2005 Chevrolet 6.0L Misfire at an idle

Scott Owner Moreno Valley, California Posted   Latest  
Question
Driveability
2005 Chevrolet Silverado 2500 HD 6.0L (U) 4-spd (4L80-E)—1GBHC29UX5E298695
Misfire

Hi All,

This vehicle has 358,932 on it. The engine was replaced with a GM engine almost 3 years ago and it had slightly less than 300k on it at that time. So this is still under warranty if it's a mechanical problem, but I need to find out what is wrong.

The misfire is not always there, but happens at an idle only and this goes away when it reaches operating temperatures, or when accelerating. I can't say that's always the way that this has been going on, but from what I've experienced. The misfire can be a dead miss, or intermittent. (worse at times)

I replaced the plug on cylinder 8, and it had AC Delco 41-162, which is correct for this vehicle and that's what I put in. Injector balance was tested, spark from the coil was tested with a ST125, and a compression test on that cylinder, which was 160 PSI. A relative compression test (using ear sounded fairly even, but there was a drop out at times)

I'm thinking a valve sealing fault, but...

Here's some waveforms from this vehicle. Channel A - sync for cylinder 1 Channel B - vacuum waveform Channel C - WPS500 Compression cylinder 8

diag​.​net/file/f5fx2rq51…

diag​.​net/file/f4fqhl5aq…

Is there a problem that you can see?

Is there something else that I should do, or you would want to see?

Thank you!

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Jerry Owner/Technician
Wakonda, South Dakota
Jerry Default
 

I had one same way pulled the head and ground the valves problem solved

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Jerry, I can appreciate that, but if this guy is going to have GM fix it under warranty, I need more than it's thought to be a valve sealing fault.

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Barry Owner/Technician
Columbus, Ohio
Barry Default
 

We've had problems with #8 due to lifter. Sometimes makes noise, sometimes doesn't. Compression OK.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Barry, I've run into that before, but as I replied to Jerry, if this is a mechanical problem that is going to fixed by GM under warranty, I'm going to need more to go on. As this point even if I have conclusive proof it's what I think it is, I can see the customer getting the run around. This has nothing to do with dealers, or independent shops, it has to do with what can be proved and the…

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Rudy Technician
Montebello, California
Rudy Default
 

Scott- Im not sure I understand your goal. You said even if you have conclusive proof, the customer is going to get the run-around. So whats the point? What are you trying to accomplish? Sounds like this is an intermittent issue, going to be hard to catch, much less prove......

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Rudy, Your point is taken and I explained this to the customer. They've been a semi-decent fleet customer ever since this engine was put in 3 years ago. In fact after another shop installed the engine they brought it to me to fix something they couldn't. They're going to need a smog test on this, so the MIL is going to have to be taken care of, or they're going to get rid of the truck. After…

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Mihail Technician
Rockville, Maryland
Mihail Default
 

I am trying to learn more and have only watched a few training videos on the use of pressure transducers. It seems you’d need to place markers on the graphs indicating the locations where the valves open and close and label them with the degrees before or after TDC to be able to tell if there is a problem with a valve opening or closing too soon which could be a clue for a mechanical problem. I…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Mihail, I didn't post a screen shot, but it's in the Pico file I put up where I did snap the throttle with it running. I'm going to have to change the scaling as it went above the screen. Thank you for your thoughts.

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
   

Scott, you haven’t mentioned why you are focusing on cyl. 8. Is it the scan tool telling that, can you trust it? Seeing a 15-second RC waveform would be helpful. A lengthy CKP + ign​.​sync capture would reveal an intermittent misfire.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Dmitriy, Cylinder 8 was detected using the scan tool and I have verified that's the correct cylinder when testing for spark. I'll try and put up what you asked for. Thank you!

