kajuraelai

iTrader: (8)

So 350z community after pulling my hair out and spending countless hours trying to find my problem i know come to you for advice before i head toward towing my car to my tuner for further help.

Background So in the last week, my car started stumbling during acceleration, and when im talking stumbling my car's boost gauge will read 0 when i press the gas pedal and the AFR sensor leans out to about 17 and sometimes off scale. but when i "downshift" the gas kicks back up and the car then is able to drive a little bit further before this happens again. it got real worse at a light once time on the way home where the car wouldnt accelerate at all and i had to pull the car to the side the best i could, wait a few minutes and restart the car. This only happens when i push the gas, and the entire time even when the car crapped out , ive had zero CEL come on which scares me alot.

So.....

What ive done so far I changed the plugs thinking ok, work your way back and see if thats the issue with spark, i inspected the plugs and although they didnt look worn, i went ahead and changed them anyway, gapped the plugs to .30 since im FI and found that at the stock .44 sometimes wouldnt play nice.

Also. Inspected the MAF sensor to make sure my V2 wasnt spitting oil or if it was a seal issue, the MAF sensor was clean and with no residue. Also checked connections on my coil packs but like i said no CEL so im not seeing multi cylinder misfire etc.

also cleaned out my oil catch can to make sure the engine wasnt having excessive blow by, oil catch can had very minimal oil (arc v2) maybe 8cc total in the last year.

ive had my vortech now for almost 2 years with no problems, i was thinking walbro fuel pump maybe an issue, but when i turn the key i can here the pump priming but without any CEL i cant get a good read to even begin so i wanted to ask everyone here, am i missing something? is there a another test or even another component i can check? i noticed the battery is original (my car is an 05 roadster) but the car starts on command with no leaning issue its just when i get on the road and start driving for a while itll cut out boost will shoot to 0 and the car starts stumbling.

I was thinking possible MAF sensor also but after calling osiris uprev they said its most likely not, which i believe because AFR will be steady at idle.

I put gas in (premium) even put some octane boost just to be sure (a little voodoo science i know as well as fuel injector cleaner) and the problems still there ( i knew that was going to be the end result)

so any suggestions would help and be greatly appreciated as far as what the next step should be

Thanks
Ray

binder

iTrader: (8)

sounds like it has a lean spot in the map that needs fixed.

edit: so now reading this i'm confused. The boost gauge isn't tied into the ecu so that is weird that it goes to zero at the same time it's stumbling. That sounds like a hose is disconnecting or there is a huge leak. A large leak like that would cause the a/f to increase as well as the boost gauge to see atmosphere (0psi)

kajuraelai

iTrader: (8)

Exactly binder ! my thoughts exactly, i mean if it is a huge air leak , i mean then wouldnt it read 0psi on idle? i mean i can drive for a while (talking 5 minutes) then bam it starts to stumble at 0psi and i thought it would also show 8-9 + on the A/F if that was the case, but it doesnt it leans out , and im talking sometimes off the map until i downshift and bam , the AF reads 14-15.

initially i thought it also might be a lean spot on the map, but i havnt changed anything electronically and its been the same map shawn from church automotive has programmed from day 1 with no problems.

so i did a run through with the charge pipe to see if i have any leaks , i havnt seen anything on the top end , but as far as anything near the IC , do you have some common areas that might be a place to look?

so will post my finding tomorrow, also note, checked my charge pipe top end where my methanol bung is , and the connection seems a little loose, (where the bung meets the pipe) loose enough that maybe air might be seeping in

binder

iTrader: (8)

Meth fitting sounds like the perfect place.

Since it's going lean that means the air lean is AFTER the maf sensor so it's unmetered air. The meth bung would be a good thing to try first. After that i would start checking plenum and throttle body areas.

kajuraelai

iTrader: (8)

Thanks Jeff, going to clean the meth bung and reseal to make sure its not moving anymore, last night i went out and took a look at it and notice there was a little play from the joint and the pipe will update the status once done your the best bro!

R

binder

iTrader: (8)

although i didn't do much, you're welcome.

Hopefully you figure it out. It sucks having car issues.

kajuraelai

iTrader: (8)

so i checked out the meth bung and pulled on it a little bit and noticed a small 1.5 cm gap of play, would this be enough to throw me into lean mode and 0 boost ? i mean its seems irrelevant and such a small hole but i sealed it and im waiting for an hour for the quik weld to set in before i go test drive it and see if that was the cause. Also inspected my plenum and noticed some of the middle bolts were a little a loose so i tightened them up a little bit. As far as inspecting the throttle body what parts should i take notice of? just thinking ahead incase this proves to be back at square one .

someone PM'ed also a possibility of a failing walbro but thinking to myself if it was the pump i mean wouldnt there be other signs? is there something i can point out as far as a test that could inspect if my fuel pump was failing or not

kajuraelai

iTrader: (8)

So... after sealing the wounds , i went on a run with the car , the car finally got to 6 pounds of boost, but when i let her calm down and bam... started up again woe is me


edit: dismantled to check if my V2 is blowing oil on my maf if its a sealing issue, negative.... maf is clean, in fact no weird sounds coming from blower.

