I installed a new 355 in my formula, and ever since its been running rich, and runs like crap at idle, but once I get going, it's fine. The cam is the only mod I made, and its a COMPCAMs 212/212 duration and .440/.440 lift. As you can see, its not really that big, but I think its messing with the MAP sensor, what do you think?

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1990 Pontiac Formula 350
Rebuilt 355,
COMPCAMS 212/212 .440/.440 cam
Flowmasters soon...

 

This should be moved to the TPI forum.

Yes, it might be too much for the map sensor. What kind of vacuum are you getting at idle? Do you have any vacuum leaks?

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.23 @ 107.62 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

I think i was getting like 14 hg at idle, which is very low. I have searched for vacuum leaks, but cannot find any that I haven't fixed.

P.S.-Just answer me this, and I'll move this ? to the TPI forum.

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1990 Pontiac Formula 350
Rebuilt 355,
COMPCAMS 212/212 .440/.440 cam
Flowmasters soon...

 

You're right, 14" is pretty low. I am getting 16-17" with my LT4 HOT cam, 218/228. It looks like you have a vacuum leak somewhere. Did you install the cam advanced, straight up, or retarded?

 

I think the machine shop put it in straight up.

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1990 Pontiac Formula 350
Rebuilt 355
COMPCAMS 212/212 .440/.440 cam
Flowmasters 80 series.

 

Moving to TPI forum