I Just Dont Know What TO Do Kid.

Got a 92 Caprice With The 305, And Lately Shes Been Acting Really Strange. When I Go To Start It After Maybe An Hour Of Just Sitting There, She Acts Like Shes Gettin No Fuel, And Every Now And Then Shell Backfire. After A Few Minutes, She Runs Fine. Also When This Occurs, She Sounds Like Shes Got A Ballsy Exhaust. Got Curious And Popped The Hood, And Its Coming From The TBI. Any Help Yall Can Provide Would Be Great. And Ill Upload A Vidoe Of Whats Shes Doin If Itll Help. Thanks!!!

Got a 92 Caprice With The 305, And Lately Shes Been Acting Really Strange. When I Go To Start It After Maybe An Hour Of Just Sitting There, She Acts Like Shes Gettin No Fuel, And Every Now And Then Shell Backfire. After A Few Minutes, She Runs Fine. Also When This Occurs, She Sounds Like Shes Got A Ballsy Exhaust. Got Curious And Popped The Hood, And Its Coming From The TBI. Any Help Yall Can Provide Would Be Great. And Ill Upload A Vidoe Of Whats Shes Doin If Itll Help. Thanks!!!

how many times a week do you get the ambition to open the hood and check on things?

start by checking on things before starting every day..see whats up ..start engine hood up look/listen ..you got tools ? what you or the shop done lately to this lady ..she could be mad at you valentines day a couple weeks ago ..

..she could be mad at you valentines day a couple weeks ago ..

Actually I Could Believe It. She Can Be A Bitch, And She DOes Have A Personality. Lol. But Im Usually Under The Hood At Least Once A Week Checkin Fluids. But I Do My Own Work On It, And The Last Thing I Did Was A Fuel Pump Change Out Last Month. Did It By The Book, Just Like I Did Last Year. Crazy Thing Is She Acts Normal Every Now And Then, But This Problem Is Pretty Constant... Like When Im Goin Through An Intersection. She Wants To Acts Up In The Middle Of It.

Several questions/comments:

I know you say you changed the fuel pump. Did you change the fuel filter and the screen on the fuel pump when you changed the pump?

Have you verified the fuel pressure since the change? 9-13psi for TBI cars.

Have you messed with your base timing at all during all of this?

Check for vacuum leaks. May sure all of the vacuum lines running to and from the TBI unit are in good working order. No cracks splits etc...

Do you have an SES light on? I would be surprised if you don't.

How do I read my computer codes?

Tools needed:
Your car keys
A paper clip or a three(3) inch long piece of safety wire.

First thing you need to do is find your Assembly Line Diagnostic Link or ALDL. It s small black plastic piece about two (2) inches wide by one half(0.5) inch tall. It has twelve (12) female connector inside. The ALDL can be found under the driver's side of the dash, usually attached with two (2) screws to the bottom side of the dash.

The ALDL :

Now that you've found the ALDL, bend the paper clip or the piece of wire into a U shape. With the ignition in the OFF position. Insert one end into the A slot and one into the B slot. Now turn the the ignition to the ON position. DO NOT start the car. As the ECM begins it's self-test if will begin to flash the SES light to provide the codes. The flashes will appear like this : *flash* short pause *flash* *flash* long pause then repeat. Each code will be displayed three(3) times. Code 12 will be repeated to indicate the end of the set codes. If you all you get is Code 12 then you have no codes set in your ECM.

An example of a sequence for a common code :
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM
*flash* *flash* *flash* short pause *flash* *flash* long pause = Code 32, EGR
*flash* *flash* *flash* short pause *flash* *flash* long pause = Code 32, EGR
*flash* *flash* *flash* short pause *flash* *flash* long pause = Code 32, EGR
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM
*flash* short pause *flash* *flash* long pause = Code 12, Testing the ECM


Clearing the codes is really quite easy. Unhook your battery for about 2-3 minutes and then hook it back up.

These codes cover the OBD-I computers only.....
All currently listed codes are from the 1989 B-car Service Manual. Why? Because that's what I have. If you have others that aren't listed or need to be added, just let me know.


