2002 Dodge Ram 2002 Ram 1500 Van Misfire on 3 & 4 Cyl

Tiny
SLAMMED63CHEVY
  • MEMBER
  • 2002 DODGE RAM
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 130,000 MILES
Ram 1500 Van

I have a misfire in cylinders 3 & 4! I changed rotor, cap, wires, and spark plugs and it's till misfiring. My scanner is saying P0300, P0303, P0304. Before I start throwing parts at it I thought I might ask.
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Friday, September 3rd, 2010 AT 7:52 PM

5 Replies

Tiny
RASMATAZ
  • MEMBER
Random misfire are caused by vacuum leaks and bad gas.
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Saturday, September 4th, 2010 AT 5:05 AM
Tiny
SLAMMED63CHEVY
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Wouldn't that make the other cylinders misfire also? I have a constant misfire on the 3 and 4. The 3 and 4 are the center cylinders on the right and left bank that are misfiring. I thought it might be bad injectors but before I got them I did a compression test to make sure and this what I found.
1. 120psi
2. 120psi
3. 90psi
4. 90psi
5. 120psi
6. 140psi

I'm guessing "intake cracked"?
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Saturday, September 4th, 2010 AT 12:01 PM
Tiny
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Just by looking at the cylinders arrangement your suspicion could be right -try doing a leakdown test.
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Saturday, September 4th, 2010 AT 12:08 PM
Tiny
SLAMMED63CHEVY
  • MEMBER
Ok here is an update on the Van.

I got to thinking about the low compression in 3 & 4 and I'm NOT a pro by any means but I couldn't see how a cracked intake would result in low compression like I 1st thought. I can see a misfire but not low compression. So I got to thinking ether bad valves or rings. The motor has 130,000 on it so my guess was the valves. With noway to do a leak down test I shot a squirt of oil in the 3 & 4 to see if compression came up but very little changed. Next I hook my air compressor to the 3 & 4 with them at TDC put about 30-50psi in and I had hissing and air coming out of the exhaust pipe.

So I'm thinking bad exhaust valves
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Monday, September 6th, 2010 AT 2:22 PM
Tiny
RASMATAZ
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Bad exhaust valves if its coming out of the exhaust end-either way it still has to be open up and find out what's causing the low compression on this 2 cylinders
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Monday, September 6th, 2010 AT 3:39 PM

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