That's like saying the black notes play louder than the white notes?



Anyone else remember Peter Cook & Dudley Moore's Piano Teacher sketch?

 

Thanks for the great information. I do not think that anyone in Arkansas is doing any EFI conversions on the 930. Most of our local dyno guys do either American iron or sport compacts. It appears that I need to find a tuner that is reasonably near, use the ECU and other components that he is familiar with and put the car in the trailer and take it to the tuner.
Once again, thanks for sharing your knowledge and experience.

 

Protomotive is in Arkansas. Google them and you'll find their site. I think he converts Motronics stuff. I've not heard good or bad about them.

 

Yes I also found one bank runs ricker than the other (but can't remember which side). It's because of fuel pressure drop across the fuel rail (lower pressure on the far side. My injectors were trimmed via ECU to compensate.

 

"It's because of fuel pressure drop across the fuel rail (lower pressure on the far side."

I have considered this as a possible reason, however, in theory, the pressure in the rail should be in equilibrium though. Whenever I've done the 930 conversion, I have used the factory 3.2 fuel rails, lines, etc. which feed both rails at the same time.

 

And here comes the need for sequential injection also...Batch injection, especially with BIG injectors make nasty pulsation in fuel rail.
But obviously you use it in order to correct the fuel in cylinders independently.

 

So I'm not loosing my mind? My plugs are white on the left bank and very dark brown on the right. I've added 20% more fuel to the left and taken away 5% from the right and the plugs don't look any better. I figured it was a ground problem to the left bank injectors or cam timing. Any idea what else it could be?

 

Yeah Geoffrey, what else can it be if not unequal fuel pressure? It's puzzling and I should then check my plugs to see if I still have this problem

My tuner tells me that he's seen this phenomenon in all 930/965s that he's tuned and that's why he made the trim adjustments.

 

How are you determining plug color between L/R bank ,after driving or after power runs and or pulls ?

 

More than likely it is the pancake intake manifold that was used on the 930/965. There's a flow imbalance in the runners.

 

I have seen it with ITBs, 930/965, 3.2 Carrera, factory 3.8RSR, and 964 plastic manifolds.

 

Are there solutions?

Add a fuel damper(s)?

Change from series to parallel fuel rails?

 

The 3.2 Carrera factory fuel rails include a damper and are fed in parallel.

 

Would it have something to do with camshaft timing ?

 

If the camshaft timing is off between the banks, the AFRs will differ, yes. I see this often in the 993 and 993tt engines where there is a friction nut rather than the locating pin cam gear setup is used. I can tell you that my engines have the cams in correctly and the same bank-to-bank because I use a degree wheel and piston stop to setup the camshafts, not lift at TDC method using the Z1 mark.