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Malibu #4 cylinder not fireing


rugby_7
10-03-2012, 09:57 PM
Hi all Im a new guy but have been working on cars for years. I purchased my 1998 malibu 2.4l two months ago for $400 and had 6000 miles of no problems until yesterday.
I was driving home and hit a bump then my engine started running just on 3 cylinders. I got it home and checked the plugs. The #4 plug was wet with gas. I checked for spark and all 4 cylinders are getting spark (it may be just my imagination but the #4 plug looks weaker). I switched plugs and boots around still no change. Switched the coils around still no change. Switched the injectors around still no change. Checked compression #1-150 #2-150 #3-150 #4-125, The number 4 cylinder is lower but not enough to effect if it is fireing or not.
It is getting a check engine light but Im waiting on my code reader in the mail.
I also had some coils from another 2.4, I put them in still no change.
Sorry for the long post, just wanted to get all the details. Anyone know what could be wrong? Thank You!

oldblu65
10-03-2012, 10:34 PM
Sounds like you had a wiring issue that was just looking for an excuse to become a problem ? I suspect that " bump " you mentioned pushed this potential problem into a real - time issue . I'm not an electrical / electronic expert but I would start the engine ( making sure it is secured with the parking brake and wheel chocks ) and look at the wiring in the engine compartment to see if anything is obviously wrong ? If not , try gently moving your hand around on wiring in the engine bay ( making sure to stay clear of any moving or hot engine parts ) to see if it improves the running of the engine as it idles . Also make sure all electrical connections are secure . This would include wiring on the firewall as well . There could even be a connection in the wiring under the dash , that's not quite completely connected as intended , that the bump loosened just enough to cause your problem . Electrical " gremlins " can be a nightmare to track down so don't get frustrated and you'll find your problem - Good luck !

danielsatur
10-03-2012, 10:44 PM
1) Reset/clear code and monitor.

Tech II
10-04-2012, 01:38 PM
You say:

"The #4 plug was wet with gas. I checked for spark and all 4 cylinders are getting spark (it may be just my imagination but the #4 plug looks weaker)."

Exactly how did you do this?

#4 compression doesn't look bad(slight wash down from fuel?)......

More often than not, the problem is the ignition tower itself.....

rugby_7
10-04-2012, 10:33 PM
I checked for spark by running jumper cables to each plug as a ground and had someone turn the key. I know the proper way to do this is have a HEI tester, but this was a quick way to see if it was at all getting spark. I think I am going to hook it up to my multimeter and see what reading are coming from each pole, maybe that one will be showing weaker. I wish my code reader would hurry up and get here so I could read the codes.

A loose connection could be a possibility since it happend the way it did, Ill have to go pull them apart and plug them back in, not something Im looking forward to...

I also read that with these engines the coil housing sometimes cracks or gets carbon tracked and grounds out the current, that could be the problem as well. Maybe also a stuck valve. Just going to have to try different things, Thanks for the input so far guys, Its good to get some different ideas!

rugby_7
10-04-2012, 10:36 PM
#4 compression doesn't look bad(slight wash down from fuel?)......

More often than not, the problem is the ignition tower itself.....

What does slight wash down from fuel mean?

The ignition tower is where the coils are housed?

Tech II
10-05-2012, 11:17 AM
If no fire to the plug, fuel can wash down the cylinder walls of oil.....

Ignition tower and coil housing are the same thing....

rugby_7
10-07-2012, 05:56 PM
Ok yeah that makes sense. Would reading the poles of the housing with a multimeter be the way to see if it is bad?

rkvons
10-08-2012, 12:20 PM
You could remove the coil that has the #4 spark plug wire on it, check under it, then swap it with another coil that is next to it. Make sure the wires are moved correctly from one coil to the other. then see if the problem moves to another cylinder.

Tech II
10-08-2012, 01:00 PM
Rkvons, this is not a DIS system with external coils and wires......the coils are inside an ignition tower/housing and uses no wires(boots connect the plugs to the housing).....

Rugby_7, an ohm meter doesn't help.....the carbon tracking is inside, and shorts out.....

It's just like wires....you can ohm them and they are ok.....but a break in the insulation causes the spark to jump to ground and cause a misfire....

