Jeep Strokers

I6FAN wrote:Am I missing something here??? The torque and horsepower curve always intersect at 5250rpms!!! According to your graph, they intersect at ~4400rpms. I am suspicious of the indicated engine speed on the graph. It looks like it pulled to more than 5250rpms.

his torque is in kg and with the fuel cutout could also count for fault

atias wrote: yes sir i do.

Have you reviewed if for any abnormalities? If you want a second eye I could take a look at it.

-Chris

http://rapidshare.com/share/53DEAEF8EC5 ... 7FE2954178

thanks chris.

ill get back with the updates after ill bypass the MSD box.

Weird. Take a look at the fuel injector duty %. Right before the RPMs drop the FIC shows an injector duty of 240+% on all injectors. However, the FIC isn't modifying the fuel trim abnormally, around -17.97%, which isn't abnormal for your programing. The FIC doesn't show any timing being pulled, but that could be due to the MSD controlling that.

The resulting "lean" AFR was probably the engine misfiring from too much fuel, not an actual lean condition.

What speed was your speedometer and tach showing when this happened? The dyno shows 66mph, but doesn't say what your PCM is seeing.

I would expect if this was an FIC problem it would have showed prior to 4620 RPM.

Do you have any OBD logs to go with this?



Zoom in:

SilverXJ wrote:Weird. Take a look at the fuel injector duty %. Right before the RPMs drop the FIC shows an injector duty of 240+% on all injectors. However, the FIC isn't modifying the fuel trim abnormally, around -17.97%, which isn't abnormal for your programing.

yeha i saw that, i always thought that this is the ecu cutting fuel and spark at the rev limiter.

SilverXJ wrote:The FIC doesn't show any timing being pulled, but that could be due to the MSD controlling that.

i don't pull any timing (i started tunning with 1 degree for 1 psi and sneaked up a little bit timing every time and the engine liked it, and it wouldn't detonate with the premium fuel and water meth,i also check for detonation on the sparkplugs and it was always clear, i can advance the timing even more with the CPS mod and then cut the timing down on boost, but the leaf springs at the rear axle cant handel the power as is(need a traction bar asap).

SilverXJ wrote:The resulting "lean" AFR was probably the engine misfiring from too much fuel, not an actual lean condition.

the lean spot is always there no mater how much fuel i dumb on it or takeing out.

SilverXJ wrote:What speed was your speedometer and tach showing when this happened? The dyno shows 66mph, but doesn't say what your PCM is seeing.

after the two first pulls on the dyno i also thought that it may be the speed governor in the ecu kicking in (my speedometer is actually going backwards ) so i disconnected the VSS and the problem was still there .

SilverXJ wrote:I would expect if this was an FIC problem it would have showed prior to 4620 RPM.

i'm very much hoping so .

SilverXJ wrote:Do you have any OBD logs to go with this?

no sir that one i don't have.

i'm going to disconnect the msd box and get back with the updates i'm hopping that maybe it just the msd box developed some high rpm miss.

& thank you guys for all the help.

UPDATE: MSD BOX WILL MAKE VALVE FLOAT SOUNDS LIKE A REV LIMITER!!!! or at least in my engine it does

after disconnecting the msd box i took the jeep for a spin and i have a major surge at 4300 rpms, even at idle the jeep wouldn't rev past 4300 rpms and the wideband goes flat lean when it does this surge...

fuel pressure is ok.
i increased the fuel at the surge spot in the FIC by a ton and still no difference.
its now sounds like a very soft rev limiter.
i'm thinking that the valve springs gave up since i took them out from the previous stroker that i built 10 years ago . i guess they did their time
just hopping that the cam is ok since he is 10 years old also, but the valve train sounds very normal and pretty quite so i still have my hopes up
i have a fic log of this surge (valve float) that i will upload later.

http://rapidshare.com/share/0DF3E905605 ... DDA1323FC0
this is the fic log for the valve float.
gear in neutral + full throttle.

I6FAN wrote:The torque and horsepower curve always intersect at 5250rpms!!!

That's only true provided that power is measured in horsepower (not KW), torque is measured in lbft (not Nm or Kgm), and that both measurements are graphed on the same numerical scale.

Cheromaniac wrote:

I6FAN wrote:The torque and horsepower curve always intersect at 5250rpms!!!

That's only true provided that power is measured in horsepower (not KW), torque is measured in lbft (not Nm or Kgm), and that both measurements are graphed on the same numerical scale.

That's what I was missing; saw the horsepower units, and assumed it was in English measurements on the torque also.

new springs just arrived .

changed the springs and even shimmed them to 1.650 to get more pressure and the problem is still there.
now what??
according to crane spring pressure chart my new springs should be at:
seat pressure #113
open pressure exhaust #270
open pressure intake #260
coil bind at 1.080
spring rate #328lbs/in
springs max.net.lift is 0.560
cam lift:
intake 0.456
exhaust 0.484

the jeep pulls like a rocket up until that fuel cutoff at 4300-4500 rpms.

atias wrote:i got 8-9 psi at 5000-5200 rpm, now i'm only seeing 6 at 4300-4500, give or take half a psi.
it have water to air intercooler with a water tank for ice in the back and a heat exchanger up front of the radiator.
water meth injection, split headers with two exhaust systems,43lbs injectors, massively ported 7120 head, Crane 753905 with the 99833

Do you have water-to-air and an air-to-air charge cooling, as well as water/meth injection? I was wondering what your static compression ratio is(?). That's seems lot of intercooling for only 8-9 psi unless you are running a relatively high static compression ratio. That 905 cam suggests a 8.0 to 9.5 to 1 for n/a. I actually have seen your video, independent of this sight, while "cruising" youtube...cool. Anyway, it seems kind of like something, a sensor (map) could be getting out of range possibly(?), or some detonation and timing retard could be getting out of range, and causing the o2 readings you see(?).

are you running a cat by chance? i had a supercharged grand prix that did almost the exact thing with a plugged cat...

my static compression ratio is 9.3 to 9.5, i did not checked the combustion chamber volume after the polishing
water to air and water/meth injection, the heat exchanger is for the intercooler's water.
changed the: map , cps , tps , flywheel . still the same cutoff
no cat.
chris(silverxj) saw something interesting in my datalogs, that my injectors duty cycle becomes weird and cutting the fuel off to the engine.
ill try to change the ecu tomorrow and see what the outcome will be

wow that sure would be a head scratcher if it's the ecu