Rolling Thunder

As the title says my new to me 86 bird has a bit of an issue with a code 36 trouble code. Ive reset the code several times to check and see if it was an intermittent problem and every time it comes back. I ran through the troubleshooting chart in the factory manual for the car and everything checks out to be fine. Lastly when I run the car for a while and shut if off you can see the sensing wire in the MAF glow for a short period of time after the car is turned off telling me the wireing is fine and the ECM is running though the burn off routien as it should. Everything that I have done in the line of testing indicates to me that the burn off circuit is functioning fine yet I still have the code 36 comming back. According to the manual its time to replace the ECM but is this really where I stand? I guess what im really trying to ask is what conditions does the ECM look for to set a code 36? The manual is great for explaning what conditions set the other codes but it seems like for this one they just say its bad, the comp knows it is, fix it.

Rolling Thunder

No one knows what the ECM actually looks for to set a code 36?

Drumer919

Sorry I cant help but here is what alldata says, sounds like you already have a diagnostic flo w chart but I can email you the alldata one if you think it might help you, just not going to take the time to host it, I also have the wiring diagram I could email you too. Let me know if you want either.

CODE 36 - MAF BURN-OFF CIRCUIT

Circuit Description :

The Mass Air Flow (MAF) sensor measures the amount of air which passes through it. The Electronic Control Module (ECM) uses this information to determine engine load for fuel delivery control.

Due to contaminates in the atmosphere a residue may build up on the MAF sensor sensing wire. To maintain an accurate reading from the sensor, a "burn-off" cycle will occur when the ignition is turned off after the engine had been running a specified amount of time and engine warmed up. The burn-off function is enabled when the ECM grounds CKT 900 which energizes the MAF sensor burn-off relay. With the MAF sensor burn-off relay energized, voltage will be supplied to the MAF sensor terminal "D". Voltage will also be supplied through the normally closed set of contacts in the MAF power relay which will supply 12 volts to terminal "E" of the MAF sensor.

Test Description : Numbers below refer to circled numbers on the diagnostic chart.

1. This test will determine if the burn-off function is operative or if the Code was set due to an intermittent condition.
2. Checks for continuous 12 volts supply to burn-off relay.
3. Grounding CKT 900 should energize the relay and close the contacts.
4. With the burn-off relay energized there should be 12 volts supplied to the MAF sensor on terminal "D & "E" (CKTs 993 and 994).

Diagnostic Aids :

The Code 36 could have been set due to a poor connection at any of the relays or the MAF sensor. Be sure that these connections and terminals are OK. A faulty MAF sensor should not be considered as the cause if Code 36 is set.

Refer to "Intermittents" in Diagnosis By Symptoms - No Trouble Codes Stored.

Rolling Thunder

Well thanks for the info and doing what you can. Ive checked out alldata (which is the exact same thing thats in the factory manual) and unfortunetly unlike for other codes they have completely neglected to say what exactly caused this code to be set. Ive run through the trouble shooting procedured in the factory manual (again same as all data) and everything test out fine and i can see the burn off cycle happening. I decided to replace the MAF power and MAF burn off realys and clean all conections just for good measure and the problem still exsists. The manual says at this point replace the ECM but ECMs are pretty reliable pieces of equipment so i doubt thats what the problem really is. Unfortunetly if no one knows what the ECM looks for to set a code 36 i cannot test anything to see if thoes conditions are true and if so why or if not replace the ECM. So im pretty much stuck makeing educated guesses and throwing money at it till its solved lol.

ikeepitreelz

Did u try changing the MAF power relay and the MAF burn off relay? i changed it and solved my problem..about $12 each at auto zone..one of the part numbers is MR22

y84pauloflondon

Courtesy Of CHEVY8588:

