1996 Chevy Problems

So I have been having problems with my Blazer for the past month or so. Here are the details:

Car: 1996 Chevy Blazer 4.3L 4WD 117,000 miles

Problems:
1) It started a couple of weeks ago on a long drive (about 100 mi one way) where I would be going at highway speeds (60+) and the car would just start bogging down. It would start chugging and loose power. I would let off on the gas and pull over and it would be a super rough idle. I would get a flashing check engine light, but once I turned it off it would just be solid. I got the code and it was for a "random misfire". It happened 3 times on that trip.

2) Took it into get serviced and changed out all the plugs, which all looked pretty good. Changed the air filter and the fuel filter. The fuel filter was full of water and was the original. All other fluids looked fine and got an oil change. Check my cat converter (it has had a loud rattle) and I'm guessing that the plate in it has broken its welds, which I hear is a real common problem. New distributor rotor was also put in.

3) Today I got on the highway and my car would barely accelerate. It wouldn't change gears until 3-4k rpms. There seemed to be a little chugging as I was driving (wasn't as pronounced as the last time). Pretty much automatically it gave me a check engine light, which I will post the error in about an hour when I find out what it is.

Need help (and don't want to spend huge amounts of money to figure out the problem)

So I have been having problems with my Blazer for the past month or so. Here are the details:

Car: 1996 Chevy Blazer 4.3L 4WD 117,000 miles

Problems:
1) It started a couple of weeks ago on a long drive (about 100 mi one way) where I would be going at highway speeds (60+) and the car would just start bogging down. It would start chugging and loose power. I would let off on the gas and pull over and it would be a super rough idle. I would get a flashing check engine light, but once I turned it off it would just be solid. I got the code and it was for a "random misfire". It happened 3 times on that trip.

2) Took it into get serviced and changed out all the plugs, which all looked pretty good. Changed the air filter and the fuel filter. The fuel filter was full of water and was the original. All other fluids looked fine and got an oil change. Check my cat converter (it has had a loud rattle) and I'm guessing that the plate in it has broken its welds, which I hear is a real common problem. New distributor rotor was also put in.

3) Today I got on the highway and my car would barely accelerate. It wouldn't change gears until 3-4k rpms. There seemed to be a little chugging as I was driving (wasn't as pronounced as the last time). Pretty much automatically it gave me a check engine light, which I will post the error in about an hour when I find out what it is.

Need help (and don't want to spend huge amounts of money to figure out the problem)

Sounds like a poor service jobb to me.

I would take it back to who serviced it and tell them you still have a problem and tell them to lick there calf over.

Flashing or solid check engine light?

Was codes cleared and rechecked?

Was fuel pressure checked?
Confirm good fuel pressure when acting up.

Good hot blue spark to all plugs?

Post back fuel pressure readings when acting up and back pressure on cat and any codes.

If cat rattle back pressure needs to be checked.

The problems that were encountered when I checked the codes were:

P0300: Random Misfire
P0101: Mass or Volume Air Flow Circuit Range + Performance
P0420: Catalyst System Efficiency Below Threshold Bank 1


The service I had done to it I trust the mechanic a lot so I doubt that it was bad servicing.

The problems that were encountered when I checked the codes were:

P0300: Random Misfire
P0101: Mass or Volume Air Flow Circuit Range + Performance
P0420: Catalyst System Efficiency Below Threshold Bank 1


The service I had done to it I trust the mechanic a lot so I doubt that it was bad servicing.

Codes should be cleared and rechecked.

Engine missfire could give the 420 code.

After codes cleaqr drive and see if missfire or Mass air flo circuit code returns.
If code 101 returns better go threw the flow chart for taht code.
Sometimes a good cleaning helps on mass air flow problems.
Any after market air filters?

A good service wolud have included checking out the code 101 and missfire codes.

Just throwing plugs in it and a rotor is not a very good service.
Unless that is all you asked for.

Did you tell him what it was doing and give him the codes?

I just wanted to start with changing the plugs, rotor, fuel + oil filters. The codes happened after the servicing, so he didn't know about it. The new thing though was that I did some driving on the freeway and around town and my car has a really hard time accelerating. It will accelerate very slowly and won't shift until high rpms. I'm think I'm going to take it in and have a more detailed diagnostic run on it. I also reved it up in idle and the engine sounded fine (no labouring) all the way up to 4500 rpms.

I just wanted to start with changing the plugs, rotor, fuel + oil filters. The codes happened after the servicing, so he didn't know about it. The new thing though was that I did some driving on the freeway and around town and my car has a really hard time accelerating. It will accelerate very slowly and won't shift until high rpms. I'm think I'm going to take it in and have a more detailed diagnostic run on it. I also reved it up in idle and the engine sounded fine (no labouring) all the way up to 4500 rpms.

Speeding up setting still will not tell you much.


Any aftermarket air filters?
Good AC Delco plugs installed?
A good scanner test by a good tech/mechanic may tell you what the problem is.
Codes should be cleared and drove and checked for what ones are coming back?
If codes come back post back what code/codes.
I would also run a full fuel pressure check.
Also with a cat rattle check that back pressure and engine vacuum.

Just to add a little to this..

The P0101 MAF out of range could easily give you the chugging problem. This sensor is very important to the proper operation of the engine. For it to go in and out like you mention, this is most liklely the problem. Take the MAF sensor out and give it a good cleaning, with some brake cleaner and let it dry. Check the connector and connections real well and reinstall. Clear the codes and go for a drive. If P0101 comes back, chances are you need a new MAF sensor.

I drove about 30 miles today (urban and highway driving) and no new error codes or problems. It does seem to still accelerate slowly.

I pulled the MAF sensor out and sprayed some brake cleaner on it. Also I noticed that one of the little sensors was black on one side so I very lightly wipped it of with a paper towel.

The P0300 and P0101 showing up together along with the symptoms you describe, are classic for low fuel pressure, as MT mentoned in his first post. Key on, engine off, fuel pump running: pressure must be 60psi to 66psi and must remain above 55psi for 3 to 5 minutes after the fuel pump shuts off.

I will check it out tomorrow if I can get ahold of a pressure test gauge to use.

I will be checking the fuel pressure tomorrow, so I'll post that then. I have put around 300 miles on my car since cleaning the MAF and it seems to be running better. It does seem to be sluggish still. Also I have gotten the P0420 error again.

I checked the fuel pressure and the reading when the pump was on was ~60 psi and after 5 min it stayed at ~58 psi. I am probably going to take it in to a exhaust shop and see if they will run a back pressure test to see if anything in the exhaust is causing the problem.

I checked the fuel pressure and the reading when the pump was on was ~60 psi and after 5 min it stayed at ~58 psi. I am probably going to take it in to a exhaust shop and see if they will run a back pressure test to see if anything in the exhaust is causing the problem.

You need to do the full test on fuel pressure.
A plugged exhaust can be checked with a engine vacuum gauge.

Engine vacuum at 2 K rpm should be more that idle vacuum.
If not you have a plugged exhaust.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.