SOHC_MShue

I am having some very weird issues now all of a sudden with my car running completely lean at about 5500-6000rpm range. It will go from high 11's to 14-16afr's once it hits that rpm. The car has never once done this before in the 3 years its been boosted. I had just finished racing my roomate and it was fine. I went to get on it again and all of a sudden this lean issue was occuring. I thought maybe it was something with the ecu or program so i switched my neptune ecu out for my crome tuned ecu and it was doing the same thing. My fuel pump sounds fine, and my car runs perfectly fine in lower rpms. Afr's havent changed. In fact it even does this lean stuff at part throttle boost say under 5psi(full boost is 15psi). As soon as it gets up into those rpms it leans out. Whats strange is that if it were a fuel flow issue it would seem to me that it would go lean in higher rpms at lower loads, but then go lean a little earlier at full load. Also this just happened so suddenly. Everything was fine earlier on in my drive and now all of a sudden its doing this ****.

Has anybody seen anything like this before? I'm so stumped right now and its really annoying me ...hopefully i can do more testing tomorrow when its not 3am.

BTW: my fuel system includes dsm 450's, a resistor box, walbro 255lph pump, and a fuel filter that has been on my car for probably 4 years




Modified by SOHC_MShue at 3:11 AM 5/1/2007

SOHC_MShue

any ideas?

BlackCRX

long time no talk there matt, i would almost guess that it was a missfire but im sure you are running the det cans. plus being the tuner that you are im sure you checked it already

sohc_turd

I once had a similar problem when a fuel pump was getting weak, it would idle drive fine during low load situations but would not put out sufficient pressure under high load situations.

It might be worth looking at the pump.

EE_Chris

What's the fuel pressure looking like when it goes lean?

Misfiring is another possibility...

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BlackCRX &raquo;</TD></TR><TR><TD CLASS="quote">long time no talk there matt, i would almost guess that it was a missfire but im sure you are running the det cans. plus being the tuner that you are im sure you checked it already</TD></TR></TABLE>
How ya been man? Yea i'm sure its definately not a misfire. I replaced the fuel filter today, cleaned out the fuel filter on my pump, and it still is doing it. In fact it seems to have gotten worse and does it at even lower loads. I am getting a new set of injectors tomorrow to test and if that doesn't work i guess i'll get a new fuel pump. The resistor box probably isn't bad because the car still drives alright at part throttle.

Boostfed

Are you able to monitor fuel pressure though?

What type of fuel pressure regulator is on it? I know that some had said before that DSM's don't get along too well with Hondata, though many have used them BUT also alot of people including my tuner has had issues with the DSM injectors. I have to ask him what probs they had though

Good luck with it

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostfed.com &raquo;</TD></TR><TR><TD CLASS="quote">Are you able to monitor fuel pressure though?

What type of fuel pressure regulator is on it? I know that some had said before that DSM's don't get along too well with Hondata, though many have used them BUT also alot of people including my tuner has had issues with the DSM injectors. I have to ask him what probs they had though

Good luck with it</TD></TR></TABLE>
oh **** sorry forgot to answer that. I am not able to measure fuel pressure under load unless i can get it on a dyno anytime soon. I have a gauge under the hood and thats it. So far none of the cars i've tuned with dsm injectors have had any problems except for one that just would just dump in a ton of fuel on all cylinders and wouldn't start for some reason. After swapping in some other dsm's it was fine. Also they've always idled very well for me. Not very finicky like you would think they would be because they are low impedance. I guess there is a first for everything though .

Boostfed

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">
oh **** sorry forgot to answer that. I am not able to measure fuel pressure under load unless i can get it on a dyno anytime soon. I have a gauge under the hood and thats it. So far none of the cars i've tuned with dsm injectors have had any problems except for one that just would just dump in a ton of fuel on all cylinders and wouldn't start for some reason. After swapping in some other dsm's it was fine. Also they've always idled very well for me. Not very finicky like you would think they would be because they are low impedance. I guess there is a first for everything though . </TD></TR></TABLE>


Is the turbo spooling any differently like maybe now SPIKING at that RPM all of sudden adn coming back down?

SOHC_MShue

Nope none of that. I've pretty much looked over everything i can at this point without replacing stuff.

Boostfed

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">Nope none of that. I've pretty much looked over everything i can at this point without replacing stuff.</TD></TR></TABLE>


Possible VTEC issue?

Edit: Well that doesnt make sense since you said it does it part throttle too , weird man weird

EE_Chris

You should really try and monitor what your fuel pressure is doing under load....unless replacing it all was just easier anyway.

W O T

I had the same problem at the very end of last season, never figured it out, car would peg lean after 5500, no matter how much fuel I added in turboedit, but I ran perfect part throttle

Brand new 255, 450's.

So this year I put a fuel gauge on the fuel rail wth some detatchable fittings so I can unscrew it and put in a fuel line with the gauge attached to it and strap it to the windshield and go for a drive

Please LMK what it ends up being

SOHC_MShue

I'll let you guys know how it does after i replace those injectors. I'm getting them for free so its easier right now than trying to monitor pressure under load. If they dont work then i know its probably the pump.

W O T

After I did some research last year, I found a guy that had the exact same problem and it ended up being his fuel dampner.....

WHy I dont know, I was giong to see if I had the same problem this year after a retune and then go from there

Might be something to look into

SOHC_MShue

hmm i think i remember reading about that now too.

W O T

haha, I couldnt find the thread when i tried to go back and look either, he musta had some weird thread title

If you find it LMK

SOHC_MShue

now that i think about it though my engine doesn't have a fuel dampner like a b series where the feed line goes in the rail.

EE_Chris

I don't think D-series (at least OBDII) used a fuel pulsation dampner...

I know my Y7 doesn't and I can check on a Y8 this evening.

Boostfed

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by W O T &raquo;</TD></TR><TR><TD CLASS="quote">After I did some research last year, I found a guy that had the exact same problem and it ended up being his fuel dampner.....

WHy I dont know, I was giong to see if I had the same problem this year after a retune and then go from there

Might be something to look into</TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SOHC_MShue &raquo;</TD></TR><TR><TD CLASS="quote">hmm i think i remember reading about that now too. </TD></TR></TABLE>

Yeah me three.

SOHC_MShue

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">I don't think D-series (at least OBDII) used a fuel pulsation dampner...

I know my Y7 doesn't and I can check on a Y8 this evening.</TD></TR></TABLE>
yea i'm using a y8 fuel setup and it doesn't have one to the best of my knowledge.

W O T

ANyone got the link to that thread?

White Smoke

Are you running a stock filter? Try replacing that...

Boostfed

Matt, I spoke to Dr Emmett Brown and he said it is definately your Flux Capacitor that went bad, change that it will be all good! Thank me later man

White Smoke