CODE AND CIRCUIT POSSIBLE CAUSE

CODE 12 = System check
Indicates that the ECM is functioning.

CODE 12 = No Engine Speed Reference - VIN 'Y' CARB
Indicates an open or ground in the distributor reference circuit.

CODE 13 = OPEN Oxygen Sensor (O2)
Indicates that the oxygen sensor circuit circuit or sensor was open for one minute while off idle.

CODE 14 = Coolant Sensor (CTS)
Sets if the sensor or signal line are grounded for 3 seconds. HIGH Temperature indication.

CODE 15 = Coolant Sensor (CTS)
Sets if the sensor wires or connections are open for 3 seconds. LOW Temperature indication.

CODE 21 = Throttle Position Sensor (TPS)
TPS voltage of more than 2.5 volts for 3 seconds at an engine speed less than 1200 rpm. HIGH Voltage Signal.

CODE 22 = Throttle Position Sensor (TPS)
A shorted to ground or open signal circuit will set code in 3 seconds. LOW Voltage Signal.

CODE 23 = Manifold Air Temperature Sensor (MAT)
Sets if the sensor wires or connections are open for 3 seconds or Intake Air Temperature (IAT) LOW Temperature indication.

CODE 24 = Vehicle Speed Sensor (VSS)
No vehicle speed present during road/load deceleration. NO Vehicle Speed Indication.

CODE 25 = Manifold Air Temperature Sensor (MAT)
Sets if the sensor or signal line are grounded for 3 seconds. Or Intake Air Temperature (IAT)
HIGH Temperature indication.

CODE 32 = Exhaust Gas Recirculation (EGR)
OR Vacuum switch shorted to ground on start up. Switch not closed after the ECM has commanded EGR for a specified period of time OR EGR solenoid circuit open for a specified period of time.

CODE 33 = Manifold Absolute Pressure (MAP)
MAP sensor output too high for 5 seconds or an open circuit. LOW Vacuum.

CODE 34 = Manifold Absolute Pressure (MAP)
Low or no output from sensor with engine running. HIGH Vacuum.
CODE 35 = Idle Air Control (IAC)
IAC error.

CODE 42 = Electronic Spark Timing (EST)
ECM has seen an open or grounded EST or Bypass circuit.

CODE 43 = Electronic Spark Control (ESC)
Signal to the ECM has remained low for too long or the system has failed a functional check.

CODE 44 = LEAN Exhaust Indication
If voltage to oxygen sensor remains BELOW .2v for more than 20 seconds code is set.

CODE 45 = RICH Exhaust Indication
If voltage to oxygen sensor remains ABOVE .7v for more than 1 minute code is set.

CODE 51 = PROM - Faulty MEM-CAL or ECM.

CODE 52 = Faulty or missing CAL-PACK.

CODE 53 = System overvoltage
Indication of a faulty alternator or regulator. Camaro/Firebird uses a Code 53 for Vehicle Anti-Theft System (VATS).

CODE 54 = Low Voltage To Fuel Pump
Sets when the fuel pump voltage is less than 2 volts when reference pulses are being received.

CODE 55 = Faulty ECM

CD, You Officially Rock. Didnt Even Think Of Checking Pressure Or Vacuum. Now Im Sure Theres A Special Tool Needed To Check Pressure. Would I Be Able To Rent One From Auto Zone? As For Your Questions, I Did Replace The Filter And The Strainer, I Did Not Mess With The Timing, And I Get An SES Light Every Now And Then. Sometimes Instantly Upon Start up, And Then Like Today, Didnt Get One Till After About 75 Miles Of Continuous Driving. I Guess A Question For You, The Paper Clip Idea Sounds Really Good, Yet Kinda Redneck Engineered. Im Almost Positive It Wont Fry Out My ECM, But With My Luck It Could Happen. Is There A Possibility This Might Happen?

You can rent/borrow the tool at most major parts stores. Make sure you specifically tell them you are testing TBI though.

