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5.4 low rpm misfire..Stumped

 
  #16  
Old 06-04-2019, 11:44 AM
PlumberScott
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Originally Posted by F150Torqued View Post
I just re-read this whole thread and you got a bunch of savy, sincere members trying to help. Don't throw the towel in.

I am struck by a couple of points. You seem like a savy guy also. Through all this you have given descriptive diagnostic diagnosis (obviously from a scan tool) - but never a code. What code are you reading that you say is a 'Misfire'? If it is a P0352 - shut this rabit trail down and start looking the other direction toward the PCM. I confess, in my prior reply I also assumed, and focused my reply on a P0302 - and failed to ask.

Also (for full disclosure, I'm just a 73 yr old driveway mechanic - experience limited to tearing up lots of stuff [both by abuse & wrench] as a kid), but your compression test... ??? On cyl #4 now BY ITSELF?? That suggests to me that you are doing compression test with all other spark plugs "IN PLACE"... ??? It has ALWAYS been my understanding a compression test is done with starter motor while all plugs are removed {once dry, then once with a squirt of oil}. If I'm right, we still don't know if compression on number 2 (or 4 for that matter) is good. Although 119 or 120 should not, IMO, result in a constant P0302.

Don't think I'm trying to beat up on you. I, like my fellow members here, just want to help.
Yeah I've heard mixed ideas on how to 'properly' compression test an engine over the years. I don't really see how leaving the other spark plugs out would effect the results besides letting the engine turn easier. But I'm willing to give it a shot.
I forgot what codes I'm getting off the top of my head. I'll let you know when I get back to the van. For sure 'cylinder 2 misfire' pending and permanent. 'Cylinder 7 misfire' permanent. Since it's post 2010 the codes stay on until you do the driving procedure. I took a laser temp reader to each exhaust port on the exhaust manifolds and got roughly 250 degrees on each port EXCEPT cylinder #2 which read 140 degrees.
Interesting that you mentioned PCM. I bought the truck with a bad spark plug hole and the spark plug was melted. I think I remeber reading somewhere that you can damage the PCM by leaving the coil unplugged for too long while running the engine. Maybe that could be an issue?
And thanks for calling me a 'savvy person' lol I'll let my wife know someone thinks that of me.
 
  #17  
Old 06-04-2019, 06:58 PM
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So one more update,
Did some tests that I found online.
Hooked up an LED light to the 'signal side' of the coil"s plug. It had a good rhythmic flash.
Hooked up the LED to the injector's plug, also had a good rhythmic flash.
So... Still stumped.
When I get a chance to make it to harbor freight I'll buy a leak down kit and give it the dreaded leak down test.
Still hard for me to wrap my head around how that cylinder had seemingly decent compression but could still fail a leak down. But its a learning experience!
 
  #18  
Old 06-04-2019, 08:29 PM
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Here's what the scanner is telling me at idle

Fuel sys 1: CL
Calc load: 23.9
ECT: 190
Stft b1: -1.6
Ltft b1: 9.4
Stft b2: .8
Ltft b2: 15.6
Rpm: 615
Spark adv: 15.5-21.5
Iat: 81
Maf: .65
Tps: 12.5
O2s b1s2: .165-.845 (oddly this is the best it has looked)
Stft b1s2: 99.2
O2sb2s2: .275-.475
Stft b2s2: 99.2
Command evap: 0
Evap_vp: 0.0 - 0.2
Baro: 29
Lambda b1s1: 1.028
O2s b1 s1: .03
Lambda b2 s1: 0.988
O2s b2 s1: -.08 - -.25
Cat te 11: 723
Cat te 21: 723
Ecu volts: 13.9
Load value: 15.3
Eq rato: .999
Rel tps: 1.6
Ambient: 73
Tps b: 14.5
Acc pedal d: 15.3
Acc pedal e: 7.5
Command tac: 2.7
Alch_pct: 0.0

I understand about 50% of those outputs. So if anything looks goofy to anyone let me know. Thanks all
 
  #19  
Old 06-05-2019, 09:25 AM
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I don't want your wife to think I am retracting my complement ... BUT don't feel like I'm beating up on you this time either. Still just trying to help.

