Am I out of injector?

[NHRA Super Gas]

After going to the track recently and being a little bummed, I had to remove the volt booster. Now the car revs freely up past 110mph where before it used to fall on its face. Problem is I'm getting some really low numbers on the scanmaster, and high numbers in the knock department. The numbers below are with the absolute minimum boost I can run, 20lbs. Alky knob about position 5. FP set 43 line off just like Eric recommends. I currently have Sunoco 100 octane unleaded in the car, so I can't imagine having any more fuel stability than I have now.

No fuel added to TT chip: 726mv/19.2knock both at 111mph, top 3rd gear
Add 7% fuel: 699mv/2.6 knock 104mph

I believe if I add fuel, it will add DC up to a point. Correct me if I'm wrong but if I add 10% fuel and am going 6000 RPM in 3rd gear, it won't matter if I've added or not it will be maxed.

Is it just a problem with my reporting methods (scanmaster)? If I went to direct scan/wideband or even the dyno, would I be seeing different results?

Sooo...what do you guys think? Do I need to look at 60's? Want something that runs perfect around town (have that today) but can still click off a low 11 or so. Worst case I optimize this combo for the 1/8 mile since any street scuffle would be over quickly.

 

[mikestertwo]

Looking at your combo I would say you are out of injector. Go to 60's, you won't regret it. Very good street manners with a TT chip.

 

[GNVYUS 1]

Post your DC %, but don't stay in it too long as you are getting way to much knock.

There is no way at 20lbs you are detonating due to octane or inlet temps with 100 octane AND alky.

It definitely sounds like you have a fuel volume issue. I no longer trust the MV readings on these cars as end all say all for tuning but your numbers seem to be consistently low. You can try adding more alky by turning up the knob and see what happens. But if 20psi on a 60 turbo is showing 90% + on the DC%, see ya later to those 42lb injectors.

 

[Chuck Leeper]

21st century tools...

Suggest a scanner with faster update rate, some 60's, and a wideband. Continuing as you are, will get a "membership" in the DOTCC...

 

[NHRA Super Gas]

Thanks all...I would agree on paper I should be able to run faster than I am with these injectors. One thing I have to check is to make sure I'm 255 MAF at WOT (stock MAF).

I do have scanmaster fast update.

 

[MIB]

I maxed a 42.5's out with just a PT-51 years ago.

 

[DavzGN]

Is the fuel pump keeping the Fuel pressure at 63PSI that 20lbs boost requires? If not you need to check out your fuel pump. Also how old is your fuel filter. And I assume your pump is hotwired.

HTH
David
87GN

 

[NHRA Super Gas]

Is the fuel pump keeping the Fuel pressure at 63PSI that 20lbs boost requires? If not you need to check out your fuel pump. Also how old is your fuel filter. And I assume your pump is hotwired.

HTH
David
87GN

It's a Walbro 307 or 340, going from memory would need to check receipts. Yes on hotwire. Not sure on WOT fp...what's the best way to check that? Some sort of temporary gauge? I will check the fuel filter, It could be something very obvious like that.

 

[turbocody]

replace fuel filter, and put a temporary gauge on the fuel rail and tape to winshield. go test......1psi boost=1psi increase over base fp. so if your running 43psi line off on fuel psi, and 20psi boost then you should see 63psi on the gauge under full throttle and full boost. if it's good then your fuel pump is NOT the issue. then looks at the inj. go test this stuff before jumping to conclusions and buying bigger inj,etc. btw, 42.5's have been well over 111mph safely. more like 120-122

 

[NHRA Super Gas]

This is great stuff....thanks. Is there a fuel filter that is better than OEM?

Thanks,

 

[NHRA Super Gas]

Fp

Also correction, it's a red's xp plus fuel pump.

 

[turbocody]

i read your first post again, i thought you meant you took it to the track and ran 111mph. sorry bout that.