New build running lean

[Darkhorse]

Help! I've just had my 1981 3.3 engine rebuilt and we cant get enough fuel into it so its running lean. The mechanics are stumped so I need some ideas.
Here's what we changed:
964 cams
3.4l pistons and sleeves
long neck intercooler
cold air intake
ported heads

It has a K27 and we are running a 0.8 spring at the moment.
Here's what we have checked:
replaced the fuel pumps
rebuilt the WUR
checked the injectors
apparently the fuel pressures are all ok

What are we missing??????

[dos531]

Which wur are you running? What are your fuel pressures? Youre probably close to the limit for cis.

[Darkhorse]

Just running the standard WUR.
The fuel pressures have been checked and apparently they are what the manual says they should be.

[JFairman]

There's one incredibly easy way to get a lot more fuel from CIS... just unplug the 12 volt bimetallic heater element supply plug on the WUR... takes about 2 seconds to do that The WUR stays in semi cold start control pressure mode then.

Only downside is it richens up the mixture across the range everywhere including idle so it will oscillate at idle and may almost stall after blipping the throttle.
What you could do is install a wire wound potentiometer in the 12 volt supply wire to the plug on the WUR and after experimenting with it you might find a resisitance setting that gives more fuel where you need it and then after adjusting the idle CO screw and warm control pressure you might find something that works well at all speeds and engine loads. The WUR might end up getting around 8 or 10 volts or less then instead of the full 12-13.5 volts it usually gets.

Anyway, it's a thought. I havn't tried installing the potentiometer but I have stopped and unplugged the 12 volt plug on the WUR after the motor was fully warmed up from driving a half hour or longer and after 10-15 minutes control pressure dropped down from 60 psi to 40 psi and my steady cruise AFR went from around 15:1 down to 12:1
I have an onboard control pressure gauge and wide band AFR gauge in the car so I can see them while driving.
Also have a CIS flowtech modified fuel head on the car so I don't need any more fuel but I wanted to try that and it definately worked.

[dos531]

Originally Posted by Darkhorse

Just running the standard WUR.
The fuel pressures have been checked and apparently they are what the manual says they should be.

Here's what you need Adjustable 930 WUR Website
Factory pressures are great for factory horsepower, but you're probably 100+ over that. Gotta get that extra fuel dialed in.

[Ronnie's.930]

Originally Posted by Darkhorse

Just running the standard WUR.
The fuel pressures have been checked and apparently they are what the manual says they should be.

As dos noted, the pressures in the factory manual apply to a stock engine - you have to now alter the pressures to suit the new fuel demands of your highly modified engine (an adjustable WUR being a good way to do that).

[Darkhorse]

How about additional injectors? When do people start adding those?

[911nut]

Originally Posted by Darkhorse

How about additional injectors? When do people start adding those?

You are making this far more complex than needed. I don't believe that you are at the limit of what CIS can provide yet.
Procure a Leask adjustable WUR (mail him your WUR and he will mod it for you). Use an Innovate LM-1 or LM-2 to monitor your afr. Adjust warm and boost control pressures until you are in the box.
I just went through this when I went to a larger turbo and SC cams.
I'm running .2 bar lower on both warm and boost control pressures and my afr's are right back to what they were when my engine was stock.