06blackGTO

iTrader: (20)

Im just curious, I went and got a whole new dynotune from a person/company since I needed it since the new topend. Anyways he tuned it na, then we turned on the nitrous. When we hit the 150 shot, he said all was well for the 1st. few seconds, then the a/f went to 13 so he shut it down right away.
And that was that. He said I needed a bigger fuel pump. I have a walbro 255 in the tank and it was enough last yr. for 540/551. When it went lean this time it got up to 448/565 right before he shut it down. But it never went lean when he tuned na and Im at 461rwhp. Shouldn't he have added fuel to the tune and maybe have tried it on the bottle?
He never attempted to adj. the fuel in the tune. Im just trying to figure out how it went lean so fast, when it was allright last yr. at much more hp.

2TR

You tune a WET kit using the fuel/nitrous jets in the kit AFTER tuning NA. The only thing you actually adjust in the NA tune is removal of timing in the PCM.

Why not just add a larger fuel jet to obtain the desired A/F on nitrous? When it doesn't respond to larger jet its clear your pump can't handle the demand.

What was the A/F on the NA tune prior to nitrous?

I'm betting your fuel pump can't handle the NA + Nitrous fuel needs. Hence the larger pump statement. That is IF tuner is telling you the truth.

06blackGTO

iTrader: (20)

Sorry should have mentioned this. It is a wet kit. Okay thanks for clearing that up for me.

Unaffliated Racing

iTrader: (15)

running lean doesnt hurt anything...... too much timing does.....

tpcaz

Yes too much timing on the spray is not good. But sorry, running lean while spraying IS NOT desireable and NOT a good thing. Good way to melt a piston or get a really mean Nitrous backfire. I had a fuel solenoid malfunction when stomping on it last year and the backfire tried to take the intake off the engine. It actually stretched the intake bolts enough that I had an intake leak afterwards. Blew the airlid loose and had singe/burnt fuel rsidue in the TB. Before anyone can determine if you're getting enough fuel or not is by putting a fuel gauge in the system and seeing exactly what it reads before and after spraying during WOT runs. I have a 150 wet shot system and a stock fuel pump. It normally runs at 60psi and at WOT settles in at 55psi. It's the same with or without spraying.

If you went lean during your run while you were spraying, you could have a bad solenoid, or it or the jet could be plugged. If the car runs OK while NA, I doubt the fuel and timing tables are screwed up or the problem.

06blackGTO

iTrader: (20)

Before anyone can determine if you're getting enough fuel or not is by putting a fuel gauge in the system and seeing exactly what it reads before and after spraying during WOT runs. I have a 150 wet shot system and a stock fuel pump. It normally runs at 60psi and at WOT settles in at 55psi. It's the same with or without spraying.

If you went lean during your run while you were spraying, you could have a bad solenoid, or it or the jet could be plugged. If the car runs OK while NA, I doubt the fuel and timing tables are screwed up or the problem.[/QUOTE]

I believe the a/f at wot when na was 12.8.
I do have a autometer elec. fp gauge in the car, but the damn sending unit is bad. sometimes when I start it, it will set at 20 psi. another time 100psi. I will def. get a new sending unit and put it in and see what it reads.
I will test the solenoids, by pulling off the fuel line off the plate and see if it squirts fuel when activated. and of course I will keep the nitrous closed.
The whole nitrous kit was new. Only used on my car and only 6 bottles ran thru it. The car runs great while na. It pulls like a beast. I pulled the fuel jet and it's not clogged. Im leaning towards picking up a aeromotive 340 in a few weeks and dropping it in the tank, fixing the sending unit, and then hitting the tuner up to try out the nitrous again.

Higgs Boson

iTrader: (3)

You're wasting your money.

I have a 408 that put down 530 rwhp NA on a Walbro and 42lb green tops at 65% DC.

On a wet 200 shot it put down 730 rw/ft lbs.....And I had to lean the fuel jet way out from recommended.

