perhaps something plastic. Happy Wrenching!

Thanks Sleeper!

I'm having trouble opening the file. Tunerstudio won't recognize it nor will winzip. What am I missing?

That's good to know. I'll have to look into my grounds and the wire routing to see if I can clean that signal up a bit. I'm having more trouble from a relatively small, slow throttle tip-in than from a quick stab.

Very good article! I have a related question. When you run the calibration wizard for the TPS, how big is the dynamic range? I ask because my TPS signal goes from ~0V to ~5V at WOT. This translates in the wizard to ~0 to ~700 "units". Are the units in analog-to-digital units? Because with a 12 bit ADC I would expect to get 4096 steps so it seems like I am not getting the resolution I should get thus a noisier signal for TPSdot. Should by TPS put out 0 - 12V? My TPS is from a 240sx if that makes a difference. So for anyone who cares - what does your TPS calibration read at no throttle and full throttle? MS2 V3.57 board, don't have the firmware version in front of me if that makes a difference. Not running the latest version of TunerStudio yet, I think I have the next-to-last version.

I have had a similar problem the whole time I've had my MS (MSII v3.57 board) running (~2yrs). I've always chalked it up to my own poor tuning ability, which is a definite possibility, but it does seem common, based on this thread. FWIW I'm running a stock 83zxt engine, Ford 370cc injectors, around 70/30 MAP/TPS enrichment (noisy TPS like Cannonball). I've never been able to get rid of the lean stumble at throttle tip-in. Embarrassing when easing away from a group of admirers

When you say stock EFI do you mean the stock turbo ECCS system or did you use the 78 EFI system on the L28ET engine? Makes a big difference. If you have the turbo ECCS components, get a factory manual and follow the ECCS troubleshooting procedures. All you need is a volt/ohm meter and you can diagnose a whole lot of problems.

Check the valve clearance and adjust as necessary.