Delner

Hello Guys,

i got the trouble Codes from my Pontiac Firebird 88´2.8l MFI.

he tell me
Code 34: Low Voltage (high vacuum) at mass air flow sensor (or MAP sensor)
MAF Sensor Low

now i looked up for the complete vacuum system and its ok, no loss of vacuum and the wires are at the right position.
i checked up the air intake system and it is clean and tightly

so what can it be? is the MAF defect? ore are there other variants?

and i got trouble with my radiator, he doesn´t run only when i hanging on a wire in the pole 5 and 6 from tghe DLC Connector, whats wrong with my radiator?

Thanks for Helping

Delner

Thus i testes it now with tech 1,

in the idle mode the air flow is more than 4 g/s it switch at 5 to 6 g/s
the Engine speed is arround 900-100 RPM and when i test it over 5 minutes nothing happen. When i press the gas Pedal it runs higher at 2000 RPM it have arround 11 g/s



Typical causes for this code include:
Faulty air ducting to or from MAF sensor
Faulty ECM-to-MAF connections
Poor routing of MAF harness (i.e. near coil packs)
Maladjusted TPS Sensor
Defective MAF Sensor
Defective ECM



i testes the Plug at the MAF Sensor with a volt meter and it tells me arround 9 to 11 Volts normal it is 5 Volts its to much high but dont know why.

I testes all vacuum wires, they have no defect
I testet the TPS Sensor and the Values are ok

so what can i do?

Delner

No one have an idea?

i changed now
MAF Burn off Relay
MAF Power Relay
Fuel Pump Relay
TPS Sensor


i checked all wires, they are all ok
i cleaned all contacts

i testet to get off the MAF Sensor and he dont give me Code 36 only and alltimes Code 34 not more.... when i start it is for 3 seconds off than it tells me the Code 34

Pls guys need help dont know more...

Vacuum System is ok
He dont get wrong Air
the Air intake is tightly
the Vacuum wire´s are all on the right place

what i haven´t seen?

Gumby

Is it running bad?

ASE doc

When this code is set, the grams per second airflow data means nothing. Its just the system's default value being displayed. Do a search though the tech articles on this forum for the diagnostic flow chart for code 34.

A quick test is this: with the key on use a test light to check for battery voltage at pin A of the MAF connector, use a dvom to check for 4-6 volts at pin B, Use a test light to battery+ to test for good ground at pin C, the test light should be bright. (look for a bad ground at pin C as this is a common problem) If these tests are okay, check the connector pins for good connection. If okay, replace MAF sensor.

Delner

i checked up it has 9 to 11 volts at Pin B, so what the hell is wrong there?

i found in the search on Forum a diagnostic about the MAF sensor they tell when he tell me Code 34 i have to Disconnect the MAF Sensor, when he give me after a Code 34 and Code 36 the MAF Sensor is defect, but he tells me no other Code only Code 34.

he dont tell me what he must have, he tells me what he get for information, and the MAF Sensor give me the information that he get 5 - 6 g/s in the idle mode. If i turn the gas pedal on 2000 RPM he tells me that he get 10 - 11 g/s, that are the right values. Thus i see at this diagramm that the MAF Sensor work and he tells me how many Air there is in the Air intakte.... so i think he cant be defect. He regulate the Air...

i changed today the idle control valve because the idle rpm are where on 1000-1200 RPM but he dont come down he allways stay on 1000 to 1200 RPM normal is 700 to 800 RPM...


i hope that it is not the MAF Sensor, because im from Germany and the MAF Sensor is not available here, and a order are be very very expensive.....

Can it be the (sorry i dont know it in English in german it called) Lambdasonde in english Lambda probe?

ASE doc

Did you test with the MAF disconnected? You need to look for a short to power in the MAF signal circuit. Thats the wire that runs to pin B of the MAF connector. Trace it back to the ECM. This is circuit 528 and should go directly to ECM pin B6, with no splices or connectors in between. Look for any repairs to the harness. Someone may have mistakenly spliced the circuit to power.

ASE doc

By "Lambda probe" I assume you mean the O2 sensor. The O2 sensor will not cause code 34. You have the Tech 1. You can use it to test the O2 sensor. Warm the engine. Then run it at 2,500rpm for 30 seconds while monitoring O2 voltage. O2 voltage should toggle rapidly between .200 and .800. Return engine to idle. O2 voltage should drop off sharply when throttle is released and stay low for a moment. This is decel fuel cutoff. It should then continue toggling between .200 and .800 for several minutes, as long as the sensor stays at 600f.

Delner

Ok i will check up the O2 Sensor,

i was running my car yesterday on street and drived it hot and turn him off and on, than there was no error anymore, but when i drive and after some minutes the Code comes again.

Thus the MAF Sensor is ok.

i think something wrong with vacuum ore any i will check up today again for for leaks ore something.

griemar

Good luck with solving your problem. I'm also having the same issue with my car. No SES light when I start the car, but after a few miles of driving I get a code 34. I've installed a new MAF, a new power relay and have adjusted my TPS. So far no luck. My next step is to also replace all of the vacuum lines and trace the wiring.

