i have a 86 rx7 rebuit motor. Compresion is great, sensors and grounds checked, coils checked, pretty much everything checked.

it has a 89 manifold with 86 electronics. After 5k it fils like timing isnt advancing and sputers very slightly, wideband showing mid 13s.


My exhaust is 3" with 2.5" hks in the back with a few lil leaks, i dont know if that could be and issue.

I also checked my timing and since i dont have timing advance gun i marked the pulley where 15 deg and 20 deg atdc would be and it looks like the total advance is about 20 deg atdc with engine reved to 4k rpm

 

wait. so this is an s4 n/a block with s4 electronics but s5 manifolds, including 6port and VDI system?

 

this is very simple but check the plugs if you haven't already. one time a single plug on my 91 coupe was loose and after 7000 it was pretty messed up, the needle would struggle to get up to 8, much more than usual. but you're talking about 5000 rpm so probably not.

 

s5 block and s5 manifold with vdi, i didnt change ecu, tps or afm.

 

I have it narrowed down to some type of signal interference. Ive read that b9egv's , none resistor plugs can mess your electronics by EMI, even says that on ngk website. After i installed msd 6al it made things worse, alot of bucking and miss firing.

 

check all the grounds they are the cause for the 3500 hesitation could cause this .... also check your boost sensor and tps

 

vdi needs to open/close some how. i'd recommend putting on s4 manifolds.

 

i got big 5k rpm misfire, i did check grounds and sensors.

Wideband showing normal afr.

 

Yea i know, it can be wired open,

 

Found out that leading coil spark is weak, it ohms in specs but that doesnt mean its good.

My trailling is giving out alot more spark, im thinking of running 2 trailing coils from one leading igniter, would that work?