Rido everyone,

i need opinions, heres the deal, I have been stuffin around with different rear housings for my new 3040. anyway, when i had the rediculously laggy 1.06 rear on it i made 330 HP @ 7100 no worries, curve was beautiful! I changed it to a .82 rear and took it back to the dyno yesterday and i made 30HP less but the curve was very rough. for starters i shouldnt have lost much power at all and 2nd why the hell did the power start going downhill at 5700. was very strange. Tuner had no idea what was goin on.

Only thing that was changed was a fuel pump. went to a bosch 044. we checked the plugs and found no. 1 was lean no. 2 was richer no.3 was black and no.4 was bout same as no. 2. Very strange.

So does thins point to a flow issue from the turbo or from the fuel system... what do you guys rekon...

Other info is that the fuel pump sounds like its sucking air and the pitch of the pump seems to change as the revs do. (perhaps a voltage drop) (was never a prob with last pump though)

Gareth

voltage drop, fuel pressure difference, just some ideas

Definately thinking pump related, but if the air fuel ratio is coming out at 11.5 then how should that be limiting top end? it should show it going very very lean. The plugs did show different colours on each cylinder so unless the rail is nearly drying out and each cylinder is running different??? what you guys rekon?

Gareth

The answer is in you plugs.

If you are getting a different combustion in each cylinder it does not mater what air fuel ratio you are getting at the back of the exhaust.

If one cylinder is running lean, then two are running rich and one is running supper rich. Then none of the cylinders are making power.

Things to check:
• Fuel injectors are clean.
• Fuel rail is of adequate size.
• Fuel pump is holding pressure.
• Fuel reg is holding pressure.
• Engine management is not playing up. (Wolf’s are notorious for problems).
• Inlet manifold design. (Equal pressure and equal flow to each cylinder). The larger the volume of air traveling through the inlet manifold the more critical the design is to get equal flow. (Maybe try a standard inlet manifold)

The pitch changing on the fuel pump sounds like a voltage problem.
Do check that it is not sucking air, but if it was sucking air one would think there would be a pretty strong smell of fuel near the pump or its pick up.
Turn you head lights on and off, and blinkers on and off and listen if the pump changes pitch. Or do it properly with a multi meter.

Cheers,

Maybe change your fuel rail just as a test and definately get those injectors retested. Change all fuel filers while your at it and run thicker and new wires to your pump. You should find the best ground possible for your pump which is easily done by checking with a multimeter like juggernaut said (after i whopped his ass with my pimp cain ). Make sure you fuel pressure stays constant under load also. If these are done and you still have problems, its the wolf. Give em a call and tell em youve tried everything (even olive oil) and that its basically the wolf....

Dam, I have a wolf too...but my spark plugs are fine

Good luck and cruise soon

LOL, Duna nuna nuna nuna Sebman.
Don't you know who I am??? I'm the juggernaut B17ch!!! Hehe.

Gareth,
All so just found out your fuel pump's pick up is from a really small outlet on the surge tank.
Get this changed so it is at least the same size or larger than the feed side on the pump. You maybe choking the fuel pump.

Cheers

Hi guys,

Sorry for the delayed reply, ive been in sydney!

Ok, Juggernaut, Guessin Matty told you about the pump suply, he seemed to think that was an issue too. Now in the past ive made more more power with a completely stable tune and with the same turbo and everything else the same. It comes down to 2 things that ive changed since last it was at the dyno. Fuel pump and rear housing. The smaller rear housing should still draw the same lines and make the same lookin power curve on the dyno but just trail off a little earlier.

Should what ive written above be the case??

ill check the feed and get a bigger one done for the surge tank. Other than that... im outta ideas...

Gareth