|
no spark, coils get power. help please
i have an 87 N/A rx7 fc and it doesnt get spark. i tested the b/y wire going to them and it gets power. i know the g/y wire going to coil packs doesnt send the signal to fire the spark plugs and i dont know why, the wire is good. im thinking its a possible CAS problem but i know they are unlikely to fail so im kind of stuck on what to do next. any help is appreciated. |
I had the same issue with the 87 turbo i am trying to get running. Check the wiring plug at the CAS real good and if thats ok then use a multimeter to ohm out the 4 wires between the CAS plug and the ecm. I found a broken wire in my harness near the 4 prong connecter by the driver side firewall where the cas wires plugged into the main harness.
|
i agree with Cmore, the wires going to the CAS can be problematic, I'd definitely start there
|
Originally Posted by Cmore9mm
(Post 12248005)
I had the same issue with the 87 turbo i am trying to get running. Check the wiring plug at the CAS real good and if thats ok then use a multimeter to ohm out the 4 wires between the CAS plug and the ecm. I found a broken wire in my harness near the 4 prong connecter by the driver side firewall where the cas wires plugged into the main harness.
i tested all 4 wires and they all got .6 ohms when i set it at 200, im thinking thats good? also i just recently tested my coils and the trailing coils didnt read anything when i tested it, i set it at 20k and went down and up to see if anything showed. the leading coils tested high 14k ohms. so i know the trailing coils are bad but wouldnt it still run on just the leading coils? or do the trailing have to work for the leading to work? |
Yeah .6 ohms means your wires from CAS to ecm are good. You can ohm out the wires coming out of the CAS too to make sure its within specs. Ive not tested my coils but it was my understanding that special resistors were needed to test it properly. I was also under the impression that it would start with just the leading coil working. Have you checked with an inline spark tester to confirm you are not getting any spark? If your cas tests good, the terminals in the plug by cas are all good, and the wiring to ecm is good, and you have 12 volts power at the coil but your sure your not getting spark, sounds like the ecm is not sending the signal to coil to fire, or your coils are bad
|
Heres a thread on testing the CAS... https://www.rx7club.com/2nd-generati...g-cas-1107891/
|
Originally Posted by Cmore9mm
(Post 12248211)
Yeah .6 ohms means your wires from CAS to ecm are good. You can ohm out the wires coming out of the CAS too to make sure its within specs. Ive not tested my coils but it was my understanding that special resistors were needed to test it properly. I was also under the impression that it would start with just the leading coil working. Have you checked with an inline spark tester to confirm you are not getting any spark? If your cas tests good, the terminals in the plug by cas are all good, and the wiring to ecm is good, and you have 12 volts power at the coil but your sure your not getting spark, sounds like the ecm is not sending the signal to coil to fire, or your coils are bad
i pulled the plugs out and tested them (no spark) and tried known good plugs (still no spark). while i was testing things at first i thought it was the ecm not sending the signal because i tested the green/yellow wire at the leading coil with a test light and i didnt get anything when i cranked the car, i also tested the power wire and it got 12v. would the ecm still send the signal wether everythings working or not? and how would i fix that if it is the problem?. im pretty sure it could be my trailing coils and the shot leading spark plug wires, but before i spend money on something thats not the problem i will test everything and make sure my problem is what i think it is. |
Originally Posted by Cmore9mm
(Post 12248211)
Yeah .6 ohms means your wires from CAS to ecm are good. You can ohm out the wires coming out of the CAS too to make sure its within specs. Ive not tested my coils but it was my understanding that special resistors were needed to test it properly. I was also under the impression that it would start with just the leading coil working. Have you checked with an inline spark tester to confirm you are not getting any spark? If your cas tests good, the terminals in the plug by cas are all good, and the wiring to ecm is good, and you have 12 volts power at the coil but your sure your not getting spark, sounds like the ecm is not sending the signal to coil to fire, or your coils are bad
|
[QUOTE=vince578;12251043]
so i got new spark plug wires and a nee coil pack, it still doesnt start. how would i fix the ecm not sending the signal to make the coil fire? |
[QUOTE=Cmore9mm;12251044]
Originally Posted by vince578
(Post 12251043)
so i got new spark plug wires and a nee coil pack, it still doesnt start. how would i fix the ecm not sending the signal to make the coil fire? |
I'm trying to remember this correctly... g/y wire... check that wire to see if it peaks at 5v when you turn the engine by hand with the key on. You should be seeing 0 and then 5v. Turn the engine slowly as you're taking constant readings. If it isn't cycling to 0-5-0-5 then your ecu isn't sending the signal. I'll brainstorm this a bit more for you as to why it's not sending. A bad ground? Maybe so.
|
If you test this and it fails... then you have to test the pin V at ECU.
If the pin is reading voltage then you must test your wire from ecu connector to coil for resistance to confirm that the wire is good(and so you have). EDIT: Just read that you did crank for G/Y voltage check. Unless you have an analog meter you might get a faulty reading because it happens too fast. Also if your CAS is giving you trouble(those things last forever in most cases) then you'd probably have a code 02 or 03. It would be nice to know if you're spitting codes out. EDIT: It sounds stupid but have you done a wiggle test? Have you tried to start it while someone plays with the ecu harness? |
| All times are GMT -5. The time now is 06:29 AM. |
© 2024 MH Sub I, LLC dba Internet Brands