I'm just curious as to how the gen 6 dfi calculates fuel requirements? Does it just go off of MAP / O2 sensor values along with tps? I'm having a problem running rich across the board, but all my sensors check out fine ( except for the O2 which I haven't checked ). The car used to run fine, but the plugs are all pitch black now and the car misses and jsut runs like crap. Does the DFI also have open and closed loop? Even under wot I'm pig rich, so if in fact it has both I should be able to rule out the O2 sensor given that. I appreciate the help.

 

The MAP, IAT, CTS, TPS, and RPMs all come into play in the fuel calcs for a typical SD system. If its blowing smoke and is rich across the board, the CTS and fuel pressure would be items to look at. If it was a high MAP issue, at WOT it would probably still be ok.

Bad misfires from ignition problems or lean issues can also turn the plugs black, but it wont be a heavy soot like running way rich, just a charcoal grey color.

 

I have a brand new cts anyways, so I will try that tomorrow. As far as the fpr ... I tried applying vacuum to it with a vacuum pump to see what it does, but it wouldn't hold any at all. I would assume if it won't hold vacuum, then it also won't open when the engine is pulling vacuum on it? Is there another way to test it with the car not currently running? I have the regulator off the car .... but it seems like that may be my problem.

 

It may be that the FPR diaphram is bad, which will cause it to not hold vacuum (while testing), and allow fuel to be pulled through it while the engine is running.

With the regulator off the car, apply vacuum to the port. Then check if air is being pulled through the regulator from the fuel side. If so, it is bad.

RBob.