17 AFR and 95 injector duty at only 12 psi

InvaderGSX · 06-28-2008, 11:35 PM

Something happened recently and I cannot figure out what is going bad. First off I am datalogging with DSMlink and AEM WBO2. I have FIC 750cc injectors, Walbro 255 and MAFT with blow thru setup using 3" GM MAF. I am breaking in the engine, so I currently run directly off of the Tial 38mm wastegate so it is only about 12 psi running a Bullseye BorgWarner S256. Well running at WOT up to 5K I have no problems. Hitting AFR of 11.1 or so. Once I get to about 5500 and up it shoots to 17 AFR and my duty cycles go to 95% and obviously my car starts to sputter. I have a stroker motor with FP3 cams and I run an Aeromotive FPR. I also have braided stainless line with a high flow fuel filter from the rail to the tank. I have the MAFT zeroed out and just run all the fuel setting on dsmlink. I even put in some 110 octane race gas last night to see if it would make any difference and it didn't. I need to figure this out before I put the boost controller on. Any suggestions? Fuel pump I can toggle on and off with DSMlink so I verified that. The only issue with my pump is I think the sending unit might not be installed good after the fuel pump install because It shows a quarter of a tank when my gas light comes on. So now I put more gas in when it gets to the quarter tank mark. I get pretty bad gas mileage also.

turboglenn · 06-28-2008, 11:47 PM

I had this same issue, thought i had EVERYTHING i needed...stand alone, big fuel pump, big injectors etc..etc.. Turned out that i had to rewire my fuel pump. I had just skipped over that when i went straight to a wally 255 thinking it would supply enough fuel either way, and it did until i started upgrading the FPR and return line on the fuel system, then it did the exact same thing as you're describing.

I've got 5 bucks that says your problem will be solved if you re-wire the pump with some 12 guage wire from the battery and it's own separate relay

There's a great write up on how to do it in the VFAQ page. I used some of it's ways and then wired it up in my own fashion with a relay right there at the pump hangar and used the factory ground wire instead of running a new one to the chassis and it's working fine

InvaderGSX · 06-29-2008, 10:30 AM

Funny thing is I never did the rewire, but was going to do it last night right before I posted this problem, but then I read that a rewire wouldn't effect high injector duties. I'm going to do it anyways, but the weird thing is I datalogged the car a couple of weeks ago and didn't have this issue, so I am thinking something went bad. I'll do the rewire tonight just to get that out of the way. I just don't think this issue would cause a problem only running 12 psi.

JayRolla · 06-29-2008, 10:46 AM

I dont have a rewire and im running enough fuel at 30psi but only on an evo16g. I dont see that s256 pushing enough air at 12psi but looks to be the only reasonable explanation. May be a vacuum leak at the FPR not allowing fuel pressure to rise with boost.

turboglenn · 06-29-2008, 11:03 AM

Quote:

Originally Posted by JayRolla

I dont have a rewire and im running enough fuel at 30psi but only on an evo16g. I dont see that s256 pushing enough air at 12psi but looks to be the only reasonable explanation. May be a vacuum leak at the FPR not allowing fuel pressure to rise with boost.

But are you running an AFPR? Mine was fine on the stock FPR. it wasn't until i upgraded to a aeromotive AFPR, then mine started doing the exact same thing as he's describing.

JayRolla · 06-29-2008, 12:48 PM

Yea im on the stocker. Is it when you raised FP or just upgrading at the same FP.

92awddsm · 06-29-2008, 01:17 PM

Quote:

Originally Posted by InvaderGSX

Something happened recently and I cannot figure out what is going bad. First off I am datalogging with DSMlink and AEM WBO2. I have FIC 750cc injectors, Walbro 255 and MAFT with blow thru setup using 3" GM MAF. I am breaking in the engine, so I currently run directly off of the Tial 38mm wastegate so it is only about 12 psi running a Bullseye BorgWarner S256. Well running at WOT up to 5K I have no problems. Hitting AFR of 11.1 or so. Once I get to about 5500 and up it shoots to 17 AFR and my duty cycles go to 95% and obviously my car starts to sputter. I have a stroker motor with FP3 cams and I run an Aeromotive FPR. I also have braided stainless line with a high flow fuel filter from the rail to the tank. I have the MAFT zeroed out and just run all the fuel setting on dsmlink. I even put in some 110 octane race gas last night to see if it would make any difference and it didn't. I need to figure this out before I put the boost controller on. Any suggestions? Fuel pump I can toggle on and off with DSMlink so I verified that. The only issue with my pump is I think the sending unit might not be installed good after the fuel pump install because It shows a quarter of a tank when my gas light comes on. So now I put more gas in when it gets to the quarter tank mark. I get pretty bad gas mileage also.