Only a couple of things in the Freeze Frame data jump out at me - THE FIRST one, explains my opening comment. The freeze frame data is 'captured' at the instant of DTC occurrence. Oddly (IMHO) OBD engineers did not include the the DTC code in the list. Without knowing that however, along with some surrounding conditions leaves a vacuum in the diagnostician's head. For now, I'll 'assume' it was a misfire (associated with current discussions), that occurred upon startup while sitting in the driveway, in Park gear, following a lengthy soak time, without any drive cycle distance. Those assumptions are all based on: Calc load, Maf, (Iat/Ambient), Tps, Cat mid-bed temps, Tps and Acc pedal positions.

I do not know what "Units" your scanner is reading Mass Air Flow in - but brief efforts to make sense of it didn't result in a good conclusion. Point 65 makes no sense to anything except kilograms. The standard measurement is grams/second. I am most familiar that which should be around there - between 5 and 7 at idle RPM of 615. But here again - a misfire (ON STARTUP) wouldn't mean a lot if it occurred during cranking. but based on other readings I do not think this FF snapshot was taken during the first 200 revolutions (Those misfires are treated differently)

I'm not saying this is "IT" (or anything). It's just curious and deserves watching/verifying. If the MAF fails, the PCM implements a Failure Effects Management Mode (FMEM), and uses a 'default' value. Often THAT value is close enough to keep one running fairly well if everything else is working right.

Your added comment ('oddly ... ...') is curious. You have previously stated Cats were replaced. --AND in your original post you stated "O2 sensor B1S2 is giving weird signal. Just sits around .825 V at warm idle. No fluctuation like the other bank or my other van that runs well."

These readings are all hard to wrap our heads around - but at warm idle (after a cat warms up to 1300 - 1500 degrees) downstream O2's should be relatively steady at .75 to .80, [indicating there is NO oxygen in the post CAT exhaust. ie: it is working]. I notice in FF data, they are both swinging - probably because they haven't warmed up enough (723 degrees). This contributes to my assumptions stated above. But your Bank 2 sensor 2 isn't swinging as high or as near .75 to .80. That makes 'perfect sense' becuase the Fuel Trims on bank 2 (both STFT & LTFT) are higher than bank1, and Lambda on bank1 & bank2 are tilted that way.

I do not think you have a vacuum leak. (a little longer term monitoring necessary - but a vacuum leak will effect Trims more at Idle and less at elevated RPMs.) At this point - only suggestions I have are to Watch that MAF, and make sure you have a 'hospital clean' spark plug job with new boots, springs, and all GOOD clean contact points with COP clips snapping on solid. ALSO, verify NO exhaust leaks around those NEW cats.

Hope something here helps.
 
  #20  
Old 06-07-2019, 07:28 PM
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Originally Posted by F150Torqued View Post
I don't want your wife to think I am retracting my complement ... BUT don't feel like I'm beating up on you this time either. Still just trying to help.

Only a couple of things in the Freeze Frame data jump out at me - THE FIRST one, explains my opening comment. The freeze frame data is 'captured' at the instant of DTC occurrence. Oddly (IMHO) OBD engineers did not include the the DTC code in the list. Without knowing that however, along with some surrounding conditions leaves a vacuum in the diagnostician's head. For now, I'll 'assume' it was a misfire (associated with current discussions), that occurred upon startup while sitting in the driveway, in Park gear, following a lengthy soak time, without any drive cycle distance. Those assumptions are all based on: Calc load, Maf, (Iat/Ambient), Tps, Cat mid-bed temps, Tps and Acc pedal positions.

I do not know what "Units" your scanner is reading Mass Air Flow in - but brief efforts to make sense of it didn't result in a good conclusion. Point 65 makes no sense to anything except kilograms. The standard measurement is grams/second. I am most familiar that which should be around there - between 5 and 7 at idle RPM of 615. But here again - a misfire (ON STARTUP) wouldn't mean a lot if it occurred during cranking. but based on other readings I do not think this FF snapshot was taken during the first 200 revolutions (Those misfires are treated differently)

I'm not saying this is "IT" (or anything). It's just curious and deserves watching/verifying. If the MAF fails, the PCM implements a Failure Effects Management Mode (FMEM), and uses a 'default' value. Often THAT value is close enough to keep one running fairly well if everything else is working right.