Notes 88pontiac01
Number 87-6(Gasoline)-83 Date 1/88 MASS AIR FLOW (MAF) SENSOR SYSTEM DIAGNOSIS CODES 33, 34 AND 36 Subject: 1986-87 FIREBIRD MODELS EQUIPPED WITH LB9 OR L98 ENGINES Some vehicles equipped with 5.0L or 5.7L port fuel injected engines may experience "Service Engine Soon" lights with some combination of codes 33, 34 and/or 36 stored. This bulletin summarizes diagnostic procedures to be used in troubleshooting these codes. All 1986 model year vehicles should be updated to the latest service PROM per bulletin: 86-6G-66 and checked for "Service Engine Soon" light reset prior to further diagnosis. The MAF power relay should be checked to assure that it is part number 10067925. If it is not, then it should be replaced with part number 10067925. Please do not substitute.
DIAGNOSIS
CODE 33 (MAF SENSOR VOLTAGE HIGH)
1. Inspect to determine that part number 10067925 relay has not inadvertently been installed as a burnoff relay or incorrectly connected as a burnoff relay. (reference Bulletin 87-6G-57) NOTICE: SOME SERVICE PARTS BOOKS REFLECT THIS INCORRECT USAGE. For proper relay parts usages, please refer to the relay usage chart provided at the end of this bulletin. No substitutions, should be made.
2. With the engine fully warmed up and operating in closed loop, check the airflow at 2000 RPM in neutral using a Tech 1. If it is below 16.0 gm/sec for a 5.0L or below 18.0 gm/sec for a 5.7L engine and the block learn value is greater than 138, replace the MAF sensor. If code 33 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
CODE 34 (MAF SENSOR VOLTAGE LOW)
1. Inspect the plenum side of the throttle blades for deposits. If even a small amount of deposits are present, clean the throttle body per Bulletin 87-6G-30. 2. Thoroughly inspect the vehicle for sources of air entering the engine without passing through the MAF sensor. Specifically, look for a cracked, cut or loose duct between the air meter and the throttle body, poor inlet runner to plenum or manifold sealing, a split PCV hose or any type of vacuum leak. A large quantity of air does not necessarily have to be involved. If any leaks are found, repair the condition, clear the codes and check if the code resets. 3. Check resistance of the MAF power relay contacts per bulletin 87-6G-31. The resistance should be less than 1 OHM across closed contacts. If the resistance is greater than 1 OHM replace the relay. 4. Check the minimum air rate and compare to specifications found in Bulletin 87-6G-30. If the air rate is below specifications, please reset by connecting a vacuum gauge to port A on the throttle body, increasing the air rate by turning the minimum air screw until one inch of vacuum appears on the gauge and then reducing the minimum air setting by one half turn of the screw. If Code 34 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
CODE 36 (MAF BURNOFF) 1. Inspect to verify that the MAF power and burnoff relays currently on the vehicle agree with the usage chart provided at the end of this bulletin. 2. Check the relays for proper function per bulletin 87-6G-31. Also, check for PCV plugged condition per the same bulletin. 3. Check all electrical connections carefully. If Code 36 still resets, refer to section 6E of the appropriate service manual for further diagnostics.
RELAY USAGE CHART:


Make sure you update to the proper relay PART #'s as stated above!!!!!!!!!

tequilaboy

The MAF signal A/D value is checked with respect to two thresholds: 1.90 V DC and 400 mv DC. If the MAF signal is greater than 1.90 V or less than 400 mv, then a failure is detected.

6 failure occurences are required to set a Code 36.

