code 34 (MAF)

ruberpoliceman · #1 12-10-2005, 12:23 PM

My ECM keeps putting out this code, where is the Mass Air Flow sensor?

ruberpoliceman · #2 12-10-2005, 12:24 PM

oh yeah- 305 V8 5.0 vin H 86 caprice

CD Smalley · #3 12-10-2005, 04:46 PM

MAF sense the amount of air coming into an engine, a fuel injected engine that is... Your VIN H engine would not have one.

FRom the 85 FSM that I have it mentions a code 34 for a VAC sensor. From what I read its output is exactly opposite that of the MAP. But in another section it references 34 for both the VAC and MAP sensor.

I can find no picture of where the VAC sensor would be in my manual either.

How about a MAP sensor. Does your car have one of those???

ruberpoliceman · #4 12-10-2005, 05:43 PM

honestly i couldnt tell u, you kinda lost me through all of that a little. But yeah i have a diagram of all the vacuum hoses and it shows were the the vac sensor is -(my fault about the MAF i forgott i was reading a site for fuel injected engines) But yea i have the spot were it would be and pretty well located it i believe, i hooked up the necessary hoses from what the diagram shows but still getting the code. I dont know whats wrong, the whole damn engine is not working right as far as the ECM and HEI sytems go. It missfires after i have changed almost everything possible in it except for the control module and the coil in the cap, i have changed the rotor, plugs, plug wires, Cap, and pickup coil. After all that it still manages to stumble during acceleration and while holding a steady speed even. i think im going to rework the carb and check out the distributor again and go from there, and if that doesnt work then the first person to bring $1000 before it rots can take it away.

Oh and yea where is the map sensor located. thanks

capriceforever · #5 12-10-2005, 05:48 PM

According to my 1000 page shop manual, my 1988 caprice (which mechanically bares little resemblance to every other caprice made), the computer inputs a 'differential vacuum' reading, which is the difference between the BARO sensor and MAP sensor reading. So basically the difference between outside air pressure accounting for altitude (BARO) and engine manifold vacuum (MAP).

I suspect this isn't working right on my 1988 caprice as I have a hesitation that gets worse with higher altitude.

Problem: I can't find the either the BARO or MAP sensor on this car. The shop manual doesn't say bugger all about where the sensors are. All the diagrams are just electrical schematics.

So hope you guys figure out where the heck it is. Can't replace it till I find out what it looks like and where it is.

ruberpoliceman · #6 12-10-2005, 06:12 PM

hey CD Smalley i thought i saw that name somewhere before. Your on the yahoo 77-90 B body group, im up there as just my name Lucas. Nice seeing u again.

CD Smalley · #7 12-10-2005, 06:31 PM

Thats me. I started the list several years ago when GMF went down.

Guys, your MAP sensors should be mounted on the firewall. There should be a 3 wire connector going to it and a vacuum line. If that vacuum like is broke or disconnected that will contribute to your driveability issues and your codes.

ruberpoliceman · #8 12-10-2005, 06:50 PM

alrighty then. Let u know if anything works out, if i can even find it. later...

silicon212 · #9 12-10-2005, 07:23 PM

The MAP sensor on those cars is mounted on the passenger side inner fender, at the top in the center.

It's the rectangular looking thing with a vacuum line attaching the bottom and a 3-wire WP connector.

ruberpoliceman · #10 12-11-2005, 08:07 AM

Ok, i was gonna say that all i remember seeing was the little box on the fender and nothing on the firewall but i guess u beat me to it. i realy dont remember any vaccum line coming or going to that, i know i heard a clicking sound coming from it before but i havent realy checked into it since, i guess ill go do that now.

ruberpoliceman · #11 12-11-2005, 08:16 AM

ok i found the MAP sensor and the place where the hose goes and guess what, no hose. Now would anybody know what hose goes here cause my little diagram doesnt show one for it. thanks

CD Smalley · #12 12-11-2005, 09:28 AM

It should run from the MAP sensor to the base of the carb someplace. Probably near the front so that it gets the draw of vacuum thru the primaries.

ruberpoliceman · #13 12-11-2005, 10:11 AM

yea i hooked it up there (up front) but from my diagram that hose goes to the vacuum sensor, could i just put a T their or would that cause a malfunction? Well i guess trail and error would solve that but anyways.

Right now it wants to bog itself down when im accelerating, i belive this is due to improper carb adjustment. Im pretty sure its getting to much fuel because its puffin blue smoke. It only bogs down when i put the petal to the metal or try to get a quick start but other than that it moves on along pretty fine. what does this sound like to u guys.

CD Smalley · #14 12-11-2005, 01:22 PM

It should be a dedicated line to the MAP sensor. You don't want anything else pulling vacuum from what it is reading.

ruberpoliceman · #15 12-11-2005, 04:50 PM

ok i think i can rig something to work here. thanks for the help on that. So far as the carb mixture, i just flipped the lid for the air cleaner over and tightend it back down so it can breath easier so that should solve my bogging down problem for a while, and yeah it still boggs a little but not enough for me to pull the carb off and apart. thanks again guys u never fail me.

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