A bit of an update here. First my issue was becoming much more consistant. Living in a small town again, I have a short list of places I go. From my house, it is roughly “equal work” to drive to the ferry terminal, the big store/hardware store (same parking lot), or the local market. Most days, if I start with a cold engine and drive to any of these locations, I’ll start to run rough just as I get to my destination.
Second big update: A few days ago, I was going to visit a friend back on the mainland. At the ferry terminal, my truck was having a lot of issues. In line, I was trying to test the EGR valve or at least check the vaccuum lines involved. When I pulled the vac line to the EGR, the truck started to run better within about 20 seconds.
I wasn’t sure if it was the problem or what the long-term effects of having this vac line disconnected, so I hooked it back up. There was no immediate effect after this, but a lot of other variables changed in the mean time.
I swung by my old Mechanic’s (a personal friend) shop on the way through to ask his advice on replacing the valve myself or cost for him to do it. I showed him the video and explained all the various info. He concurred that the EGR was probably bad.
He asked me “Wait, what year is your truck?” It’s a '95. “Your truck is not OBD2 so it will run fine without your EGR. It’s just an emissions thing that cleans up your exhaust, IF IT WORKS. If it is broken, it makes your emissions worse. Here: let’s do some diagnostic testing on it. Unplug the vaccuum line from it and drive your truck for a week. If you still have the problem, then it’s something else. If your problem is fixed, then your EGR is bad and ‘should be’ replaced. If it is the EGR, just leave the vaccuum hose unplugged and we can probably get around to replacing the valve, sometime in the next year or 3.”
2 days later of driving a lot in diffeent areas, I haven’t had the problem at all!
Happy story Brian! Great feeling to learn it was something simple and not the end of the old truck.
reminds me of an old car I had years ago that I bought cheap from friends. It would just completely die sometimes going right down the road. They took it to a dozen mechanics who replaced lots of expensive parts to no avail. When I bought it, I drove it a couple weeks while taking notes about what conditions it misbehave under. then I took it to my excellent mechanic. He found the trouble. the ground wire from the computer was not making good contact. cleaned it up and it ran like a new car. a couple times after that, it started acting up again and I cleaned up the contact, worked perfect again.
Brian, the EGR valves are famous for getting pieces of rust stuck in them from the exhaust manifolds even though they usually have a screen in them. It sounds like you have a vacuum operated one. You can open that manually usually by pushing on the diaghram. They are electronic on most of mine now and have a motor / servo to open and close them. Make sure you plug the vacuum line to the manifold when you unhook it or you are adding air to the intake. There are half a dozen other things I could mention but I have to go to the post office … Mike L
Brian, I just started up and looked at my 93 Chev Silverado with 4.3 L and it has a vacuum EGR on it. The 4.3 is a 350 minus 2 jugs. All else is the same. The 95 being near the same probably does as well. you can reach into it and work it manually with your fingers when it is acting up. Spray WD40 on the shaft on it where it goes into the manifold and work it by hand a bit. When we run woodgas, the intake manifold vacuums are no where near what they are on gasoline. I’m very often near WOT (wide open throttle) and when going down a hill I open the throttle to pull on and stoke the gasifier for the next hill as we are up and down hills here non-stop. The truck won’t idle right if there is a chunk of crud stuck in the valve part of the valve. My 95 S-10 has an electronic valve with it’s 4.3L. My 98 S-10 2.2L is all electronic controlled and OBD2 … Mike
EGR sounds like it’s ok (sealing with no vacuum and opening with it). Replacing it will likely do no good. Check the solenoids, switches before it to see if your getting vacuum when you don’t need it. May run fine without it but watch for pinging from running without it.
Mike: What my mechanic friend was saying, without directly saying it, is that my vacuum EGR without computer is effectively not needed, so we disabled it. I will plug up the vacuum line that was unhooked though.
Marvin: From what I’m gathering, is that it was sticking open when it wasn’t supposed to be doing so and throwing off my O2/Air:Fuel ratios.
Could be sticking, could be getting vacuum when it isn’t needed if something upstream is sticking. You can start swapping parts or figure out what parts to swap.
