Strage Problem, came out of no where

[jo89k5]

Hey guys, I'm having a strange problem with my blazer that started yesterday.

A little background: 1989 Chevy Blazer 350 fuel injected with 700r4

So I went to start my car yesterday morning, and it wouldn't start right away, when it did start it idles very rough, when I put it in gear it seems to idle even lower and will stall if I don't stay on the gas, the transmission also seem to take longer to shift, it will stay in gear way to long, like when getting on the parkway

I'm a little worried and hope it's not a major problem, as of right now, it's my everyday car and can't really afford to fix anything major

Thanks for any help in advance

Jim

 

[philjafo]

Theres a lot of things that can cause problems like your describing, so lets start with cheap and easy and work towards hard and expensive. Check the vacuum lines, a carefull visual inspection of them cracks and dry rot can all add up to act like a big leak. If in doubt replace the line its cheap and will prevent future problems if its not the cause of todays problem. Then grab the wd-40 and with it running, spray the intake manifold to head gaskets then the base of the throttle body all the way around, any change in rpm will indicate a leak there.
Now with the engine off pull the distributer cap and take a look at the condition of the cap rotor and coil, depending on age you may just want to replace them, more expensive then vacuum lines but replacing these wear parts miht prevent future probems. If they are in good condition and relitively new, give the cap a shot of wd-40 inside and reassemble. Check the plugs, and same as the other stuff when in doubt some new plugs won't hurt.
Does your check engine light come on, either when the key is on engine off or while its running? If not make sure the bulb is good and pull the diagnostic codes.
The transmission acting up at the same time makes me lean more towards vac leaks though.

 

[jo89k5]

Ok, hopefully it's just a vacume leak, is there a diagram that I can find that shows all the vacume lines?

Theres a lot of things that can cause problems like your describing, so lets start with cheap and easy and work towards hard and expensive. Check the vacuum lines, a carefull visual inspection of them cracks and dry rot can all add up to act like a big leak. If in doubt replace the line its cheap and will prevent future problems if its not the cause of todays problem. Then grab the wd-40 and with it running, spray the intake manifold to head gaskets then the base of the throttle body all the way around, any change in rpm will indicate a leak there.
Now with the engine off pull the distributer cap and take a look at the condition of the cap rotor and coil, depending on age you may just want to replace them, more expensive then vacuum lines but replacing these wear parts miht prevent future probems. If they are in good condition and relitively new, give the cap a shot of wd-40 inside and reassemble. Check the plugs, and same as the other stuff when in doubt some new plugs won't hurt.
Does your check engine light come on, either when the key is on engine off or while its running? If not make sure the bulb is good and pull the diagnostic codes.
The transmission acting up at the same time makes me lean more towards vac leaks though.

 

[philjafo]

http://www.gmsquarebody.com/forum/showthread.php?t=3520

 

[jo89k5]

Ok I replaced all the vacuums lines and the MAP sensor and still no luck

 

[philjafo]

Did the trouble codes say bad map sensor? Because that code would also come up for a bad vacuum leak, for example a chunk of the intake gasket broke off.

 

[jo89k5]

Did the trouble codes say bad map sensor? Because that code would also come up for a bad vacuum leak, for example a chunk of the intake gasket broke off.

The Service Engine Soon light doesn't stay on, it comes on randomly and I don't have a tool to pull the error codes

 

[philjafo]

The only tool you need to get codes from an obd 1 computer is a paperclip, connect terminal a to b in the aldl and the check engine light will flash the codes. It will start with 12 one flash short pause two flashes, then a long pause. Each code is flashed three times then it the next code. 12 is no distributor reference pulse. I've got my book nearby so let me know what it flashes and I'll translate it. I think the aldl should be labeled but if its not terminal a is the top right corner as you sit in the drivers seat, b is next to it in the upper row.

 

[philjafo]

Oh yeah connect a to b then turn key to run position, but don't start engine.

 

[jo89k5]

Oh yeah connect a to b then turn key to run position, but don't start engine.

Ok I'll grab my jacket and run out in a second, thanks again for all the help bro

 

[jo89k5]

Ok, two codes

The 1 long, 2 short
and 3 short

 

[philjafo]

Ok, codes are always two numbers, so if your getting 12 and 13, your getting a code for oxygen sensor, check the wire to the sensor could also be a sticking throttle position sensor. If your getting code 33 that's map sensor, check how much vac you have at the sensor. You should be able to unplug the electrical from the sensor and that should force the computer substitute a fixed value for that and use the tps to control fuel delivery. Might not work if you have a big vacuum leak because the extra air throws of the air fuel ratio at idle, but it should run better at higher rpms because its ignoring the map sensor.

 

[jo89k5]

Ok, codes are always two numbers, so if your getting 12 and 13, your getting a code for oxygen sensor, check the wire to the sensor could also be a sticking throttle position sensor. If your getting code 33 that's map sensor, check how much vac you have at the sensor. You should be able to unplug the electrical from the sensor and that should force the computer substitute a fixed value for that and use the tps to control fuel delivery. Might not work if you have a big vacuum leak because the extra air throws of the air fuel ratio at idle, but it should run better at higher rpms because its ignoring the map sensor.

Ok, so I rechecked, it flashed 2 codes
One was 1 flash, pause, then 2 flashes - it did that 3 times as it should
the second one was 3 flashes no pause - it did that 3 times too

I replaced all the vacume lines that I saw, and it's also a brand new MAP sensor

So the second code I'm getting is for the oxygen sensor? whats the easiest way to diagnose if thats the problem

 

[philjafo]

All codes are two numbers, code 13 would be 1 flash, pause, 3 flashes. If its 33, it would be 3 flashes, pause 3 flashes. After its given all the stored codes it will give code 12 again. Have you tried spraying the intake manifold gaskets and the throttle body gasket? It doesn't have to be wd-40, any spray lube works starting fluid carb and choke cleaner anything that's going to either temporarily seal the leak or cause a change in rpm. Do you have a vacuum guage, a normal reading would be between 15-25 if its down near 3-8 you've got a big leak.

 

[jo89k5]

All codes are two numbers, code 13 would be 1 flash, pause, 3 flashes. If its 33, it would be 3 flashes, pause 3 flashes. After its given all the stored codes it will give code 12 again. Have you tried spraying the intake manifold gaskets and the throttle body gasket? It doesn't have to be wd-40, any spray lube works starting fluid carb and choke cleaner anything that's going to either temporarily seal the leak or cause a change in rpm. Do you have a vacuum guage, a normal reading would be between 15-25 if its down near 3-8 you've got a big leak.

Ok, then its a code 33

I'll check the gaskets with spray in the morning