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Discussion Starter · #1 · (Edited)
Hi all, new member here. Bought my '03 last December w/39K miles on it. (78K miles now) Never a problem until yesterday. After .5 mile leaving our church parking lot, the truck began a mild progressing to a pretty severe vibration. In a nutshell, hauled it to a nearby Autozone, scanned it and it threw a P0300 "Multiple Cylynder Misfire". Is there a scanner that I can find from a local parts shop that will be precise in giving me the trouble codes?

When cranked up, more than the usual amount of moisture being thrown out the exhaust, very rough idle, no smell of unburned fuel, no blown fuses, engine light on, Bosch plugs just installed about 5 months/20K miles or so ago. Checked the manual for fuel filter location but only info given for Diesel engines.

Finally found a Hayes manual for it today and am about to begin pulling & metering out the coil packs. The manual says that there aren't any published secondary resistance readings for the Hemi motor, of course. Truck just went out of the 7/70 warranty.

I'm not a gearhead and can perform the basic engine work. Any help from you all is very greatly appeciated as everyday this truck is down is lost revenue for me.
 

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Discussion Starter · #2 · (Edited)
Nothing...anyone...? :huh:

Ok, this is what I have done so far:

What I thought was the problem was not it. I have changed all plugs, new wires, properly gapped to .045. *(Had to wait a day for plugs/wires, nobody up here carries them!)

- New Wires: Autolite Pro Series P#97097
- New Plugs: Autolite Platinum P# AP-5263

- Removed and checked all coils primary resistance, all read out @ 0.8 ohms as the Haynes states should be 0.5 - 0.8. When placing the leads on the terminals, it was at 1.0 - 0.9 (typ.), then move the lead around slightly and then read down to 0.8. Since there are no published resistance values for the secondary, could this be the culprit on one or more of the coils? (I am assuming the secondary is the direct fired plug, correct?

- Pulled the neg. cable, reset the PCM
- Turned key on/off three (3) times, speedo read "done", then several dashed lines and that was it.
- Crank engine over, still the same problem. VERY rough idle, almost dies and hovers at the 500-550 RPM range. Will hold a steady idle if I kick it up to or above 2K RPM's.

Now the MIL is off. I have cranked it over (3) times and let it run for a minute or two each time.

What can I check next? I am at a loss. Since the OBD II only spit out Code P0300 - Mult. Cyl. Misfire instead of a specific cylinder.

Tried to find an ignition tester, nobody has one. Can I make one efficient enough out of an old plug to check for a good spark, pull the fuel pump relay, start w/cyl. 1, connect the "homemade" spark tester & turn the motor over? Would this confirm the coils are all supplying enough power to fire the plugs? As long as I see a nice, crisp blue spark on the old plug? Do I need to create some sort of ground or just let the wire hang? Guess I will have to pull the coils again so I can check the spark for the direct fired plugs.

Torque: Yes, they were Bosch Platinum 2's #4314
Tcon: Yep, I read your post, I am praying it's nothing like that as my warranty was depleted 9K miles ago.

I also did not find any info on the voltage/resist. requirements for the cam/crank sensors.

Thanks to any and all that can help me out in this desperate situation. *(No truck = no money being made)
 

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All Around Great Guy
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What engine? I have seen multiple engines with cracked cylinder heads between the valves.
 

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Discussion Starter · #4 ·
hemi1569 said:
What engine? I have seen multiple engines with cracked cylinder heads between the valves.
Is it not showing in my original message header? I have the 5.7L engine.
 

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All Around Great Guy
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I would say a flash of the computer could be suspect. Let me check it out for you and i will post anything i find.
 

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Discussion Starter · #6 ·
Thank you very much!
 

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All Around Great Guy
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No flash for a po300 code. There are flashes available, but none that apply to your symptoms. Did you get any bad gas lately? That would make it run like crap and throw codes. I have not yet seen any head problems with hemis and only a couple exhaust valves drop. I would fill it up with 93 or the highest octane available and put some fuel injector cleaner in the tank. If this does not work, do a compression test.
 

