We had our drivers side bank running lean originally because of this problem. As soon as we split them, the problem went away. This was on the initial tune at 12 psi.

It's the right way to run it like this anyway and doesn't really cost much more. (maybe $100.00 between lines, fittings and a Y adapter)

This is where I would start, for sure if his fuel pump is a 255 or larger and it in good working order.

EDIT: Also, at the 12 PSI it was only at lower loads that it went lean. At higher loads they got closer together.

 

what do you call "lean"? his is 18:1. If you are talking about a .5 bank difference or something then that is nothing in vac.

the other issue is the car drives perfectly fine and it keeps saying 18:1. A car that is truely 18:1 will not drive fine which is why i'm very skeptical that the car is actually lean and it's just a lean reading on the sensor.

 

Ah, yes, would probably help for me to start reading the thread from the beginning.

For us we noticed a 1 to 1.5 difference. 18-1 it would definately be spitting and sputtering.

I don't think a crack in the exhaust manifold would cause that much of a lean condition or if it did, I am sure it would be loud enough to hear clearly that the exhaust has a leak. We only notice about a .3 to .7 with some pretty major cracks.

I have to assume the tuner put his wideband in Bank 1 to verify the OP's wideband on bank 1 right?

I would change the fuel system so it splits before the rails then check fuel pressure on each rail individually before going any futher. At least this way if you see both rails have the same amount of pressure then it's wiring (injecor not firing, etc) or something internal since the injectors have already been replaced especially if your not throwing misfire codes.

If you have enough slack, you "could" reverse your fuel setup by swapping the fuel feed to bank 2 and connect bank 1 to the FPR and see what happens.

I just don't see it driving right if it really hit 18:1. I will spit and sputter like crazy at 17:1.

 

ya, they swapped the widebands to double check it wasn't just a wideband issue.

your thoughts are exactly mine, i don't see a true 18:1 a/f reading driving normal....especially not under boost.

 

Well took the car out of the shop today. I got it back to my house and I'm taking it tomorrow to the other shop. I looked at the fuel system and it does T off first befor it feeds the rails. It does not feed only 1 rail first. My father drove the car cause I have a broken leg. He said the car ran great even tho it wasn't under load he said it still ran good.
From what the other shop told me they said there were no signs of bucking or running bad when it hit the lean spot so I can understand why you are saying you don't think it's a true a/f reading. I'm going to leave it to the new shop to dig into it. This is compleatly out of my my league at this point. I don't know enough to start digging into it on my own. I will end up making things worse. I want to thank you binder and everyone else who has tried to help. I hope we get to the bottom of this so maybe this thread will help someone else.

 

I got to thinking, if the wideband at the rear of the car is reading 18:1, it may actually only be 16.5 -17 which "may" not cause bucking under light to no load. Until the exhaust really starts flowing, it won't match the one in the down pipe.

That's good to hear it's split before the rails but is it a "T" or a "Y"?

I hope the other shop can figure it out for you so you can drive it, when your leg is no longer broken.

 

Yea I hear ya. I was in a bad jetski accident. yea really sucks put my heart and soul into this car and i can't enjoy it. As far as Y or T I'm Why whts the difference?

 

Well I am not sure how much of a difference a T adapter would have vs a Y block but I can't image a T would be ideal. A Y block is designed to split or combine fluid effeciently by guiding the transition (picture a "Y"). A T adapter requires, depending on flow direction of course, the fluid hitting a wall before it takes the path of least resistance OR fluid running in to each other then following the path of least resistance.

Since the fuel is under pressure, I am not totally sure how much difference there could be, if any. I was just wondering.

Again, I would start by checking the pressure at each rail first then move forward but I am sure the shop you took it to has more experience than I do and will hopefully get it resolved for you.

Sorry to hear about your accident, be thankful you are alive. Jet Ski accidents happen all the time here in Florida and they usually don't turn out well. I have even been run over by one and I was on dry land, 10 feet or more from the water!

 

OMG, the fuel comes out of the pump at a L shaped. How can it even work???

No that doenst make any difference. Neither does goin in 1 rail at a time. Look at how LS engines are plumbed. in 1 rail cross over to the other side and to the regualtor.

You guys are nit picking on issues that have no effect on fueling....

