need help diagnosing a problem..running lean
07-20-2010, 08:23 PM
#21
New Member
iTrader: (8)
Join Date: Jan 2007
Location: terre haute, IN; STL, MO
Posts: 6,457
Likes: 0
Received 7 Likes
on
6 Posts
I think the first line of business is to swap the fuel pump and don't think about it until you do that.
07-20-2010, 08:31 PM
#22
no rise in pressure. It wouldn't be pulling fuel therefore there is less chance of a "drop" in pressure. Basically if an injector is clogged you could pretend that you only have 5 straws sucking fuel. Pressure doens't change, but flow will.
I think the first line of business is to swap the fuel pump and don't think about it until you do that.
I think the first line of business is to swap the fuel pump and don't think about it until you do that.
thanks...yeah i am kinda sitting on it until i swap the pumps..hard to not think of it..look at me im up now past midnight searching around trying to come up with answers and i have to get up in 4 hours
a vacuum leak would cause a rough idle most likely right?
07-21-2010, 06:12 AM
#24
please if you are commenting to try and help read above so you are aware of whats on the car and whats been on the car..everything that was on the car is now off as far as F/I components..it is just intake, plenum spacer and exhaust now and thats it, everything else stock, fuel system, ems, etc ...The car does run like a stock car it is just leaning out after 3500 rpm and feels down on power once it gets up in the rpm's, no stumbling or real hesitations, for some reason is not getting enough fuel it seems..If the wideband wasnt in my car i probably wouldnt know there is a problem...
im swapping the pump in a few days and move from there and eliminate possible problems
Last edited by tylerxfire; 07-21-2010 at 06:17 AM.
07-21-2010, 06:35 AM
#25
Vendor - Former Vendor
Join Date: Oct 2009
Location: Houston, TX
Posts: 400
Likes: 0
Received 0 Likes
on
0 Posts
07-21-2010, 10:56 AM
#28
One thing to take into consideration, Z's have fuel dampeners. I haven't found a ton of info on the diferences but I would assume the dampener wouldn't hold exact pressures like some other styles of regulators (so I would imagine the 4 PSI fluxuation is not the problem). Have you had a chance to data log the injectors duty cycles? The numbers may help to diagnose the problem. Also check for intake air leaks, unmetered air can do the same as too little fuel (mixture-wise).
07-21-2010, 11:05 AM
#29
Also note, some Z's run lean in those areas. I know mine gets pretty lean (14.5 - 15.0) at full throttle in the upper midrange and then at 5000 starts to richen up all the way to redline. This is untuned, but the tuner (a tech at Technosquare) said it was nothing to worry about and is quite common for cars with a lot of bolt ons, mostly plenum spacers and HFCs/test pipes.
07-21-2010, 12:17 PM
#30
New Member
iTrader: (8)
Join Date: Jan 2007
Location: terre haute, IN; STL, MO
Posts: 6,457
Likes: 0
Received 7 Likes
on
6 Posts
One thing to take into consideration, Z's have fuel dampeners. I haven't found a ton of info on the diferences but I would assume the dampener wouldn't hold exact pressures like some other styles of regulators (so I would imagine the 4 PSI fluxuation is not the problem). Have you had a chance to data log the injectors duty cycles? The numbers may help to diagnose the problem. Also check for intake air leaks, unmetered air can do the same as too little fuel (mixture-wise).
07-23-2010, 04:48 PM
#32
it should be rock solid psi and should not drop as from everything ive been told...fuel pump is here im debating to change it right now or wait till tomorrow...earlier on my way home from work i ripped on it a bunch to really pay attention to the wideband and honestly i dont think there is any problem with the car and that my wideband might be off...i dont feel a hesitation and think it was in my head from seeing the gauge lean out..
if i lug it down and hit it the a/f is in the 13's until about 3500 rpm, then right straight to 15's and even 16's ive seen, then it will drop back at 5000 and up to around 14.0-14.1 up to redline but pulls the whole time normally...
