threewaycraps

my 89 RS 2.8 new engine trans ,and just about everything else is new,but i keep getting code33 34 . replced MAF 3 times ,but still get trouble code,not every time i start just sometimes,this is driving me and my wife batty!! any suggestions?

89-28gp

i'd check out your EGR

camarogirl18

iTrader: (2)

threeway...ive had same problems with mine....every year i get new MAF put on it....everyone on here tells me to switch to a "Speed Density Update" kit....so in the spring im switching!!

TomP

Every year, Camarogirl? Where are you buying these MAF's from, a guy on the street corner?!? They shouldn't blow that often; I'm on the same one I bought in '97, for $90, from Strauss Auto.

First off, have either of you two checked for air leaks around the MAF sensor? A leak/cut in the tubing between the sensor and TB will really screw up the sensor.

Second, do any visual inspections? The MAF used on our 85-89 2.8's is a frequency film MAF, unlike the v8's, who got a hot-wire MAF. The frequency film MAF has an orange frequency film (of course) inside it. That orange film vibrates with incoming air- more air, more vibrations = higher frequency (code 33). Less air, less vibrations = lower frequency (code 34).

Visual Inspection #1: Check for air leaks around the MAF.

Visual #2: Pull the MAF and make sure the orange film is completely FLAT- no wrinkles, no creases, no nuthin'. Gotta be FLAT.

Visual #3: Make sure the circuit board isn't cooked

Not So Technical Test #1: With the engine running, and your clothing/hair/jewelry/etc away from the fan belts, wiggle the 3-pin MAF connector. If the car stumbles, or the SES light comes on, your connector is bad- either with corrosion, or a cracked wire. Gotta replace the connector.

Not So Technical Test #2: With the engine running, tap on the MAF housing with a screwdriver, if the engine stumbles, the MAF is bad.

Not so Technical Test #3: (Used for people who don't get a SES light) Car off, unplug MAF, tie the connector up out of the way of the fan belts. Start the engine (it'll stall immediately, but start on the second try) and go for a ride; if the engine improves, the MAF was bad. With the MAF unplugged, the computer uses a default value for the sensor. You two don't need to do this test, since you both get a service engine soon light.

Technical Test, straight from the GM/Helm service manual: Checks all your wires from the MAF to the computer. If you've got a bad wire or MAF relay, you'll always throw codes. I had a bad MAF connector; instead of spending $15 at the auto store for a new one, I pulled the entire MAF harness out of a junkyard car for $10, put it in, and have been fine ever since. Three wires go back to the engine's harness from the MAF harness- a ground, and a signal wire, and a "power on" wire.

The Code 34 chart follows; it's more simple than it looks.

-----------------------------------------------
DIAGNOSTIC CHART FOR CODE 34 (2.8L MPFI ENGINE)
---------------------------typed by Tom P------

First off, they want you to check out the air intake duct for being loose or
damaged.

Since you are getting the code 34, and no other error codes, we can kind of jump into
the middle of the chart:

1. Ignition off. Disconnect the MAF sensor wire. Connect a voltmeter between the
____harness pin "B" (center) and ground.
_______Less than 1 volt? Go down to "1A"
_______Over 4 volts? Go down to "2"

____1A: Disconnect ECM A-B connector. Check circuit 528 (brown/white, on connector
_________"B", terminal #6) for an open or short to ground. If it's not open/shorted,
_________it's faulty ECM connector terminal B6 or a bad ECM. By the way, this is the
_________MAF's "signal" wire.



2. Connect a test light between MAF harness pins "A" & "C".
_______Light on? Go down to "2A"
_______Light off? Go down to "3"

___2A: Faulty MAF sensor connection or sensor. So since you've tried two sensors,
________I'd imagine the connector's at fault. Try checking for corrosion on the
________connector's pins- I had that happen once. Also, try wiggling the connector,
________and seeing if you get a SES light. If I wiggle my current one, I can make
________a code 34 set, and the car almost stalls. I've gotta get another connector
________from a junkyard... Pep Boys sells new ones, but for an outrageous price.
---------update 10/2000: I replaced the connector (actually, the whole MAF harness!)
---------with one from a junkyard car. No more connector problems!



