Found disconnected EGR/EPR sytem: responsible for lack of power?

[sailchg]

Just started to jump into my first 6.2L engine and noticed the vacuum pump is disconnected from the EGR/EPR system. I put a gauge to the pump and it was only sucking 5 psi (or Hg) when I read it should be around 20. Hmmm...

At the same time, I also noticed a severe loss of power when going up a grade for a couple of miles into the mountains--I can only do about 35mph with the pedal to the floor. When I get offroading at 4,600 feet going up an incline, I get virtually no power (5 mph) with the pedal floored and a moderate amount of black smoke. I almost can't climb a 10% grade. Not good.

At sea level, around town and on level ground, things are good and the truck "feels" ok.

Any ideas?

-P

[john8662]

Welcome to TDP online Forums!

I want to start off by letting you know that the EGR being disconnected is NOT the source of your lacking power. The EGR system is just as it stands for, an Exhaust Gas Recirculation system. The simple explanation of what it does it recycles exhaust gasses and injects them into the intake to be re-burned, for better emissions. The problem with this is that it's going to sut up the intake when the sut mixes with blow-by oil and take hot exhaust and heats up the intake. Anyways, the EGR system does work, but when it malfunctions, the easiest and best way in this case is to disconnect it from a vacuum source, so it can't open the valve that sits in the middle of the intake plenum.

Next, where are you reading your vacuum? The vacuum system should remain intact, but not running the EGR system because it also runs the HVAC controls in the cab. So make sure you don't have any open lines coming off the vacuum pump.

EPR, this is more or less an exhaust flapper in the driver's side exhaust manifold. This is to heat up the engine sooner during cold conditions. By all means, you can disconnect the vacuum supply to this. I'd be concerned that the valve flapper in the exhaust might be stuck almost closed. You can get underneath the truck and verify that it isn't, it's located just above the exhaust pipe connection to the exhaust manifold (looks like a manifold extension). Just grab the arm and make sure it moves with some resistance (spring) but is not stuck.

I'm not sure why you have such low power, but you'll have to give us a little more information on your truck. Things like tire size, gear ratio and what tranny you're using would also help.

[Quack_Addict]

I second that on checking the exhaust manifold (EPR?). I have always just called it a heat riser.

When I bought my `82 K5 with 6.2L, this valve almost completely rusted shut and engine performance was similar to what you describe. The engine made a hissing sound because of the valve being so restrictive to the exhaust - does your engine hiss? I fixed the problem by removing the exhaust pipe from that side of the engine and used the oxy/acetylene torch to cut the valve out. When I bolted the pipe back up and started the truck, it ran like a champ.