I have a 95 blazer, 4x4, 4.3 engine, W on Vin horizontal distibitor cap.

My car is running really rough, OK on flat ground, but when I hit a hill it loses power and the CEL light starts to flash! It feels like a missfire, but not sure. Not getting any kind of backfire. I could see flashes of light coming from the wires on the passenger side near the cap. Thought it was the coil wire or the coil itself, replaced both but no improvment, and flashes are still there! Must be another wire or a fouled plug?

Another odd thing! I had the air intake hose off and I look through the throtle into the plenum and there was wet gas inside the plenum. I thought only air flowed through there, how could gas get in there? Could a bad EGR valve let gas in there and cause a missfire? Could the air intake sensor cause a missfire?

I tryed to read the CEL codes, but I have a 95 and my reader won't read it! And Yes I have the OBD2 computer! My reader is a Gen Tech 99722 from Harbor Freight. If anyone has any good ideas on how to get it to read my car, that would be great!

I hope someone out there has some good ideas, I don't have any money to throw at this and it's my only car!

Thanks for your time guys, and MERRY CHRISTMAS!!!

 

Sounds exactly like what started on mine last night. I am leaning towards EGR since it came on suddenly in my case. If I give it more throttle it will overcome and take off. But anywhere between 0-25% and it is caughing and feels like trying to push against a wall.
I will be pulling the EGR again(I have to do it about once a year) and spraying it down with carb cleaner. I also have a '95 so I completely understand not connecting with a scanner. I have tons of little problems which is probably why the EGR starts sticking open.
So far a '95 Chevy has been added to my 'Avoid List' along with leather seats.

As for the fuel in the plenum, a leaking fuel pressure regulator or other fuel system parts will cause that. It will make it run rich. There are a few threads on here about troubleshooting and rebuilding those parts. They are not super cheap so you can either fix it completely or just pick and choose from where it leaks the worst.

 

95 used one of two different injection systems, controlled by one of three different computer systems. Each combination has its own diagnostic procedure and specs. We need to know which system you have. Horizontal plug wires on the cap eliminates one possibility. The fact that your scan tool will not communicate, indicates the likelihood that you have what is commonly referred to as "OBD 1.5". It is not OBDII compliant, but it does have the OBDII connector under the dash.

To determine which system you have: when you look into the throttle body, are looking horizontally toward the rear of the vehicle? Or are you looking vertically straight down?

EDIT: Entry level scan tools, (like yours) will not communicate with OBD1.5

 

You are looking Horizontaly into the throttle body.When you open the throttle body and look strait in, the inside of the plenum is wet with gas. I thought the injection system was under the plenum and seperate from the air intake! How can gas get in there? Pics would be great if you have them!

Are the pins in the OBD 1.5 located in a different spot then the OBDII? If so, do you have a pic that shows where the pins are in each one? That way I'll know for sure which one it is! And is there a way to read the codes without the scanner, or to get my scanner to read it?

 

You'll need a scan tool with the proper software to retrieve DTC's. DON'T try jumping pins in the port, unless you have another PCM ready to install, it will be toasted

You have CMFI, (Central Multiport Fuel Injection) using OBD1.5 engine controls. It would be very helpful if you would put this info in your signature line It has one "batch fired" fuel injector in the plenum that feeds all 6 cylinders simultaneously each time it fires. For each two crankshaft revolutions, it fires 6 times.

The injector, fuel metering block, fuel pressure regulator, lines to each cylinder, poppet nozzles, along with a fuel pressure and a return line, are all inside the plenum. If there is a leak in any of these components you could notice fuel in the plenum. Here's what it looks like when you remove the plenum:




First step is to check fuel pressure and leakdown. If you follow the pressure line rearward from the injector, there is a service port with a black plastic cap on it. This is where the readings are taken, (you can see it in the image).

 

I'm not sure if we are talking about the same thing. I mite have the plenum confused with the air intake manifold, or are they the same thing? What exactly is the plenum? Also, that pic is of an engine with a vertical distributor cap, mine has the horizonal distributor cap. Do you have to change the gasket every time you remove the intake manifold?

 

The piece that has been removed in post #5, is the plenum, sometimes referred to as the upper intake manifold. Here is an image with the plenum in place. Your engine should look very similar to this one:




The intake air is heated inside the plenum before it enters the combustion chambers. When the EGR valve opens, exhaust gasses are sent into the plenum causing a black carbon mess inside the entire plenum area, (normal). If there is a fuel leak in the plenum, it "washes" the carbon off of the lower intake manifold, (visible in post #5) and turns it a golden brown color.

The vertical cap distributor has a pick up coil and ignition module inside. Yours only has a camshaft position sensor inside. The ignition module and crankshaft position sensor are externally mounted on yours. These are two modifications that contribute to the OBD1.5 "status" instead of OBDI, like the image in this post.

The plenum gasket should be replaced if the plenum is removed.

 

Thanks Captain! Because of the Holidays, I havn't got much done on it. I did pull the EGR valve and clean it, didn't help! I think I need to take it in and have the CEL read before I waste anymore time on it!

It would be helpful if anyone out there can list all the posible things that would make the service engine soon light flash!

THANKS, and HAPPY NEW YEAR'S TO EVERYONE!!!!

 

Only one thing will make it flash, a misfire. Post the DTC's in the order they are retrieved.

 

Does that mean, the problem has to be in the plugs, wires, or cap and rotor?