dyno day + rev limiter problems

[atias]

changed the ecu still the same fuel cut.
but i noticed that if i give it quarter of a throttle it goes strait to the 5200 rev limiter without a problem.
and if ill give it half a throttle or more its doing that curst fuel cut at 4300.

[sly-jeeper]

hmmm is your map causing the fuel pull under boost? im sure you thought of this already. its just strange it does it under heavier throttle

[SilverXJ]

Have you checked the TPS?

[atias]

today:
changed the TPS again and also checked it with the DRB tool + calibration in the FIC.
made a piston stop from an old spark plug and checked the balancer for timing mark accuracy.
installed a new dizzy + indexed spot on (turned the engine clockwise to the 0 mark to keep the chain stretched).
closed the sparkplugs gap to 0.30.
disabled the internal logging in the FIC + disabled the 12VDC (water meth activation).

and still NO...

hmmm is your map causing the fuel pull under boost? im sure you thought of this already. its just strange it does it under heavier throttle

the engine is getting to the 5200 rev limiter only if ill give it the lightest load possible , but if ill press the throttle a little bit faster it is cutting in 4300-4500.
something is causing the ecu or the FIC to shut the injector pulses down.i have tried to add fuel in that location on the map but that didn't helped.

[sly-jeeper]

has it ever ran right with the supercharger on it?

[atias]

the problem is definitely the FIC or the fuel injectors.
i checked today 3 more jeeps with an FIC installed.

two of them have FIC with the same injectors like mine,
and they both have the same problem...(one is stock 4.0 with a turbo FIC 30-1910,and the other is supercharged stroker FIC 30-1913)

the third one is a stock 4.0 with a turbo but with different injectors and he is working flawlessly.(FIC 30-1910)
maybe these bosch green giants 43lbs injectors just don't play well with the FIC.. i really don't know what to think anymore.
ill need to borrow this guy's^^^ FIC and connect it in my jeep to make a final diagnostic.

has it ever ran right with the supercharger on it?

i guess it did ran right with the VORTECH FMU and the smaller injectors (too bad i sold these), this FIC made me nuts , next time ill go with the megasquirt..

[SilverXJ]

I'm running a 30-1913 without issue on my stroker. We should be running the 1913 and it has the correct injector drivers for the Jeep PCM.

[atias]

I'm running a 30-1913 without issue on my stroker. We should be running the 1913 and it has the correct injector drivers for the Jeep PCM.

i have the 30-1913 too , its the one for all OBD2 jeep (you taught me that )
but all the jeeps around here are old OBD1 sbec ecu (ex military jeeps), so they both work ok.

[turbojeeper]

I am just throwing this out there but is it hitting the cut in each gear. Didn't see if it was auto or manual. When mine was on the dunno I hit the same cut at 4200rpm in 4th gear of my manual. We then did a pull in 3rd and it pulled clear to redline. Come to find out the stock ecu had a factory speed limiter some where around 100mph.

[I6FAN]

i have the 30-1913 too , its the one for all OBD2 jeep (you taught me that )
but all the jeeps around here are old OBD1 sbec ecu (ex military jeeps), so they both work ok.

So, are you OBD1 or 2, and is your vehicle an ex military vehicle? That could be very important clue as most military vehicles are equipped with speed limiters which could be even lower than the 100 mph that turbojeeper has brought up.

[atias]

my jeep is OBD1 and manual transmission (AX-15),
and it does this fuel cut even in neutral and in first gear, the first thing i thought was the speed limiter also , maybe a bad VSS = so i disconnected the VSS on the dyno,
still the same

i'm gonna keep torture this thing until the problem is solved or the whole engine goes


just kidding this jeep is lucky that i love him.

[atias]

and still
1)tried today to lower the injectors duty cycle, i though maybe i was maxing the injectors out, because all of the fuel cut is happening at 83% DC
so i raised the fuel pressure to 4 BAR and lowered the fuel map to compenscate, and managed to cut the DC to around 75%. and still no.
2)updated the fic firmware to the new x3.81 with the new 3.07 software, maybe something will change...... no no..
3)wanted to downgrade the slave firmware to z104 but the hex files that i downloaded from AEM was corrupted. logs on to their site and the forum is down for who knows how long and that file is nowhere to be found on the net (searched for hours). so i sent a email to chris(silverxj) who send me that file and saved my day .
downgraded to the z104 slave firmware, calibrated the FIC with the DRB tool and still a fuel cut, but i think that now it moved up a little to 4900 rpms .
the jeep runs good with the z104, maybe its because i'm OBD1. and the duty cycle graph in the datalogs looks alot better and more accurate between all 6 injectors.
4)when i was looking for a good z104 file in my computer i stumbled on some old datalogs that i kept from when i had the smaller injectors and the FMU.
in those logs the jeep goes flawlessly to the 5200 rpms, and the DC even goes beyond 105% without one miss or a cut.
so that let me think that maybe there is something wrong with my fuel injectors and maybe the bosch 42lbs injectors that i got from ebay are a knock off,
and they locks up under load... aaahhhhhhhhhhhrrrrrrrrrrrrrrrrrrrrrrrr

gonna keep trying something else tomorrow.

thanks again to chris(silverxj)

[atias]

tried a lot more things to try and fix the problem.
cleaned the ecu wires, checked the power grounds, changed coil and closed the gap on the sparkplugs (maybe spark blowout ) , made a better power line to the ecu + fuel pumps,
and more $h1t that i cant even remember,the engine works better even stronger but the damn fuel cut is still there
then i disconnected the aem with the bypass plug after the engine got warmed up and nail it to the floor -WOT- in 1st blowing black smoke from the exhaust like a diesel cummins,
the engine went strait to the red line like a cheetah on cocaine and start bouncing on the original rev limiter 5200-5500 .
so i know now that the engine is fine , the stock ecu + harness is fine , the injectors(looks genuine by the way) is fine , sensors is fine , AEM = BAD...
does somebody has an idea what can cause this ???

[atias]

changed the AEM with one from a friend jeep and the fuel cut is still there,
and both AEMs work fine in his jeep (rev limiter 5200rpm).
rewired the FIC harness from the start.
and still NO, fuel cut at 4400-4800 RPMs.
without the FIC the rev limiter is just like it should be at 5200 RPMs, all checked out with the laptop , gauge , DRB tool .
what the hell is going on with this thing....