i doubt there is anything wrong with the MAP. it seldom goes bad, and yes - its very expensive.

 

Bad mileage like that is attributable to a spent CAT. Low power, bad MPGs, rough idle etc. Replace that CAT- especially with that many miles on it- if it's the OEM one that is.

 

For a quick test, you can unscrew the front o2 sensor and see if it runs any better.

 

I hope there's nothing wrong with the MAP. I just remember there was a thread on here not long ago about how everyone was replacing their MAP sensors and how much better their trucks ran.

And yea, its the stock cat. My dad doesn't want to me to test the cat via unscrewing the o2, because he says "it will make it so obnoxiously loud, you won't be able to get any good results." I'm probably going to do it anyway when I replace the o2 sensor though lol. Because even with the plenum fixed, it still feels kinda sluggish.

 

i don't remember it that way. i remember it that they wasted $100 and it ran the same.

 

It will be loud, but your only doing it for a quick test. And as far as the MAP sensor goes, I was referring to that thread also as far as mpg's go. It doesn't have to be bad for it not to work to it's full potential.

 

You put an M1 intake on. Your low end is gone, unless you run at least a 2400rpm stall with a cam to match, or stroke the motor.

More air isn't the answer at low RPMs, air velocity is. The M1 lowers velocity because it's designed to flow more air at high RPMs. You can't put race parts on a DD and expect it to increase DD performance.

There are always tradeoffs.

A truck that wins the 60' traps because it's a torque monster may not win the race at the end of the 1/4 mile to the truck that opens up in the higher RPM band.


Have you ever messed with the throttle plate set screw on the TB? If you did, then you probably need to reset the IAC counts, or minimum idle spec.

 

The reason I put the M1 on is that my plenum gasket was shot, and the stroked 360 block I bought came with an M1, so I figured instead of paying for the Hughes, I'll just buy some gaskets and throw my M1 on my 318 for now.

Anywho, my dad did jack with the throttle plate set screw last night. How might I go about resetting the IAC counts?

 

The Hughes intake doesn't make any more low end torque than the M1 in any test I've seen.

FWIW mileage actually got slightly better after the M1 swap.

 

When I siad Hughes, I meant the plenum fix now the FI Intake. NO WAY Im paying that much lol.

And yea, I heard multiple people talking about higher MPGs with the M1.