6K RPM miss
 

Hi guys ,
i have only tried this with the car at operating temp( water 80 C + ) oil 60 C +

free rev in neutral WOT .. 6K miss then keeps accelerating to red line
free rev <WOT .............. sometimes no 6 K miss to red-line
boost in any gear any boost pressure < 5.5K ...no miss
boost in any gear any boost pressure >~6K ... miss then continues .. ( i do not really insist on it continuing ,i let off )
ECU reset no change

stock ecu
full intake and exhaust
simplified sequential
injectors cleaned and flow tested < 5000 km`s ago
does this with 9`s stock plugs in all 4 ...
checked coils , within specs , wires also ( ~15000 km`s old ) ,
engine grounds are tight , clean , + additional
fuel pump rewired to get full Battery voltage at WOT ( rewired in the fuse box next to left shok tower )
new fuel filter ,
seems to leave a cloud of blackish smoke when this happens
no A/F reference ,
EGT`s Normal
TPS within spex
No CEL codes ..
steady idle,
brownish spark plugs when examined

.. what`s so special about 6K ?....


pulls very strong otherwise even boosting,max ~ 8 psi ( lowered boost until i figure out problem )

any input .. ideas .. suggestions would be much appreciated

thx

just came back from another run ...
changed coil pack ( all 3 ) with previously working , all test good ,
changed plugs to b9egv .035" gap ( which i used previously with great success boosted up to 13psi )

same problem

boost = 8psi

1st i can wind it to red-line it will go no problem but miss/ backfire around 6 K
all other gears i can boost fine to 5.9k ...
the moment i go to +6 .. sometimes 6.5K RMP .. it misses/ backfires

once again no CEL ,not nothing

im gonna try a different ECU

i can pull fine in all gears hard between 5-6 repetitively no problem
but the moment i pas 6.2 K .. backfire and miss

Is the car North American spec or Japan spec? The reason I ask is that some of the Japanese and Euro spec versions did not come with a Check Engine Light on the dash.

it`s jap spec ..

the only code i pull out of the ecu ( fromthe diagnosit conector .. with the led McGuiver techinque [bridge TEN then led FEN ... etc ] ) is code 6 speedometer ... that cuz i cut the wire lol :) to go over 180 back in the days

sounds like fuel cut....I'd double check to make sure your ~8 psi is really ~8 psi. That and maybe check out the knock sensor

that would make sense if it did not do the same thing in free-rev mode ... in neutral ..

but i can also increase the boos to 10 PSI ...and rev all the way to 6K no problem ...

can a knock sensor cause that .. without codes ?
thx

Yes, it's possible. It could retard the car without throwing a code. You could try extending the wire to the sensor and then relocating it to the rear housing. This was a common practice for those running the PFS PMS ECU.

ok thx im going to look into that

Update 3

-Relocated Knock Sensor ( used a spare one ) to rear Housing , ran dedicated shielded wire from ECU to knock , grounded shield ECU side
-Installed Fuel Pump relay so it always gets full voltage ( Relay energizes by factory wiring ) power is straight from batery to fuel pump + and grounded to trunk floor .

same damn thing ... 6K+random misfire-backfire then continues to rev

next step .. resend injectors for testing/cleaning .....

can a slightly stuck open secondary Injector cause this .. too much fuel dump and choke my precious spark ?

thx

You rewired your fuel pump for full voltage and say you have no A/F references. I'd say rich misfire due to your new abundance of fuel.

the car was working well when i rewired it last season, the only difference is that now i wired it straight from the battery with a relay ( by batt is in the trunk ) instead of stock wiring with bridge in the fuse box


but this 6k miss was happening prior to me rewiring the pump

Ok so after looking everything over I didn't see anything about your wires. Have you spec'd them out or even swapped them with a known good set? Also, look in to all of your grounds, especially the ones for the coil packs.

Just throwing you more ideas

..also maybe try getting a video up....it's a lot easier to diagnose when you can actually hear/see what's going on.

and you should test the knock sensor (new and old one) because they can be pretty erratic and will 100% cause the problem you have.

Yeah coils are within spex as per manual ,
wires are 20,000km`s old and also within spex
grounds are all clean + extra ... continuity exists from all wires to ecu pins

i have tested the new knock sensor from the diagnostic box by smashing ( gently ) the engine with a metal hammer ) and i pick up voltage fluctuations

i have also reinstalled my piggyback system ( HKS FCON V ) which i usually remove after the "track"season is over and .. run the stock ECU for street ...

and what i have notice is that now the miss/hesitation has moved into the 72-7400 RPM range both under full WOT in neutral .. and wot accell in all gears which is confirming my suspicions about possibly faulty 2ndary injectors ... as the HKS has it`s own maps about injector duty cycle /timing etc ...

i have sent my spare injectors ( both primary and secndary`s ) set to clean/test .. should be ready tomorrow morning


im almost 100 percent sure it`s a lazy 2nd inj. causing this ... so weird i had these flow tested and cleaned less than 5500 km`s ago .

ill keep uz updated .. thx for the inputs .. and if anything else comes to mind .. shoot it my way :)

I had a similar problem with my car. It turned out that the M2 ecu was overcompensating, and flowing too much fuel at high rpm. The car went rich at around 7k, stuttered, then pulled hard. Getting a pfc solved the problem. I suggest getting a pfc. You won't have to limit your boost to 8 or10 psi either ;)

it would make sense but right now my problem is that the car is misbehaving on stock ecu which it previously did not ...

so i have to fix it ... i don't want to semi-bandage it

i appreciate the input

The M2 ecu is a stock ecu!! They just reprogram the fuel maps to run higher boost.

But he's suggesting that nothing has changed and the problem didn't exist before (i.e. with the same setup). If that's the case, masking the problem with an ECU upgrade is NOT the correct course of action.

David0ff, it's time then to investigate your fuel & ignition systems.

yup .. i just got my injectors back from cleaning ... damn my spare pair was nasty .. 2 ultrasonix ( 9 mins each ) to get them flowing ... but at least now they spray and flow great all 4 like this i can certainly know for sure

im gonna go in the garage and work some mahjik ...

stay tuned

Maybe I missed it, but I don't see where he stated nothing has changed since the car was running well. I sort of assumed that he had added some mods and this problem stared.

i had a faulty secondary injector when i was doing my break in.. it would hesitate and not go over i believe 4 or 5k rpm if it had about 40-50% throttle. but if i would go slowly i could get it to go over that..

Update ...

so ... i am disappointing but .. happy ... after tearing my fuel rails form the block i find out that i have a leaking 2nddary injector ( at this point .. im all smiles and ... say yeah for sure this little mofo is causing my problem ) ... NOT ... fresh form the cleaners injectors ... same hesitation


one thing i have never ever changed on the car that was brought to my attention by ADAM at rx7 specialties after a quick phone call .. is the coil harness

so far :
swapped ECU
swapped plugs
swapped injectors ( with clean fresh 1 day old )
swapped Leading coils
swapped and relocated knock sensor to rear
checked TPS ..
NO CEL

no go :(

next step .. coil harness ?....
crank angle sensors ... can they be defective ?
crank angle .. sensor wheel thingy on the main pulley ?

any ideas ?
thx

i love this car it`s teaching me ... many things but i have had enough lol

I still think the stock ecu is the problem :)

i am 100% sure that it`s a problem... it`s a pig rich situation which my spark cant ignite ... i know that ... from the way it`s .. behaving under different pedal conditions
im gonna try to borrow a wide band

im leaning towards throwing money at the problem ....twin power .... :)