;--------------------------------------------------------
; ERR # 36 Params
; >> MAF Burn off Diag <<
;--------------------------------------------------------
LC221: FCB 3 ; 0.3 Second Dly prior to Burn off
; CAL = Arg * 10
LC222: FCB 6 ; 6 fails req for ERR #36 If HLM air meter
LC223: FCB 95 ; 1.90 VDC, Fail B/O test if HLM A/D GT 1.90 VDC
LC224: FCB 20 ; Fail B/O test if A/D < 400 mvdc
;--------------------------------------------------------


;---------------------------
; CK ERR 36 Params
; MAF Burn off Diag
;---------------------------
LEB05: LDAA #$A0 ; A/D Ch A, (Mass Air Sensor Ch)
JSR LF1BE ; To A/D subroutine
CMPA LC223 ; Fail B/O test if HLM A/D > 1.90 VDC
BHI LEB19 ; BR IF MAF A/D VAL LT 1.90 VDC
; ... else
CMPA LC224 ; Fail B/O test if A/D LT 400 mvdc
BCS LEB19 ; BR IF MAF VAL L.T. 20
; ... else
BCLR L0003,$40 ; CLR b6, ERR 36, BO FAILED
BRA LEB39 ; EXIT via RTS
LEB19: LDAA L0120 ; ERR 36 COUNTER
CMPA LC222 ; 6 fails req for ERR 36
BCC LEB27 ; BR IF ERR EVENTS L.T. 6
; ... else
INCA ; INCR ERR 36 COUNT
STAA L0120 ; SAVE NEW ERR 36 COUNTER
BRA LEB39 ;
LEB27: BSET L0003,$40 ; SET b6, ERR 36, MAF BURN OFF FAIL
BRA LEB39 ; EXIT via RTS
LEB2C: LDX #$D000 ; 53,248
STX L3FDA ; Mass Air B.U. PW TMR
BRCLR L0003,$40,LEB39 ; BR IF b6, ERR 36, MAF BURN OFF FAIL
; ... else
BSET L004E,$80 ; SET b7, NEW ERR 2
LEB39: RTS ;

Rolling Thunder

Well i did finally get this solved but im glad that someone posted the section of code that sets a code 36. I never really did figure out diffinativly what the problem was but the result turned out like this.

1. I ran through the service procedure as the factory manual stated. Everything turned out good.

2. Checked out the service bulletin reguarding the code 36 and still no solution.

3. More throughly tested the relays (MAF and power) to check for maybe a internal resistance that was too high. Everything cleared but replaced them anyways just to be safe. Still not fixed.

4. Tried to do some more manual testing but shutting off the car and watching the burn off function work to try and confirm that it came on when it was supposed to for the right amount of time. It did everything consistently just as it was supposed to but still set a code 36. I couldnt measure the voltage at the output of the MAF to see if it was correct because the factory manual didn't state what correct was and i hadn't got any responses on that matter.

5. I continued to troubleshoot the problem until unfortunately my cheap bran new napa burn off relay failed and it failed on! Needless to say it burnt out my MAF sensor and drained my battery (i must have been on like all night and it set a whole bunch of new code i think 33-34-36). Napa refused to give me a new MAF claiming the warrenty was on the part only no labor or subsequent damages so I was stuck getting some new relays and MAF sensor. However once the relays were replaced and the MAF was replaced the code 36 was gone and has not come back since (like 2-3 months ago). I dont believe it was the relays because the originals ones were fine and even after replacing them with new ones the code 36 was still there. Only after replacing the MAF did the problem go away. Its odd because i had no other codes and the factory manual says specifically not to suspect the MAF if no other codes are present. I cant say it for certant as unfortunetly not knowing what the signal output was supposed to be i had no idea how to more thoroughly test the MAF burn off function and then the MAF got burnt up by a faulty burn off relay so now unfortunately ill never really know for certain. Still though i believe it was the MAF somehow.

alexiroc

I've been searching a long time for this data, thanks tequilaboy! If I read what you're writing correctly, during burnoff, the voltage at the ECM is supposed to be between 0.4 and 1.9 V? Mine is reading 2.5 V, and yes, it seems like 6 failures set the check engine light. I had to stick a sewing needle into the connector block at the ECM and drive around with it like that. Its a new Cardone MAF, so I need to bring it back to the auto store. The burn-off occurs for 10 seconds after shutting off engine, but the voltage at the ECM seems too high. Thanks.