Im gonna change the pump cause i have it but idk...and really if my gauge is reading correct and working properly that seems pretty lean in the mid range that shouldnt be happening it would seem to me..
i tested the gauge and it tested out right though a week ago or so with brake cleaner in a rag and the gauge went and stayed full rich...has anyone ever tested a sensor for a wideband and have it test out then still truly be wrong?
if i lug it down and hit it the a/f is in the 13's until about 3500 rpm, then right straight to 15's and even 16's ive seen, then it will drop back at 5000 and up to around 14.0-14.1 up to redline but pulls the whole time normally...
Im gonna change the pump cause i have it but idk...and really if my gauge is reading correct and working properly that seems pretty lean in the mid range that shouldnt be happening it would seem to me..
i tested the gauge and it tested out right though a week ago or so with brake cleaner in a rag and the gauge went and stayed full rich...has anyone ever tested a sensor for a wideband and have it test out then still truly be wrong?
Last edited by tylerxfire; 07-23-2010 at 05:03 PM.
07-23-2010, 04:54 PM
#33
i only have a one wideband on my driver side..After i change the pump if the gauge still says what it says now i am gonna go get on the local dyno for a few pulls with a/f reading to get a second reading from another gauge besides mine to rule that out and rule out if my gauge is truly working correctly..
07-24-2010, 08:52 AM
#35
New Member
iTrader: (8)
Join Date: Jan 2007
Location: terre haute, IN; STL, MO
Posts: 6,457
Likes: 0
Received 7 Likes
on
6 Posts
unmetered air should affect the car throughout the rpm range, not just wot. You would experience at least a small change in idle. Might not be huge things with low rpm and low load but unmetered air will cause that to change.
also, if it's truely going to 16:1 during wot you would notice a huge loss in performance. Hell, when i was setting up my vac map on my car just putting around if it bounced to high 15's at low load my car would fall on it's face so i would imagine the impact at high rpm to be a huge hit in performance.
also, if it's truely going to 16:1 during wot you would notice a huge loss in performance. Hell, when i was setting up my vac map on my car just putting around if it bounced to high 15's at low load my car would fall on it's face so i would imagine the impact at high rpm to be a huge hit in performance.
07-24-2010, 10:00 AM
#36
unmetered air should affect the car throughout the rpm range, not just wot. You would experience at least a small change in idle. Might not be huge things with low rpm and low load but unmetered air will cause that to change.
also, if it's truely going to 16:1 during wot you would notice a huge loss in performance. Hell, when i was setting up my vac map on my car just putting around if it bounced to high 15's at low load my car would fall on it's face so i would imagine the impact at high rpm to be a huge hit in performance.
also, if it's truely going to 16:1 during wot you would notice a huge loss in performance. Hell, when i was setting up my vac map on my car just putting around if it bounced to high 15's at low load my car would fall on it's face so i would imagine the impact at high rpm to be a huge hit in performance.
Yeah i have no problem with idle or anything, just leaning out at wot so it most likely is not the maf or any sort of leak...i idle and cruise right at 14.7-14.8 and have no stumbles
It is hard for me to determine if it is down on power, i dropped about 200 horse from removing the vortech kit so its kind of hard to tell for me on how much its down on power if any, but it does feel it..I mean it feels slow but it would probably feel slow anyway to me even if it is right..
I am changing the pump when i get home from work tonight to see how that works out, ill update after
07-24-2010, 10:05 AM
#37
i will say though it felt fine and not down on power or anything when the vortech kit was on and i noticed the gauge leaning out..it was going from 11's where it should have been and into high 13's after 3500 rpm but i never held it to see what would happen as i didnt wanna pop it..
has to be a fuel problem
has to be a fuel problem
Last edited by tylerxfire; 07-24-2010 at 10:08 AM.
07-24-2010, 10:28 AM
#38
There was another thread about a similar odd leaning out at one point in the rev range and his ended up being a fuel system item that was just slightly bound up. If you think it is fuel related start at the fuel pump and work your way forward checking to see if anything looks to be malfunctioning.
07-24-2010, 11:35 AM
#39
i get home at about 7pm. so thats when i will swap the pumps...ive basically looked thru everything and there are no kinks or leaks of any kind in the fuel system...If its not the pump then what else could cause a drop in pressure? the fuel dampener? it doesnt seem that would fail it is a pretty basic part with not much to it