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

So I am no expert at these put here are some pointers. I agree that your compression is a little low but hard to tell without a known good to compare to. There does look to be a repeatable pattern on intake vaccum during the number 8 intake pull. However before we go down a rabbit hole post up the following waveforms so we can better assist you: 1: Relative compression test with a sync and…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Caleb, I'll try and get that up. As far as the cranking compression & vacuum test that's the first pattern and that was done with the throttle to the floor. I didn't disable the fuel or ignition, but I also didn't have the air inlet off on the TAC motor, so I don't know if the throttle blade was wide open. I'm thinking it should have been, Thank you!

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Ok so probably just need to change the scaling on the intake vaccum waveform then.

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Richard Technician
Stony Brook, New York
Richard Default
 

Can you do the vacuum cranking test over without a WPS in any hole. Just a cylinder sync and perhaps one in the intake and one in the tailpipe.

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Richard Technician
Stony Brook, New York
Richard Default
 

One other thought would be the intake manifold gasket. Is there any chance it is leaking and sucking in air while cold?

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Randy Diagnostician
Glendora, California
Randy Default
 

Just toke a class this week will bernie thomson and he said you should leave throttle plate closed for cranking compression ???

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Jamey Owner/Technician
Ventura, California
Jamey Default
 

I took the same class. For cranking with a transducer in the cylinder, closed throttle is best. On a regular compression test with a gage, open the throttle.

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Gerald Owner/Technician
Winfield, Missouri
Gerald Default
 

I actually leave the throttle unplugged to do this, it will make the "pulls" more pronounced. On some gm models I block the intake with an easy intake so it can only breathe through a small hole, it's like zoom. And makes the pulls much clearer

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Ray Diagnostician
North York, Ontario
Ray Default
 

These files are from a cranking 08 Yukon 8 cyl with a FLS in the intake and an ign sync. HTH Don't have the WPS hose in any cylinder.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Ray, Did you see anything in the scope captures on my vehicle? Are you in agreement with the others on what I need to do next? Thank you!

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Ray Diagnostician
North York, Ontario
Ray Default
 

I didn't see any obvious problem in your scope captures and you should follow the tests that Caleb Mohler suggested. We look forward to look at your new captures!

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Ray Diagnostician
North York, Ontario
Ray Default
 

Hi Scott, if you suspect a pitted lifter roller, you could remove the valve cover and feel the roughness on the rockers with the engine running.

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Michael Technician
Amherst, Massachusetts
Michael Default
 

Bernie Thompson from automotive test solutions has some videos on using a pressure transducer you can watch on their website. You should be able to get the idea of how to do it from those videos even if it is not a Pico. Also perhaps use a battery maintainer for the cranking compression test portion to eliminate the battery as a variable.

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Pam Owner/Technician
Tampa, Florida
Pam Default
 

After checking proper voltage, related TSBs, etc. - all the stuff we are supposed to do, but don’t - let‘s stop for a moment and push the scanner, pico and DOS-stuff aside. (Don’t get me wrong; they have a ”million-and-one” uses...when needed.) After verifying #8 was the issue (scanner report/thermal imager confirmation) - and, you believed it was a mechanical issue - did you put a set-of-eyes…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Pam, I appreciate your input. Thank you! You don't know me, but I'm in agreement with using scopes as the first tool out of the box. There's a time and a place for them. I joined iATN back in 1998 and I thought I was missing out as there were some pretty intelligent people that used scopes as part of their routine. I remember the debates on ringing injectors for GM TBI and some other…

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Pam Owner/Technician
Tampa, Florida
Pam Default
 

Anytime, Scott. Instructed in scope “tech” back in the 80s, in college. That same prof was a retired NASA engineer; he’s the one who emphasized to use your eyes as well as tools. Gave us the Apollo 1 story (which he was involved - before and after the fact); told us to always expect, look beyond for a false positive. He said had they done that, at NASA, the fire most likely would not have…

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Jamey Owner/Technician
Ventura, California
Jamey Default
   

I suspect you may have a bad lifter roller. Much like one I had. The roller starts to pit and it affects the valve opening see my captures below. I have a companion cylinder side by side comparison.

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Jamey Owner/Technician
Ventura, California
Jamey Default
 

by the way, I took those captures but the mark up and zooming can be credited to Mike Jones from Autonerdz. (Mick) One of the sharpest scope users there ever was.

