Problems with 93 chevy blazer

The vacuum lines on a 1987 Chevy S10 Blazer are responsible for routing vacuum to various components such as the brake booster, EGR valve, and other systems.
A vacuum line diagram for your specific make and model of Chevy S10 Blazer can be found in the vehicle's service manual or in some cases, it can be found under the hood on a decal or sticker.
If the vacuum lines are loose, cracked, or damaged, it can cause various issues such as rough idle, stalling, poor performance, or even a failed emissions test.
It's best to consult the service manual, a professional mechanic or the dealer for proper diagnosis and repair of vacuum lines issues. These lines are crucial for the proper operation of many systems in the vehicle, so it's important to fix them as soon as possible if they are found to be damaged.

Is the check engine light on ?
Have you checked the fuel pressure yet ?

An EGR that is stuck opencan very well cause the symptom you are decribing, including surging at idle and poor acceleration.

Failure of GM EGR Valves is quite rare.
A common problem on the 4.3L Vortec engines is failure of the Central Multiport Injection Assembly located between the plastic upper intake plenum and the lower intake manifold.

Sometimes failure of injector lines and/or the fuel pressure regulator (Part of the MFI Assembly) will cause fuel to spill into the upper plenum area. This can dislodge carbon deposits in the upper plenum which then get stuck in the EGR Valve and cause the symptoms that you are describing. The EGR Valve can be removed and cleaned. Replacement is not usually necessary.
Ido recommend replacement of the injector assembly however.

check out this solution page for more info regarding this.

http://www.fixya.com/cars/t3218505-misfire_code_rough_idle_full_tune_up

the one possible problem is the egr valve. If your blazer has the Vortec 4.3, the valve is located on the front of the intake manifold. You must remove the intake rubber boot on the throttle body to see it better. It's very possible that there is chunks of carbon holding the valve open. I recommend cleaning the egr valve ( carb. cleaner works great ) and replacing the Egr gasket with a screened gasket. This will take care of it stalling and surging.

Carbon blocking the EGR movement and EGR passage tube.

====

Check for

vacuum leaks on intake manifold,

the air tube between the air filter.

intake manifold vacuum hose.

===
clean throttle plate with Berryman carburator cleaner

SEE sample picture HERE
===

Also remove carbon built up behind the EGR valve and the EGR passage tube.

===

Vacuum leak WILL offset the intended 14.7 to 1 air fuel ratio.

More un-metered air (leaks) will lean out the fuel mixture.

Use small amount of Berryman carb clearer at potential air leak area will help you identify trouble spot.

At idle,just spray and listen for the RPM surge.

The in-rush of carb clearer will increase the RPM on the motor.

Record the problem spot(s) and address it later.

===

EGR carbon built up require 2+ hours to clean from start to finish.

You will need a new EGR base gasket before your start.

Locate and remove the EGR valve after the vehicle is cool down.

Carefully record the connector and vacuum line (for older vehicle) location by drawing an easily to follow diagram.

Remove the EGR valve.

Inspect the location of the carbon built-up inside the valve and the EGR passage tube.

SOAK these areas with WD-40 spary.

You will need a small screwdriver,cloth hanger and lot of newspaper and time to get this cleaning done right.

RE-SOAK the carbon and let it sit for over-night will also help.

One the last round,pass a shop vacuum of the EGR valve and the passage pipe.

Install the new EGR gasket and connectors.

Allow the vehicle to warm up outdoor to burn up any remaining WD-40.


Take it for a test drive.


Please rate my answer if it's useful to you.


Cheers,

Mustgo

Probably the EGR valve, although mine was having similar problems and found out the oil lines going to the filter were being pinched by the air filter box, bent the lines a little bit and all was well.

How is it running before it quits onyou. This could be the culprit of an egr valve. How many miles on thevehicle. The egr seems to die on a certain mileage pattern. Also youcould start by cleaning the egr valve before replacing it. This couldvery well help the situation, but this is just a guess. Hope thishelps!!

Check the Fuel pump with a presure guage.

This make/model has a chronic problem with EGR clogging. If you have a dashboard indicator showing "check engine" most likely it is a trouble code indicating and EGR (exhaust gas recirculator) valve problem. Symptoms are rough idle, and surging and stalls.

What happens is sediments from the exaust manifold get sucked up into the valve when it opens, then stick in the valve and keep it from closing. When the valve is open when it should be closed, the engine runs very rough.

I removed my egr and then dislodged the sediment (pea-sized debris) and then re-installed the valve. Three days later, the same "check engine" and same rough idle. I must have did this at least three or four more times.

What I found that gave me a permanent solution was an aftermarket filter gasket that keeps debris from clogging. I don't remember the name of the product, but a search for "EGR filter gasket" may lead you to the product.

Install the gasket between the EGR and the exhaust manifold and you should be good to go. Note: on 1995 and newer models, disconnecting the EGR from the wiring harness (common on R&R) may require the computer to be reprogramed.

Had a similar probelm, cleaned the EGR valve and problem went away.