low vacuum?!?!?!
low vacuum?!?!?! hello, i just installed my cam and i had a timing problem which was fixed when i put in the lt4 km...but for some reason now i am pulling DTC code 33..which is MAP sensor circuit or low vacuum...i am hardly getting any vacuum out of my throttle body...is this normal after installing the gm847 cam or is it because i need a tune?!?!?!?
thank you
thank you
TECH Senior Member
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Joined: Oct 2006
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From: Decatur, TN (N-W of Athens)
I'm no cam person, but my understanding is that bigger cams = less vacuum. At least at idle. And who knows, the MAP could've just taken a random crap and needs replacing. Mine gave that code too but it was due to a vacuum leak elsewhere. So you may want to check that.
That code is normal with large cams, gm847 is fairly large.
Just get it scanned to make sure the reading is what you should expect from that cam (i.e. you don't have a leak somewhere) and then you can tune that code out.
Just get it scanned to make sure the reading is what you should expect from that cam (i.e. you don't have a leak somewhere) and then you can tune that code out.