350z006

iTrader: (79)

Fuel pumps can fail as boost increases...the best way to view this is to check the fuel pressure as you go into boost...if the the pressure drops significantly as you increse boost then your pump may be bad...

binder

iTrader: (8)

fuel pump doesn't explain why the boost gauge drops to 0psi (atmostpheric). Fuel pump has no effect on that.

psychoballistic

iTrader: (8)

You said it is leaning out correct?... Have you checked to see if the meth system when trying to go into boost isn't functioning properly? If a Meth pump dies, that would definitely explain your lean fuel state, which would also explain why the boost cut is happening...

binder

iTrader: (8)

If i'm understanding him correctly this is happening after boost when he lets off then tries to give it gas again. That means it was in cruise (vac) when it happens.

str8dum1

iTrader: (11)

wait, so you mean that only stumbles at 0psi (ie the boost transition)?

So when you are transitioning into boost, you get a lean spike?

Are you using the stock MAF sensor?

binder

iTrader: (8)

no, when he pushes the gas it stumbles with high a/f ratio and then the boost gauge reads 0 and it won't go any further. It's an intermittent problem also.

shift_love

id also like to know why hes not making boost...as im having the same problems, but then again...if hes running a tune that has fuel requirements for a set amount of boost, his car would run pig rich at 0psi, and not lean...thats whats strange about it...fix your boost problem first and then set up a fuel pressure gauge you can view while driving, it should be at a minimum of 43 psi, thats what the stock injectors and pump are set for

psychoballistic

iTrader: (8)

Then it wouldn't be pump related if trying to go back into boost after coming out of boost, however there should be no meth theoretically speaking in Vac, only in boost which was what made me think of that system having a failure somewhere.

binder

iTrader: (8)

To me it sounds like there is a huge air leak causing it to show 0 on the boost gauge and then also go extremely lean.

The meth fitting was loose which i thought could be the problem but apparently not so now i'm kind of stumped but fuel pump doesn't explain boost gauge readings. The only thing that fits both 0 on boost gauge (not reading vac or boost) along with high a/f ratio would be a leak after the maf. I think i'm not seeing the whole picture though so i'm lost.

psychoballistic

iTrader: (8)

Fuel pressure doesn't have to be at a minimum of 43lbs... if its been tuned with a RFS he can run 38-41 with zero issues... I set mine at 37psi at idle and I still idle slightly richer... If he is Vortec super charged, he would need different injectors and an aftermarket pump. Stock injectors will not flow enough for boosted applications unless the power level is EXTREMELY low.

psychoballistic

iTrader: (8)

I 100% agree with your thought process, assuming the boost gauge is tied into the maf and there isn't a separate sensor for the gauge.

What type of MAF are you using OP?

kajuraelai

iTrader: (8)

Pmaf i think what its called by the way ive got a good update

Update: So went to church automotive today in wilmington , basically babied my car up there (trying to hard not to go above 4000 rpm , driving behind big rigs etc etc) and got there safely by the grace of god. so shawn connected all the diagnostics and read my readings to see if we could mimic the boost leak type symptoms. everything read normal minus a slight misfire but nothing that would say "bingo" but he did notice my car voltage spiking irregularly (which i thought was odd as well)

after i sealed the bung from the meth and also a rather large hole on my tubing connector from the charge pipe the boost pressure loss hasnt showed up again, what i think it was , maybe the gator clamp was loose as the car was going in boost it must have been moving the sleeve in such a way that when my car came a relax state the car saw a huge air leak and shot the car into stumble mode ( again a guess)

after i checked all the connections, i went and bought a new battery ( it was time the thing was over 80 months old) and just changed it out today (right now ) so will keep everyone posted , im more confident its not maf now though since the reading came back great, with no complications. Hopefully the answer was a combination of errors that just seem to resolve with all the vacuum sealings, but im going to go more WOT tomorrow and test this out to make sure.

Shawn was saying if it was the fuel pump, i would have seen more of a pressure choke issue at high temps, so i told him i would log my temps and also log any further characteristics, i did notice when my car started to stumble it was usually when the bar was bouncing up and down from a slight bump in the road, so i dont know... i thank everyone for the help and the insite! especially binder! will keep everyone informed with tomorrows results! till then, thanks again!