 

Str8, coming out of the fuel pump in a L is different because it's just changing direction where a "T" splits the fuel. I am not saying it is causing it, I just know it's not ideal especially if one line from the T is longer than the other line off the T. Again, we are not saying this is the issue just that idealy, a Y would be better.

Going in 1 rail at a time vs splitting to two rails DOES make a difference. After every injector fires, a little bit of pressure is lost thus you loose pressure further down the line, after every injector. When running a lot of fuel, the less amount of injectors in a line that the pressurized fuel has to run across, the better, thus splitting to the two rails is better.

We are not nit picking, we are talking about issues that "could" pose a problem either now, or later.

 

Fueling is not your issue here. I ran a single rail feed for two years, and never had any problems regarding lean/rich (I have Haltech logs to prove this with dual widebnds). Many others will say the same.

Leave the fuel stuff alone, and focus on the exhaust leaks. Once those are out of the way, you can start speculating other things.

The pressure regulator is the last thing before your return line, so the rail pressure won't be changing much, if at all.

 

I am not saying "fuel" is his issue although I do think he should check pressure at the end of each rail to make sure there isn't a blockage. It's a simplle test with little labor involved that can help diagnose further.

While an exaust leak could cause this, it seems like for the amount of leaness that it is reading, it would be a very large leak. Very little "air" comes in on a little leak because the pressure coming from the exhaust is greater than atmospheric pressure. I good example of this is watch people that drill a hole for a EGT sensor while the car is running. Enough pressure is inside to blow out the metal shavings as the drilling is happening.

I would however like to see what the O2 sensor reads at the down pipe on that bank in the event there is a leak further down the line before the exit of the tail pipe where it is currently being measured.

At any rate, this is a very confusing issue that I am sure the shop will resolve it. I am merely suggesting that fuel pressure should be checked at the other end of each rail.

While many run their fuel system in a loop and most cars from factory are designed this way. This does not mean it's the best way for higher fuel demands. The more injectors on that rail, the more of a pressure drop you will see from one end to the other when the car is running and injectors are firing.

Again, I am not saying this is his issue, especially since it won't make that drastic of a difference in your AFR bank to bank. I am merely stating setting it up this way is best.

 

the widebands weren't placed in the tail pipe. They were placed after the headers in the downpipes. standard locations on greddy and gtm systems.

 

I am aware of the locations where widebands are placed.

He has 1 wideband (from what I read) and it's on the downpipe. The wideband used to see the "lean" reading was the wideband the tuner was using (whether it be a handheld or connected to the dyno) that was palced at the tail pipe.

I am saying it would be good to move "his" wideband to the other downpipe. This would allow him to get an accurate reading while in these low load conditions where a tail piped placed sensor can't. This would also determine if there in an exhast leak, if it is before or after the downpipe.

 

the tuner covered it. Both widebands have been checked in the same location with the same results. They moved his to the other bank and used the dyno's wideband on both banks. All times they had the same results on the same bank.

 

So they moved his wideband to the downpipe on the bank reading lean and it jumped to 18:1?

Sorry, either I missed that or you personally know him. Either way, that means if there is a leak in the exhaust, it's before the downpipe.

I am interested to see what this issue is. Seems to have everyone stumped.

 

yes, tuner swapped the widebands because it was an in car wideband on one downpipe and dyno on the other. They were swapped and the same bank was still lean. Tuner changed the wideband to a new sensor (on the dyno) and outcome was the same.

 

Have you made sure you dont have the fuel injector harness swapped between bank 1 and 2?

 

No I have not. When I reinstalled it I placed it the wat it seemed to fit properly. I'm just asking what this would cause if it were backwards?



And yes widebands were swaped and it was the same reading. Along with Binder a lot of people are pointing fingers at exhaust leak. If it is and it is getting tested for it in the next few days then it is a leak that can not be heard.
I want to thank everyone for helping out!!! Like I said tho this is more then I am able to deal with. I don't know enough at this point. I droped the car off today and I will be going over everything tomorrow with him. I will keep my fingers crossed and keep reading and taking suggesstions from everyone.. Thanks again guys......

 

It can make your AFRs really wonky since injection events wont be timed properly and you will be getting a lot of fuel build up on the back of valves, etc.... Just something else to check.