Faster Behr
Club Member
Anyone who has been following my thread on my Fairlady Z escapades may recall that it was originally fitted with a Holley carb and a Bob sharp Racing manifold. I have set about replacing that with a FAST EFi retrofit fuel injection system in order to get it on the road for the summer. During this work I found that the 280ZX distributor (the one with the E12-80 module) that was fitted with the car had a faulty vacuum advance mechanism. I sought to replace this and iron out any timing issues before setting about finishing off the set up of the EFi. After lots of reading and researching - including a very informative thread here which I re-read many times - I decided to give the 123+ distributor a try.
This is where my troubles really started and where I need some help/fresh ideas/emotional support..
Ok, so I fitted the 123+, added resistor plug leads and resistor plugs (NGK BPR6ES). I couldn't get the car to run at all. I had sequential spark across all 6 plugs except for a weak spark/missing spark on #2 and 5#. Timing was checked and rechecked and rechecked. Compression 175psi +/- all round. Cam timing checked. All back to basics. I tried all different permutations. I removed the original 280Z 0.9ohm coil and tried a 1.5ohm coil (all of which I measured with a good multimeter). No start. I tried changing settings in the 123+ app. I checked all ground points and wiring. No joy.
I put the original distributor back in, timed it up and no start. I hot wired the coil direct to overcome any voltage drop through the start circuit. No good. I could not get the car to run. It should be said that on multiple occasions I pulled the plugs and they were wet with fuel. I cleaned and regapped them many many times.
My starter got weaker and weaker to the point where I had to fit another. RIP.
I changed the HT leads back to standard leads, no joy. I refitted the original BP5ES (hotter, non-resistor) plugs and boom. It started and went straight to a clean idle like nothing had ever happened. I was gobsmacked. There were nearly tears. I reckon I had about 25+ hours of time just into this issue.
What I can't understand is why the plugs made such a dramatic effect. It's either a case that it wants hotter plugs or that it is having a real problem with their being resistance in the secondary ignition circuit. Unfortunately I don't have any other plugs on hand to try to diagnose this.
This all begs the question of what is really going on here. And this is what has me stumped and looking for good advice. The issue was the same for two different distributors and two different coils. I hotwired the coil supply ruling out any errant voltage issues to the coil. It just looks like something doesn't agree with their being resistance in the secondary HT ignition system.
PS. much kudos and thanks to @jonbills who was very helpful with heping me on this.
This is where my troubles really started and where I need some help/fresh ideas/emotional support..
Ok, so I fitted the 123+, added resistor plug leads and resistor plugs (NGK BPR6ES). I couldn't get the car to run at all. I had sequential spark across all 6 plugs except for a weak spark/missing spark on #2 and 5#. Timing was checked and rechecked and rechecked. Compression 175psi +/- all round. Cam timing checked. All back to basics. I tried all different permutations. I removed the original 280Z 0.9ohm coil and tried a 1.5ohm coil (all of which I measured with a good multimeter). No start. I tried changing settings in the 123+ app. I checked all ground points and wiring. No joy.
I put the original distributor back in, timed it up and no start. I hot wired the coil direct to overcome any voltage drop through the start circuit. No good. I could not get the car to run. It should be said that on multiple occasions I pulled the plugs and they were wet with fuel. I cleaned and regapped them many many times.
My starter got weaker and weaker to the point where I had to fit another. RIP.
I changed the HT leads back to standard leads, no joy. I refitted the original BP5ES (hotter, non-resistor) plugs and boom. It started and went straight to a clean idle like nothing had ever happened. I was gobsmacked. There were nearly tears. I reckon I had about 25+ hours of time just into this issue.
What I can't understand is why the plugs made such a dramatic effect. It's either a case that it wants hotter plugs or that it is having a real problem with their being resistance in the secondary ignition circuit. Unfortunately I don't have any other plugs on hand to try to diagnose this.
This all begs the question of what is really going on here. And this is what has me stumped and looking for good advice. The issue was the same for two different distributors and two different coils. I hotwired the coil supply ruling out any errant voltage issues to the coil. It just looks like something doesn't agree with their being resistance in the secondary HT ignition system.
PS. much kudos and thanks to @jonbills who was very helpful with heping me on this.