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Robert Diagnostician
Fair Oaks, California
Robert Default
 

I did notice in your running compression waveform that when the exhaust valve closes and the intake opens that only on #8 Cylinder you get a higher pressure pulse. That would indicate valve opening/closing and sealing problems with the exhaust valve. In order for that higher pressure to be achieved more gasses need to be entering the intake from the cylinder when the intake valve opens. Could be…

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Paul Mechanic
Harvey, Illinois
Paul Default
 

It would have helped if you would have set up the rulers for all 8 cylinders on the vacuum pulls on your running compression shot. You also want to sample way more events on one screen and you can see via cylinder pressure if you have a valve sealing issue as your compression pressure instead of being relatively straight (even repeated compression) line across. A leaking valve as it rotates will…

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Gerald Owner/Technician
Winfield, Missouri
Gerald Default
 

Another thing that might be worth trying is a leak down test on 8. If it doesnt work at first, start the engine and run it for a little bit and shut it off and try again till you can get the suspect valve to maybe show its face

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

On the running capture, at about 360*, there is a jump in the intake pattern. It repeats every time. That has to be mechanically induced. It looks like a pressure increase but, I expect the pressure to go negative there, not positive. There is a “signature” of a double hump in the intake waveform. Ray Y’s cranking waveform shows the double hump also but his is on the bottom, yours is on the top…

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Greg Technician
University Place, Washington
Greg Default
 

I’ve had one that the only thing I could see was lower running compression but waveform was exactly the same as other cylinders. I needed to verify for extended warranty. They said OK to tear down. The lifter and cam were pitted. Since customer had taken it to another shop where they tuned it up and then drove 500 miles before he tried again they didn’t pay for it so I can’t tell you if it fixed…

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Bill Technician
Rosetown, Saskatchewan
Bill Default
 

Scott, Grabbed a quick peek at the file this morning. Looks to be a fairly big delta shift in intake pressure during the intake opening. Maybe I am late to the party though. Did not read all replies.

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

Random thoughts and observations; Any codes stored? Freeze frame data? Where are you connected to for your vacuum measurement? The measurement seems off. Have you used your ignition scope on the misfiring cylinder? Then compared it to the other non misfiring cylinders? I think you have another cylinder with a problem that isn't showing up yet. An ignition scope check of all the cylinders…

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

Cylinder 5 is the companion to 8 and would be on power stroke when the pressure spikes. I wondered about it being the cause but, figured it should be misfiring too. Unless it IS the misfire.

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Danny Instructor
Montréal, Quebec
Danny Default
 

I am dealing with very similar troubles 2009 Avalanche Cyl 4 misfire 0 psi comp. found colasped lifter Sent head to be checked replaced all lifters on bank 2 new plug and wires

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Scott Owner
Moreno Valley, California
Scott Update
 

Hi All, I appreciate your responses. I'm going to have to spend more time with this stuff. I realize the time to do this is on good vehicles and not broken ones. I didn't have a lot of time today, but I was going to try and put up what was asked for. I blew the dust off my high current clamp to do a relative compression test, but the batteries leaked and...Sigh. I used voltage, but it was…

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Carnage, filtered and zoomed in: diag​.​net/file/f1zbdxx41… ​

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Douglas Engineer
Webster, New York
Douglas Default
 

Scott I took Dmitriy's update to your data and added overlays to identify Intake, Compression, Expansion and Exhaust strokes. I also identified the cylinders on your voltage drop test (replacement for relative compression test) and noticed Cylinder 5 is missing a voltage drop which points to lack of compression on Cylinder 5 (valleys instead of peaks for voltage drop). You may want to do a…

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Scott Owner
Moreno Valley, California
Scott Default
 

Thank you Dmitriy!

