koatic

Okay heres the issue.

When I accelerate hard (more than 30% throttle) the RPM's on my tach jump instantly from 4000 up to 11000 then back down to 2000 then all over the board. while this is happening my engine seems to be misfiring and the car is jerking back and forth..

I know the clutch is not slipping. it seems to be an electrical issue..

I have JDM b18c spec-r with 11:1 compression. (obd2 rewired for odb1 ECM)
I have a chipped p28 with skunk 2 program.
I have a first generation apexi V-AFC.

Note = while the tach is all over the board the rpms on the V-afc are steady, yet the car is jerking like somones first time starting a manual car.

I swapped my Chipped p28 ECM with a STOCK p28. the systoms were the same except the engine cut off when the tach shot up to 11,000. (I was only doing about 30 in second gear)

Now for some background info.. Last week gas were i live was unavailable cept for 87 octane. I put only two gallons in till i could get some 93. drove about 30 miles then filled up with 93 when i could find it. ( damn hurricane katrina).

Anyway.. it was running fine after that but starting acting wierd last night, 100 miles after I filled up with 93..

I figure either my apexi V-afc is messed up.
or my oxygen sensor is messed up.
also.. if my throttle is less than 30% it runs fine... it only acts this way with more than 30% throttle according to my V-afc.

any info would be greatly appreciated.

Deemeetree

How's your timing?

e jay one

this sounds like what happend to my friends civic. only after 3k when you smash it the tach jumps and would some time cut out. his problem was the dizzy cap and rotor. just a thought.

koatic

How would my timing belt cause my in dash tach to jump around?
if my timing belt jumped off a notch or two wouldn't my tach still function correctly while my engine would run rough?

I am pretty sure its an electrical issue.. I am just not sure which component its deriving from.. thinking more and more its my V-AFC malfuntioning...

koatic

humm... the distributor cap could cause the symtoms the engine has..

The RPMs on the tach are calculated from a sensor on the distributor right?

I will have to investigate further on the distributor being the culprit..
would be nice to simply put on a new rotor and cap and call it a done deal..

thanks for the input.. much appreciated..

koatic

Update..

Today I took it out for a test drive with my chipped p28 back in it..
first run it was fine..
second run it didnt mess up until about 7500 rpms.
third run it ran fine..

I am thinking the 87 gas screwed it up but is working itself out..

proof that high compression and low octane DONT MIX..