5.4 V8 Misfiring AGAIN!

Thread Tools
 
Search this Thread
 
Old Apr 2, 2011 | 07:15 PM
  #106  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
So far on cyl 2 & 3 testing with oil resulted this:
2: without oil was 97psi with oil 130 psi
3: without oil was 135psi with oil 150psi
 
Reply
Old Apr 2, 2011 | 09:17 PM
  #107  
jethat's Avatar
Senior Member
Joined: Jun 2007
Posts: 5,522
Likes: 6
From: Utah
2 is low but it should still fire..
 
Reply
Old Apr 2, 2011 | 09:34 PM
  #108  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
2 still fires and I don't think I've ever had an issue with cylinder 2 misfiring. Oddly enough it always came up as cyl 8 misfiring, along with 4. 8 seems fine pressure wise.

Anyone have a link from here how to tear into this and get them (rings) replaced?
 
Reply
Old Apr 3, 2011 | 01:54 AM
  #109  
glc's Avatar
glc
Senior Member
15 Year Member
Veteran: Navy
Veteran: Reserves
Joined: Dec 2006
Posts: 43,532
Likes: 817
From: Joplin MO
Have you done the AutoRX treatment yet? I'd also start throwing Techron in the gas.
 
Reply
Old Apr 3, 2011 | 10:18 AM
  #110  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
RX was done, ticking went away. Plus it's been much warmer so I'm thinking they were sticking.
 
Reply
Old Apr 3, 2011 | 10:54 AM
  #111  
jbrew's Avatar
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Originally Posted by FF Titus
Compression check is complete and here's the results.
Cyl 1: 195psi
Cyl 2: 97psi
Cyl 3: 135psi
Cyl 4: 95psi
Cyl 5: 190psi
Cyl 6: 175psi
Cyl 7: 133psi
Cyl 8: 185psi

A few things to note, throttle was fully opened, and did 5 full cranks of the motor.
Right the throttle plate should be pinned back during testing. Did you use a auxiliary starter ? It's just a PITA without one.

Compression Test—Interpreting Compression Readings

Did you oil test it your low readings ? If one or more cylinders reads low, squirt approximately one tablespoon of clean engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.

1. If compression improves considerably, piston rings are damaged.

2. If compression does not improve, valves are sticking or seating improperly.

3. If two adjacent cylinders indicate low compression pressures and squirting oil on piston does not increase compression, the head gasket may be leaking between cylinders. Engine oil and/or coolant in cylinders could result from this condition.

Also, use the Compression Pressure Limit Chart in my sig if you want or if you don't have one. Keep in mind when checking cylinder compression, the lowest reading SHOULD be within 75 percent of the highest reading.

Your numbers are all over the place lol. I'd check it again following procedure and add in a shot of oil when getting a low reading to confirm where the problem is. IMO, it's hurt, but reconfirming might help you decide whether or not a new/used motor would be in order.
 
Reply
Old Apr 3, 2011 | 11:29 AM
  #112  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
I had my wife in the drivers seat with the gas peddle on the floor and turning it over for me while I counted 5 turn overs then stopped.

So far on cyl 2 & 3 testing with oil resulted this:
2: without oil was 97psi with oil 130 psi
3: without oil was 135psi with oil 150psi

I was using that link in your sig as a guide, and my numbers are all over the place.
 
Reply
Old Apr 3, 2011 | 12:02 PM
  #113  
jbrew's Avatar
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Originally Posted by FF Titus
I had my wife in the drivers seat with the gas peddle on the floor and turning it over for me while I counted 5 turn overs then stopped.

So far on cyl 2 & 3 testing with oil resulted this:
2: without oil was 97psi with oil 130 psi
3: without oil was 135psi with oil 150psi

I was using that link in your sig as a guide, and my numbers are all over the place.
What were 1&4 ? During oil soak on 2 and 3 ?
 
Reply
Old Apr 3, 2011 | 12:06 PM
  #114  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
Did not get a chance to check them, ran out of time, going to do that today. Should I redo 2 & 3 then do 1 & 4 again? I think I should, but just want a 2nd opinion.
 
Reply
Old Apr 3, 2011 | 01:13 PM
  #115  
jbrew's Avatar
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Yea, I would re-soak for each comparison test (adjacent only). Just because oil can eventually leach back into the pan. How fast depends on ring condition and piston/stroke position. So,depending upon where the piston is, oil may leach faster. These engines tend to have a little piston slap @ #1 and #2 cylinders, it's common and generally not a problem, but if the piston is positioned opposite of TDC, it will leach faster. So, to perfect testing a re-soak of adjacent would be in order.

Time consuming and a hassle, but worth the effort IMO.
 
Reply
Old Apr 3, 2011 | 01:18 PM
  #116  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
I'll do it and report back with the results.
 
Reply
Old Apr 3, 2011 | 02:03 PM
  #117  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
And here's the results:

Cyl 1 was 195psi with oil is 230psi
Cyl 2 was 97psi, 1st oil test was 130psi now it's 180psi
Cyl 3 was 135psi 1st oil test was 150psi now it's 200psi
Cyl 4 was 95 psi with oil is 150psi

What do you think?
 
Reply
Old Apr 3, 2011 | 02:34 PM
  #118  
jbrew's Avatar
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Think you misunderstood, - just oil in the low compression cylinders as the write up suggests. Test adjacent to see if #'s change. No oil in adjacent tho. This test verifies the gasket condition.
 
Reply
Old Apr 3, 2011 | 02:40 PM
  #119  
FF Titus's Avatar
Thread Starter
|
Senior Member
Joined: Dec 2010
Posts: 239
Likes: 0
From: Coventry RI
Now I understand, test the cylinders next to the low psi ones after putting oil in them but not putting oil into them.

Well sadly I misread and put oil in all 4 of them to test,so now what? Do I wait a while and test them again?
 
Reply
Old Apr 3, 2011 | 02:46 PM
  #120  
jbrew's Avatar
Technical Article Contributor
Joined: Oct 2005
Posts: 25,641
Likes: 19
From: MI
Iduno lol. - Run the engine up to operating temp. Then start over. It is more accurate when the oil is warmed.

Yea, I didn't think you were going to like that answer lol.
 
Reply



All times are GMT -4. The time now is 09:46 PM.