S-10 Blazer woes.

[Mickey_D]

Been trying to figure out why I'm only getting 10-12mpg out of my little 4.3 Vortec CPI beastie. Figured it down to that my temperature sending unit is toast, which has the truck running "cold" all the time. Which has probably toasted my O2 sensor, fouled the plugs, and in general just made it run like total dog crap. Unless the engine is in fact cold, in which case it runs like a raped ape.

So, picked up a temperature sending unit, an O2 sensor, and all the ignition stuff. Went to go change the cause for all this mess...





I finally found the sending unit. Buried behind the AC compressor and the serpentine belt tensioner. There is absolutely NO way to get it out without taking half the damned engine compartment out!! Not to mention how I'm supposed to get the driver's side plugs out without taking the steering shaft apart. Oh, and that's not taking into consideration the whole cap and wires fiasco...

Still haven't found the O2 sensor yet. No idea where the %$#@ they hid that thing on me.

Ah, the joys of trying to work on an injected vehicle, huh?

[Kurt L]

see your local snap-on man for your new spark plug socket.31.25 on the truck.or order on line from snap-on.it's made especilally for that one plug.i know i had to get one for my wife's blazer[2001].

[GMC AMI]

Extensions and go thru drivers side front wheel well to get the plug out. You may have to put a pry bar against the steering shaft to move just enough to clear. I have done this many times.

[Mickey_D]

Well, I pulled the #1 plug and it looked fine. So I stopped there. Went to go find the O2 sensor.

HAHAHAHAHAHAHAHAHAHA!!!

How in God's name are you supposed to get a wrench on that stupid thing with it between the body and the exhaust pipe?!?!?! Good Lord, it took me almost 10 minutes just to find it.

Oh, and which temperature sender actually goes to the fuel injection computer? The one in the left head, the right head, or the thermostat housing?

And what would cause a "W" Vortec 4.3 to surge at idle, lose all semblance of power once warm (power available is fine when it's cold), and varying power while cruising at 55-60mph? The cruising surge I think is abut the same as the one at idle, so I'm going to guess they are both the same. Oh, and it surges at idle the worst when it's cold, but does it also when it's warm. Just much more pronounced when cold. Almost to the point of stalling then it revs high, idles for a while, then rinse and repeat.

[Tink]

The sensor at the t-stat housing goes to the computer. The one at the head goes to the gauge.

Have you ever replaced the fuel pressure regulator or lines in the intake on this Blazer? Common systems of these failing are bad idle, hard to start, shaky revs, low gas mileage... certainly could have fouled your O2 sensor.

If you remove the upper intake manifold (10 bolts, 10mm deep
socket), a leaking fuel system will have washing on either side where you can
see the 'gold'. This is where the fuel has leaked into the intake and cleaned
the inside. Your able to determine which component is leaking by which side
has the washing. If the drivers side of the intake is washed the fuel lines are
leaking. If the passenger side has washing the fuel pressure regulator itself is leaking. Its not common, but it is possible for both items to fail and leak.

[Mickey_D]

Yeah, I've already been through that PITA with it. Had to change out the regulator.

Something I just noticed tonight is that the Check Engine light comes on with the key, but immediately goes out as soon as there is spark. I always thought these things stayed on for a couple seconds...

Oh, and I jumpered the ODB port and the only code is 12 (SES light verification).

[Tink]

How rusty is this truck? It might be a corroded/bad ground.... I had an 89 S10 in NY that wouldn't idle... it would almost stall, rev up, go back down and almost stall again. I also had a surge at speed and an intermitant loss of power. The problems all stemmed from corroded ground to the ECM. I also had several other bad grounds... the one to the neg. battery cable was so bad the wire wasn't even copper anymore... so, you may want to check the grounds.

[Mickey_D]

I will definitely look into that as this one has quite the case of cancer. Not nearly as bad as my truck, but there's several places where it's taken hold.

Thanks for the tip. I'm going to change out the O2 sensor this weekend anyways as I already have it and can't find the receipt...

