Who here is using a megajolt? Need help

[Desp]

I know this is the forced induction forum, and I don't have a forced induction VW, but I do have one using a megajolt and was seeing if anyone here was running one and could give me a hand with it. I have a stock 71, 1600cc singleport VW motor and anything below 2000rpm I'm getting no power under load and it's acting like it's missing. It revs fine sitting still and after 2k rpm it takes right off, but if I'm in first rolling along at 1500 and floor it, it sputters and bogs like it wants to die. I set up my ignition curve based off of a 009 distributor just to get close... not sure where to start.

[miniman82]

I have MJ/EDIS on my Corvair, and MS/EDIS on the VW so I'll try to help.

Post a screen shot of your timing map, and double check initial advance with a timing light. Make sure that the advance the computer has on the screen is what you have in reality, and make sure it moves around when you rev the engine so you know MJ is talking to the EDIS module. In a pinch if you want to see if your map is what's killing you, unplug the SAW wire going to the EDIS module so it runs in limp home mode (10* timing). If the problem goes away, your map is likely jacked. If the problem remains, you might have the sensor indexed to the trigger incorrectly.

[Desp]

Here is my ignition map and the graph of what I was basing it off of. Originally I had it retarding some under load then changed it to try and fix the issue. It made no difference. I'm just a bit confused on why it runs pretty much perfectly sitting there in neutral and revving the engine, and then anything over ~2000 RPM it runs fine as well, its only in the low RPM range under load it sputters and acts like its missing / no power. I have put a timing light on it, and it does advance as the speed increases. I am going to pull out the #1 spark plug and make sure its TDC where it's suppose to be later.

[miniman82]

You have an engine that (I believe) originally had a vac advance distributor, and you now effectively have mech only. I believe you are experiencing the 'mech only flat spot' most people complain of, sometimes accompanied by switching to something like an OO9. First, advance could come in a little faster on the 100 kpa line, I'm all in with 32* by 2400 or so RPM.

If that doesn't work it could possibly be coughing back through the manifold. In that case, take timing away and see what it does. My turbo engine loves timing, because it has a slow burning large chamber and generous deck. Tighter engines tend to burn faster, so will need less total timing. Make sure the pump jet on the carb is working too, otherwise you'll have a huge flat spot that won't go away no matter what you do with the timing.

Add more advance for the lines under 100 kpa, between 3200/4200 RPM. This is your 'cruise' zone, but make sure you have a suitably lean mixture at the same time. Reduce your 'cranking bin' (the green one in the pic) to something like 8 degrees, this will make hot starts much easier. Hope that helps, should be a good start.

[55superbeetle]

You sure its ignition related? Sound like accelerator pump issues to me.

[miniman82]

Could be, but lazy timing will do it too.