Ecu question need help asap

[1990gsx1781]

ok so i just threw my spare motor in that i bought off some kid. everything is hooked up and grounded so i threw my ecu in but i did no bolt it up its just laying on my rug. i have fuel but no spark... is the ecu grounded threw thew mounting bracket? thank you

 

[steve]

i have fuel but no spark... is the ecu grounded threw thew mounting bracket? thank you

No it's grounded via the harness.

So, I'll ask the normal questions.
Do you get a CEL for 5 seconds when you turn the ignition on?
Does the boost gauge move to 0 and stay there until you start cranking the ending?
Can you talk to the ECU with your datalogger?
Does the fuel pump turn on if you rotate the CAS by hand?

 

[willydsm]

No it's grounded via the harness.

So, I'll ask the normal questions.
Do you get a CEL for 5 seconds when you turn the ignition on?
Does the boost gauge move to 0 and stay there until you start cranking the ending?
Can you talk to the ECU with your datalogger?
Does the fuel pump turn on if you rotate the CAS by hand?

What do these 4 symptoms mean? Is this normal when you have a bad ecu? I don't have any of these symptoms but I am curious and would like to know, I get the ecu datalogger one but the other 3?

 

[1990gsx1781]

No it's grounded via the harness.

So, I'll ask the normal questions.
Do you get a CEL for 5 seconds when you turn the ignition on?
Does the boost gauge move to 0 and stay there until you start cranking the ending?
Can you talk to the ECU with your datalogger?
Does the fuel pump turn on if you rotate the CAS by hand?

ok good questions i havent payed attention to any .

well i just checked

no CEL when the key is turned on.

when key is on the boost gauge stays on 0 when cranking it goes to 6 ( stock boost gauge ) the aftermarket one doesnt move

my datalogger cable is broken so im not sure if i can talk to the ECU

and the CAS does turn the fuel pump on and off. i got plenty of fuel just no spark.. hmmm

all the help or tips you can offer are greatly appreciated!!!

 

[steve]

What do these 4 symptoms mean? Is this normal when you have a bad ecu? I don't have any of these symptoms but I am curious and would like to know, I get the ecu datalogger one but the other 3?

Indications that your ECU isn't running.

No CEL, bulb out, blown fuse, bad ECU.
Boost Gauge doesn't move, bad gauge, blown fuse, bad ECU.
Fuel Pump doesn't run with CAS, bad CAS, blown fuse, bad ECU.

See where this is going?

ok good questions i havent payed attention to any .

well i just checked

no CEL when the key is turned on.

when key is on the boost gauge stays on 0 when cranking it goes to 6 ( stock boost gauge ) the aftermarket one doesnt move

my datalogger cable is broken so im not sure if i can talk to the ECU

and the CAS does turn the fuel pump on and off. i got plenty of fuel just no spark.. hmmm

all the help or tips you can offer are greatly appreciated!!!

You should see the CEL turn on for 5 seconds and then go off. It's part of the ECU's bulb test. Could be a problem with the lightbulb too which is why I was the other questions.

ECU is not ruled out since the boost gauge moves. Next step would be to check the power transistor and coil.

It's also a good idea to check compression too so you don't overlook anything

 

[1990gsx1781]

Indications that your ECU isn't running.

No CEL, bulb out, blown fuse, bad ECU.
Boost Gauge doesn't move, bad gauge, blown fuse, bad ECU.
Fuel Pump doesn't run with CAS, bad CAS, blown fuse, bad ECU.

See where this is going?



You should see the CEL turn on for 5 seconds and then go off. It's part of the ECU's bulb test. Could be a problem with the lightbulb too which is why I was the other questions.

ECU is not ruled out since the boost gauge moves. Next step would be to check the power transistor and coil.

It's also a good idea to check compression too so you don't overlook anything

yeah i just got my compression tester from my shop im gonna do that tomorrow the weather here has been soooo shitty after that im going to test the coil and transistor.

thanks alot for all your input!