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#1
09-28-2006, 12:42 PM
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MAP sensor-high #'s
What in the world would cause a reading of 9.7 on the MAP, when the truck is sitting at idle, warmed up? I was able to check with a scanner. I have no codes coming up, but the truck just idles horribly. The longer it runs, the worse it gets. After long rides, it seems like it almost wants to stall, but hasn't yet.
What's been done? plugs&wires-ACDelco cap&rotor air filter fuel filter fuel pump cleaned MAF new MAP last year-(threw the code for it) tranny rebuilt last year double checked new cap& rotor,air filter,MAF Still can't figure out what I'm missing. complete readings from scanner are at old post: Actron Live Data-translation? http://www.automotiveforums.com/vbul...d.php?t=585965
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98 Blazer LS-2WD 4.3 vortec-W vin 
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#3
09-30-2006, 04:06 PM
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Re: MAP sensor-high #'s
9.7 what? PSIA? Inches Hg? Volts? Depending upon your scanning software, the display may be different.
If it idles at 9.7 PSIA, that would be about 10.2" Hg vacuum, which would be a little low. If it's idling at 9.7" Hg, that would be even worse. However, if it's idling at -9.7 PSIG, that would be 19" Hg, which would be perfect. Which is it?
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#4
09-30-2006, 07:02 PM
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Re: MAP sensor-high #'s
poor mixture (either way), retarded timing, bad cam, valves, air leak, low compression, all can cause low actual readings.
A questions, what is the reading when decelerating, cold idle, and when held in neutral at 3000-4000 rpm?
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#6
10-05-2006, 05:29 PM
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Re: MAP sensor-high #'s
at cold idle, still 9.7, holding at between 3000-4000 rpm's it goes to 8.6, on deceleration it drops to 4.6 and back to 9.7
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98 Blazer LS-2WD 4.3 vortec-W vin
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#9
10-06-2006, 12:05 PM
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Re: MAP sensor-high #'s
I did a vacuum test and it shows in the "normal" range, with no flucuations. Any suggestions are very appreciated.
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98 Blazer LS-2WD 4.3 vortec-W vin
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#10
10-06-2006, 12:12 PM
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Re: MAP sensor-high #'s
Also checked PCV, it's good..this beast just idles horribly, sounds like it's gonna stall anytime it's at a stoplight. The longer it's running, the worse it gets. Somebody? ANYBODY?
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98 Blazer LS-2WD 4.3 vortec-W vin
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#11
10-06-2006, 12:12 PM
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Re: MAP sensor-high #'s
I seem to get mixed up when converting from traditional vac readings to MAP, but your reading of 9.7 is "better" than mine at 10.9 and I agree with your vac gage as it sure looks normal to me.
Have you checked the egr valve and checked for vaccumm leaks ?
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#12
10-06-2006, 12:26 PM
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Re: MAP sensor-high #'s
I'm using an Actron scanner, the one with the live data option. I honestly have no idea what any of the numbers mean. We just bought to check for codes.No, I haven't checked the EGR yet. Actually, I worried about busting the thing. I'm going off the Chilton's manual, and it says take it to the dealer. Says nothing on how exactly to clean it. It's a 98. I checked the vacuum off the intake. Where else should I be checking it?
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98 Blazer LS-2WD 4.3 vortec-W vin
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