Your added comment ('oddly ... ...') is curious. You have previously stated Cats were replaced. --AND in your original post you stated "O2 sensor B1S2 is giving weird signal. Just sits around .825 V at warm idle. No fluctuation like the other bank or my other van that runs well."

These readings are all hard to wrap our heads around - but at warm idle (after a cat warms up to 1300 - 1500 degrees) downstream O2's should be relatively steady at .75 to .80, [indicating there is NO oxygen in the post CAT exhaust. ie: it is working]. I notice in FF data, they are both swinging - probably because they haven't warmed up enough (723 degrees). This contributes to my assumptions stated above. But your Bank 2 sensor 2 isn't swinging as high or as near .75 to .80. That makes 'perfect sense' becuase the Fuel Trims on bank 2 (both STFT & LTFT) are higher than bank1, and Lambda on bank1 & bank2 are tilted that way.

I do not think you have a vacuum leak. (a little longer term monitoring necessary - but a vacuum leak will effect Trims more at Idle and less at elevated RPMs.) At this point - only suggestions I have are to Watch that MAF, and make sure you have a 'hospital clean' spark plug job with new boots, springs, and all GOOD clean contact points with COP clips snapping on solid. ALSO, verify NO exhaust leaks around those NEW cats.

Hope something here helps.
Thanks for all the knowledge f150torqued. I definitely learned some stuff from this thread.
So.. The Bad news. Finally got around to giving it a leak down test. It looks like a bad exhaust valve. The cheap leak down tester is showing it in the "moderate" range, but I can easily hear the air going through the exhaust. I'm doing it by myself so I'm not 100% sure I'm at TDC at the compression stroke, but I would think as long as I'm in the ballpark within lets say 10 degrees I still shouldn't hear anything in the exhaust because the cam would be on its base circle for the exhaust lobe.
Now the question is, is it possible to pull the head with the engine in the van? Looks like a PITA but as long as I can get the head bolts out I would think its possible.
On the bright side, I made a cool adapter for the leak down tester using an old spark plug and a tap. Hammered out the por

celain and ran a tap down the top of the spark plug.
 
  #21  
Old 06-07-2019, 07:58 PM
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Welp, I answered my own question. YouTube to the rescue. This guy pulled both heads with the engine in the van. His commentary sums up the job pretty well. Worth the watch.
 
  #22  
Old 06-08-2019, 05:30 AM
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^^^ That video is NOT safe for delicate ears----good thing the audio is almost muted. I'm not offended and understand the frustration----just need to warn others who might not appreciate the "colorful" language.
 
  #23  
Old 06-09-2019, 11:27 AM
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I admire enginuity - and like your creative tool. Convinces me you'll be fine.

I don't know if it applies to the VAN, but I 'understand' on the F150 the head has to be lifted out - and back in with a couple of rear head bolts setting loosley in the head. They are too long to extract with head in place ?? Otherwise, it should be no problem other than the major effort involved.
 
  #24  
Old 06-11-2019, 06:26 AM
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Originally Posted by F150Torqued View Post
I don't know if it applies to the VAN, but I 'understand' on the F150 the head has to be lifted out - and back in with a couple of rear head bolts setting loosley in the head. They are too long to extract with head in place ?? Otherwise, it should be no problem other than the major effort involved.
Here's a few images of the 5.4 as installed in an E-Series---2005 extended body to be exact:




The engine bay is pretty tight as shown----once the head is separated from the block any bolt that can't be fully removed can be left in the hole while one person in front and one inside the cabin can lift and slide the head towards the valley. Once there its pulled out from the front or through the cabin easily enough.

More often than not I'll simply remove one the front seats, typically the passenger side since there's no steering column. T55 PLUS socket for front bolts, 18mm socket for the rears.

HTH
 
  #25  
Old 06-15-2019, 06:47 AM
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Yes it can be done

We removed both heads from my V10 van with the engine firmly in place. Just months ago.

V10 van: both cylinder heads removed without removing the engine.
 
 


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