Mazda Rotary Club

Cars by Model Type => 2nd generation RX-7's => Topic started by: BinoX on October 01, 2012, 01:26:20 PM

Title: Spark Woes
Post by: BinoX on October 01, 2012, 01:26:20 PM
I\'ve been doing some tests on my RX7 recently to work out some more of the rough running issues and I\'m wondering if my Trailing coilpack is busted...
 
I have confirmed that it IS sending some voltage to the plug... (I gave myself a bad shock when I unplugged it with my finger too close)
 
When I put my timing gun (Inductive pickup type) on the Leading side and it sparks, the strobe goes off... When I tried the same thing with the Trailing side I get no strobe... Also, when I unplug the Trailing leads from the plugs it doesn\'t seem to make the engine sound any different at idle...
 
Is any of that behaviour normal or do I need to get a new coilpack? Or is there anything else I could do to test it?
 
Thanks,
Luke
Title: Spark Woes
Post by: m1tch on October 01, 2012, 02:02:14 PM
When were the HT leads replaced? They are a perishable item like air and oil filters.
Title: Spark Woes
Post by: BinoX on October 01, 2012, 04:13:48 PM
About 6 months ago with magnecor leads :) Good suggestion though
 
Spark Plugs are also about the same age.. I\'ve done less than 100 miles since they were put in, lol
Title: Spark Woes
Post by: m1tch on October 01, 2012, 07:19:09 PM
That is a bit odd then, perhaps check that everything is earthed properly
Title: Spark Woes
Post by: BinoX on October 01, 2012, 09:42:48 PM
Sadly did that recently as that what I suspected originally... I went around and checked, cleaned and re-attached all earths including the ECU ground..
 
I\'d say that the car acts like it\'s choking up under load.. And after replacing fuel hoses, lines, filter and getting the injectors fully serviced and tested. Replacing plugs, leads and re-doing the earths I\'m running out of things to check...
 
I did a resistance check on all the sensors I could find number for and they all seem alright as well...
 
From it\'s behaviour I\'d say it\'s overfuelling quite badly (or not combusting properly), rather than underfuelling
Title: Spark Woes
Post by: Prof on October 01, 2012, 09:50:20 PM
The 13B will run quite happily on only the leading plugs, and these fire at the same time, so it doesn\'t matter which war around you connect the leading plug leads (to the lower plugs).  The Trailing plugs fire alternatey and not together.   There is a signal from the ecu that selects which coil/igniter will fire.  That is fed from the CAS sensor pickup, and the wiring to these has been known to get brittle and crack causing shorts - the symptoms can be everything form poor running, heavy fuel usage, or even total engine shutdown due to no spark.  A missing tooth or badly aligned coil pickup could cause symptoms at higher RPM only.
 
The CAS device is located to the right of the alternator as you look at the front of the engine - it\'s the circular black lidded device at an angle to upright.  Check the wiring on the 4 wire white plug - it\'s probably a good place to start.
Title: Spark Woes
Post by: BinoX on October 01, 2012, 11:56:20 PM
Thanks very much :) I\'ll start investigating that as soon as I get the chance :D
 
I did do the engine timing recently and got that all done, but I suppose that\'s no real guarantee of proper functionality... it\'s just one of those irritating little problems that gets you a bit disheartened after poking around at it for so long with no real results... lol