Engine miss (help) acts like a dead cylinder all the time

[turboclam]

I have checked so far...............

No smoke
No fluids mixing
Not losing fluid
Got spark
Got injector fire
Spark plugs changed (look OK)
Plug wires changed
Coil and module changed
Compression test (good)
Filled all cylinders with air checking for leaks (good)
Cam sensor OK
Crank sensor OK
Roller rocker assembly seems to be working correctly (valves are working equally)
Mass air and translator OK
Only thing I haven't checked is the ECM. I don't have an extra modded ECM.

Am I missing something? Thanks

 

[wormy-28]

engine miss

You can pass a compression test and a leakdown test,,,,,but that doesn't mean the valves are opening. Check for a worn cam lobe, bent pushrod, something. I just went through this on mine. Found no exhuast lobe on cylinder 4 exhaust.

 

[turboclam]

.

I've got a roller cam and I ran the motor with the valve covers off. Everything looks OK.

 

[3point8]

out of touch etc.

Ignore this post. Wrong forum

 

[Chuck Leeper]

"Got injector fire", does not necessarily mean the inj is working.
Maybe check each exh port tube w/ a infrared gun. If the cyl is dead, you'll see it in the temp reading.
Unhook the plug wires 1 at a time. Same w/ the injs. See what you find.
Cam sensor in 180* off?

 

[turboclam]

Thanks Chuck

I let the motor run while unplugging each injector and the idle fell each time. I will go purchase one of those lazer temp guns so maybe I can track a cylinder(s). Cam sensor has not been messed with and the indicator is still where it's suppose to be. Any other ideas let me know. Thanks

 

[davinci50]

were all changes in Rpm equal?? you could have a lazy injector as well. Good Luck

 

[Chuck Leeper]

Cracked plug?
Plug wire w/ bad end?
Module not grounded?
EGR stuck, leaking at stem?
Carbon tracks on coil tower?
Maybe try a look at nite. Have someone load the engine against the converter, and look under the hood for spark "leaks"...

 

[SloGN]

how lean is the motor running at an idle ?

one running lean at an idle will make it run like crap.

 

[turboclam]

Update and a question for Chuck.

1. Replaced all plugs and wires.............no change
2. Coil pack and module replaced and grounded........no change
3. Purchased a laser temp tool and............. #1 cylinder is about 300 degrees cooler than the others.

Hey Chuck, the coil pack that was pulled off had a rusty powder on the #1 coil post. I know that the coil is about a year old. What causes that?

I think I found a working modded ECM that I'll try tomorrow.
Rocker arm assembly again seems to be functioning correctly.
Before I remove the intake and driver's heads does anyone else have any ideas? Thanks Michael

 

[turboclam]

Oh and I don't have an.......

Egr

 

[Chuck Leeper]

Next ??

1. Replaced all plugs and wires.............no change
2. Coil pack and module replaced and grounded........no change
3. Purchased a laser temp tool and............. #1 cylinder is about 300 degrees cooler than the others.

Hey Chuck, the coil pack that was pulled off had a rusty powder on the #1 coil post. I know that the coil is about a year old. What causes that?

I think I found a working modded ECM that I'll try tomorrow.
Rocker arm assembly again seems to be functioning correctly.
Before I remove the intake and driver's heads does anyone else have any ideas? Thanks Michael

** 300 degrees is a big differential for exh temps..As in that cyl could be the issue.
** The rust on the coil tower is likey caused by a loose connection. Did you use dielectric grease on all the tower pins and the plug ends of the wires?
** If the intake is leaking at the gasket, that is a problem that needs fixing, that's for sure. B4 you pull the intake off, pull the plenum, and take a look in the ports for gasket problems, oil in the runner.

 

[turboclam]

Thanks

I have not used the dialectric grease. I will pull the plenum off and inspect the runner tomorrow and keep you informed of any changes or findings. I also will swap ECMs because it's easy. Don't go under your rock yet!

 

[83ttypecooled]

Hi,
When you have a rusty tower on the coilpack,you can count on it having been caused by long term high voltage firing of that cylinder.Dielectric grease helps, but I would take a close look at that cylinder's wire and sparkplug. It's usually the wire, open or nearly so.A simple resistance test will tell.
So #1 is probably your misfire culprit.The #1/4 section of the coil took a beating,so may not be up to high voltage demands anymore. Compare the coil tower resistance between the three groups, beware if major discrepancies are present.
Other issues are possibly present,but getting ignition in order is paramount to getting the car running properly. Good luck with your trouble!

 

[Mike70gtx]

I'll be curious to find out. My #1 cylinder is not as hot by looking at plugs. It almost looks a little wet or darker. I've about changed out everything. I'm wondering if I got a leak in the intake gasket when I did my headgaskets.

 

[turboclam]

Update

Removed plenum and found traces of carbon. Not a lot but enough to raise a brow, so I removed the intake. Nothing out of the ordinary found. I put#1 on TDC and filled cylinder with a steady flow of air. I could hear some hissing so I sprayed brake cleaner into the intake valve and it started bubbling. The intake valve is not sealing so It seems. The spring looks OK and clearly has some tension to it. Guess I'm yanking the head? Stop me if there could be something else. Thanks

 

[turboclam]

I found it

Broken exhaust valve spring. Where can I get (1) 130# spring? Thanks Michael

 

[Chuck Leeper]

Change all 12!

 

[turboclam]

Will do.

Thanks Chuck!