No pulse to coil

[ndcjr]

I bought a 97 eclipse gs n/t with a bad knock. To make a long story short I bought a used engine and cant get it to fire. I've checked for pulse voltage at cps, cas, and at the coil but none. Then I checked the auto shutdown relay and it showed good. I changed the 2 sensors (cps cas) because I drove the car home with the knock but it was firing. I still only have supply voltage and no pulse.

 

[luv2rallye]

The spark plugs would not be firing (and engine running at all) if you did not have a coil pulse. How are you measuring? You can only see the pulse with an oscilloscope. The pulse is way too short (narrow) to see with a voltmeter.

 

[ndcjr]

I cant get it to fire. Ive checked the coils with an ohm meter, and the sensors have input voltage but Haynes says to locate the output at the plug ins and crank the engine and i have nothing.

 

[luv2rallye]

Some coil tests (note NT don't have power transistors however):
http://www.dsmtuners.com/forums/pro...k-cam-angle-sensor-testing.html#post151298008 (see posts 16-17 for coil test)
http://www.dsmtuners.com/forums/articles-electrical-wiring/58091-2gnt-checking-coil-pack.html
If coil, CAS, and CPS are good, you may have a bad ECU (open up and check for leaking capacitors, and/or swap with known good one).

 

[ndcjr]

Thanks for the help. This is where Im at: I drove this car home with 3 cylinders, no1 rod was broken. I bought an engine with 60k and 6mths warranty, changed the usuals (waterpump, belt, tensioner), then did the swap. I think I had the cas plug to the coil and tried to start the car. First I pulled the plugs they were wet smelled like gas. then checked for spark by grounding to exhaust and cranking. No spark! Went to the Haynes and read all on ignition, cas, cps, and asd relay. Now I figured out the plugs were all the same so I switched the cas and coil. Still no spark at no1 plug. Tested both coils(new engine and old) both read good. then I began trying to chek with voltmeter the plugs at cps and cas both have approx. 12v incoming. So I then tried to check outgoing while cranking the engine. Nothing. Ithen proceeded to change the 2 sensors from the old eng.(that i had driven home) to the new one and repeated pretty much all the above. still nothing. I still dont think Ecu but Im unsure about what you mean by leaking capacitors or how to check them. Ill search the site but just in case lettin you know. Really appreciate the help, Ive never dealt with hall effect, mainly just older small block V8's.

 

[luv2rallye]

Leaking caps and other typical problems in ECUs: http://www.dsmtuners.com/forums/art...585-troubleshooting-fried-ecu-components.html

 

[ndcjr]

Found it!!! I unhooked the battery and traced down the wires from cps and cas, found nothing. After searching last night I saw the caps you were talking about so I decided to check them. I just decided to try it one more time and it ran. Iguess when I had the two connectors mixed up it messed something up, and unhooking the battery reset the ECU. Unbelievable!!! Thanks a lot luv2ralleye, I really appreciate your help.

 

[ndcjr]

did not find it. Drove the car about three miles put gas in it. Went inside for about 1 hr came out started fine then died like no spark. I had no tools so wiggled and removed neg batt terminal for 20 secs and it started. So I tried to make it home and it died again, went thru same procedure but finally it wouldnt work. No cel, towed it home and again no spark. Im thinking ECU but dont want to panic. Shouldnt I be able to test codes even no cel is present? Thoughts?