RexTech

Hi pals,
I see how my engine detonates -J&S knock sensor monitor- sometimes -I´m not sure why- it happens when I am driving at medium (30-50 mph) or high speed (60 or more) and the gas pedal is released and suddenly I press the gas pedal -WOT-

I think that it happens because the presure at the injectors decrease and they can not inject all the gas that the engine needs at that moment. After few seconds there is no more detonations and I can reach 140 mph and 10 psi of boost without problems, no detonations.


Maybe I need a bigger fuel pump or should I decrease the sensibility **** from the J&S unit?

What do you think about it?

My mods:

*Pettit street ported with 3mm apex seals engine.
*Non sequential Pettit HF turbos.
*Custom cold air intake.
*Pettit ECU upgrade -it handles until 14.5 psi-
*10 inch Magnecor wires.
*Profec B bost controller.
*J&S Knock sensor with monitor -v0 unit-
*DP
*MP & CP -3 inch diameter- with free flow resonator. -no cat-
*Apexi cat-back. -4 inch diameter-
*Aluminium flywheel
*Stillel anti stress bar.
*Short shifter.
*Eibach springs.
*Hawks pads.
*Autometer A-pillar pod
*Autometer temp gauge.
*Autometer A/F gauge.
*Autometer boost gauge.
*Pettit AST
*Unleaded 95 octanes gas -all time-

How many HP do you think my car has at the flywheel or rwhp?

PS: We don´t have a dyno near here.

Thanks ,
RexTech.

Bacon

iTrader: (12)

yea with all those mods a fuel pump wouldnt hurt...althought the inital knock could just be caused by delay in the fuel pump comin up to press..not reall the fuel pump lacking flow...
still better safe than sorry
id get the fuel pump and a new fuel filter

rwhp @ 10 psi? or higher?

RexTech

rwhp @ 10 psi? or higher?


Ok, I run 10 psi, sometimes 11 psi.

Thanks.

jspecracer7

holy crap! I can't believe you have all those mods and no fuel pump!...

but seriously, if you get a fuel guage and check to see if your fuel level is dropping under acceleration, you'll know for sure if you need one or not.

Either way, it's a good excuse to get a new fuel pump. I think that the stock one will hold up to 330 hp at the flywheel, but don't quote me.

CYM TKT

iTrader: (4)

10 inch magnecors!! muahahahaha mine are only 10 mm lol

RX7FAN

Hey J-spec, Where can I get this mod? you so silly.

RotaryKnight

Damn you like living on the edge!!!!! No fuel pump and you haven't popped yet? I really think you shoud get a Fuel pump and a FPR for reliability.

RexTech

Ok, Ok , I´m sorry a wanted to write 10 mm magnecor wires.

Could you answer my question? how many hp my car has?

Thanks.

Excuse my english, my everyday language is the spanish.

RexTech

Looking at my fuel gauge, I can see how all the light goes off -0 volts- when I just push the gas pedal to WOT, 2 or 3 seconds later the lights goes on again to yellow and green.

badass7

What kind of temperature are you doing these runs in? I noticed you don't have an intercooler in your list of mods.

RexTech

Yes, I have the stock intercooler.

With the parking lights on, about 210-215 °F with turbos on line @10 psi at the highway.

With the parking lights off about 230 °F.

I ALWAYS use the parking lights on.

KZ1

I get much higher knock readings from my PFC as well when going from on and off gas, and when under light throttle around 3 or 4k. I think it is normal to a certain point. I have been told to be only concerrned with WOT knock readings, maybe you need to adjust you J&S a bit more to be less sensitive.

the fluctuating a/f ratios I get to. If I am cruising and slam gas down, I get ratios that will bounce a few times before going rich. I can;t see it being a problem with pump flow, as previously mentioned.

hope it helps, I would like some more definitive info as well.

RexTech

After install your new fuel pump, please tell us if you see the same behavior than before about knocking.

Thanks, RT

RexTech

Well, almost a year ago we started this thread and now I think that my knocking problem is fixed. A month ago I upgraded the fuel pump for a supra one -just like some of you recommended- ; I took the car for a ride and i did not notice differences the knocking continues at the described situation, so I was very dissapointed , then i changed the spark plugs -they had like 16000 miles- for a new set and the problem still there. Then I replace the fuel filter and boala, the knock reading dissapear i made a lot of tests , 7 psi, 10 psi and 11 psi, no knock reading, from no throttle at 3000 to full throttle at 7000 10 psi wow, what a good feeling. I tought that the J&S was damaged but nope it was fine.
Now i feel free to run, no worries about knocking. Before, each time that i saw knocking on the display I released the gas pedal. Now i will enjoy my 7 and keep on reliability mods like a second oil cooler.


It took me 2 years and half to tune this car. I bought it from a guy that used a mechanic that knows about power but not about reliability. All the 7 that goes to that place takes the green mile or "the supoused golden path"

I needed the pump and the filter.

Is very hard to me to buy parts for my seven because here mazda did not sold rx-7, so i have to import parts from the U.S. .Talking about filters and disposable parts no other car uses the same fuel filter that the 3° gen uses neither the spark plugs.

The key factor on my reliability was the J&S knock sensor, without it I could blown my engine easily. Some guys says that the J&S take a lot of power and bla bla bla. I really preffer to loose some power instead to pop my engine.

Thanks for your help, i really appreciate it. This forum rocks!!!

RT.
Sorry about my english.

mod list:

*Pettit street ported with 3mm apex seals engine.
*Non sequential Pettit HF turbos.
*Custom cold air intake.
*Pettit ECU upgrade -limited-
*10 mm Magnecor wires.
*Profec B boost controller. Max. 11 psi.
*J&S Knock sensor with monitor -v0 unit-
*DP
*MP - with free flow resonator. Hooker Aero chamber-
*No cat
*Apexi muffler. -4 inch diameter-
*Aluminium flywheel.
*ACT street/strip clutch.
*Stillel anti stress bar.
*Short shifter.
*Eibach springs.
*Hawks pads.
*Autometer A-pillar pod
*Autometer temp gauge.
*Autometer A/F gauge.
*Autometer boost gauge.
*Pettit AST
*Fluidyne radiator.
*Supra fuel pump.
*Toyo proxes T1S rear and Dunlop SP8000 front.
*Unleaded 95 octanes gas -all time-