chevy1963

Ok just installed a fuel pressure gauge and the readings are 38-40 lbs Is this ok? I dyned the car last week and the A/F ratio was around 17. and H/P around 207 Check my sig for my mods.

I'm also hooking up an A/F ratio gauge. I have Jet hot/ hooker LT's with the emmisions hook ups.
My car had 2 O2's before the cats and 2 after the cats. I bought extention for the 2 O2's after the cats and installed them in the LTS. Should I have installed the first set. ? I just left them dis connected under the car. Is this a good thing?

I also just blocked of the the emission on the top of the headers. The air pump is still working but I left the 2 brass pipes open, I didn't block them off.

Can some one help not sure whats wrong.

anaik

The 02s before the cats are the ones that determine your A/F ratio, the ones after just tell the PCM whether the cats are working or not. Your fuel pressure is okay if it is with the vacuum hose connected.

chevy1963

crap thats what I thought, I have those disconnected, would that cause the car to run lean since the PCM isn't getting a reading?

What about my other question? air pump questions?

anaik

The AIR pump you can just unplug. You'll get an SES that will have to be programmed out. Also you'll need 02 sims for the after cat 02s. I'm not sure about the WOT A/F ratio. I thought the PCM didn't use the 02s for WOT, but a different fuel table.

chevy1963

well the emissions are supposed to be programmed out, from pcmforless. What are these shims that your talking about.?

anaik

Sims are used to replace the post cat 02s, but if you have the emissions programmed out, it shouldn't be an issue.

chevy1963

cool thanks for your help.

LWillmann

OBDII cars use 4 o2 sensors. One before the catalytic converter for each bank (side) of the engine. These pre-cat o2 sensors tell the PCM if it's guesses about air-fuel mixture are correct. The post-cat o2 sensors tell the PCM if the cats are working properly.

Typically when people install LT headers, they install an off-road y-pipe (no cats), so they have to use o2 simulators in order to "fool" the PCM to think that the cats are there and functioning as they should be.

They usually also have to install o2 extending wires to make the pre-cat o2 sensor wires long enough to reach the o2 bungs on the headers.

Hope that is explanation enough for you.

chevy1963

Do i need the simulators if the O2's are programmed out?

LWillmann

That question, I cannot answer.

LPEdave

No, you don't. You need one or the other. Even if you did neither, all you'll have is an SES light. The car would still run the same.

Dave