It's been 2 years since my last full tune up, so I figured that this weekend would be the perfect time. New plugs, plug wires, distributor cap, rotor, air filter. It was running just fine before I started. But as it goes....

After installing all the new items:
AC Delco Rotor and Cap
Autolite Plug Wires
Bosch Platinum 2 Plugs

...now when I crank it over, it sounds like the motor is missing, like I got a wire crossed or a plug is fouled.

Just to be sure, I checked the firing and my wires are correctly placed. I even went in reverse order to try locating the problem. I first replace all the old plug wires. Same problem. Then I pulled out the new Bosch 2 plugs one at a time and replaced them with the old ones. After each replacement, I started the motor to see if it would run smoothly. Every time, it still ran rough. I even went as far as to replace the original rotor. Same new problem with the rough idle. If I try to put some gas to it, the motor chokes and knocks like someone trying to kick their way out of a box! I've replaced this stuff many times before and never had this problem. Could my "tune up" have caused a timing issue? I've never had to set timing before. Could it be the Distributor itself? Coil? If so, then why?

What could be the cause of my new problem?
Thanks for ANY suggestions. I'm at a loss.

1994 S10 Blazer Tahoe 4.3 Vortec W with 270K miles

 

Double check the firing order, I know there is 2 that are easy to mess up cause they actually cross the center of the distributor, its 2+5 as you can see. It looks messy when put together, and when you cross the 2 it looks nice and clean. You didnt pull the distributor up out of the hole did you? If you didnt, then the only thing it can be is crossed wires. This is the pattern.

6--5
4--3
2--1
FRONT OF ENGINE

-4--3-
5----2
-6--1-
FRONT OF DISTRIBUTOR

If it was running fine, even with 2 wires taken off it will still run just horribly. Not wanting to run is cause there is 2 that actually fire at the wrong time. Remove 2 and 5 and see if she will run just sloppy. Im sure you just got those 2 crossed.

 

That is the order that I have hooked up. But I just went out to check everything again. Once verified, I removed 2 and 5 and cranked her over. She started and ran like normal! Not even horribly! I could smell fuel, as if it were flooded. I turned it off after about 15 seconds. I reconnected 2 and 5 and she started right up again. She idled smoothly for about 10 seconds, then started choking again. I turned off the ignition, and once again removed 2 and 5 to see if I could get the same result. When I cranked her this time, she fired up, but idled not just rough, but horrible.

When I removed the original rotor, the new one gave me a challenge to put on, so I used a hammer to lightly tap it onto the distributor. I never pulled it up and out, but when I removed the new rotor in my backtracking, I had to pull it up with a lot more force than the original. Is it possible that I could have somehow spun it a tooth or two? It does have a little vertical play if I pull straight up on the rotor.

We MUST be getting close to the solution.

 

Oh,
And I haven't read it all yet, but I'll be following your 93 build thread. Let me know if you have any leads on that spiffy digital instrument cluster. I've been driving with mine out for over 3 years now. Can't seem to find one under $100.

 

well other members have gotten one from digitaldashsolutions.com and liked them. He wants 200, and you get 100 back when you send in your old dash... Im going to send in my current on with 100 so I get the same milage once its repaired since I dont need the truck to drive around.

My builds gonna be on hold till it warms up a little, then complete teardown starts. Order up a superlift kit and some rolling stock once I get my work bonus methinks.

Back to the topic, for ****s and giggles what happens if you hook up 2 and 5 backwards? And you may have cracked that new rotor hitting it. Pull it off and use some diletric grease or veggie oil if you dont have the silicone grease to put it on properly if its not cracked. The distributor wil have a little up down play, just no lateral play. No you didnt jump it a tooth hitting it - maybe broke the rotor though.

 

The rotor still looks good. And during the troubleshooting, I replaced the new rotor with the old one and got the same result with the rough idle. I still have a little grease left. Decided to keep what's left until I get the ol' girl back on the road. I'll try switching 2 and 5 in the morning and see what happens, but I know we have it wired the way it's "supposed" to be.

And thanks for the tip on the dash. I may have to break down and spend the $100 when I decide to finally replace it.

 

I'd check all vacuum lines around the cap and make sure none were messed with or wiggled loose. EGR? Maybe a line to that. No CEL I suppose. Its usual to not get a cel for your problem your describing. I'd bet if you would put everything back to the way you had it, like you'd said, it would still be a rough idle. Maybe try disconnecting the battery. Never know. Did you have it disconnected during your tune up? I'm wanting to think something got bumped or went bad. Check all wiring. Does it still idle rough when its warmed up? Maybe the IAC? Just throwing things out there. OXY Sensor wires okay?

Hate to ask this and no pun intended, gap on plugs proper? That killed me one time with a horrible idle and run all together.

 

As it sits right now, all the old is re-installed and the idle is still rough. I never disconnected the battery for any of this work.As for the spark gap, the plugs I'm using (Bosch Platinum 2) are non-gap for both the old and the new. (As in no gapping required) Since nothing has worked going back to old, I will reinstall the new parts again tomorrow and check your suggestions while I'm at it. I should have a new update posted no later than about noon Eastern time.

 

Grrrrr!!!
So I put in the new plugs this morning. Looked for other lines that may have got knocked loose. Nothing. Disconnected the battery for a minute. Satisfied with the look-over, cranked her over. Started just fine and ran perfect at idle. So I just let it sit there and run while I timed it. At 2 1/2 minutes...

COUGH! COUGH! CHOKE! COUGH! Shutdown.

During this fit, I happened to notice...white smoke from the tailpipe. (You gotta be kidding me!) So, now what?

By the way, I live in Central Florida and we've been in the mid 80's all week and the current temp outside is 61.

 

After researching "white tailpipe smoke" in the forum, I found quite a few suggestions that could prove to be helpful with my scenario. One (of the many, apparently) possibility is a blown head gasket and one way to check for this is to start with the engine cold, remove the radiator cap, and look for bubbles when started. This would be an indication of a bad head gasket. (Can anyone confirm this?)

When I attempted this test just now, I discovered that I was low on coolant...like a gallon of water low! After filling it with the engine running, I think bubbles were present, but hard to tell if they were just from the new addition of water.

Also, this time the motor stayed on. It just surged about every 1.5 seconds. And consistently as if synced on a timer. (Vroom...pause...vroom...pause...vroom...pause...) And the whole time, white smoke from the tailpipe.

I just don't get why this problem would show up suddenly and instantly from changing out parts that should have made everything better, not worse! It's frustrating. Back to the research until more of you gurus chime in again. You guys rock, and I'd never be able to fix this on my own without all of your help.