i have a 1986 rx7 n/a, i bought it from someone who couldnt get it started after someone else "re built the motor" from what i can see he painted the engine bay so i have re done most of the grounds and made sure they are all good i found a ground cut on the CAS harness, re installed that

my problem is it cranks all day but wont fire,
i have no spark signal to the leading coil, but i have 12v with key on to the black/yellow wire at the leading connector.
when i check the pin labeled "5v reference" spec is 4.5v- 5.5v but i am reading a fluctuating number with one ecu n326 and i have another n326 ecu that the ref. reads .1 volt.
any ideas?

one thing i found odd and im winging it here, is that if i check my resistor for the injectors (i have low imp.) the resistor checks out great but theoretically i should be able to do the identical test in reverse on the plug right? and be able to ohm the injectors? well i cant when i try no readings from any pins on the connector to the injectors.

parts replaced by previous owners to remedy the problem:
starter (unconfirmed)
CAS (confirmed and timed correctly)
ECU (still a n326, could be the issue but not sure)
primary injectors (first builder had high imp. primaries and low imp secondaries...)
fuel pump (stock)

i have searched for like two weeks already so i apologize if its already on a thread lol

 

replace the spark plugs?
check compression?
swap the coil?

 

Sounds like you might want to replace the leading coil pack then. Had no spark on mine but they had power and was causing my car to not start (among other things).

 

Check for continuity on all reference wires.

 

Unplug resistor, check resistances between the common wire and the other four. Should be similar ohms.

 

Trying to understand what's going on a little better.

First, you're sure the battery voltage and cca are good and everything is cranking strong?

Next you say that the CAS has been replaced and is properly hooked up and set. If not, check that the red and yellow marks on the eccentric pulley are aligned according to the service manual. If not, loosen the CASand turn it until it is.

You say the main problem is you have no spark? So you have verified that there is no spark at lead/trail wires correct?

Next you say you have good 12v voltage with the ignition on when hooked series to the black and yellow terminals on the leading ignitor correct?

If yes to all of these go ahead and check the resistance of the coils. All coils should have a resistance below 1 ohm (spec is 0.2 to 1.0 ohms) and preferably be similar.


I'm not sure which wire you're referring to fluctuating in reading based on ECU usage. Can you draw up a diagram or take a picture of the wires in question to give us a better look?

 

check the maf

 

I had this same issue no spark on the leading, but I had spark on the trailing... replaced ecus,coils,plugs,wires,afms,cas,nothing...ended up finding the harness was shorting to ground.ran a single wire bypassing the harness from the ecu pin that sends the signal for leading 0-5v's...

 

Pics. of this supposed ground?