01ssreda4

iTrader: (96)

Could be a failing Walbro.

06blackGTO

iTrader: (20)

It's only 1 yr. old, but yes it could be. Im going to order a new fp sending unit and see what's going on with it.

tpcaz

I'm surprised the tuner didn't hook up a fuel pressure gauge in the first place. Two different shops I have taken my car for dyno runs installed a fuel pressure gauge along with a A/F meter. Since I use HPTuners a lot, I decided to install a DynoTune fuel pressure gauge and a FAST Dual Wideband. Once the NA is dialed in, the A/F is sitting around 12.2 @WOT. On the spray, it will run real rich like around 10.5-11.0. I too will have to adjust my fuel jets this year to get it to lean out just a touch. Too rich is not a good thing either.

Anyway, when had my problem, I took all the filters out of the solenoids and blew them out, then I blew out the fuel and nitrous lines and manually activated the system without the car running to test the electrical. This is when I found out if I tapped the solenoids while activating the system, I could get it to fail. It was intermittent and why it was so hard to find.

Definitely check out everything you can first before buying parts you may not need. Also, as someone else previously stated, make sure you have the correct jets installed for the shot you are hitting. Hope you find the issue.

SSpdDmon

iTrader: (10)

Yeah - bottom line (as mentioned above) - you or your tuner needs to hook up a guage to monitor fuel pressure. I'd even argue you should have one in the car permanently for such a setup. In your instance, it's just as important to monitor fuel pressure under spray as it is to monitor oil pressure.

If fuel pressure is good, it'll point you to the nitrous components. If fuel pressure is bad, you either need to check the connection to the pump, replace the fuel filter, or replace the pump itself.....or possibly the regulator is failing....could be that too.

06blackGTO

iTrader: (20)

I have a autometer fp gauge in the car. the fp sending unit started acting up, I have a new sending unit on the way, and Im saving up to get a standalone fuel system for the nitrous, so I can wipe out any fuel issues, then it's back on the dyno. Thanks for the help guys.

edcmat-l1

iTrader: (10)

That's overkill at your power level.

06blackGTO

iTrader: (20)

Really? Because from everyone im hearing from a walbro255 can't handle 610rwhp. I was told that I either need to mount a fpr on the rail, or a return style fuel system, or a standalone, and the standalone seems much easier to do. I think the fpr on the gto is in the tank. I have never seen a aftermarket fpr for the gto. So that's why I was leaning towards the standalone. Thanks for all the help guys, I really appreciate the info.

edcmat-l1

iTrader: (10)

I responded in your thread over on the GTO forum. Once you have an operational FP gauge, you can determine if there's a real problem, or if it's just a lean spike from the solenoid opening.

ALL returnless fuel systems have the FPR in the tank, or use a return fuel filter, like the Y bodies (vettes)

For your power level, you should not need a stand alone fuel system. It's not going to hurt you, it's just overkill. Fix whatever is wrong with your fuel system (if there is something wrong), and it will run just fine.

tommygjunior

I honestly think you need to just up the fuel jet on the wet kit and watch your gauge. A walbro 255 should handle that power fine. We had a trans am 2 years ago on a single walbro 255 that made 612/642 tq on a wet NOS kit and had plenty of fuel supply. However the first time on the dyno the car went lean. Upped the fuel jet 3 and all was fine.

06blackGTO

iTrader: (20)

I will try that also.

JonCR96Z

iTrader: (33)

How do you know that 13:1 is lean?

06blackGTO

iTrader: (20)

13.1 is lean. Lean enough to burn a piston is it not?
I have been told that the idea a/f on the bottle is 11.5-11.8
Atleast that is what my tuners have told me before.

JonCR96Z

iTrader: (33)

Ideal AFR on the bottle is whatever the engine wants on the bottle. If that's 14:1 then that's what it is.

You ever go in the nitrous section on here?