More than likely, either the fuel pump install was botched and the o-ring cocked/rolled, or the pressure line to the fpr is unhooked or leaking. Either of these will cause the problems you are seeing. Basically, it is a low fuel pressure problem in boost and higher rpm.

JayRolla · 06-29-2008, 01:49 PM

Quote:

Originally Posted by 92awddsm

More than likely, either the fuel pump install was botched and the o-ring cocked/rolled, or the pressure line to the fpr is unhooked or leaking. Either of these will cause the problems you are seeing. Basically, it is a low fuel pressure problem in boost and higher rpm.

I agree here fully, I dont think the fuel pump is running out just yet at that boost level.

InvaderGSX · 06-29-2008, 02:36 PM

Thanks for the ideas. I'll check out my hose going to the AFPR. I'm gonna have to buy an in car gauge for fuel pressure as I have the typical one that is mounted on the regulator itself which I obviously cannot see while I am in boost.

CanadianTSi · 06-29-2008, 03:15 PM

Quote:

Originally Posted by 92awddsm

or the pressure line to the fpr is unhooked or leaking.

Thats what popped into my head.

InvaderGSX · 06-30-2008, 10:21 AM

Now one thing I just thought about since my last datalog before this problem occurred. I just installed a COP setup and on dsmlink I have misifire detection unchecked. Is it possible that it is a spark issue?

turboglenn · 06-30-2008, 02:38 PM

No, running out of fuel isn't a spark issue, some times it can trick a wideband to read all kindsa funky, but you would feel a mis-fire that bad even if you didnt know much about cars.

JayRolla · 06-30-2008, 02:50 PM

Like Glenn said its not a spark issue. There is only a few things that can cause you issue. Your running out of fuel up top, so its either too small fuel pump or maybe rewire, low fuel pressure(leak on fuel line from improper fuel pump install), or vacuum leak at FPR causing FP not to rise with boost. Make sure these things are all in check.

Car Cannibal · 06-30-2008, 10:22 PM

Voltage at the battery and pump would give you a baseline, then do the hotwire and recheck.

Alternators ok at WOT??

turboglenn · 06-30-2008, 10:34 PM

You get that pump re-wired yet?

InvaderGSX · 07-01-2008, 04:52 PM

It was the fuel pump not seeded good. Funny thing is the fuel pump install was done a long time ago, but the reason why it didn't show up in the logs previously was because it doesn't have that problem if there is a full tank. Only when it was low. Thanks for all the input guys. I am still going to do the rewire to see if I notice difference.

turboglenn · 07-01-2008, 05:21 PM

Glad you got it figured out and you should re-wire like you said since you will most likely be able to lower the duty cycle a little bit more by having more fuel on tap at a more consistant pressure.

92awddsm · 07-01-2008, 06:14 PM

I know it is already done but I would highly suggest replacing the o-ring and cap with a short section of fuel safe hose. It has proven to be more reliable to me and many others.

Getting tired of Walbro

InvaderGSX · 07-01-2008, 10:21 PM

I already have the fuel pump done with the hose section. What was causing the problem was the O ring. It was in there side ways. Got that taken care of and that cured the problem. I am going to the do the rewire. I just wanted to make sure that the O ring was the issue 1st.

InvaderGSX · 07-04-2008, 03:46 PM

OK I did the fuel pump rewire, but I must have something installed wrong because once I put my battery terminal back on without the car on you can here the fuel pump going. I used the faq from RRE and used the VFAQ on the FWD 2G SPyder and they kind of contridicate where what wires goes to what. Anyone know what wire I have to swap to get it to only kick on when I have the car on? Like what do you guys use to have the main power wire from the battery going to? I think I have it going to 87.