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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #1
I've been reading through the posts regarding EGR valves, and especially the one where 964pt3 left that huge post about the history and complete functionality of the EGR.

What I'm starting a new thread about, is the problems I've been having with my S10.

Some of you probably remember me as the guy who just can't seem to keep his truck running right. I'll go into a bit more detail, but first here's what I have.

1998 Chevy S10 Extended Cab
4.3 Vortec V-6
5-speed
Black with stepsides ;)
148,000 Miles on it today.

Now...in this year alone I've done the following to my truck:

Wrecked in Feb -
replaced bed,
rear left axle,
rear left drum brake setup

couple of months after I fixed it, it died on the interstate. I replaced $300 worth of stuff on it at that point to make it run.
timing chain and gear
timing chain cover
oil pan gasket
crankshaft sensor
ignition coil
ignition module
distributor cap
rotary button
water pump gasket
antifreeze
(not in that particular order)

so all that stuff is new.
the check engine light came on after driving it for about 15-20 minutes, and stayed on.

At that point, I was too tired to work on ANYTHING for awhile. I just drove it like it was.

Replaced the idler pulley a thousand or so miles after that, cause it had set in the rain and rusted the bearings.

About 2000-3000 miles after that, the truck starting losing power and mileage...just happened on the interstate one day almost all at once.

Lightly pressing the gas was fine. Pressing it all the way down would make the motor bog down quite a bit, and wouldn't exceed 3000 RPM. Pressing the pedal down anywhere inbetween would cause the motor to start jerking. I guess it was missing really bad. It was weird. If I was in Neutral, and I revved the motor up, it would start pinging really bad at anything above 3000 rpm. It would also ping if I let the rpm's slip below 500 at any time. It's never done that before.

I had Autozone check the codes, and the codes said I had the following codes:

P0101 - Mass Air Flow Sensor
P0300 - Random Cylinder Misfire
P0404 - EGR valve out of range

Catylist efficiancy below threshold ( I think this was for an oxygen sensor ).

Well, I wasn't about to start replacing stuff that I wasn't sure about, cause, at this point, I'm broke, I did go ahead and replace the Fuel filter and Spark plugs. The wires have about 10,000 miles on them, so I left em. My K&N air filter has been recharged in the past 15,000, and still looks clean.

I took it to a mechanic (kind of a back yard mechanic.) so that he could use his test equipment to try and solve the problem. He had me replace the MAP sensor, to no avail, and just this weekend, he replaced the Mass Air Flow Sensor and my coil wire. Still, nothing. He finally unplugged my EGR valve, and managed to keep it from jerking really bad, but the power loss is still there.

I forgot to mention, the truck ONLY has a problem once it's warmed up. When it's cold, I can get the rpm's up without a problem, and it runs like it should.

I'm begging for help at this point. I'm willing to replace the EGR Valve, or even put one of those restrictor plate mods on there instead, IF I can be reasonably sure that's the problem.

I've spent $1200 on this truck just this year alone, not to mention the payments, etc, etc, etc. Any help at this point would be greatly appreciated!
 

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Project: Sabriel
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12,507 Posts
go to a dealership and have them test your cat. that might be the problem for it running poorly when it gets hot. i had a cat gt itself, and when it got heated up, the cat elements would expand and block the exhaust pipe, to the point of the truck not running anymore. if its a lot more, id seriously consider trading the truck for another one, with a clean bill of health.
 

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Early Member
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3,136 Posts
I would clean out the EGR before I would replace it. It does sound like your cat. is bad. When mine went it was ok cold but would loose power when it was warm. The last day I drove the truck before I had the cat. replaced it pinged real bad and I couldn't drive faster 45 mph.
 

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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #4
That sounds right!

Both myself AND the mechanic have removed and cleaned the EGR Valve. It wasn't dirty in the least and the little valve inside moved very freely.

My truck won't get over 50 if I'm going up a hill. I still don't understand how it happened all of a sudden though.

I realize that this may screw up my emissions, but what would happen if I just removed the stuff in my catalytic converter? I've heard of plenty of people doing it to give them a bit more horsepower, and where I live, I don't have to worry about emissions when I get my tags.

You think it would help?
 

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Project: Sabriel
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12,507 Posts
you'd have to get an O2 sim for the O2 sensor after the cat, but its worth a shot. however, i think the O2 sim is as much as a hi-flow cat.
 

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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #6
I called a service center to see how much it would cost to have my cat checked. They want to charge $70+ for it. Is there an easier/cheaper way to get this done?

As for the O2 sim..I'm guessing that's a fake oxygen sensor tells the computer what it want's to hear? *shrugs*

I like the sound of a Hi-flow cat though. Any suggestions on that? Brand? how much they run?, etc.
 

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Project: Sabriel
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12,507 Posts
catco makes them, ive heard prces from $25 to $175, guess it depends on what kind and what company you buy it from. if its going to cost $70 for a at check, id just go ahead and buy a new one, especially if the one on your truck is stock (mine died at about 62,000 miles, and youve got more than double that).
 

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1,329 Posts
Waverly360 said:

P0101 - Mass Air Flow Sensor
P0300 - Random Cylinder Misfire
P0404 - EGR valve out of range

I'm gonna go with the cat also. The three godes you have are pointing at it, plus the facts you list as how it runs.

P0101- is the sensor is out of range and far as reading
P0404- Is saying to much egr is being added.
P0300- is backing it also.

