fast951

FQS #3 & #7 are the same for fuel mods. Keep it on #7 for now...

Indycam

"Can you run these cars without the 0/2 sensor????"
Yes . But you want one .

"well the sensor is brand new. maybe I wired it wrong but I don't think I did. "
I have read that it is a bad thing to splice the O2 wires .
That the wires are hard to connect .

mjshira

I got my sensor off ebay and it is a 993 part number. I assumed it would be fine to use. I am going to get an actual 964 part number o/2 sensor.

In the meantime if anyone could tell me how much vac it takes to make the fuel pressure regulator work I'd appreciate it. However I suspect that it is working fine because when I disconnected the o/2 sensor the car was smoking due to unspent fuel.

I think and I hope that what has been happening is that the DME has been pulling fuel or changing timing in due to faulty readings from the o/2 sensor. This is becoming my working theory. Now I need to prove it with testing.

Indycam

The wide band O2 sensor you have been using , where are you putting the sensor ?
Are you before or after the cat ?

mjshira

I don't have a cat (shhhh!) I have B&B exhaust with a built in port for the sensor.

John I will leave the setting as it is. Thank you for posting.

Indycam

With or without heat exchangers ?

mjshira

with heat, come on man, I am an idiot but not crazy! ;-) in this weather you have to have heat! they don't work great for heat but enough to keep the cabin warm.

Indycam

"With"
To bad , with makes it hard to do a heat test on each exhaust .

I never meant to say you were an idiot .
I really hope you didn't think I said any such thing about you .

mjshira

since I had to splice the 993 sensor that is where my focus is now. It was a three wire sensor if memory serves me well here and the old one was not. I've located a 964 specific o/2 sensor and will install it tomorrow. Then I will have eliminated that variable. I will also be checking fuel pressure and vac suction to make sure these are within spec.

Indycam

"Will install it tomorrow"
I'll be waiting for the update .
What time will you be posting the results ?

look up the thread ,
'90 C4 power loss , but still idles

mjshira

reviewed that thread, similar symptoms but not totally the same, for example my car will drive but not as it should which is leading me to think that the readings being sent by my current o/2 sensor are causing the DME to modify timing and or fuel resulting in the lean condition.

Indycam

I didn't mean to say it was same same .
That car is now running without an O2 sensor
and is maybe better for it because the wires between the O2 sensor and the DME seam to be the problem .

I also think a three wire O2 sensor in a two wire car is probably not the hot set up .
IIRC the 3rd wire is a heater .

I've got to go to a class to be an election clerk now , talk with you later .

mjshira

ok, thanks Indycam, I very much appreciate your comments and support. I think we 'may' have found the issue. That said I won't hold out too much hope until I've proven it by testing.

fast951

If your car is running abnormally under WOT, then the problem cannot be the O2 sensor. Under WOT, the DME operates in open loop and ignores the O2 input.

MitchB

Not to Hi jack, but how well does the MAF kit work with the larger injectors? Many have said the stockers were at max around 300 HP (Est 260 RWHP..?).