Sudden lean condition, need help.
 

OK, so I have been running the hack with 450's for about 9 months and it has been running great. I dialed the VAFC in on the dyno with a wide-band so my settings are good. All of a sudden, yesterday under a full boost run (~11 psi) the car starts to feel hesitant under full acceleration, like it possibly is detonating, and my A/F gauge stays in the lean section all of the time. Normally the gauge hovers in the stoich section and is rich under full throttle, rarely ever lean. Any suggestions? I have no CEL and the car seems to run fine out of boost or under lower boost. Is there a possiblity that my resistor box could go bad? Should I just go back on the dyno and retune the VAFC? I checked it and all of the settings look the same. Any help is greatly appreciated. I have a spare P28 that I need to get chipped for Uberdata, maybe this will fix my situation. I'm just confused as to why it would start doing this all of a sudden. Should I get a compression test? Would that have any thing to do with it? Please help.

Re: Sudden lean condition, need help.
 

if u can get a hold of a wideband that would probably be best
a compression test wouldnt hurt unless u ---- something else up when ur doing it ;)

Re: Sudden lean condition, need help.
 

Maybe your fuel pump is starting to go? Only at WOT you say?

Re: Sudden lean condition, need help.
 

Its a new walbro that I put in at the same time as the injectors and the hack. I don't think it could be the pump. Yeah, at WOT I get some hesitation in the upper RPM range, and at any throttle position, the AF meter stays lean. ???

Re: Sudden lean condition, need help.
 

did someone touch your vafc settings?
check for fuel pressure, fuel leaks, check your fpr, check timing. maybe one of the injectors is on it's way out?

Re: Sudden lean condition, need help.
 

Running a B&M FPR?

Re: Sudden lean condition, need help.
 

Yes, I am running a B&M. I never thought of that.

Re: Sudden lean condition, need help.
 

it's hung open, check your fuel pressure.........another clue is the smell of gas INSIDE the car, becauase so much gas is being bypassed back to the fuel tank.

I now run a Aeromotive instead of the B&M POS.

Re: Sudden lean condition, need help.
 

Mista Bone may be on to something, but from my experience the only time my a/f would read lean no matter what is when one of my plug wires popped off. :D

Re: Sudden lean condition, need help.
 

Checked plug wires and fuel pressure is OK, according to my underhood gauge, although i haven't checked pressure under WOT. Is it OK to peg the throttle while under the hood looking at the gauge? Or does the car need to be under a load? I'm still stumped. :-[

Re: Sudden lean condition, need help.
 

those autometer gauges arent too acurate if you've got one. if ur running too rich it goes into the red area. check ur o2 also. see if its clean could possibly be dirty ???

Re: Sudden lean condition, need help.
 

Yeah, I'm stumped. I'm gonna get it on the dyno with the wide-band to see what exactly is going on. I might be in the market for some more DSM 450s if its a bad injector. I hope thats all it is. Or somethig cheaper. O0

Re: Sudden lean condition, need help.
 

those 1.5" underhood fuel pressure gauges don't last, I'm on #4, never another Autometer 1.5" gauge again! Marshall gauges have treated me well.

BTW anyone want a purple B&M modified 93 DX FPR with the TOO mod, I finally found the corner I threw it into!

$25 shipped (get this fucker away from me!)

Re: Sudden lean condition, need help.
 

I've been having the same problem with my B&M fpr at wot but with the exception that i'm still n/a. It seems to dog out hard at full throttle, fpr gauge goes red and then blank, but when you let off and ease back into the throttle, it works fine. It's gotta be a problem with the b&m's...cheap pos's :P

Re: Sudden lean condition, need help.
 

Im running the hack too and Im in a situation similar to this. THe upper rpm range it will hesitate at wot, but I find that if I set my vafc settings leaner in the upper rpm (more into the negative to about -43) it will smooth it out a good bit!? My autometer a/f gauge lights up the entire stoich spectrum and a little of the rich the whole time at WOT. How can you tell if your car is detonating or running lean???

Re: Sudden lean condition, need help.
 

read the plugs :)

Re: Sudden lean condition, need help.
 

just run WOT then shut the car off and pull em out right? what should I be looking for exactly, isnt a cinnamon brown color showing a good a/f mixture

Re: Sudden lean condition, need help.
 

if ur running a narrowband guage and ur reading slight rich when ur flooring ur car it means ur running really really lean

those guages are for NA cars not boosted cars

Re: Sudden lean condition, need help.
 

youmaybe maxing out your map sensor voltage. when i had the hack at around 10 11psi. keep boost at 10 psi orless and see if you have the same issue

Re: Sudden lean condition, need help.
 

Have put anything on the car lately or increased the boost?