MAP sensor faulty???
MAP sensor faulty???
HI,
I've got a code 32 and a code 34 on a LG4 qjet, I've cleaned my EGR valve and checked every connection, vacuum was checked as well for leaks and bad connections. The car is running very rich and I get a poor milage (150 orso) Today I checked the voltage coming from my MAP sensor and found out that in Park (idle) the voltage was about 0.07 V and when using the throttle it stays a while on 0.07 V and the shortly jumps to 1.27 V and then back. Is this my voltmeter that can't measure the signals returning from the MAP or is it a faulty MAP. It seems when I'm slowing down from 60 mls to 20 mls/H if the car misfires, but at idle it's ok. (timing is 6 deg at idle (700 - 800 rpm (no tach in car so not sure how much exactly)
Any help would be more than welcome...
Not many firebirds in holland I can borrow parts from.
greetings
marald
I've got a code 32 and a code 34 on a LG4 qjet, I've cleaned my EGR valve and checked every connection, vacuum was checked as well for leaks and bad connections. The car is running very rich and I get a poor milage (150 orso) Today I checked the voltage coming from my MAP sensor and found out that in Park (idle) the voltage was about 0.07 V and when using the throttle it stays a while on 0.07 V and the shortly jumps to 1.27 V and then back. Is this my voltmeter that can't measure the signals returning from the MAP or is it a faulty MAP. It seems when I'm slowing down from 60 mls to 20 mls/H if the car misfires, but at idle it's ok. (timing is 6 deg at idle (700 - 800 rpm (no tach in car so not sure how much exactly)
Any help would be more than welcome...
Not many firebirds in holland I can borrow parts from.
greetings
marald
Supreme Member

Joined: Feb 2000
Posts: 1,416
Likes: 0
From: Johnstown, Ohio
Car: 84 Z28
Engine: 355 (fastburn heads, LT4 HOT cam)
Transmission: 700R4
Axle/Gears: 9-bolt, 3.27
Well, I don't think I've ever replaced a MAP sensor, but I'm sure it's possible! Did you make sure the wiring is good to it?
Most all GM's used this same MAP sensor for a long time, so you can try one from a non thirdgen.
------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!
Awaiting results from all 8 ASE tests.
Starting to look like the Kicker poster child!
Most all GM's used this same MAP sensor for a long time, so you can try one from a non thirdgen.
------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!
Awaiting results from all 8 ASE tests.
Starting to look like the Kicker poster child!
Not sure if a LG4 has an oxygen sensor or not, but if it does, try replacing that also. A bad oxygen sensor will definitely cause it to run rich and get crummy gas mileage. If you have one on yours, change it and see what happens.
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."
Thanx for the info, and yes I do have an oxygen sensor but I thought it came in action after your car has warmed up, so it doesn't really do anything while the car isn't warmed up yet.
Today I had lots of troubles keeping the car idling right (10 deg Celsius outside temp) and driving it was even more impossible,
only on WOT it wouldn't die on me but then again why use WOT on a cold engine, so I unplugged the MAP sensor while idling, the idle immidiately smoothed out and the SES light came on, but the car drove fine since then. The only thing I had was when cruising at 60 to 70 mls/Hour the car was kind of shaking (maybe to advanced timing???) but it is a lot better than trying to gas out the neighbourhood while pulling away from the car park. 
Can it hurt to leave my MAP unplugged till I get a new one??? (6 days orso for ordering)
greetings marald
Today I had lots of troubles keeping the car idling right (10 deg Celsius outside temp) and driving it was even more impossible,
only on WOT it wouldn't die on me but then again why use WOT on a cold engine, so I unplugged the MAP sensor while idling, the idle immidiately smoothed out and the SES light came on, but the car drove fine since then. The only thing I had was when cruising at 60 to 70 mls/Hour the car was kind of shaking (maybe to advanced timing???) but it is a lot better than trying to gas out the neighbourhood while pulling away from the car park. 
Can it hurt to leave my MAP unplugged till I get a new one??? (6 days orso for ordering)
greetings marald
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