100% duty cycle PFC @ >6000RPMS reading on a stockish RB25 ?????? HELP

[silviasgp06]

Stock turbo @ 8-10psiPower FC with factory apex map.WB fuel pump w/ appropriately set FPR

So some reason my power fc is saying my injectors are maxing out on a stockish RB25. Can anyone tell me why this may be happening?

Now otherwise my car seems to be ruining fine just the high duty cycles are odd to me. My wideband isnt leaning out so Im lost.

my guess:dying pump or it not getting 12v?

let me know what you think. Thanks

-Daryl

[Cjmartz2k]

Your PFC can't tell if the fuel pressure is dropping off or something and turn up the injectors. You have some kind of sensor malfuntion making you go to a rich spot on your map and maxing out the injectors. What's the peak MAF voltage? Might have a back coolant temp sensor. Bad grounds can do it too.

[silviasgp06]

Thanks for the fast responce. I'll start checking tomorrow.

Any one else feel free to chime In to offer more insite if you want

-Daryl

[Darius]

cjmartz2k- If he is running in closed loop and the fuel pump is not keeping up for whatever reason, will the PFC automatically increase injector duty to compensate?

If he's running the stock map, there's no way there would be a rich spot on it that would cause the injectors to max out at only 8-10 lbs of boost on the stock turbo. Exhaust leak upstream of the O2 sensors?

silvia- Do you have the PFC boost control kit or a separate boost controller?

For the coolant temp sensor, what does it show for the coolant temp on the hand controller? Should be like 80-85C.

[WhatsADSM]

cjmartz2k- If he is running in closed loop and the fuel pump is not keeping up for whatever reason, will the PFC automatically increase injector duty to compensate?

If he's running the stock map, there's no way there would be a rich spot on it that would cause the injectors to max out at only 8-10 lbs of boost on the stock turbo. Exhaust leak upstream of the O2 sensors?

silvia- Do you have the PFC boost control kit or a separate boost controller?

For the coolant temp sensor, what does it show for the coolant temp on the hand controller? Should be like 80-85C.

Darius you are right that the PFC will compensate under closed loop, i.e cruising. However once he goes WOT, it will switch into open loop and run solely based on the map. So it shouldn't have anything to do with it.

Yea check the sensors for anything out of the ordinary in terms of temps and post up what the MAF volts (and wideband reading) when you are getting the 100% IDC.

[silviasgp06]

water temp is showing normal 80-85*

ill have the MAF voltage/wide band reading posted after i go for a drive later today.

just to double check im using an E60(pink label) 3rd gen maxima MAF which I found/was told is the same as a S2 rb25... right?

EDIT:

it rained and is wet here in Dallas today so I wasn't able to go for a drive to get WOT readings. Maybe dry tomorrow or this weekend...
Modified by silviasgp06 at 2:28 PM 1/14/2010

[Cjmartz2k]

Not sure about the MAF, but as far as the temp sensor goes, it's hard to catch it screwing up sometimes. It might just have a loose connection and if it jiggles loose for a second it can show some ridiculously low temp for a split second and make it spike way rich. It would show the peak value on your injectors, but since it would be a really low temp, the peak of a normal 85* would be what was showing. Even if you were watching the non-peak values it would probably be real tuff to spot.

[silviasgp06]

interesting point on the loose connection. I have datalogit just since Ive bought it I havnt had much time to play with it. When it stops raining Ill try to log, and the low spike might show up on the log if it was happening.

[Cjmartz2k]

I'm sure you'll figure it out in no time with the dataloggit. Let us know what you find!

[silviasgp06]

UPDATE

Ok Finally have some information. Never got to data log because Ive been trying to solve a richness issue which now seems to be fixed. but I do know the MAF is reading greater then 5volts! on a stockis set up at low rpms....

Totally never realized the units under the power fc's Air Flow monitor were in (mV)milla-volts.(so 1000mV=1V). In the past I thought it was just some random associated number because it was a 4 digit number and didnt see the units, and never looked at it again until recently.

but yeah on the way home at WOT, dont think I was above 6000rpms and had high duty cycle with a 5.025ish volt max before I let off(also had a slit misfire type sound by this time too)

So guessing something is up with the MAF, Going to clean it, check the wiring and see what happens.

-Daryl

[Cjmartz2k]

Maybe you had a high flowed turbo and didn't know it LOL. Also, you might have a giant boost leak. Make a boost leak checker and find out.

[robbie2883]

.....stupid double post....site maintenance ftl! LOL

[robbie2883]

just out of curiosity how much boost are you pushing on the stock turbo? the stock injectors pretty much max out around 1 bar. and the maf does too. it'll read a little over 5 volts at upper rpms at those boost levels too.

[silviasgp06]

Boost leak definitely possible

Would be awesome if it was a highflowed... but im not betting on it lol

[robbie2883]

nm...i must have some how missed the boost pressures you posted. so you're on completely stock maps? no timing has been messed with? have you checked the base timing?

[silviasgp06]

correct as of now its just the stock PFC base maps.

Was about ready to start tuning via datalogit but these issues poped up on some pre-tests.

[robbie2883]

i meant the base timing as in checked with a timing light

[silviasgp06]

havnt checked in it a while due to my timing light being semi inop atm, but I make it a point to check the CAS bolts for tightness regularly.