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Robert Diagnostician
Fair Oaks, California
Robert Default
 

You have a Valve problem when the exhaust is closing and the intake is opening. Since it is not there every time on that capture, I would say you have a bad lifter that is bouncing on the cam as the pits in the roller hit the cam lobe. Probably Exhaust lifter is bouncing open in the process of closing giving you the pulses you see in the waveform. That waveform should be enough to say it is…

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Ray Diagnostician
North York, Ontario
Ray Default
 

CH A is COP 1 secondary sync CH C is cylinder 8 cranking compression CH D is the cranking battery voltage The battery voltage drops on each cylinder's compression stroke, when the starter amperage draw increases for each cylinder's compression stokes. There are no battery voltage drops on the compression strokes for cylinders 5 and 4

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Ray, diag​.​net/file/f1ffwg6ss… OK, so I played around with this some more and this is what I came up with. I appreciate you looking at this. I'm a little slow sometimes. Are you saying the fault is occurring because of something on cylinders 4 & 5, even though cylinder 8 is the misfiring cylinder? I noticed you pulled out the vacuum waveform. Is that because there was…

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Ray Diagnostician
North York, Ontario
Ray Default
 

You should do another cranking test with the WPS500 in cylinder 5, then in cyl 4. It would be interesting to see what the good and the bad cranking cylinder waveform looks like. I pulled the vacuum waveform because I was trying to keep things simple in determining which cylinder or cylinders have the intermittent low cranking compression strokes. In your capture, the intake manifold vacuum…

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

You did check compression on the whole engine with the voltage drop. It showed that 4,5 and 6 have different compression than the others. Just not how much. Checking those with a transducer would be fairly fast. Or temporary some batteries in the current probe to get an accurate current profile of all cylinders. Divide the psi of a known cylinder into the current draw to get a relationship…

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Ray Diagnostician
North York, Ontario
Ray Default
   

Scott, the cranking intake manifold vacuum pulse measures -7.7 psi or 15.4 inches of vacuum for cylinders 5 and 4. The second GIF is from an 07 Suburban 5.3 CH C is a WPS in cyl 7 and the cranking compression measures 16 psi The intake valve is not opening. The bottom of the expansion stroke vacuum pocket and the intake stroke measures -13.5 psi or -27 inches of vacuum cranking. CH D is the…

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

It’s odd that the period from 2 to 6 is about 40% longer than the periods of the 4 previous cylinders. The voltage drop is also more for 6. I wonder why 6 is so much harder to roll through. Also odd is that Dmitriy’s markup seems to show that the “fault” happens every other cycle of 8 cylinders. What could cause a cam, lifter, valve to fail everyother operation? Now I really wonder if 8 is the…

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Scott Owner
Moreno Valley, California
Scott Default
 

I was really trying to avoid something like this again. As I mentioned to Pam here's some pictures of that 4.8L when it was taken apart. There was a problem, just not THE problem. Sometimes I wonder how I make it out of bed... diag​.​net/file/f5g017ivp… diag​.​net/file/farxqbxpg… diag​.​net/file/f4y3drmev…

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Ray Diagnostician
North York, Ontario
Ray Default
 

Good example! Thanks Scott

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Robert Diagnostician
Fair Oaks, California
Robert Default
 

bases on the waveforms I suspect your lifter will look like the one above.

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Greg Technician
University Place, Washington
Greg Default
 

Did you by any chance get a waveform from the 4.8? I would like to know what showed up on waveform.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Greg, There was a variation of about 7 PSI on the compression waveform from what I recall. I'd post the files, but Jim was the one who captured the data.

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
   

Scott, Every time you have one of those odd events happen, where the cranking voltage rises and you get the large dip in vacuum you also get an increase in engine cranking speed. If you measure the distance between the compression peaks during a normal 720 degree revolution you get about 154 rpm or about 775 ms duration for 720 degrees rotation, if you measure between the peaks of a disrupted…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Eric, Sorry I didn't get back to your response. That's the thing that I mentioned earlier, that there was a difference in cadence, it just wasn't consistently that way. As far as DTC's stored there was a P0300 and a P0455. According to them the gas cap was lost. It does have a cap on it now and the EVAP system is passing tests. Here are the misfire counts - Cylinder 1 - 103 Cylinder 2…

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Rudy Technician
Montebello, California
Rudy Default
 

Scott- If you become familiar with these methods, it will save a tremendous amount of time int he future. Keep going......

