bigport 6500rpm rev limit

[ke70dave]

as the title sais, it seems my 4age bigport has a 6500 rev limit.

its a jap 4age (im pretty sure) stock as a rock in my ke70.

now i know what your thinking, he doesn't have the speed signal hooked up. but i have!

i made a circuit that pulses the speed signal to ground, about 4 times a second.

now before i made this circuit i would get the speed signal error popping up (ecu light would turn on/off when i gave it some curry), but this circuit has stopped speed signal error completely.

now i have tried both an adm ae82 ECU (blue label) and a jap ae86 ecu (orange label).

both give a rev limit of 6500 and the engine seems to "struggle" to rev past 6000rpm, it still revs all the way to 6500, but it doesnt sound all that happy past 6k. its a proper rev limit at 6500, pops and bounces back. the jap one is a bit more powerful obviously, but yer still brings things to a hault after 6500.

also this rev limit appears to be the same with revving it out of gear (free rev) as well as driving in gear (1st and 2nd definitely, didnt try 3rd...)

now i am only running the standard jap ae86 rwd primary and secondary exhausts (cast iron 4-2-1) and i understand this may be my restriction above 6000rpm, but i don't believe that this would cause the rev limit.

now acording to the reliable source that is Wikipedia, 4age is suppose to make maximum power at 6600 rpm.

im not even getting to 6600!!

suggestions?

(the other thing ive just thought, i wonder if my tacho is reading me the corret rpm....)

[s14seriesII]

tacho innacurate ?

weak valve springs ?

[ke70dave]

yer thats about the only conclusions i can come up with.

how high do other ppls stocko 4age's rev?

admitedly i dont really need to rev that high, but it should be able to..

i hardly see anyone adding a speed sensor, so do all you blokes with standard 4age's in your ke70s only rev to 6500?

and surely the valve springs should be able to handle standard reving? unless they are stuffed i guess...d

[Matt-AE86]

Distributor
ignitor/coil

[s14seriesII]

7700... but the tacho in my car now only says its 7200/7300... obviously incorrect.

ive never had a speed sensor hooked up and never had an issue.. not to say its not possible

[Touge Boy]

My bigport has the limiter set @ 8300 rpm. Adaptronic ECU.

Ill be going a bit higher when it's retuned.


Is an aftermarket ecu another option?


I know Shaun @ Philcom Rally had the same problem with his KE70... maybe Jason (jaz_ae86) can shed some light on it? I know he had the answer then.

[ae71]

if it was breaking down at high revs due to a spark issue then that would be different from pampampam of rev limit cut.

if it was in some kind of limp mode due to a sensor/wiring error it shouldn't rev that high. have you maybe got a aftermarket tacho you could try?

[ke70dave]

hmm i have a new dizzy cap and rotor. (as of a few months ago)

my dizzy has a bit of an internal oil leak. wonder if thats the problem...

coil/ignitor seems to be in working order. both are solid state so they should be alright id hope...

wow i took to long to reply, and missed all the other replys!

7700rpm...daym.....is that with a standard ecu s14seriesII?

id love to get an after market ecu, so i can know exactly what is going on, but dont really have ~$1500 to throw around at the moment...

ill see about obtaining an aftermarket tacho at some stage. anyone want to sell me one real cheap?!

also..i changed the frequency of my speed sensor to a frequency where i can just see the LED flashing (so pretty high...30hz maybe...)

and i got it to rev to 7k. once.....then i tried again and it only went to 6.5k....its starting to annoy me.

[corknose]

my stocko 4age revs to about 7800 well thats what i have done neer hit limiter but.

[Instigator]

My bigport hits the limiter at around 7500