Hey guys, new user here.

First off, hats off for the awesome forum site.

I am not a master mechanic by any means, I'm a metal fabrcator/welder, and do my own oil changes, brakes, belts, and routine maintenance. So I'm not illiterate on the subject but I really need some sound advice, so here goes:

I just bought a 94 Blazer Tahoe LT edition, 4.3 v6, 275,000 miles... (ahem)

Got it for a grand, it runs good, the 4x4 high and low still work, all the power seats, lights mirrors and crap still work pretty good.

I have a couple concerns but for now the most immediate is fixing the idle. Since purchasing it, at idle it would occasionally act as if it was going to stall and sometimes it will, in park, or waiting at a light in gear. Give a little throttle and its fine, so temporary fix I wrapped some tape around the idler arm since there is no way to adjust the idler screw. This worked for a while, then I was experiencing high idle, making it hard to stop and really rough putting the vehicle into gear. Assuming the plunger moved and got stuck again.

A former mechanic at Autozone said his first guess would be the idle air control valve, which made since when I took it apart the plunger did not move freely, was seized, and looked original. I bought the part and installed it, Instantly I noticed a lower and smoother idle, shifted into gear just fine, after a block or so it started idling really low again, stalling or wanting to stall.

Where do I go from here so I do not waste any money?

I have some rough looking vacuum lines, and one that comes from somewhere behind the engine seems to be cut and just goes no where, looks to lead to the left of the engine with a couple other vac lines and there is a round evap canister possibly up front to the left behind the battery but it has a vac line. Pinching certain vac lines and fooling with them seems to do nothing, I looked for loose connections to sensors etc etc, not knowing much about this kind of engine.

I know it could be a vac leak or maybe an oxygen sensor, pcv or egr valve or many things. No one can test it since it is a 94 and the code readers autozone etc has will not work. I read about putting a jumper, or paper clip into the two top right terminals???? of the code reader port and starting the engine and writing down the moors code type flashes and checking.

I'm temped to rip all the sensors valves etc off and convert it to carbureted LOL.

SO... hoping someone with knowledge of this engine can give me a few things I can try first, trial and error type of advice etc is much appreciated.

She isn't much to look at but it was in my budget and runs great, I have some all terain tires and better wheels I am putting on, I was just going to throw on a 40 series flow master maybe a brush gaurd etc and be done with it, either keep it or sell it when I get something better, if I can get it running properly.

Thanks in advance for any advice guys!

 

How do I add photos? I was going to post some of my Blazer but it will not let me, is it my 10 day probate period? Thanks again guys.

 

Not sure if it matters but it is the vortev "w" motor, no idea what that means to me personally LOL

 

Forgot to mention my blazer also has new plugs, wires and distributor cap to rule that out.

 

There's a lot of information in your post. I'll see if I can help you sort some of it out. I just sold my '94 Blazer to a friend for his kid to drive.

• The "W" in your VIN means your engine uses central multi-port injection. That means you have one central injector that feeds six poppet nozzles in the intake manifold. It's commonly called a "spider" injector. During the early years of that injection system GM was still putting throttle body injectors (TBI) on those trucks so the distinction is important.

• Just because you have new plugs, wires, cap, and rotor doesn't mean they're not a problem. These trucks only like AC Delco ignition products. A common problem with aftermarket distributor caps is cross firing. You don't seem to be having that problem, though. But be aware that there can be problems with new after market ignition products.

• The first thing I would check on your motor is the EGR valve. It's underneath the throttle body on the intake manifold. Check to see that there aren't any chunks or flakes of carbon causing the EGR pintle to stick open. Also check to see if there is any carbon clogging up the EGR passage in the manifold.

• The next thing I would check is the IAC valve. Clean it well with brake cleaner. Clean the IAC passage in the throttle body. Gunk can cause problems with the function of the IAC valve.

• After that check the vacuum lines. Make sure they're all in good working order with no leaks. Make sure they're routed to the correct places. It's somewhat of a confusing system since there's one port off the back of the intake manifold near the distributor. That line has a bunch of tees and wyes coming off it. One goes to the 4WD system, one to the HVAC system, one to the cruise control servo, and others go other places. Get a good diagram and verify the routing of everything.

Good luck!

 

A stuck open egr can cause bad idle. It sounds like the iac is working, if the passage was dirty it would idle high. Pretty much with these engines the ECM's diagnostic abilities are terrible, if it even throws a code. Mine was black smokeing and stalling all the time with no codes at all. You need to get a vacuum pressure reading and fuel pressure reading. Also if you know how to use a multi-meter it would help ALOT. There are 2 major sensors that control idle quality, TPS and MAP. The IAC is controlled by them. If fuel pressure is between 55-65, vacuum pressure is above 15, base timing is correct at 0, then its one of those 3 sensors. The O2 doesnt effect this engine greatly and wont cause idle issues. And AcDelco ignition parts is a must (cap, rotor, plugs) standard copper will do.

