I am having problems with my V6 and the ECM is giving me 3 codes. 33, 42, &
43. The 33 is MAP sensor. Is there a way to check to see if this is working
right other than buying a replacement MAP Sensor?..... Code 42 & 43 I have
had a problem with on and off in the past. I get these codes often when the
single wire going to the knock sensor falls off. It's a problem I have had for a
while and have been to lazy to fix permantely, but tonight the car stranded me
aways from home and it acting like the timing is off or the its not getting any
fuel. i have checked the timing 6 different times over the course of 4 hours.
Every time I try to start the car the engine will rev for about 3 to 4 seconds
just fine then go to hell. I have to floor it just to keep the car running, and
even at that its running like ****. I am thinking my problem is the MAP sensor,
but not sure how the car runs when this goes bad along with my other known
problems.

Basically any help would be great, and is there a way to tes tthe MAP
sensor?......

 

What is your car??

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Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

 

92 V6 RS

 

Assuming yours is similar to those on V-8 equipped models: To check the MAP, turn your ignition key to the "ON" (not start) position after you ground the diagnostic terminal (under the driver's side dash, use a paper clip or pick up a special key for it at autozone). Check the MAP sensor by separating the weatherpack connector and using three jumper wires. Take your voltage reading between the one in the center (signal wire) of the three wire connector and the leftmost wire (ground, the one closest to the vacuum hose connection). The third wire is a five-volt reference. Apply 10" Hg of vacuum to the sensor with a vacuum pump and the sensor voltage output should be around 1.2-1.3 volts. If the voltage change to 1.2 is slow, the sensor could be defective (it should respond to the vacuum almost instantly). Make sure that little vacuum hose to the sensor doesn't have a hole in it, I fixed one with electrical tape once upon a time. Hope this helps.

 

Frobozz, you have a knock sensor in that 3.1? No f-body 2.8 got a knock sensor... where did GM stick it?


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

lol....
1. My car does have a knock sensor
2. Why bring up the fact that a 2.8 never had a knock sensor when we are talking about a 3.1L and not an 86 2.8L? Yes, yes the blocks are the same with a few subtle differences here and there, and just for your information the next time. The knock sensor on my car is located on the block just aft (back) of the starter.

 

You shouldn't have a knock sensor and v6 testing goes:

MAFS- can be tested using a tachometer on the signal wire (since they are frequency mafs [mica film]) The range is 33Hz at idle to no more than 160Hz at WOT. MAFs going bad on these cars usually cause stalling when coming to a quick stop (low minimum air adjustment symptom too) and setting the code

MAPs can be tested by using a voltmeter on the signal wire. You should have more than .5v at idle up to 5v at WOT. Check the gray wire (5v ref) to make sure there's 5v there. Check your vac hose.


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'88 Camaro RS 2.8L
'88 Formula 350 (Too many mods to list...)

[This message has been edited by JoelOl75 (edited February 28, 2001).]

 

AND why should my car not have a knock sensor?.....

 

2.8L's dont have a knock sensor. 3.1L's do.

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West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Why did they put them on sixes? Detonation never seemed to be a prob with them.

My 2.8 doesn't have one so i ASSumed....



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'88 Camaro RS 2.8L
'88 Formula 350 (Too many mods to list...)