I think your EGR is the same as mine … The main purpose of the damn things is when you go down a long hill and take your foot off the gas pedal, it will open from the vacuum created in the intake manifold which is probably 30 times anything we do on wood and feed some exhaust gas into the intake manifold to equalize things and prevent the carb, tbi, etc from sucking fuel into the engine and wasting it and also to force the fuel wasted to the valve opening back into the engine to prevent and lower HC emissions … In the old days we didn’t care … I’ve had many cars with draft tubes on them … They don’t design engines for hydrogen / carbonic oxide so make the best and keep us updated … I have never had to disconnect one so I still suggest you reach in and work it by hand and feel how it moves and also spray WD40 or similar on the shaft. I usually rev and then suddenly stop revving the engine while doing all this to clear the “seat” of the valve. Of course some crap may go through the engine but remember we trust a hay filter to keep crap out … I have 20+ feet of tubing going straight to my engine after that … I do have a stainless grid in line but it is around 1/8" squares. The earlier GM MFI engines had a ceramic grid in them to disperse the air flow so the Mass Flow sensors with thermocouples would work right and these provided a safe filter but they also used plastic gaskets and manifolds on the intakes which would shrink and leak and liquid lock and otherwise blow a piston and wreck an otherwise perfect engine. I will never buy a 3800 again … I doubt your 95 350 will ever have these issues. My 93 is so rotten now and the whole series is history here in the salt belt … Mike
Oh, I just wanted to add that if you disable the EGR valve on a car or truck with a cat converter that any unburned gasoline (etc.) may hit the converter and cause it to explode. They run at a 1000 or 2000 degrees if I recall right … I have exploded a few … I hate that bang … Mike
Mike L. “They don’t design engines for hydrogen / carbonic oxide so make the best and keep us updated …”
I should probably note that this truck is NOT on woodgas or have any woodgas related modifications. It is pretty damned near bone stock dino-fueled.
Mike L “The main purpose of the damn things is when you go down a long hill and take your foot off the gas pedal, it will open from the vacuum created in the intake manifold which is probably 30 times anything we do on wood and feed some exhaust gas into the intake manifold to equalize things and prevent the carb, tbi, etc from sucking fuel into the engine and wasting it and also to force the fuel wasted to the valve opening back into the engine to prevent and lower HC emissions”
Does the fact that I hate “compression braking” and generally shift in to Neutral any time I go down a hill negate the need for the EGR in my case? The idea of using Dino juice to slow my vehicle just seems ridiculous to me…
Neutral coasting on newer vehicles actually uses more fuel than coasting in gear. The term is DFCO, or deceleration fuel cut-off. Any fuel injected system is programmed to do this, when revs are high and throttle is closed. If you go to neutral it will simply idle, and burn some gas.
Compression braking does not use fuel to slow you down. It takes the momentum of the vehicle and forces the engine to turn over, which is hard work and uses up your momentum, thus slowing you down. No fuel is used, and again on modern engines they will even shut off the idle flow.
Another controversial technique (only for manual transmissions) is engine off coasting in neutral. This gets you the most from your momentum without any idle gasoline. It only makes sense when you can make use of the momentum, ie there’s no stop sign ahead, and your speed won’t increase significantly in neutral. But this is technically illegal, and can be dangerous if you’re not careful. Not recommending it…
Shifting into neutral is very baaaaaaaaad. If you put the truck back into gear it has to make the clutch packs rapidly engage and slip to get the engine back up to speed and may have to shift through several gears seeking where it is supposed to be. Never mind accidentally putting it into reverse. I drive stick shifts now.
Just free up and lubricate the shaft on the egr valve so it works like it is supposed to … I thought you were running wood and having the problem … Check the fresh air intake for the PVC system which is probably on the back of the collar under the air cleaner. They tend to rust shut … M
I forgot to mention that if the engine has a bad EGR and it doesn’t idle without revving the motor, it will probably stall while coasting and you will lose both power brakes and power steering. That truck will not start when you put it in gear if it has stalled and the engine won’t crank unless it is in neutral and the switch actually works in that position . I usually wire a switch across the neutral safety switch in case my cars stall so I can crank the engine in any gear and hopefully it will re-start and the steering and brakes will come back on line. M