 

Andrew and Toby thanks a great deal for the insight, Toby were can I get a good pic or diagram to show me exactly where and what the EGR and IAC valves are??

I always use AC Delco plugs ect but this work was done prior to me buying it, I assume he was trying to fix the idle problem.

One "spider" injector? Wow I have never heard of that, I know taking out fuel injectors normaly means buying and replacing all the O rings on the fuel rails nd injectors themselves and still is a pain getting it all to fit back properly, is this the case with these single spider injectors as well?

Back to the vac lines and ABS, My ABS light is on. The lines were FULL of air when I got it and had to replace the rear wheel cylinders on the rear drums since the guy b4 me broke the bleeders off. I have heard brake booster problems and ABS/master cylinder problems can cause a vacuum problem for the entire engine... The ABS connectors were disconected when I got it, I plugged them back in and the light came on, any significance?

Also a good diagram of the vac lines would be great also as I said one of the rear ones is rotted broken and leads no where, and I do not see anywhere that is missing one.

Also what about unhooking the negative battery cable to reset the computer in the vehicle?

Thanks a million guys!

 

Well I found and took off the EGR valve, there was alot of black carbon grime but didnt see any chunks, i blasted it thoroughly with carb cleaner and did the same for any and all ports i could find. During so I found a vacuum line the went in the bottom of the intake that was not connected. I reconnected that and put everything back together, the EGR gasket was in really bad shape but I had no money to get one. It is idling a little better now still acts like its going to stall but doesnt completely die everytime like before, only seldom now. I located the "spider" injector unbolted it but could not easily remove it so I just left it alone fearing I would ruin the O rings etc.

I did notice that when the engine would try to stall the voltmeter in the dash was dropping the same time as the engine trying to stall, oil pressure gauge was doing the same thing, is this simply because the alternator is spinning slower when it tried to die or could it be a spark or distributor issue? Next thing I am going to do it buy some vacuum line and replace everything I can see.

Thanks again for all the help guys!

 

ok, there is a vacuum line right below the throttle blade. I forget where it goes, i think evap canister. It wont cause a noticeable vacuum leak. Then on the back of the intake there are 2 ports. The driver side is a large line for the brake booster. On the passenger sider is a smaller port that should go to a 4 way spliter, These lines are for cruise control, ac vent control, transfer case vacuum, and a vacuum ball.
The IAC valve is on the upper intake near the throttle blade, its bolted in the passenger side of it.
The spider injector is accessable after taking off the upper intake. Its not a typical injector set-up. Only O-rings needed to replace are the ones for the fuel lines into the injector housing. The injector is in a housing with 6 tubes coming out of it with poppet valves on the ends. The poppets are clipped in and all you have to do is squeeze them and pull (not too hard). When you take the upper intake off it should be black inside there. Any clean spots indicate fuel leaking which is bad. 2 spots leak fuel are the pressure regulator and the plastic lines going to the housing.
You should get a screened EGR gasket
If the engine is dying the voltage will drop and so will oil pressure because rpm's are so low. Hell, my lights are dim at idle but brighten up when i give it gas. Thats the difference between 700 rpm and 1000. The motor might be getting as low as 250 rpm when it tries to die.

 

Thanks Andrew.

The screen seemed to be attatched to the EGR housing as it did not come off with the gasket, I also saw no way to take apart the EGR to clean it thouroughly so i sprayed carb cleaner into the port with the screen and the other one with the tork head screw plunger. That screw seems to just spin freely and go in and out. I do know where the vacuum ball is located, right behind my battery, those lines look pretty rough, ok the vac line under the blade is the one that was not connected, does it go around the engine and come out the left side behind the distributor? because that is where I have a broken line that goes no where, finding a vac line diagram would be great but no idea where to look for that, google isnt much help these days either.

So when I take the "vortek" black cover off and the air filter assembly that black round housing in the middle ontop of the intake is the spider injector or no? It had two tork olts on it, I removed them and it did not budge, I actually have to take the upper intake manifold off?

At this point I am guessing a vacuum leak or possible a fouled plug since it has a pretty regular pattern when stalling almost like its only doing it on one cylinder wanting to stall every 3 seconds or so, I discounted this since the plugs wires and cap are new, autolite not ac delco, and it runs fine at speed....

Thanks a million.

P.s. on a second note, my read window and tailgate will not lock, i just trist the black handle and the glass and gate open right up, I have tried both the ignition key and door key to lock it but the tumbler does not seem to spin freely of the housing or whatever, when i turn the key the whole handle turns with it, and when trying to hold the handle still the lock does not engage, was there a speperate key or should i try takin it apart etc.