Recent content by daveH

so assuming the ECU has power and ground, throw a timing light on any plug wire and see if it has spark at crank. if it doesnt, either the ecu isnt seeing RPM stemming from a bad crank or cam sensor or wiring to them. or the ECU is cooked. if it has spark, then its a fuel delivery issue...

looks nice but i wouldnt run that much timing on your specs. even too much for an NA LS3.

Another common problem on this old mefi systems. First…..your ignition key. Many used a toggle that was two position…..run and start. The switch will go bad and drop the voltage on the run leg during crank, starving the ecu for run power. Second, many had exposed GM blade fuse blocks. Sand...

I dont know what color wiring your harness uses, but likely your green wire here is the trigger wire from the ECU, so grounding it would cause the pump to run. grounding the ECU to the case should never be an issue. a MEFI will do goofy things, if it doesnt have a constant and switched power...

fuel pump control (ground) is J1 pin 6. the fuel pump should turn on briefly when the key is turned on. if that isnt happening, then either you have lost the switched power in, or the relay is bad, or there is a problem with the crank/cam sensors and the ecu is not seeing RPM.

been a while since i touched a MEFI. but something is way wrong, the fan relay should have NOTHING to do with the running of the engine. a MEFI requires constant 12v and a switched 12v connection. constant 12v is pin J2 pin 1 switched (key on) 12v is J2 pin 19 definitely check to see the...

you might try a pull down resistor. you do this by attaching one end of the resistor to the trigger wire and the other side of the resistor directly to ground. start with 1000 ohms. a lower the value of the resistor will "leak" more to ground and could keep the fan on all the time. some...

i thought about this, but the fact that you put a traditional relay in and it worked indicates the output is going low. assuming you had 12v on the other side of the relay.

things to check if it ran properly once upon a time bad TPS bad MAP sensor or leaking line feeding it faulty fuel pressure regulator, or a leak in the line assuming its manifold pressure referenced. loose or bad plug wire(s) could be other things but these would be the most obvious usually...

why would it need a dyno tune? is this a new motor that was never properly tuned to begin with? or did it used to run properly?

first nobody makes a relay worth a shit anymore. just another reason to go solid state but thats a topic for a different discussion. OP mentioned there is a sender in the water pump, I will bet that is for a gauge and not the ECU temp sender which is typically in the head on LS motors. The ECU...

get the Hella relays with 1/4" terminals. the same relays with the smaller terminals have a habit of melting the terminals, even when well below the rated load.

i have a mefi 4 with harness. PM if interested.

fuel pressure is solid......lmao........with the car sitting static and a full tank. now run it down to half a tank, first pass through the whopps.....you have a stew of air and fuel going through your system.

i would vote NO WAY on carbs. but i get it to a certain extent.....they are easier to setup. but the tunability isnt there. wouldnt run any better than your 4 knob setup. the tough part about efi on an ACVW is there is SOME bolt on parts for doing this. Specifically, ditch the distributor and...