Idle Problems

[SweetNLo]

I have a 93 Silverado with a recently swapped crate 350 Vortec engine. The performance of the engine is great except at idle. The engine surges at idle, and the tachometer will regularly bounce between 600 to 900 rpm. Then occasionally the engine will die out at idle. I regularly get a 32 Code for an EGR valve. A test on the EGR valve and the EGR solenoid shows both are operating correctly. A fuel pressure test showed the pressure was within the correct range. I've been told that I need to get a chip with an EGR delete. I'm not certain that would solve the issue. Any suggestions? Thanks in advance.

 

[Erik the Awful]

Are you sure you don't have any vacuum leaks? Is your EGR working intermittently?

 

[thegawd]

ya...

what happens if you hold the brakes for an extended period of time then release them and stomp on the gas? does it go or does it almost die? if it dosent go you are probably dealing with a failed vacume brake booster.

honestly lately like over the last year there have been many people with these ideling problems.... my burb completely ruptured its brake booster last year.... scary **** coming to a stop sign while also blowing the front passanger line.

Anyways after I put a new brake booster on my truck it immediately had so much more power than it ever did and it was obvious to me that I had gotten used to a gradual decline in performance due to this faulty leaking BB.

I think all of these boosters in everyone's trucks are reaching the end of there life and because it is a brake part we dont realize it until after trying many other things....

Al

 

[Schurkey]

I have a 93 Silverado with a recently swapped crate 350 Vortec engine... ...I regularly get a 32 Code for an EGR valve. A test on the EGR valve and the EGR solenoid shows both are operating correctly.

Describe the plumbing that connects the EGR valve to the exhaust manifold.

 

[SweetNLo]

Are you sure you don't have any vacuum leaks? Is your EGR working intermittently?

Thanks for the advice. At this point, I don't have any vacuum leaks and the EGR valve is not working intermittently.

 

[DonYukon]

ya...

what happens if you hold the brakes for an extended period of time then release them and stomp on the gas? does it go or does it almost die? if it dosent go you are probably dealing with a failed vacume brake booster.

honestly lately like over the last year there have been many people with these ideling problems.... my burb completely ruptured its brake booster last year.... scary **** coming to a stop sign while also blowing the front passanger line.

Anyways after I put a new brake booster on my truck it immediately had so much more power than it ever did and it was obvious to me that I had gotten used to a gradual decline in performance due to this faulty leaking BB.

I think all of these boosters in everyone's trucks are reaching the end of there life and because it is a brake part we dont realize it until after trying many other things....

Al

nail on the head . There is a lot of things that many of us are starting to figure out are coming to the end that wasn’t “usual problem areas” . These trucks are getting old

 

[Schurkey]

Describe the plumbing that connects the EGR valve to the exhaust manifold.

Still waiting.

Vortec heads do not have an exhaust crossover passage. If you don't have a source of exhaust gas plumbed to the intake manifold--the OEM Vortecs had a big metal tube stretching from left exhaust manifold to the front of the intake manifold--you have no functional EGR even if the valve opens and closes.

 

[SweetNLo]

Still waiting.

Vortec heads do not have an exhaust crossover passage. If you don't have a source of exhaust gas plumbed to the intake manifold--the OEM Vortecs had a big metal tube stretching from left exhaust manifold to the front of the intake manifold--you have no functional EGR even if the valve opens and closes.

Schurkey, sorry for the delay. I thought my thread died until I checked it yesterday. My current setup in my truck has the EGR valve connected to the EGR solenoid by vacuum line. I attached a picture of it. The previous owner had this motor in a 92 Camaro. I also attached a picture of it. The EGR valve is there but there is no vacuum line connected to it. I drove that Camaro, and it did not have any idling or driveability issues. As you mentioned, I may not have a functional EGR valve then. Do you think that would cause idling issues? Would I be better off getting rid of it? Thanks for any suggestions.

 

[Schurkey]

What manifold is that? The TBI-to-Vortec Head manifolds that I'm familiar with have a passage that is either plugged or connected by a big insulated steel tube to the left exhaust manifold.

The plug would be behind the radiator hose in your photo.

In this photo, the open passage is below the thermostat area, just above the second-to-the-right manifold bolthole.

You must be registered for see images attach

The connecting tube would go over the valve cover to the left exhaust manifold.

AC-Delco aftermarket version of the EGR tube.

ACDelco 12554129 ACDelco EGR Tubes | Summit Racing

Free Shipping - ACDelco EGR Tubes with qualifying orders of $109. Shop EGR Tubes at Summit Racing.

www.summitracing.com

You must be registered for see images attach

You'd also need the fittings that screw into the intake and exhaust manifolds. The left exhaust manifold has two holes, one for this tube, one for the O2 sensor. I did a quick search online, it seems the 2-hole manifold has been discontinued; there's a 1-hole manifold with a boss for the second hole, but you'd have to drill 'n' tap it yourself. GM #12557838, with the two-hole version being 12557838DT (Double-Tapped)

Chevrolet Performance 12557828 Chevrolet Performance Exhaust Manifolds | Summit Racing

Free Shipping - Chevrolet Performance Exhaust Manifolds with qualifying orders of $109. Shop Exhaust Manifolds at Summit Racing.

www.summitracing.com

Without that connection, you have no source of exhaust gas, therefore the EGR does not function even if the valve opens and closes.

 

[SweetNLo]

Shurkey, thanks for the detailed response. The intake I have is a Chevy/GM performance intake. The picture you provided is the same one I have. I painted mine to match the rest of the engine. Based on your explanation, it appears my EGR valve is not functional. It's just for looks ;-). The donor engine came with a pair of Edelbrock headers (discontinued) that would have accommodated the EGR setup you mentioned with the exhaust manifold. I swapped the Edelbrock headers for a pair of Summit headers because it was a direct fit to my custom exhaust system. I'm going to forego setting up the EGR valve then or get a block off plate. This means I'll have to put up with Code 32 (EGR) that keeps popping up. In your opinion, do you think it's a bad idea not to set up the EGR valve? I don't have to worry about emissions test where I live. Thanks.