2003 Chev Impala 3.4 L Misfireing Cylinder One

[mmccauley]

Had intake leak on lower intake, i took it apart. I fixed the problem. At the same time I did a tune up, plugs, wires, fual filter, air filter.

When i was finished i used the garden hose to spray down the motor.

The next moring i went for a drive, and noiced a intermite misfire at speeds between 5 and 65 MPH.

So i took it to my local shop, and they deturmine that it was cylinder one, but could not fix it. They tried new coil and differnet plugs and wires.

What else could it be?????????????

[Airjer_]

You need to flow test the number one injector. It may not be it but deffinetely worth the effort. Checking for a vacuum leak (especially around the injector o-ring may not be a bad idea either.

[mmccauley]

all that has been done including new o rings

[maxwedge]

You flow tested the injector? Or did you replace it? I assume all the pushrods are installed properly, there are occasionsly situations where someone has mixed up pushrods on 1 cylinder, bent the valve or pushrod and no compression/misfire in that cyl.

[mmccauley]

i hadit flow tested and tonight i replaced both puchrods on cil#1 and siill the same thing

[Colt Hero]

I'm not a mechanic, but I DID replace my intake gaskets on my Impala and it's been on the road now 7k miles (including an 1800 miles stress test) without any apparent problems.

A few questions/suggestions:

1.) How did the shop know it was cylinder #1? Was there a code?

2.) What plugs and wires are you putting in there? I used OEM for both : AC/Delco Iridium plugs from the AutoZone (41-101, $4/plug if I remember right), wires - again, AC/Delco dealer part ($65). Some cars are finniky about which plugs and wires you use.

3.) Maybe you could try moving a coil around to see if the problem moves to another cylinder?

4.) Maybe you have a leak on your intake around cylinder #1? Before I replaced my gaskets I poured some bright green dye ($3 NAPA) into my coolant and waited for it to bleed out the side of the block. Maybe you could do this to determine whether your gaskets are sealing properly?

Personally, I'm not a big fan of blasting water into the engine compartment. Just seems like overkill to me. I carefully hand-wiped around my block when I replaced my gaskets - just wanted the "V" seals on each side to be shiny and clean afterwards so I could clearly see any possible leaks. I don't know if this is your problem, but it's just another thing to consider when you're trying to determine why your repair isn't working quite right...

[mmccauley]

last night I unpluged the EGR valve wiere the car ran perfict how can this work