[Mickey_D]

Well, I got the O2 sensor out, changed the plugs, wires, cap and rotor. So that's almost the whole ignition system new, the fuel pump, fuel filter, air filter and fuel pressure regulator.

I cannot locate the ECM. I think it's behind the glove box on these, which means I'll never be able to locate it. I took off everything I could, but the glovebox is just too much.

I give up on it. The first person around where I live that is willing to part with $750-1000 for it it's theirs. I can't spend anymore time or money on it, and where I'm moving to requires vehicles to pass smog, which it most certainly will not, so I can't take it with me.

Ah, well. Looks like I'll be "Chevy-less" very soon...

[Mickey_D]

Ok, a friend came out to bring me a stock stereo to put in it so I could sell it. I fired it up so he could hear what was going on and the stupid thing dumb founded me...

IT'S RUNNING FINE!!!

I'm scratching my head trying to figure this thing out now.

[dan42]

That's because you had someone there to help you. The demons were a little shy. But they'll be back...

[b454rat]

Did you check the EGR valve?? Mine did the same thing as yours. Replaced just about everything, but still ran like crap and got worse mileage than my old 97 3/4t with a 454 in it. The spiders were replaced by PO, so didn't think to check them. I pulled the EGR, that looked OK, so then I had no clue what it could be. Idled like crap, it loaded up and would run on 5 cylinders. Had to rev it up to clean it out. Then out of the blue, it ran/idled fine. Still not great, but alot better. If I wasn't getting rid of it, I would pull the EGR and give it a thorough cleaning. Just my .02.

[Mickey_D]

Originally Posted by dan42

That's because you had someone there to help you. The demons were a little shy. But they'll be back...

Oh, they're back. In spades. It's back to running like crap again.

Originally Posted by b454rat

Did you check the EGR valve??

Funny you should mention that, I just got a message back from ChevyTech saying the exact same thing and just now got off the phone with the local Chevy dealership (who by now know me by name just by the sound of my voice on the phone) confirming where the stupid thing is.

I seriously want to find the engineer who thought up the design of everything on this thing and beat him senseless with a Nerf bat!! The EGR valve is behind the serpentine belt and the AC compressor and underneath the throttle body part of the intake!! It's going to take me about an hour just to get to it and some SERIOUSLY creative use of socket extensions to get this stupid piece of emissions crap off so I can clean it out...

[68C15]

get the screened gasket (from Standard motor products # VG57). I get them for about $15. put antiseize on the bolts when you put it back in. I use a 10mm swivel socket and a small peice of paper to hold the bolt to the socket. some black tape on the swivel if its worn out will help. be carefull, its easy to get the bolts crooked, that's where the antiseize comes in handy.

BTW, you may want to pull the #5 plug (rear pass side) to check to fuel fouled. if so you need the lines.

[Mickey_D]

Well, got the EGR valve out, thanks especially to the absolute Saint who thought up the idea of gear wrenches!! Used my handy dandy Goodwrench 10mm and it was a cinch!! Ok, I had to manhandle the thing back in and use gasket tack to hold the gasket in place, but considering where it is, it was actually quite easy.

It didn't look all that dirty, but I cleaned it as best I could anyways and put the new gasket in (with the screen in it).

I then took it over to Walmart and had the guys do that fuel injection service on it. So far, so good. It certainly felt like it responded better to the throttle on the way home. I'll see more on the way to work tonight...

[68C15]

you could accomplish the same results with a bottle of Valvoline #VP052 injector cleaner. (~$12)

[Mickey_D]

Well, with my employee discount it only came to under $15 including tax.

It still surges when I first start it up, but it seems to run a lot better once it's warmed up.

We'll see just how good it's doing the next time I fill it up and check the mileage. So far, so good. I'm at 3/4 tank left and done over 90 miles (20 gallon tank with a new sending unit).

[b454rat]

I have to do mine again too. The wife is gonna be driving it, and I know she will b!tch about the gas mileage. Other than that it's really not a bad running truck. Now I have to get a Y-pipe for it, the O2 sensor is bad, an twisted the whole pipe trying to get it off....