Is you get too much egr, which shouldnt happen, a MAF reading out of range versus the TPS setting, well its saying not enough air, too much egr and both combined will make it misfire. WHY?? The exhaust is plugged so the motor cant breathe, adding so muc back pressure EGR is taking over the intake and causing the misfires.

Cheap home check. Drill a 1/4 hole before the cat, feel the pressure escaping, or use a vacuum gauge to read pressure, weld it shut or muffler tape. Drill hole behind cat, same test. They should be nearly the same, if the front hole really moves air the cat is screwed!!
 

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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #9
Cat clogged...

I don't really have the means to drill or weld anything at my house unfortunately. What I'm thinking about doing now (aside from spending $100 on a new EGR) is getting an O2 Sim and gutting my cat. MuddyS10, from what I've read, even if I get a high flow cat, I'll still need one of those O2 sims anyways. So, why not just do that first? It wouldn't make sense for me to put another stock Cat on the thing at this point.

Where I live, I don't even have to go through emissions.

Any ideas in addition to all that, as to why the cat would just start acting up all of a sudden? I mean...could it have been a combination of all of the other stuff that could have caused it? I figured something like that would have been a bit more gradual.

When I wrecked my truck earlier this year, the lady that hit me hit right square on my left wheel, effectively breaking the axle. Think maybe that could have knocked something loose inside the cat that would be blocking the air way? Also, my tail pipe got kinked a bit when that happened as well. Just now remembered that. Had to knock a bunch of dirt out of it. I bent it back, and although the air flow was probably restricted a little, it still seems like there's plenty of room for air to flow...I'm thinking about maybe just going straight pipes out the back.

148,000 miles...What's the normal life span of a catalytic conv?
 

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80,000 is all GM has to make them last and your at 148K. The old days in the 80's you were lucky to have one last 60K.

Its lived its life really, nothing to add to that.
As far as all of a sudden, well when they go pieces can break off and maybe clogged it right up being in the right spot. Being rich cause this to happen sooner, but again 148K is not soon!!

That women may when she hit dislodege something or the bend you may have thought you got out, isnt quite right!!
 

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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #11
It's Fixed!!!

WOO HOO!!! My truck is running like it's supposed to again!

I removed the bolts on my cat and took an old axle rod (off of this truck actually) and beat the insides of my cat to pieces, then revved up the motor several times to blow that crap out. I'm nealy positive I got all the loose junk out of there. Nothing rattles anymore when I hit the cat.

It sounds like crap of course. I couldn't bolt the muffler and tailpipe back to the cat, because I ended up snapping all three bolts off when I dissassembled it. Hopefully it'll get quieter when I have the muffler shop replace those bolts tommorrow.

I took it around for a test drive, and I got to 5000 rpm super easy, and with more power than I ever remember having!

My only concern at this point, is that the motor seems to backfire occasionally if I let off the gas at high rpms. Will my computer eventually re-educate itself to keep from doing this? If not, then obviously I have another problem somewhere that needs to be resolved.

Thanks to everyone for all of your help. I'm sure many of you understand the stress I was dealing with in trying to get this thing running like it should.

It's so fast now! I'm really itching to try a CAI and an EGR mod now...if only I could kill the speed governor ;)
 

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GET A MUFFLER ON NOW!!!! The backfire is air getting sucked into the hot exhaust and combusting. It could be very damaging to the motor if that combusts and bends a valve due to it. These motors do need backpressure and my suggestion would be not to get to free a flow muffler to help make up for the backpressure that cat would add if it was new!!
 

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98 4.3 V6 5 spd black ext
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82 Posts
Discussion Starter #13
Okay then.

I plan on bolting the muffler back onto my cat now, but I have to go buy some new bolts for it. I ended up twisting all of mine off when I tried to take it off. The muffler and pipe is still hanging back there, they're just not connected.

Maybe you can answer this for me as well. Can I replace the studs in the cat? or am I going to have to just drill the holes out and put a bolt and nut on it?
 

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Gaaoooooo
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The backfiring you speak of, are talking about crackling/popping when you let off the gas, or actual backfiring within the motor itself? The first thing is common and does no damage, while the latter definitely does some damage if it continues!
 

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MINTSICK said:
The backfiring you speak of, are talking about crackling/popping when you let off the gas, or actual backfiring within the motor itself? The first thing is common and does no damage, while the latter definitely does some damage if it continues!
Even the crackling/popping does damage but its very slow to do so. Its still a aftercombustion in the exhaust due to drawing in lower amounts of cooler air when you get off the gas!!
 

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Still waters run Deep
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937 Posts
Bringin up an old topic, where is the EGR valve on my 99 4.3 S-10 and how do I clean it?

Thanks
 

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i have a 94 4.3 tbi and it does sort of the same thing anything under 2500 rpm and it bogs at full throttle or bucks at anything more than half throttle. when it gets over 2500 it feels like a turbo kicks iin. i have a 3 inch catback and dynomax muffler on it and i put a new y pipe on it cause i ran something over and it smashed the drivers side pipe into the tranny. after putting that on i thought it would make the exhaust louder or give me some more power but i got nothing. could my cat be clogged?
 

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Clean N' Dark
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I hope you had the muffler out of the way when you cleared your gutted cat. All you might have done is plug your muffler up with junk.

Also, maybe look into a hi flow muffler.
 

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When my cat went i had to replace the whole exuast system it sucked so much crap through it(not to mention it was rusted through in some places). It was $247.00 for the cat and new exhaust but it was well worth it. This was on my 92 GMC jimmy 4.3 liter with 194,000 miles on it the orginal cat, orignal motor, and original transmission I am still amazed this thing keeps starting for me.
 
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