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

Could you add a different capture to your scope? I would like to see the coil trigger for all coils instead of just cylinder #1. You can still leave #1 as the sync, just swap out the vacuum channel and connect it to the coil power supply. I want to see when the coils are fired in comparison to the drop on cranking voltage to verify the compression voltage drops are occurring at the proper…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Eric, I haven't looked at a schematic, but to see all would be 2 more channels, and I believe it will include the injectors. Are you talking about a current probe?

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Ray Diagnostician
North York, Ontario
Ray Default
 

If there are 2 coil/injector fuses for both banks, remove the fuses and put in 2 fused jumper wires in the place of the 2 fuses. Place the amp clamp jaws around both of the jumper wires to get all 8 coil amps on 1 channel.

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

I checked, yes it would mean two channels. You don't need the sync channel since your cylinder pressure is on cylinder 8 you can use that as a rough sync. You mean you don't have the current probes? One to corrode and two for backups? :-) I don't leave my batteries installed in hardware that doesn't see regular use. You might be able to pick up the voltage changes using the volt meter scope…

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Scott Owner
Moreno Valley, California
Scott Default
 

I've got low current probes. :-) Just the high current one took a dump. That's what I get for leaving the batteries in. I contacted Fluke and it's so old they would give me $100 credit towards a new one. I'm busier than heck right now, so as it looks, when I'm coming in tomorrow to do struts/shocks/rear differential on a 98 SS, I'll get this stuff up. Ray has a good idea as well. Thanks!

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

I was trying to calculate cranking RPM this morning, with a calculator . I came up with numbers similar to yours and knew that was too slow so I didn’t believe them. Could it really be cranking that slow? I can’t feature that 5/4 is so bad as to cause 8 to misfire and then not misfire themselves. Especially in light of the RC capture. I am very suspicious of the misfire counter’s accuracy.

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default
 

That's what I get for just reading off the Pico software. I was measuring from peak to peak which of course means 720 degrees or two revolutions. So you would have to double the stated rpm to get the actual engine cranking speed. I was in a hurry and just read it off the screen, I should know better. At least it was just used for comparison and not for something that actually mattered :-)

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

I get the Homer Simpson award, again. I was calculating the time for all 8 cylinders to cycle to get RPM. I redid it and got the same answer. DOH!!

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Bill Technician
Rosetown, Saskatchewan
Bill Default
 

Scott, If you ever have interest I can show you a quick and dirty way to verify the misfire monitor with the scope. If you do find yourself with a bit of time hook a sync to to number one (Preferably inductive/Quick) and put a lead on the back of the alternator B terminal and run it while its missing. If you can get that we could walk through it later, when you are not in the heat of battle. I…

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Jamey Owner/Technician
Ventura, California
Jamey Default
 

I would be interested in seeing that method. I am out of commission for a while. Just had back surgery..... I will be back to work on Monday, but can’t really do much.

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Stephen Technician
Gallatin, Tennessee
Stephen Default
 

Me three.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Bill, I'd like to see that if you have the time. Thank You!

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Bill Technician
Rosetown, Saskatchewan
Bill Default
 

Scott, Send me a file. If I see it tonight I'll mark it up. I am on a tractor sun up to sun down Sat/Sun, so won't be able to get to it on the weekend likely.

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Scott Owner
Moreno Valley, California
Scott Default
   

Hi Bill, What a day. Whew, I'm glad it's done. 3 vehicles I'm waiting for SOP's that should have been here days ago. They show up today. 20+ phone calls. Aw' crap, I just tripped on the tangle of wires for the Pico and it fell to the ground. It's probably OK, I hope. Anyway, here's what you were asking for... Thank you!

