dynoed my rb25 only got 240 horse?

[skierdude494]

like it says in the title i just dynoed my rb25 today and only reached 240 it right about 4 to 5 thousand rpm's the motor would just flood out from fuel and dip up and down, last time i dynoed my car it was 270 and had a very clean curve. now i know it has nothing to do with fuel because i was looking over my fuel gauge as we were doing the dyno and stayed with in normal psi of rb's. the mechanic told me it might be my mafs? but i looked at it not to long ago and also cleaned it with carb cleaner it looked brand spanking new! do i need to upgrade to the q45? i have the stock rb mafs i am completely lost on what is wrong with it? oh by the way it seemed to help about 5 horse when we raised the boost from 11 to 13.5 it didnt start flooding its self out until about 5k as at 4.5 it was 11 also last time i got it dynoed i was only running 9 pounds any help guys would be great sry for the novel but any help would be great thx

[ANVIL]

what were the afr's during the flooding

[Coolwhip]

i would stay away from carb cleaner when cleaning your maf.

[Yellow4g63]

Yeah the carb cleaner prob killed it.

[skierdude494]

a/f started about 12 began dipping to about 11.5 and then about at 80mph it dipped below 10 then rose back up and stayed at 10 when it hit 10 is where the bogging down really started to happen hopefully i can get a picture on here soon for some reason the email of my dyno is corrupted and will not open so i will have to go ghetto and take a pic of my sheet haha

[ANVIL]

they do have MAF sensor cleaner in a spray can that would probablly be better...

[skierdude494]

dyno sheet (rpm's)http://s397.photobucket.com/al...9.jpg

(a/f)http://s397.photobucket.com/al...8.jpg
Modified by skierdude494 at 11:11 PM 10/27/2008

[StricNyne]

dyno looks like muhammeh ali signature... you running any kind of engine management ? or just stock ecu

[craz4240]

i would stay away from carb cleaner when cleaning your maf.

[skierdude494]

stock ecu

[Cjmartz2k]

turn your boost back down to .7 bar

[moso240]

fuel pressure regulator?

[skierdude494]

when we turned down the boost it actually ran worse? and the im pretty sure the fuel regulator is good because we were watching it and it would only gradually increase with the rpms

[Carryl]

what fuel pump are you running?

[the_garynator]

Is your ecu throwing any codes? Have you tried resetting it? It sounds like the ECU is wigging out and trying to compensate.

[skierdude494]

running a walbro 255

thats what we were thinking i reset the ecu once before maybe 2 weeks ago? it helped but seems to be getting bad again? to reset u just disconnect the negative on the battery and hold the brake for one min correct? thats what i was told atleast on the gts and gtr forum please correct me if im wrong if that is the issue though what should i do to fix it other then reset my ecu everyother day? haha and i know this is really noob to say but i dont have a clue how to check for codes?

[the_garynator]

to reset my ecu, i usually disconnect the battery for at least 5 min. I'm not sure how to check the codes off the top of my head, but I know there is a tutorial out there somewhere on how to do it. It's something with the red light on the side of the ecu.

[moso240]

is your base fuel pressure set tho? yea it goes up as rpm increase and such but if its allowing to much fuel theres your issuse

[Bluefire]

Fuel Pressure doesn't raise with RPM per say. It raises with boost. So assuming your base fuel pressure with vac line off is 42psi (Which it should be set at), then with every lb of boost you make your fuel pressure should increase a lb. ie. 42psi fuel + 10psi of boost = 52 psi of fuel.

Either way if your not running a FPR then get one. The Nismo regulators are cheap and bolt right on.

Also as someone mentioned above, you must use maf cleaner not carb cleaner to clean a maf!!

-Bluefire

[skierdude494]

do u think the maf is gone? or can i just clean it again with maf cleaner? and im still pretty sure its not the regulator it works fine at lower rpm's i dont know i could be wrong i hope its not that because im broke

[the_garynator]

you could try cleaning it with maf cleaner, but usually once it's stuffed, it's stuffed. You should be able to pick up a used one for pretty cheap. probably like $50-$75 bux.

[240z4u]

^^ is right.

Once you spray chemicals into that maf that don't belong there it is likely damaged. unless your lucky and some residue is causing it.

[gawdzilla]

tried to repair a small handful of mafs with maf cleaner and also resoldering of the connectors. never worked out for me.

probably maf or boost leak. maybe timing?
Modified by gawdzilla at 9:53 PM 10/28/2008

[skierdude494]

alright so i reset the ecu and it seems to be running better what do u guys think?

[the_garynator]

Keep driving it, if it starts to run like crap again, try resetting the ecu again. If it keeps doing it at an unreasonable rate we'll continue troubleshooting it. otherwise, don't fix what's not broken

[BoostFab]

fuel curve is pathetic; it's way too rich, it needs to be lean out more for top-end.

[skierdude494]

any ideas y just the top end fuel would be so rediculous? my only thoughts is the maf is gone but i really hate to buy a new one and find it not to be the problem? anyone have similar issues?

[ANVIL]

well, wont know if its the maf until you try a different one. see if someone local can help you out with a known working one before you buy one? i would probablly just buy one. if its not that, they sell pretty easy anyways, or its good to have a spare

[skierdude494]

alright i will see if i can round one up is there any difference between the 300zx and the q45?

[the_garynator]

what maf are you running right now?