So my car was hesitating when i give it WOT at about 3k+ RPMs. It would hesitate so bad sometimes it feels like i'm riding a horse. I would floor it, but it would feel like the car is jerking back and fourth like i'm gassing, letting it go, gassing letting it go, in first gear (like an amature stick shift driver).

So I datalogged it with Sean Church at church automotive and we found out that it wasn't getting enough fuel on the top end. I have 440cc injectors and walboro fuel pump both bought brand new and used fora bout 4000 miles. He thinks the fuel pump might be failing or defective. So i bought a new fuel pump but have not installed it.

What could be the issue? BTW, walboro warranty sucks, they would not replace it, and in order to test the pump to see if it's defective, it would cost 40 dollars for the test and i would have to pay for shipping there and back. which comes out to be just about a cost of another fuel pump. Anyone else have this experience? I have revup kit with osiris tune. and regular 3.12 pulley that comes with the kit. Anyone? please help, we riched out the fuel during lower RPMs, but it still leans out on the higher RPMs. I have no idea what it could be.

 

If your shop thinks it is the fuel pump, and you have another one yet to be installed, why not just install the new one and see if that takes care of it?

I'm assuming he checked the tune too, correct?

 

What ECU do you have. Please list all mods. THanks

 

i guess you dont have a fuel pressure gauge, or bigger injectors to swap in?

i always thought 440s were too small to begin with

 

My car was leaning out with the 440cc's when I had it tuned at Shawn's, but I did have the 2.87 pulley on though...he also recommended changing the walbro or the injectors; I upgraded to 650cc's and that did the trick...that's probably overkill for the 3.12....

however, I'm assuming you didn't have this problem when you first got tuned, so something may have gone bad, and Shawn's theory may be the issue...

BTW, did you do the phunk DIY with your fuel basket when you installed your Walbro?

 

Are you using the stock Vortech/Nissan Fuel Sysytem? Returnless?
Are you using an Vortech FMU in your Fuel System? If so what ratio? 8/1, 6/1

 

Hmm I guess people were too lazy to read lol. I have the stock fuel system (non returnless). I am not using any of the vortech fuel parts. I have 440cc rc injectors and walboro intank fuel pump (not the inline).

I snipped off the little notch part like stated in the DIY, is that what you're talking about harris?

Also something has to have gone bad because I've had the charger and the tune for about 4000 miles now with no problems, never leaned out before with these injectors, we tuned it, dynoed it, there was no problem with the injectors leaning out. I am on the 3.12 pulley.

 

Have you check the injectors? If you need new injectors in future, contact hal@IP. Ask him if they still have a free walbro deal.

 

Where in your original post, does it say that you have a stock fuel system?

I was asking questions to help me Help You!!!!!!!
I'm not Lazy, as I've taken the time to post.

Guess you really don't want my help............

 

Lol in the original post I put i had 440cc and walboro fuel pump, i didn't mention returnless because i don't have it. Eitherway, thanks for your help. I didn't mean to sound like i was arguing.

Well the problem still exists. Any ideas? Fuel pump going in very soon when I get some money and this heat becomes less than 100 degrees outside. Don't want to get heatstroke trying to put in a fuel pump.

 

Well, there 3 main things in Phunk's DIY were 1)snip off notch so Walbro will fit 2) drill little plastic part (swirljet) a little bigger 3)drill regulator a little bigger....did you do all that? Not that it's the issue for sure; I've heard some people say that some of the drilling is not necessary, but I did it anyway...

Either way, something probably has gone bad in your fuel path....Walbro is a good place to start...maybe injectors after that...

 

bump, i'm having a similar issue

when i punch the gas in 3rd gear or above, my AFR will quickly drop from low 14s (cruising) to high 10s/low 11s (WOT & max engine load). however, my AFR quickly returns to 14s as RPMs increase & the car continues to build boost. for example, from 3000-4500 AFR is ~11, from 4500-redline AFR creeps quickly back up to 14. has anyone else run into this?

relevant mods: 2005 5AT G coupe, walbro 255 pump & 600cc DW injectors (both installed at technosquare), berk HFCs, technosquare reflash dyno tune. i monitor AFRs via an innovate WB gauge.

my understanding is that the AFR should stay rich (10s/11s) throughout a WOT / high load run. my tuner is out of the country so i don't have anyone else to discuss this with. could the stock ECU be fighting against the reflash? thanks for your help.

 

Your AFR should stay pretty flat at 11.5ish from when you get on boost to redline.

You cant edit anything with that reflash, so you'll have to wait for your tuner to get back.

 

2 weeks of driving in granny mode

 

Strange indeed.
I know the Walbro's aren't the best pumps but should hold up to this "light" duty.

I finished tuning a Vortech kit today with the same setup (Walbro & 440cc Injectors) and its running great. It had a Utec on it but ditched it for the almighty UpRev.

 

hey seb! thanks again for the valve body work

yeah, tadashi at technosquare was able to richen things up under boost the first time this came up, but the car has reverted back. AFRs richen up for the first second of boost then lean back out to the 14s

 

Hi Chris!

Bizzare, how long after does it take for it to revert back to stoich?
Did you go return fuel with fuel pressure regulator? or just upgraded pump\injectors?

 

i'm not sure how long it took to revert back - somewhere between the day i dropped by (11/19) and last friday evening (11/27).

fuel system is just the upgraded pump and injectors - no RFS.

 

UPDATE

I think the issue is being triggered by an SES code that I have gotten intermittently since my original tune - P0172 rich condition. The reflash richened up the mix for FI (as it should), but whenever the code pops up, the ECU overrides the tune & leans me back out to an NA mix.

I tested this tonight by resetting my ECU before heading down to the PCH for a few pulls. Everything went back to the way it should be immediately after the reset - 10s/11s as soon as I hit boost and it stayed that way all the way up to redline. After a brief stop, the rich condition SES code popped up (makes sense given how much I was on the throttle). As soon as I restarted the car I noticed it was running leaner at idle. I did one pull to see if it the mix would stay rich while in boost - it would not. I stopped and did another reset and everything went back to the way it was supposed to be - 10s/11s while in boost.

While imperfect, I think the easiest workaround for me is to install non-foulers so the rich condition SES code no longer pops up. I had been lazy about doing this since my PLX allows me to clear codes plus the car is supposed to run richer anyway. However, I'm going to get on it ASAP now that its clear this code can VERY quickly override the reflash.

 

Sounds like the fuel trim is off. It's looking for a certain A\F and it isn't so that would make sense. I would think Tadashi modified that map along with the main fuel map.