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Bill Technician
Rosetown, Saskatchewan
Bill Default
 

Hey Scott, This one is not easy to cipher. There are a few tricks that can make the pattern more prominent. If you AC couple B+ you get more zoom with little effort. Sometimes if you have it in gear it will be more prominent. It may take using the method a few times to get the hang of. It usually works very well. This is one of those times when it didn't. Was the misfire very apparent when…

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Bill, I'll try that again with the changes you suggested. As far as the misfire it was pretty apparent when the capture was taken. I think it was Dmitriy that put a post up about getting scan data embedded in the waveform. It was - diag​.​net/msg/m5wu28vsbm… I didn't have the scan tool hooked up, but I'll take a snapshot on the next file I post. Thank you,

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Scott, indeed I can glue your waveform and scantool data, visualizing the misfire counters. You can also add CKP signal as a backup for the alternator voltage, if it’s easy on this vehicle.

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Bill Technician
Rosetown, Saskatchewan
Bill Default
 

Sounds good Scott, I am not sure how much benefit the misfire/crank rotation speed test would have in this case. It is interesting and you start to see trends in the way the misfire program is calculating misfires It is only a quick and dirty trick that is handy to have in the toolbox some times. I would say especially in anything without misfire detection.

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Scott Owner
Moreno Valley, California
Scott Default
 

Hi Bill, I had to get here a little early today. I should have asked how you AC couple the B+ signal. I'm not sure if this changes anything, but I'll play with this some more. It sounds like it would be helpful if the cylinder misfire is not being ID'd correctly. Usually for GM it's accurate. This one was a little different as cylinder 7 was incrementing misfires as well as 8. As far as…

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Bill Technician
Rosetown, Saskatchewan
Bill Default
   

Thanks Scott, I Marked out where to change from DC to AC coupling. I also created a math channel in yellow to somewhat simulate the effect that you get from AC coupling. If you look at the lower right red box you can see I have it multiplied to X50 being DC coupled but can hardly make out the humps. My "pretend" AC couple has much more definition. It takes a fair bit of filtering to get to this…

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Jürgen Owner
San Cristóbal de las Casas, Mexico
Jürgen Default
 

One more interested.

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Scott Owner
Moreno Valley, California
Scott Update
 

Hi All, I took some captures of cranking compression on cylinders 4 & 5. I labeled them incorrectly as 4, should be 5, and vice versa. I've got the current probe hooked up to INJ 1 & INJ 2. You can tell I mislabeled the cylinder as I had the coil disconnected on cylinder 5. I was trying to rush before I opened and didn't disconnect cylinder 4. The other thing was this vehicle had the…

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Ray Diagnostician
North York, Ontario
Ray Default
 

I zoomed in on the cranking battery voltage from the first PSD file. Cylinder 2 has lower cranking battery voltage drop/ lower cylinder compression. Cylinder 5 has lower cranking battery voltage drop, probably because of the compression hose in the cylinder. Cylinder 6 has high cranking battery voltage drop/ higher starter amperage draw because of the low starter amp draw from cyl 2. Need to…

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Scott Owner
Moreno Valley, California
Scott Default
   

Hi Ray, I appreciate you taking the time and looking at what I put up. I am a little confused though. Actually that seems to be happening a little more frequently. BG In the previous scope captures I was told to check compression in cylinders 4 and 5, which is what I did. Now we're going after cylinder 2. Is this a matter of the way I collected data that's a problem, or...?? "Cylinder 5 has…

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Ray Diagnostician
North York, Ontario
Ray Resolution
 

Hi Scott, this is a weird intermittent mechanical problem and the relative compression amps might be more accurate to help diagnose the intermittent compression issues in this engine. The PSD file is the one you posted about 13 days ago. In the first GIF file, in CH B, the intermittent deep cranking intake vacuum pockets show the intake valves intermittently not opening in cylinders 5 and 4, I…

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Thanks
Scott Owner
Moreno Valley, California
Scott Default
 

Thanks Ray, I appreciate it!

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Ray Diagnostician
North York, Ontario
Ray Default
 

This GIf is from the first PSD file. I inverted the CH B battery voltage to show the starter amp draw. Cyl 2 has low compression and cyl 6 has high compression. Need to ck the cranking compression in cyl 2

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