droping o2 voltage bad pump or running out of injector

[TSIfreek]

On a third gear pull my 02 voltage starts at .88 and drops to .76 by 7400. The thing is my EGTs are not going anywere near 1600F maybe 1500F My base fuel pressure is at 40.
Im on the stock 450s and unhacked mass with boost at 13 or 14 psi. Engine seams to hesatate sometimes up top like it wants to hit fuel cut but sometimes its a clean pull to 7500. I know I am maxing out my injectors but at 13 or 14 psi and a base of 40 fuel pressure with a HP rewired 255 it sould be fine? Thing to is my egts are not bad at all with the drop in o2 voltage?? I also replaced the fuel filter last year. Thanks guys

I have been doing some searching and I think I may have found my problem. I didnt put a gasket between the turbo and the 02 housing, and possibly sucking air in causing the 02 sensor to think its lean. I am going to try to put a gasket in and see what happens.

 

[dsm-onster]

On a third gear pull my 02 voltage starts at .88 and drops to .76 by 7400. The thing is my EGTs are not going anywere near 1600F maybe 1500F My base fuel pressure is at 40.
Im on the stock 450s and unhacked mass with boost at 13 or 14 psi. Engine seams to hesatate sometimes up top like it wants to hit fuel cut but sometimes its a clean pull to 7500. I know I am maxing out my injectors but at 13 or 14 psi and a base of 40 fuel pressure with a HP rewired 255 it sould be fine? Thing to is my egts are not bad at all with the drop in o2 voltage?? I also replaced the fuel filter last year. Thanks guys

It sure seams like it... I would say that you may be overrunning your 1g mas but you'd hit fuel cut before that.

Don't you have a logger? how are you reading your O2s? can't you see your injector duty cycles? If you're over 90% IDC, then I would certainly say for sure that you're running out of injector.

A weak, dieing Walbro 255 HP would have more than enough to handle flow that would max out your 450s at 15 psi. I don't think it's your pump. Besides, how old is it? I've never heard of walbros failing.

Make sure you don't have any injector o-ring leaks or leaks at the fuel rail where you've installed your AFPR or the crush washers where you put in your new fuel filter.

I have been doing some searching and I think I may have found my problem. I didnt put a gasket between the turbo and the 02 housing, and possibly sucking air in causing the 02 sensor to think its lean. I am going to try to put a gasket in and see what happens.

That's a possibility.

 

[TSIfreek]

Not sure if the stock FF has crush washers I thought both lines seal like a brake bleader would seal? All of my AFPR have AN parts that seal together. Will repace the FF also tomarrow I will see if there are any washers there but I dont remenber any.
The fuel pump is 2 years old and yea I also dought thats the problem. It hasnt gotten any louder since the day I installed it.
I do have a logger but I cant log IDC I need new software but I know the injectors are over 100%.

 

[truwarrior]

Still having problems with that? If it was the gasket, I'm not sure why it would chugalug up top. Maybe you just have a bad injector? I still have my stock 450 injectors if you want to try those for a day. Can try measureing the resistance of your current ones?

 

[TSIfreek]

I intalled the 02 to turbo gasket (and I could see were it was leaking from and injesting air from not using on) causing it to run rich up top. And installed a new mitsu 02 sensor. been driving it for 2 days now and pulls clean all the way to 7500. Yhaaaa!!!
By not using a gasket between the turbo and 02 housing it was injesting outside air into it and hitting the 02 sensor causing it to think it was real lean. Its lean anyhow with the 450s I didnt think it could be any leaner or add anymore fuel since the injectors are maxed as is and the 90 high fuel trim was maxed at 118 ??
So if it was real rich wouldnt the high fuel trim be lower than 100indicating adding fuel??

 

[truwarrior]

Fuel trims above 100 ie 101,102, 103, it's adding fuel because the car is running lean. If you had a AFC and gave it more fuel the trims should dip from 103 to 100ish.

Fuel trims below 100 ie 99, 98, it's taking fuel out because the car is running rich

I still don't get why your car is hesatateing I don't think it's the gasket especially if you WOT. Sound more like bad gapped plugs, boost leak or something.

Post a log.

Example #1: from team3s.com

Bob has a 3000GT VR-4 at BPU, boost controller (set at 14 psi), air intake, and cat-back.
Bob starts off with low and high settings at 0% across the board.
Bob lets the car idle in his driveway to set up his low throttle 1000rpm point:
Low fuel trim is at 107%
Bob adds 5% more fuel at 1000rpm low setting.
O2s fluctuate and even off and he ends up with a low fuel trim of 98%
He subtracts 1% from the 1000 mark
O2s fluctuate and he ends up at 101%
Good enough, now his 1000rpm low setting is 4%

Example #2:

Jim has a Stealth TT at BPU plus 450cc injectors.
Before turning the car on for the first time he sets the low and high settings to 20 and 25 respectively.
Starts the car up for the first time, and nothing explodes (yea!)
Gets in and starts logging.
Sets his low throttle levels fine, good gas mileage no knock etc.
Starts to tune his high throttle settings:
Floors it from 2000rpm in third gear and hold it to 7000rpm.
From 2000 rpm to 4000 there is a steady increase in timing, at 4000 timing takes a dip then levels off and finally starts increasing again at 6000rpm.
In this situation, richen up the 4000rpm setting but don't touch anything else yet. Work it like you would a book, from left to right, because what happens sooner affects what happens later.
Next run timing is steady all the way to 5000 rpm when it levels off all the way to 7000.
Once again richen the 5000 rpm setting a bit.
Next run there is a steady increase in timing from 2000-7000.
Now comes the power addition stage:
Take your 2000 and 3000 rpm setting and lower them 3%
Make a run, if no "knock" (retarded timing) decreases more, if knock is present then richen it up a little. Then repeat for the rest of your rpm settings.

 

[TSIfreek]

I did some pulls late last night and it still hesitates up top. My 02 voltage now is a constant .88 and my high FT went down to 113. My EGTs are at 1500. It does it when its cold out under 25*. It pulls clean to 7500 from first to second and second to third but problems happen around 6500 in third.
It really does feel like a boost leak or and ignition problem but if was an ignition problem I would have it in other gears as well as third at WOT but third puts the most pressure on the engine and ignition. Could be the coil as well as it is 15 years old.
I will start off with the boost leak and im sure I will find something there.

 

[spyderturbo007]

Didn't you say that you are pretty certain that you are running over 100% IDC? If that is the case, you have most likely found your problem.

Do yourself a favor and pick up a logger

www.pocketlogger.com