3. Connect a test light between MAF harness pin "A" and ground.
_______Light off? Go down to "4"
_______Light on? Go down to "3A"

___3A: The ground wire for your MAF, which is MAF harness pin "C", is open. Fix
________the problem with the black ground wire, either it's bad or burnt thru or
________it broke at the passenger-side-upper-frame-rail grounding point (a ring
________terminal on a screw).



4. Disconnect MAF relay, ignition "on" (not "start"). Connect a test light (at the
____relay connector) between CKT 840 (brown) and ground, and CKT 39 (black/pink) and
____ground.

____Okay, now, the MAF relay is located between your air filter box & radiator, on the
____radiator support, I believe. It should have one long black connector to the harness,
____NOT two connectors (one black and one gray)- that ones for your flip up headlights.
---------update 7/2001: For Camaros, you guys have a different location for your airbox.
---------But, the MAF relay's in the same spot, at the passenger side of the radiator, on
---------the radiator support. I believe it's the only relay you Camaro guys have down
---------there; just check the relay for the wire colors I mentioned for CKTs 840 & 39.


____The test on CKT 840 checks to see if voltage is getting from your MAF fuse to the
____MAF relay.

____As for CKT 39, that's controlled by your GAGE fuse. (So that's what it does! Cool.)
____It comes on with the car's ignition- that's why you need the ignition "on". When this
____black/pink wire gets power, it flips the MAF relay's magnet ON, which basically switches
____the MAF on- that's how power gets from CKT 840 to the MAF.

_______Only one light? "repair the open circuit".
__________No light on CKT 840? See "4A"
__________No light on CKT 39? See "4B"
_______Both circuits are fine? Go see "5"

___4A: If no light on CKT 840, find the MAF fuse- it's under your hood, screwed down
________to the upper-frame-rail on the passenger side of the car, closest to the
________headlights. You'll see two little black boxes, each with two wires coming out
________of them, screwed down to the upper frame rail by one screw each. One of them
________has a red wire and a BROWN wire coming out of it- that's your MAF fuse holder.
________Pop the top off to see the MAF fuse. (The holder with red & orange wires is for
________your computer and fuel pump.)

________If the fuse looks fine, try replacing it anyway... I've had that happen to me-
________the fuse looks fine but's really shot. Perform test #4 again. Still no light?
________Probe the MAF fuse holder's RED wire with a test light to ground. This checks
________the MAF fuse holder's connection to the positive-junction-block, located on the
________passenger side of your radiator support. If it's bad, follow the red wire to
________the junction block & fix it. Do test #4 again- still no light? Check
________for corrosion on the MAF fuse holder's contacts. You should get a light by now-
________unless your test light's shot!

___4B: If no light on CKT 39, check the GAGE fuse in the fusebox. As I said up in "3A",
________if the fuse looks fine, try replacing it anyway. Do test #4 again. If you've
________got no light, you get to trace CKT 39 thru the firewall, so hopefully you get
________a light on this one. This one would be a bitch to fix. All I could tell ya is
________that the black/pink wire goes to the GAGE fuse, and the GAGE fuse gets turned
________on when your ignition switch gets turned to "on".



5: Connect a test light between circuit 840 and CKT 450 (black ground wire from the
____relay connector).
_______Light off? See "5A"
_______Light on? See "6"

___5A: Fix the bad ground wire (open on CKT 450) from the relay to the chassis.
---------update 10/2000: This is buried! It follows the wiring harness along the
---------passenger side lower frame rail. You'll have to trace it the whole way. It
---------joins with 5 or 6 other ground wires at one point. Then, after that junction,
---------one wire goes to a ring terminal on the rear driver's side head.



6. Check out the condition of the orange/black wire that goes from pin "A" of the MAF
____connector to terminal "E" of the relay. If this wire is fine (not shorted or open),
____then your relay's bad... you could get a junkyard one but I think a new one is only
____$10 or so from GM.

NHRATA01

Note to self: next time go to Pep Boys for $90 2.8 MAF instead of buying AC Delco replacement for $300 from the dealer!

camarogirl18

iTrader: (2)

TOMP......well each time that this has happened to me ive always taken it to the mechanics...i would hope that the would have sense enough to do all this that your telling me to do.. & yes EVERY YEAR i have to have a new put on...each year ive taken it to different mechanics & they all put a new one on but like i said in the spring im switching to this speed density update cuz i truly believe that this MAF sensor is the cause of alot of my problems

devianb

If you had your MAF replaced 3 times and the problem still persisted after each MAF, then I suspect that the problem may not be the MAF. I can't give a technical answer like TomP, but I would check the wires going to it. There may be short in one of the wires causing an error and creating the code. I still have my stock MAF and it works just fine.


