BadRiggins

I went to Autozone and bought the Actron Code Scanner for GM 1982 & higher... My car is reading codes 12, 23, 34, 44.

According to the book with the scanner they read as this;

12... Diagnostic test is working properly. (Engine computer verifies no RPM Reference Pluses are present during engine off testing.)

23... Manifold ait temperature (MAT) sensor - signal voltage is low or high.
OR
Throttle position sensor (TPS) error.
OR
Mixture Control (M/C) solenoid - open or short circuit problems.

34... Mass air flow (MAF) sensor - signal voltage or frequency is low during engine crusie.
OR
Manifold absolute pressure (MAP) sensor - signal voltage is low during ignition on.
OR
Pressure sensor circuit - signal voltage too high or low (carburetor engines).

44... Lean exhaust indication - oxygen (O2) sensor voltage stays low after one or two minutes of engine run. (Left sensor on dual sensor engines.)

How do I figure out what is wrong with the car if some codes give me more than one answer? Thanks.

Jersey89GTA

iTrader: (1)

Do what the rest of us do, stand in a cold shower and tear up $100 bills !
Keep throwing parts at it till its fixed ...LOL



Check all the contacts going to those devices, make sure they are not dirty and/or corrodid.

Then Disconnect the neg batt cable, let the ECM clear for about 5 minutes.

Restart the car, drive it around .... then see what codes stick around.

TPS - get the book, but you can adjust that, set to .54volts.
MAF - could clean it w/ electronic spray cleaner, see if helps, if not $80 part.
O2 - best to just replace it.

Also check the CTS, they throw ECMs into a tizzy and cause confusing untrue signals, cheap too $20, just replace it.

vetteoz

iTrader: (13)

You buy a factory service manual (FSM ) for your car that has the diagnostics .Work through each chart to identify the problem.
#23
http://www.chevythunder.com/mat_code_23.htm
#34
http://www.chevythunder.com/maf_code_34.htm
#44
http://www.chevythunder.com/o2_sensor_code_44.htm

BE AWARE;
a code means a problem with that whole ( wiring , connections , grounds inc ) system; not just that the major item of that system is faulty.
Showing a MAF code should not mean you should rush out and buy a new MAF sensor because you could have a wiring or vac problem



You need to learn more about your engine and know what you have as well as only look at the codes relevant to your car (as found in the '89 TA FSM )
For starters, your 305 is MAF so any MAP codes don't apply and you obviously don't have a carb !

vetteoz

iTrader: (13)

Be aware a MAF fault may also be causing the O2 fault ,
in which case the O2 fault is not a "fault " but a real indication the computer has seen the engine go lean when it should not have
because the MAF has given a wrong airflow indication to the computer and it has adjusted the fuel to suit that wrong reading.

BadRiggins

If I am not mistaken my car has a MAF and a MAP. As I have been informed the MAP is a back-up to the MAF. I know that I don't have a carb, I was just listing what the scanner said it could be.

vetteoz

iTrader: (13)

Corrected

Not unless you have swapped in a LT1 engine that uses both.

Once again you have to be aware of what you have, as you can see Gm used the same DTC 's for several different systems and their faults

BadRiggins

I believe this is the MAF on my car...



I believe this is the TPS on my car...



And I need to know what this part is...



Thanks.

nomind

That is the EGR valve.

BadRiggins

Okay, if the hose and the wire on/beside the EGR valve are both disconnected...without getting a EGR delete kit...would that cause issues? Somebody worked on my car and just took them off, but left the EGR on the motor.

Okay, so now that you are saying that I don't have a MAP...I went to Advance Auto Parts and they have a MAP sensor for my car. Is it like a universal or something that could be added to it? I'm not sure.

T/Aperformance

First since you put up pics the first pic is a MAF sensor. The third gens did not come with both , In 89 they started the run with MAF and the 165 computer and in the later run of the year went to MAP sensor with the 730 computer.
Now if your wires and vacuum line are of your egr your third pic, connect them back up like the factory had them.
Next start checking your voltage on all your sensors . TPS should be .54 and when you open your throttle the numbers should go up smoothly and not jump up or skip. WOT just above 430 I believe.
Also clean your MAF sensor , they sell a special cleaner for it.
And that manifold air temp code you are getting , that is the wire on your egr that is not hooked up.
Do this then reset your computer and see what codes come up.

Jersey89GTA

iTrader: (1)

EGR - put your fingers under it and pull the plunger up, then put one finger over the hole where the vac hose connects, if the plunger falls back down w/finger over the hole then egr valve is bad. Also egr solinoids go bad, they are hard to get ( hve to get used ones).

Seriously, get a haynes manual or a chilton ... all this stuff is in there.

rusty vango

I must disagree ,there is no substitute for a factory service manual. a Haynes or Chilton has scanty overview type info at best .and I have found them to be downright wrong in some cases

BadRiggins

What is a CTS?