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Discussion Starter · #8 ·
Thanks Hemi. You know, bad gas did enter my mind, but I really hadn't thought of it any further. I always get mine from Quik Trip which has quality fuels. I will need to go fill up several gas cans and filler 'up to try it. Can't really drive the truck the way it is, I don't think it would make it out of where I live. Also, purchased an inline spark tester, will be running through that tomorrow morning as well, then compression test next after that. My mind is burnt, :confused: so much worry over this. It be slightly less stressful if I didn't need it for my business. Will post what I find tomorrow.
 

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Just for your information the 'secondary' plug's spark comes from another cylinder's coil, the method of the madness being only 8 coils required to fire 16 plugs. For what it's worth. Also you do need to ground the plug to get it to fire outside of the cylinder. Excessive moisture (if it is indeed excessive)out of the tail pipe tells me that the exhaust gas temperature is probably low allowing the gas to condense by the time it has passed through the muffler. What do you mean by 'vibration'? What does it 'sound' like?
 

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Discussion Starter · #10 ·
Completed my compression test a few minutes ago, not good.

See Cylinder #5

These are averages from three (3) tests on ea. cyl.:

Cyl. 1: 185
Cyl. 2: 176
Cyl. 3: 182
Cyl. 4: 180
Cyl. 5: *0
Cyl. 6: 185
Cyl. 7: 181
Cyl. 8: 183

Cyl. 5....the compression gauge needle didn't even budge during the test. I tried it several times....just hoping.
 

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Wow. Dropped a valve?
 

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Discussion Starter · #12 ·
I have no idea what's going on yet. Was going to take off the valve cover to visually inspect but started pouring rain (truck in carport), going to wait until morning when there's not so much moisture flying about. It's about all I know to do. Would running a test with a vacuum tester be of any help 1st?
 

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This is my guess. The excessive moisture out of the tail pipe is caused by low exhaust gas temperature due to cool air being pumped out of the dead cylinder. I also wonder if some of that moisture might be raw fuel. I hope the problem isn't the valve train in light of all the posts about the "Hemi Tick".
 

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Discussion Starter · #14 ·
Not sure if any of you are on DTO or not but here's a link to my thread over there. Posted photos of what I discovered yesterday under the left bank valve cover. Click on the pic's for a full detailed up close look.

DTO Thread
 

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Valve spring looks gone to me. They are a pain in the ass to change, especially with it broken. I would put some rags all around the exhaust valve and try to catch the keepers with a magnet. Put compressed air in the cylinder so that it does not fall onto the piston. I would personally change that one out and run some clean oil through it, giving it a fresh oil change. Run it some more then change it again. Everything that is accumulated will clog your pickup if you run a flush, you are better off to leave it alone IMO. I ran into the same problem(3.9 dakota with 28k). customer did not change the oil for over 12k miles and the motor dropped oil pressure, rods knocking. dropped the front diff and oil pan and sludge was outrageous on the screen. going to replace the oil pump/pickup and rod bearings. You should be fine considering your oil pressure has stayed consistent.
 

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I would also ziptie the valve above the valve seal and release the cylinder pressure. Spin the valve and if it does not look true, you will have no choice but to pull the heads due to it contacting the piston. I would only do this if it did not appear mangled at first sight
 

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I have a question. Does the rocker arm slide out of the way? I am just curious because I have a tool that can hook on the rocker arm shaft and compress the spring.
 

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No you have to unbolt the rocker shaft and remove it then install the tool.
 

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Well crap. I was hoping that it would be easy. Thanks for the info.
 

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well im gald to find this thread i have a 07 ram with hemi an in the morning with the motor cold there is a real loud pop an sounds like backfire so under warranty took it to dealer an they ahve had it for 2 days running test since it only makes noise when cold they think it has broken valve spring the last time i changed oil it was missing a quart an 1/2 of oil so im guessing that would make since an to boot after it broke in it got worse gas mileage 19.3 first 1300 miles now its lucky to get 16 also im curious why it only knocks when cold
 
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