94 Blazer easy questions from a newbie

94 Blazer 4.3 (W) 118k - OK, I got this truck for my son and we are working on this together- Some questions from a novice:

- The old owner said to put premium in because its a high performace engine - So, Ive filled up twcie now with premium - Of course, 200 miles into the first tank, the truck had a lousy idle and died, so we read on this forum about the EGR problems and pulled it and cleaned it ( Thank You Blazer_lt for the pics)- All was well for about 300 miles, and then, back to the lousy idle. The SES light blinks and comes on and off. We replaced the air filter and PCV valvel - Next replacement my kid thinks - fuel filter - The guy who had this truck before has a tuneup ( plugs, wires, cap, rotor , new injector, new fuel pump) at 100k about a year and a half ago.

- Could I be loosening up some stuff in the engine by using premium that plugs up the EGR?

- We searched this forum for fuel filter replcement- any tips here since we are kind of learning on the go?

- My son said he saw a gasket for the EGR that had a screen in it that prevents all this repetitive EGR cleaning. Any of you guys use it and where would you get one?

- We don't have access to a close facility that can do the diaganostic test on the computer, so any other hints on a lousy idle will be appreciated.

Thanks, and this forum has been real helpful to us newbies.

MariLou

so you have the check engine light on im guessing....um do you can pull the codes yourself its very very very easy....first of all get a short wire that you can use to jump 2 pins. Now you want to get under your dashboard. The link you need to jump is below the instrument panel and to the left of the center console. Remove the plastic cover by sliding it toward you. You should now be looking at a little rectangle with 2 rows of 6 pins....You want to jump the furthest right pins on the top row of pins

0 0 0 0 x x
0 0 0 0 0 0

Where the 2 x's are is what you want to jump. Make sure you don't have the key in the ignition while your doing this. After putting the wire in turn the ignition on...don't start the car. Now your check engine light will do a serious of flashes like morse code. The first thing it'll flash is code 12 ....1 long flash...then 2 short flashes...thats telling you your in diagnostics mode. Now it'll show you another code which is what you want to write down. It'll show each code 3 times...after showing the first code it'll show 12 again...then show the next code 3 times...it'll just keep looping...get the codes and post them back here so we can help ya.

OK - we just did that, we get a 32- What's that?

32 = EGR - Vacuum switch shorted to ground on start-up, switch not closed after the ECM has commanded the EGR for a specified period of time or the EGR solenoid circuit is open for specified period of time. Replace the EGR valve.

32 = EGR - Vacuum switch shorted to ground on start-up, switch not closed after the ECM has commanded the EGR for a specified period of time or the EGR solenoid circuit is open for specified period of time. Replace the EGR valve.

No you don't replace the EGR valve. You check for a short in the wiring going to it.

No you don't replace the EGR valve. You check for a short in the wiring going to it.
I was just putting what the haynes manual said....

I was just putting what the haynes manual said....

Think logically. If there is a circuit problem, it is probably not the valve.

Will do....sorry bout that.

Will do....sorry bout that.

No problem. :D

Ok - Before you guys got back to us, my kid asked his autoshop teacher, who said to tap the EGR with a hammer as this will sometimes free the thing up. Looks like it worked, becasue the Blazer is running ok with no check enghine light on. We drove it for about 100 miles and its seems ok.

Thanks for the help. I think we will watch it and see what happens.

Should I still put premium gas in this truck?

Ok - Before you guys got back to us, my kid asked his autoshop teacher, who said to tap the EGR with a hammer as this will sometimes free the thing up. Looks like it worked, becasue the Blazer is running ok with no check enghine light on. We drove it for about 100 miles and its seems ok.

Thanks for the help. I think we will watch it and see what happens.

Should I still put premium gas in this truck?

If it is a digital EGR, you NEVER tap it with a hammer.

Despite what the advertisements on TV and on the pump say, there is no benefit of putting Premium gas in our trucks. The only time mine sees premium is when it's hot, dry weather out and I am towing. Helps keep the sound of marbles down under the hood when climbing some of the Ozark hills out here when heavily laden. Otherwise, 87 octane is perfect for our machines...
...when they are tuned up properly. ;) Oh and, please - do not go bouncing hammers off of *electronic* controls. Does more damage than good. You could get away with it in the old days, but these modern trucks have stepper-motor actuator controls. Beating them with a hammer works to sieze them up when you break the precision-built insides apart.

If you are getting detonation even with 87 octane, you seriously need to check out your cooling and fuel system.

There should be ZERO ping even with 87 under load.

It was only very slight at light throttle position. Once the engine loads up it's fine. Does not ping when acellerating onto the highway or maintaining speed. Just an initial little "tap-a-tap" can be heard when going from a dead start when the butterfly first comes off the rest. However, this was also before I did a full tune up on the truck and set timing for zero - the latter done just last week. So I will know when warmer spring temperatures come. Been running around all winter just fine and hauling stuff on 87 with no hint of trouble or "marbles" rattling under the hood. Spring and summer will reveal if I got it right. ;)