evovette

iTrader: (3)

Just wondering if anyone has had an o2 sensor start to fail without seeing a check engine light. My car has had a fair bit of driveability issue's in closed loop and Im trying like hell to find out whats going on. The problem is as follows:
If I am cruising on the highway and start to accelerate from 3K rpm up to 4k rpm then let off the gas and let it coast in gear down to 3500 rpm, then ease back on the throttle again the car gets lean (17 or so to 1) and feels like it hits the rev limiter. It doesnt always happen just sometimes, I find it also happens on on ramps as I leave it in gear and sweep through the turn and try to accelerate onto the highway. Now I have for mods: hks intake, helix IC pipes, stock 9.8 turbo, 272/264 cams, front mount, 1G bov with stop leak mod, walbro FP ( brand new) SMC meth injection, BR 3 inch turbo back with test pipe, BR COP ignition (old version without ignition box) stock spec plugs ( also new) , custom dynoflash and ECU+ that is used for logging and to set my lower MAF limit (52 hz) so the car will idle well.

So anyone have a clue as to what is going on, Ive seen posts about everything from plugs to alternators to 02 sensors. Id like to see if anyone has solved the problem before I go chasing it around. And for the record I get the dreaded P0300 code all the damn time, always in closed loop and always at low load levels.

evovette

iTrader: (3)

ttt

C6C6CH3vo

iTrader: (9)

Maybe your stop leak mod - pneumatic solenoid operated pilot valve is malfunctioning

evovette

iTrader: (3)

Now if that failed open wouldnt that cause me to run rich rather then lean? It is after all on acceleration that I get this to happen, in other words just when it should be closed. So if it failed closed it wouldnt effect this portion of driveability. On the flip side if it did fail open less air would get in the motor causing the car to run fat not lean right? So by that logic ( not sure if Im right but it seems right to me) It couldnt be a BOV related issue. Now this could easily be ruled out tomorrow as I have 2 extra BOV's I could try out.

evovette

iTrader: (3)

bump it and some additional info, judging by my evoscan log its not battery voltage as it stays between 13.7 and 14.02 volts when this happens. Leads me to rule out a bad alternator like it was in smokedmustangs ( or something like that for an SN) case. I am seeing 6 knock counts here though.

evovette

iTrader: (3)

Ill give it another bump, why not

C6C6CH3vo

iTrader: (9)

I would guess the O2 sensor. It would be rather difficult to slave one in from another Evo to see (with harness attached) but still cheaper than buying one.

OT:
I'm attempting to make my own "stop leak" for my OEM BOV, using a 10 psi pressure switch, 3 way/2 pos solenoid, and a second port added underneath diaghram of BOV.

How does it work for you?