can someone help me troubleshoot my 4.3 Vortec. It wont start.

Did you notice anything unique about the design of the distributor cap, does it seem different somehow?

No not really. Pretty much the same as any other GM cap. One thing I noticed is that the engine seems to bump and sputter after I dis-engage the starter motor, almost like the rotor is in backwards. I never did take the rotor out, just cleaned it.

I wonder if these engines will run with bad O2 sensors.

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Really? You didn't notice that all the spark plug wires for the left side of the engine exit the left side of the distributor cap, and the spark plug wires for the right side of the engine exit the right side of the distributor cap (even though the firing order alternates left to right), and that the coil secondary wire plugs into the right side of the cap and not the top center and though the top of the distributor cap is somewhat flat, you didn't notice any raised areas running side to side?

Your first post mentioned that there was a O2 "heater" code(s) stored. A failed O2 heater rarely if ever causes a no start.

I didnt even notice that and I think you may have solved my problem. Firing order left to right, front to back 165432 but around the cap it goes 124653, or 135642 depending on which way it turns. Doesnt seem to match the firing order so this thing must have to spin much faster to line up the spark to the right cylinder.

I appreciate the clue that It should start with bad O2 sensors.

So let me think, I changed the plugs and gapped them to .060 The plugs that came out although pretty decent shape, had the gap slightly smaller due to metal migration. I drove the van from the dry warm garage into the rain and let it sit for 2 days. Now it wont start. I have fuel and I have spark, and it misfires, perhaps its time to replace the wires, cap and rotor.

Am I on the right track?

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Rotor turns clockwise as viewed from the top. The cap should be wired;

Coil

It's just an open O2 heater, all that will happen is it will take a few seconds longer to go into closed loop.

The rain is the #1 clue. Change the distributor cap for sure, do the wires if the mileage is nearing 80K. Buy the cap and rotor from GM (Delco), no others will give satisfactory service. The dielectric strength of the cap has broken down, you can see on the top of the cap where the secondary conductors criss-cross allowing the wires to be installed on the sides to match the engine lay out, where the secondary conductor passes close to the coil conductor inside the cap is usually where the breakdown occurs. There are two air vents on the bottom of the distributor bowl, you need to make certain that they're clear and open so that the cap is properly vented. Be careful, that distributor housing is plastic and it's not unheard of to break when removing the distributor cap screws.

Post the exact O2 code numbers and we can tell you specifically which of the four O2 sensors needs replacement.

On a vehicle only 3 years old I wouldn't think the ignition parts would be bad. I would go back through the process and figure out what you might have done wrong. Moisture in the distributor is a likely suspect. I cleaned up an engine in a Grand Am (with a garden hose!) and the car wouldn't start or wouldn't stay running for 3 months. One day it started and was fine after that.

Just curious.....did you use pliers to loosen the spark plug boots?

Dave

This is a 2003. I thought they did away with cap and rotors. Even my 1998 has dedicated ignition coil fro each cyclinders. My engine is a 3.4l.

I have the 4.3 in my 2004 Express van and it most certainly has a distributor with cap, rotor, and plug wires.

Pleae check if you have sparks at the end of plug wires.

I had a problem like yours, however my problem is bad contacts at coil. so Even i have spark, it was weak.

One more think: i thought when the spark plugs gets old, the gap gets bigger not smaller.

good luck

I changed the wires, and the cap and rotor and it started right up. Apparently this must be an early 2003 van that still has a distributor. The old cap was clean with no signs of arcing

I don't have the code anymore for the engine scan, but have ordered one for myself. Thanks

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This is Crazy! Why would a 2002 -2003 Van still have a distributor cap when it seems like it was the standard for all cars to have coil packs that fired electronically on their own for decades before 2002. Year

GM must have seriously missed the boat on this one, sticking with old school low tech engines for so long.

East-

Frank White wrote:

some of the early gm cars (buick riviera) has coil packs. In my 97 blazer 4.3 it had distributor. I think they decided to keep using considerin that it works fine.

Frank:

1. check the order of the plug wires. I hope the rotor goes in one direction. some cars can go in an other direction which is 180.

1.Please check it again that you get spark.

1. do you get fuel into the cylinders: test: unplug one of the spark plugs and ground it. crank the car, and then pullthe plug and try to smell it. or assuming that you donot get fuel, you can spray some carb cleaner in the intake as you crank. it should start then if it is the fuel problem.

1. make it advence or lean by rotating the distributor,

2. it might be wild but if you have time, rotate the spark plug wires in circular fasion on the top of the distributor cap, then advence or retard the timing. (Even the rotors goes in one direction, the distributor does not, mine (91 safari z engine and 97 blazer w engine)have a gear at the bottom).

1. start praying you donot kill starter during all these steps.

Keep us updated.

You must not look under the hood of many vehicles. There are still a lot of them that have distributors. Why toss out a system that works very well and costs less to maintain overall. GM was one of the first domestic brands to build engines using coil packs.