So I have been daily driving on megasquirt for a few weeks now and my car has started stalling at almost random and I couldn't get it to happen anytime I was datalogging. At first it was just at idle which bugged me but didn't worry to much I figured it was just close loop idle being weird. then the other night it happened cruising at about 65 on the highway three times in succession which the car started back up immediately being in gear at highway speed. I finally got it to happen with my laptop plugged in but the log says I went negative in rpm?!? if anyone can help me understand whats going on that would be amazing. My car is mainly stock 91 with a afm delete, the stock tps, and a innovate lc2 wideband. Im including the data log and a copy of the tune.

 

You're losing sync - either your CAS is failing, or you need to adjust the trimpots - but as it's mostly running, my money is on CAS. In megalogviewer you can see it happens twice - once early in the log, and then a lot at the end. Might want to check your grounds too - your voltage is wibbly wobbly at the times of your events (11v -> 14.2 during the first event, 14.3 ->15.2 during the second, back to 12.9 once the car stops running - load dump?).

 

thanks that actually helps alot, I was afraid it might be the cas I replaced the oring a year ago and I do not look forward to doing anything with that again.

 

At least on the 1.6 the leaky seal doesn't deteriorate the heater hose. Protip - remove the coil pack, and when you put it back in, leave the bottom bolt off. Makes it a lot easier (though that bottom bolt is a pain to get out the first time).

 

how I got my car the coil back has only been secure by the bottom bolt which is perfectly rounded...

 

also on the voltage issue, I had a fair bit using power on my car; fan, wideband, radio, lights. that is possibly the reason the alternator stopped suppling power from engine dieing, at least I hope its not a ground.

 

Check your main relay as well. When mine failed the car suddenly stalled out going down the road. Fired up ok and made it home, then the fuel pump was on with the key out. Found the relay failed and kept power in the system when it shouldn't have.

 

so as an update to this i replaced the cas with one pulled from a wrecked car, stalling issue is gone except now im finding occasionally when i have a power load i will occasionally have the power flux. it doesn't stall but seems voltage drops low enough to make my wideband restart, and lose headlights for a split second. have yet to reproduce this with a datalog, first i thought that i just have to much power being drawn but its a little to infrequent. My alternator is only about half a year old, could this be a voltage regulator issue?