No spark on #2 and #4 cylinders

[aleromgf]

2001 Alero 2.4L

Hello all.

Problem started with bad misfire, found arcing from the plastic housing that contains the coils. Replaced housing and car ran fine for two days.

Started missing again and I decided to change plugs (regular bosch platinum)
I found that #1 and #3 had the center electrode almost completely eaten away and I thought I had found my problem. (I later found this is normal in waste spark ignition systems).

After replacing the plugs and still having the same problem, I switched the coils around and the problem remained.

Today I replaced the Ignition Control Module, and it still does the same thing.

Please help.

Thanks.

[BNaylor]

It would help to post your mileage.

Were the old plugs Bosch or did you install Bosch plugs? Or what were the original brand?

"(I later found this is normal in waste spark ignition systems)" - Not necessarily.

[aleromgf]

Thanks for replying BNaylor

Mileage is 112,000 miles
Spark Plugs were Bosch, I installed them at about 70,000 miles, and I replaced them with the same type: Bosch Platinum Plus cat # 4011

[discnik]

How did you know that # 2 & # 4 had misfires, Check Engine Codes ?

If a coil is bad switching it in this type of system will tell nothing of the misfire since you can not pull a plug wire to see if the misfire moved.

The only way would be clearing any codes switching coils then seeing if the misfire codes were for the same cyclinders or had moved to the other two cyclinders

Have you tried listening to the injectors with a stethiscope to see if they are working ?

Have you checked the injector connectors with a noid light to see if they are receiving voltage ? Someone suggested using, I believe a 194 light bulb by unfolding the filament wires to plug into the connectors inleu of a noid light.
Have not tried this yet.

Have you done a compression test on the cyclinders ?

Just some queries, questions, posures.

[aleromgf]

discnik

I rigged a set of cables to go from the coil housing to the spark plugs. That is why I know the problem is on the same cylinders.

Have not checked the injectors with a test light but the offending spark plugs have gas on their electrodes and the exhaust reeks of raw gasoline.

I am doing a comp test today.

Thanks for replying.

[aleromgf]

OK, I was not able to get a compression tester, but I did replace the coils and my observations are as follows:

Spark Plug #4 has no soot, electrode is clean and has a film of gasoline.
Spark Plugs #3, 2, and 1 have soot around them, are dry, and the electrode points are clean.

When I remove the test cables from spark plugs #4 or #2 engine condition does not seem to change; in other words, it still runs crappy, you can hear that the exhaust is not even, but has a definite pulse. If I remove the cable from #1 or #3 the car stumbles even worse and dies.

Any ideas?

[discnik]

Now that is a clever idea. Would not have thought of that, too parochial in my thinking.

Posted this before your reply. Sorry.

[discnik]

Can you get a timing light ?
You could attach the induction clip on each wire to see if they are firing.
Is there any chaffing of the wires on the harness to the ICM ?
Possible vacuum leak near the number #4 cyclinder ?

Is the EGR valve dumping into the # 4 cyclinder. I have seen them burn the valves on the # 3 cyclinder of the Metros.

Barring a compression test not sure.

You could pull the valve cover and have a look at the valve springs condition.

Just some thoughts.

[aleromgf]

As a matter of fact, discnik, I do have a timing light that I used back in the day when I could actually adjust the timing in my cars...gotta dig it up though...

No problem on the wires going to the ICM, that I can see. I have also tested for continuity on the wiring harness for the coils and everything is intact.

Cannot hear anything abnormal at or near the engine for leaks or such.

Have not checked the EGR valve.

Knowing how this crazy waste spark system works, you could go crazy chasing your tail looking for spark, where the lack of compression would not allow a spark to be generated.

Thanks for your help, discnik.

[aleromgf]

OK, Today, I was able to rig the spark plugs outside the engine, connected to the housing, as they would be during normal operation, and they all have a spark.

Weird.

Number one plug is absolutely clean, with no signs of firing, and has a slight film of gas.

Plugs 2, 3, and 4, all have slight carbon deposits and smell lightly of gas, although they are dry.

Ideas, please!!

[discnik]

Let's try something different. Had a vehicle similar symptoms. Turned out to be a bad fuel pressure regulator. Can you do a fuel pressure test on the vehicle ?

Has the vehicle been using coolant, more than usual.

Do you have a check engine light on ?

Can you get a vacuum gage and do a vacuum test on the intake manifold ?

Some more thoughts.

[aleromgf]

discnik,

About two months ago, it asked for coolant, I filled the tank as per specs.

CEL is on now, and sometimes flashes when engine is running and stumbling.

I should be getting a code reader/resetter and compression tester soon.

I have been suspecting a leaking gasket in the heads because of the unexplained loss of coolant, and because there was a smell of burned antifreeze in the engine a while back.

Yesterday I observed that there is oil staining in both the intake and exhaust manifold flanges around cylinder #1 and #4.

What drives me crazy, if this is a compression problem, is why does the #1 spark not fire inside the cylinder, but it fires outside.

Thanks for your help, discnik

[aleromgf]

discnik:

I removed the coils from the plastic housing and insulated them from the metal IDI cover. I rigged my test cables to run directly from the coils to the spark plugs, thereby eliminating several possible paths to ground.

I also directly connected the ground strap on the IDI cover to the battery ground.

Guess what? my baby is working again!

So, the only thing this proves, is that it is not a compression problem, but just ignition.

I will continue to isolate it until I can give you all a definitive answer, but a few things are possible:

Defective (brand new) coil housing.
Defective supply wiring to coils. (that may be grounding when everything is put together the way it should)
Lack of good ground at the ICM.

I cannot post pix in this forum but if you go here:

http://www.aleromod.com/forums/showt...d=1#post426397

You may be able to see them. Thanks for all your help!

PS: Admin, apologies if violating policy by linking to another forum.

[discnik]

If you find it please post it. Glad to hear you have it isolated.

[aleromgf]

OK, after much testing and experimentation I concluded that as hard to believe as it may be; that the coil pack housing was bad (again) and replaced it with an OEM housing.

Car has been running 2 days so far.