Delner

Now the problem has changed,

i start now my engine, there is no ses light on. when i drive some miles it going on. Then i start the engine new and the SES light is no longer on.

Now he give me 2 new Codes
Code 33
Maf Sensor high
Code 13
o2 Sensor Circut


i tried to mess the o2 sensor but it dont work with tech 1.
Alltimes when i start the Test the Engine makes terrible noise
But i got all other datas

Spark Advance:
11° to 12°
Injector Pulse:
2.8 mSec
Fuel Integrator:
128
Block learn:
128
Idle Air Control at 1000 rpm:
6.5 g/s

At 2000 rpm Throth Position:
Opened: 17°
Voltage: 0.5 V

I will try in the Afternoon hang up our Sun Motortester and mess other Datas, than i will check up the compression.
And again i will check the complete air intake system and vacuum system i will test the vacuum sensor.

ore someone have other idea?

ASE doc

It is typical that the SES light will come on only after some driving. The diagnostic system in these older cars was fairly primitive and only turns the SES lamp on when it detects a current problem. The ECM is not seeing a MAF problem when the car is started. It obviously doesnt pick up an issue until the car is driven some. Connect a scanner and watch data while you drive the car. See what MAF data shows as the SES light comes on. Code 13 is O2 sensor or circuit problem. In other words, "Lambda probe". You may have a bad O2 sensor. Watch it on data as the SES light comes on. Look for O2 voltage to go low or high. You can test MAF and O2 sensor both by disconnecting either one. Watch BLM. Is it high or low?

Delner

Thus now i testet, the o2 Sensor is working.

but i found other thinks,
my vadder tells me that he went out:

SENSOR ASM,MAP
Part Number: 213-3205
Product Notes:
[Manifold Absolute Pressure Sensor]; MAP SENSOR

Per Vehicle: 1; Years: 1988-1988


and he found that Sensor, in the garage, i have 2 of this Sensors 1 from a
1988 Firebird 5 Liter
and
one from
1988 Firebird 2.8 Liter

my vadder say´ed to me that it is from the car, but my master tells me that it cant be because he has a MAF, he dont think that the Firebird can have that two thinks MAF and MAP

thus can it be that he have that 2 Parts?

ASE doc

In 88 GM used one or the other, not both. Cars were either mass airflow or speed density. Mass airflow of course uses a MAF sensor. Speed density uses the MAP sensor. Mitchell on Demand shows the 88 Firebird as having mass airflow. However, I have worked on other 87-89 GM vehicles with the 2.8 V6 that were speed density. Does your car have a MAF sensor in the inlet air tube? Be sure of which system it is. Code 34 is either MAF or MAP problem. I quite sur that your car is MAF and has no MAP sensor.

Ive been thinking about why your car would have 9-11 volts at pin B. You almost have to have a short in the MAF sensor harness between the orange/black and brown/white wires. The orn/blk is 12v ignition power to MAF sensor. The brn/wht is MAF signal to ECM. If the two are shorted, you will definitely have code 34.


Your cooling fan is not working because the ECM isnt commanding it on. Thats why you can make it work by jumping pins at the DLC. I suspect that your coolant temp sensor is reading incorrectly.

ASE doc

Is the .5v from the MAF sensor?

Delner

The .5 V are from the Throttle Position Sensor
No i have now 5V on Pin B at Mass AIr Flow Sensor.

Thus there is not both installed?

ASE doc

If you have a mass air flow sensor, you do not have a MAP sensor.

Delner

ok, thus i got now a picture from my engine room, there is a wire but i dont know for what it is.

here is the wire:


Uploaded with ImageShack.us

ASE doc

Single wire weatherpack connector. There are a limited number of these used. O2 sensor, EGR pressure sensor are two that come to mind. What color wire is it on? Does the wire terminate at a sensor or go into the harness?

Delner

i Cant detect the Color its look like black red more black than red

but to the O2 Sensor i got this its a black wire with a green line


Uploaded with ImageShack.us

and my EGR Ventil:

ASE doc

The second picture looks like it could be your fan temp switch. The 2.8 uses a reduntant fan control with the fan being operated by the ECM according to information from the coolant temp sensor. It has a redundant fan temp switch that will turn on the fan at 243F should the ECM fail to turn the fan on for any reason. The wire color is different in Mitchell but the only places where that connector is used is the fan temp switch and the knock sensor. If the knock sensor were unplugged, you would have a trouble code.

Delner

thanks i changed now the wires i found the broken radiator sensor....
the O2 Sensor works now, the car runs now better.

But the Code 34 still in.
my idle RPM is on 1500, i justed the Throttle Body and changed TPS and Idle Valve Control
i changed my Fire Order from 0° to 6°
only when i change my Fire Order to 18° the RPM are falling down to 1000-1100
but 18° is a bit to high....

ASE doc

The high idle may be unmetered air. This could also cause a code 34.

Delner

thus the MAF will be defect?

ASE doc

Not necessarily. You need to do a visual inspection of the engine, paying careful attention for any vacuum leaks. Unmetered air is any air that gets into the cylinders without passing through the MAF sensor. Check your PCV valve and make up air hose very carefully. These are common sources of unmetered air.

96Iroc

Thanks. I'm having similar problems.