Like I said, if plugs, boots, compression, injectors and coils are ok.....it's the tower.....very rarely have I seen the ICM(bolted to underside of cover) be the problem, but it has happened....

rugby_7
10-09-2012, 06:35 PM
It might just be worth buying the tower, its only like $40 so if its not the problem i have it for if it ever becomes the problem. Well I finally got my code reader in the mail today, came up with two codes. Cylinder four missfire (knew that) and injector circuit

danielsatur
10-09-2012, 06:44 PM
Suspect injector # 4, connector, or signal wire going to injector 4.

Tech II
10-09-2012, 09:58 PM
yeah, with the injector circuit code, that could cause a P0300 or P0304.....go with what Danielsatur said.....check injector circuit with a noid light....

rugby_7
10-09-2012, 10:28 PM
So by process of elimination, I moved the injectors around and it didn't change that would leave the connection??

slls
10-12-2012, 10:25 AM
Or driver for #4 injector, noid light check.

rugby_7
10-13-2012, 08:30 PM
I ordered a noid tester, Im going to have so many new tools by the time this car is running

rugby_7
10-18-2012, 06:54 PM
Got my noid tester, says the wire to the #4 injector is bad, just need to find out where...

Tech II
10-19-2012, 03:59 PM
If the noid light doesn't flash or light, with the key, on one leg has battery power and the other is the control circuit to the PCM.....If you have battery power on one leg(use test light), then you know it is the control circuit to the PCM.....check the bulk harness connector for the injectors for a bad connection........if you see nothing check the wiring from the bulk harness connector to the injector(injector connected).....do ohm check should be 12 ohms.......if ok, you know it's the wire from the harness to the PCM....if not ok, then it's the wire from the harness to the injector connector.....

If you did not have 12 volts, check wire same way you check control wire, using a test light instead of ohm meter....

rugby_7
10-28-2012, 06:09 PM
The ECM turns out to be bad, so I ordered a new one and put it in but when I try to start it the anti theft deterrent kicks in and wont let it start. Is there any way of clearing that?

rugby_7
02-28-2014, 08:43 PM
The last ECM back in 2012 turned out to be the wrong one, got the correct one put it in and ran good until the other day. I got rear ended at a stoplight and the car ran fine for about a week. Then I started it and let it warm up for about five min before I left for work. It ran good then all of a sudden it acted like it is running on 3 cylinders. Pulled it into the garage and finally got a check engine light. The code came up as a cam position sensor and egr valve. Replaced cam position sensor, still runs bad/wont start. Pulled the plugs and the #1 cylinder plug was wet. I replaced the plugs and switched around the coils, checked the plugs #1 was wet still. I just happened to find another ECM for $16 shipped on Ebay so I ordered it, should be here soon. I figured I could put it in and see if its the same problem again. If it happens to be the ECM what would make them burn up. Its weird that twice where it seen a jarring hit would make it run bad. Would the EGR valve do this? I ordered one for it but most I seen a EGR valve do is mess with idle.

rugby_7
02-28-2014, 08:47 PM
Sorry I ment crankshaft position sensor not camshaft

Tech II
03-02-2014, 07:58 AM
Since your plug is wet, it seems that cylinder is not firing......that would have nothing to do with the PCM.....chances are it's the ICM or the coil tower....see more towers be the problem than ICM's.....

rugby_7
03-02-2014, 12:28 PM
Im getting spark on all four cylinders. I ordered another HEI Tester cant find my old one. I got an email yesterday saying its backorderd two weeks. I pulled the cover and put the plugs in the boots, leaned the plugs against the block and all had spark. I did the tests on the ICM until I got to the communication between the ICM and the PCM since I don't have a HZ setting on my multimeter.

Tech II
03-02-2014, 01:52 PM
If you are getting good spark on all four cylinders, yet the number one plug is wet, have you checked compression in all the cylinders? If ok, then it's possible that the #1 injector is dumping fuel?

rugby_7
03-02-2014, 03:13 PM
Checked compression, its all good. I borrowed a coil tower from a friend and put it on mine. Started right up and ran good. I think once the tower was bolted down in the engine it was grounding somehow. Thank you for your help!

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