The paper clip trip works with no ill effects on GM OBDI cars. You will want to find a photo of the ALDL so that you know which pins to jump across. Google is your friend here. ;-)

Actually I Could Believe It. She Can Be A Bitch, And She DOes Have A Personality. Lol. But Im Usually Under The Hood At Least Once A Week Checkin Fluids. But I Do My Own Work On It, And The Last Thing I Did Was A Fuel Pump Change Out Last Month. Did It By The Book, Just Like I Did Last Year. Crazy Thing Is She Acts Normal Every Now And Then, But This Problem Is Pretty Constant... Like When Im Goin Through An Intersection. She Wants To Acts Up In The Middle Of It.

how did the fuel pump wires supplying power/ground to the fuel pump look. It is possible they are in need of replacing. with the engine running check the voltage/ground at the fuel tank area for poor electical ..

CD: Ill Be Sure To Let Em Know Its TBI. And Google May Be A Good Friend In Most Cases, But I Got The Caprice Bible... The Service Manual!!! :) Ill Be Sure To Post What Codes I Get.

Jcat: The Wiring Looked Good. Will Try Checkin Codes And A Few Other Things First If They Dont Work Ill Check Voltage. (I Effin Hate Havin To Jack Up The Car. Not Cuz Its Difficult, But Cuz Im Sorta Lazy. Lol.)

Here's my original write up. It has a photo of the ALDL for you:

http://b-body.org/HowTo/HowToComputerCodes.htm

Well... Got The Codes, Just Dont Know How To Translate Them. Lookin On Google Now To See If I Can Find Em, But All I Can Find Is Code 12.

Ok. Im An Idiot. Just Realized Each Set Of Flashes Represent A Number. If This Is True I Got Code 44 (4 Flashes Long Pause 4 Flashes). Kinda Hope Im Wrong, But After Seeing The Example Of Code 12, And 32, I May Just Really Be An Idiot. Lol.

Ok. Im An Idiot. Just Realized Each Set Of Flashes Represent A Number. If This Is True I Got Code 44 (4 Flashes Long Pause 4 Flashes). Kinda Hope Im Wrong, But After Seeing The Example Of Code 12, And 32, I May Just Really Be An Idiot. Lol.

44 is the lean fuel code..check out the supply press/voltages to pump/ pump suction tube etc..

bad grounds..

If There Was A Snapped Plastic Hose Coming Off The A.I.R. Control Valve, Would This Maybe Cause This Problem?

If There Was A Snapped Plastic Hose Coming Off The A.I.R. Control Valve, Would This Maybe Cause This Problem?


the air tube connected to the exhaust must be sealed closed. this will cause a lean condition and throw off the O2 signal generated.

Thanks Jcat.Gonna Seal It Up ASAP Tomorrow. Now, The Tube Goes Into A T-Splitter, And Thats Where It Snapped At. Is There Any Specific Type Of Automotive Sealant That I Can Use On It? Also, The Electrical Connector That Goes Onto The Passenger Side Of The Air Cleaner Box, Is That The MAT Sensor? Unhooked It To Check The Rest Of The Tube, And Now I Get Code 23.

Thanks Jcat.Gonna Seal It Up ASAP Tomorrow. Now, The Tube Goes Into A T-Splitter, And Thats Where It Snapped At. Is There Any Specific Type Of Automotive Sealant That I Can Use On It? Also, The Electrical Connector That Goes Onto The Passenger Side Of The Air Cleaner Box, Is That The MAT Sensor? Unhooked It To Check The Rest Of The Tube, And Now I Get Code 23.

yes 23 is the electrical connection to the Manifold air temp is off/broken.

repair the air tube best as possible ..use anything for now it is plastic , not gonna get too hot.. then if the engine runs better go to a scrap yard for a part to replace.

the air injection is used on cold start to help the converters get more air to reduce cold start hydocarbons common with this fuel injected system.

disabling this is no big deal. but the broken tube would mess up the operation of the engine I would think.

using marine tex and some copper tubing like 1/2 dia etc might work..