That seal has to be tight around the MAF too. Sometimes mechanics forget to tighten all the clamps. You shouldn't have had to have your MAF replaced 3 times.

NHRATA01

Here is just a shot in the dark camarogirl...Do you have a K&N filter in the car, and by any chance do you clean and re-oil it once a year? If the filter is over saturated with oil, some of it will get sucked in and coat the MAF wiring, which will cause it to go bad.

TomP

You have more faith in your mechanics than I do. Having someone replace the MAF every year is asinine. If your thirdgen.org nickname is true (an 18 year old girl with a camaro), has it occurred to you that you're being taken advantage of?

At the least, find another mechanic. Or keep paying $$, whichever you'd like. The MAF's are delicate, but not that delicate!

devianb

delecate. How delicate how you talking about. I dropped mine on the concrete countless times, not to mention getting debris on the sensors and it still works like new.

shuffle

Edited to save space...

This information is great. While I attempt to test all those things you mention here, let me give you my similar scenario.

Just swapped engines in my '85 2.8l V6 Camaro and am having a code 34. I have a 13 as well.

The engine runs fine. I start it, and the check engine light does not come on for about ten minutes. This time varies slightly but it never comes on right from the get go.

No change in performance when the light comes on. It seems to run fine right from the time it starts to when I turn it off.

If I simply fire it up and leave it on the drive way the light doesn't come on. Its only when driven.

Does that lead you to believe it is something specific?

Thanks for all the great info everyone. It makes narrowing the problem down for us non-mechanic types a lot easier with your support...

PhantomTPI

[QUOTE]No change in performance when the light comes on. It seems to run fine right from the time it starts to when I turn it off. If I simply fire it up and leave it on the drive way the light doesn't come on. Its only when driven.[\QUOTE] I've recently been getting code 33(mods in sig)....its a brand new MAFS, and I have all new vacumn lines, EGR was replaced a year or so ago...and it kinds does what Shuffle wrote...going @ highway speeds and the light comes on(you can feel the deadness in the pedal before it comes on), and then it appears....i let my foot off the gas at highway speeds when the RPS's are close to 2k, and then it starts to bog down....then go back up again...bog down...go back up again....you can hear/feel it.....the tach goes down to 1k, then shoots back up to under 2k....then back down, then back up...if i keep my foot on the gas, i dont feel that, but you can tell the perfomance isnt there. Lately, its been doing this every single time i drive the car. I'm very confused, and i need some help. I just had the idle air control valve/switch or whatever that is in the intake replaced for the 2nd time in a year(first one was defective). Can anyone help??? I'm stumped...

TomP

Have you performed the chart I posted above?

PhantomTPI

I printed that out, but I havent gotten to it yet b/c I'm constantly busy with work and school. Tomorrow, I need the car to make a trip to NJ, so I wont have time to work on it then. Maybe sunday. I have to go to work soon, so I cant even do this now. I realize this is the V6 forum, but I posted here after I found some info(very little) in a search of "code 33"....I've posted in the V8 forum in the past but I got nothing specific as to what teh probelm could be. Its very annoying to say the least. Just as a quick rundown before I leave for the night, these are the things I've changed in the last year to year and a half besides whats in my sig:

Computer(twice)
Prom(to the updated 305 TPI prom)
MAFS
MAFS Power Relay
MAFS Burnoff Relay
EGR
TPS
IAC(twice)
Coolant Temp Sensor
02 Sensor(4 times)
Oil Sender/Switch
Stoplight Switch
Fuel Filter
PCV Valve(including hose)
Vacumn Lines

I need to get this car just running right...ran great after the cam install, now I just need it to stop turning on that yellow light and making the car act up. Its my daily car, and I must rely on it. Thanks for the help.

F-Bodeee

do what i did......take the service engine soon light bulb out!!!! Viola!! NO MORE SES light!!!!

PhantomTPI

LMAO....yea, if that would also solve the driveability issues, I'd do it in a heartbeat.