Very weak spark. Help please!

[Turnwaster]

Well getting right into it... My car is cranking but wont start. Things I know are.

Fuel pump is work correctly.
Car will not start on starter fluid.
Compression is 135, 130, 125, 125.
Spark is VERY weak on all cylinders.
ECU is in good working order.
The spark plugs are brand new.
The EPI relay is new and working correctly.

Other then that I'm at a bit of a loss. I really need to figure this out as this car is my transportation to and from work. I did search.... got a few things to check which I did. Thanks for the help and your time.

 

[ENICKB]

Coilpack, and wiring to coilpack should also be checked. DEFINITELY CHECK THE SPARK PLUG WIRES. Have somebody at nighttime look under the hood while you try to crank, and see if shes giving the purple light show. Also, check your voltage with key in ON position. Maybe bad battery if not coilpack. But first swap with another guys coilpack and see if that works.

 

[Turnwaster]

Coilpack, and wiring to coilpack should also be checked. DEFINITELY CHECK THE SPARK PLUG WIRES. Have somebody at nighttime look under the hood while you try to crank, and see if shes giving the purple light show. Also, check your voltage with key in ON position. Maybe bad battery if not coilpack. But first swap with another guys coilpack and see if that works.

Actually I forgot to add that the battery is brand new. Less then a day old.

Coilpack, and wiring to coilpack should also be checked. DEFINITELY CHECK THE SPARK PLUG WIRES. Have somebody at nighttime look under the hood while you try to crank, and see if shes giving the purple light show. Also, check your voltage with key in ON position. Maybe bad battery if not coilpack. But first swap with another guys coilpack and see if that works.

Yeah nothing out of the norm happened when it was cranked at night. No light show to speak of.

 

[theoutlaw82]

Are your sparkplugs in good condition and gapped correctly?

 

[Turnwaster]

Are your sparkplugs in good condition and gapped correctly?

Yes the spark plugs are brand new... and yes they are gapped correctly.

 

[DSM1G90]

Is the spark yellow, or blue? Yellow ones are the weak spark, whereas the blue is the hot spark. What does the plugs look like -all sooty black from the weak spark?

Either coil pak or power transistor aren't doing their thing all the way...but seen ECU's do stuff like this also, which adds to the question on; how do you know your ECU is working well?

You spoke of a new battery. What were the reasons on to get a new battery?
For if you had charging problems in the past, these issues could have also affected the ECU like low DC voltage can cause issues with the capacitors on the momboard.

 

[Turnwaster]

Is the spark yellow, or blue? Yellow ones are the weak spark, whereas the blue is the hot spark. What does the plugs look like -all sooty black from the weak spark?

Either coil pak or power transistor aren't doing their thing all the way...but seen ECU's do stuff like this also, which adds to the question on; how do you know your ECU is working well?

You spoke of a new battery. What were the reasons on to get a new battery?
For if you had charging problems in the past, these issues could have also affected the ECU like low DC voltage can cause issues with the capacitors on the momboard.

The spark is yellow if I recall correctly. The plug looks new because they are basically new plugs. I know the ECU is in good working order because I opened it up and looked at it... As well as doing the turn key test. The battery was replaced because it had sat so long.

 

[DSM1G90]

I opened it up and looked at it... As well as doing the turn key test

Visual and actual tests are two different things. It can look fine but some of the drivers, that can look good, could be shot that controlls the ignition part..

..best get an actual test done on the unit.

I've been there and done that - took it out, opened it up and it looked good, but sent it to motoguys and it was a goner with their testing. Got a replacement ECU, and now off and running smooth like a new car.

-DSM

 

[DSML7dropkick]

Yep, test the ecu properly to know for sure that its working properly and check the voltage coming to coil pack from the ecu. That will let you know if you got a bad signal.