Before and after captures

Michael Owner/Technician Pennsylvania Posted   Latest  
Case Study
Driveability
2012 Cadillac SRX 3.6L (3 LFX) 6-spd (6T70)
P0300 — Random/Multiple Cylinder Misfire Detected

2012 Cadillac SRX 3.6L with only 57,000 miles

P0300. #4 (pictured below) had a few hits on my road test. More so at WOT. "Fishbite" type misfire in the bay randomly throughout 1 through 6. Walnut blasting is kind of a pain and CAN be messy but it's very rewarding seeing the results. Of course I did all 6 holes.

Blue trace - pulse sensor at center of intake manifold

Red trace - sync at #1 coil (COP Probe)

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John Diagnostician
California
John Default
 

Great job. I see you used all caps for "CAN" in your post. I agree. I have done walnut blasting with a cheap butchered media blaster that was extremely messy and inefficient and I have used a top of the line blaster with the correct adapters that was quick and made no mess at all. Both had great end results but the cheap one took a lot more time, effort and experience.

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Michael Owner/Technician
Pennsylvania
Michael Default
 

Yup, just a little setup and patience but ya I am considering this one as we do these services often. pelicanparts​.​com/catalog/shopca…

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William Diagnostician
Texas
William Default
 

We have that unit and it works very well , especially on Mini and M57.

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Edward Owner
Texas
Edward Default
 

Michael, great post like the results... But your right if you want to maximize your Profit you won't go wrong purchasing the one in your link ... Fantastic post.....

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Mark Manager
Massachusetts
Mark Default
 

I’m really enjoying these post with the before and after cleanings can you share what type of equipment you are using to walnut blast the carbon away and also the pulse sensor great captures and pictures thanks for sharing !!

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Michael Owner/Technician
Pennsylvania
Michael Default
 

The pulse sensor is one I got from a guy that contributes a lot in some tech groups on facebook. If you'd like I can put you in contact with him. Equipment was from Bavauto..But looks like ECS Tuning took over? ecstuning​.​com/b-bav-auto-too… I am considering the "top of the line" one. Much more expensive but we do enough of these to justify the cost…

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Mark Manager
Massachusetts
Mark Default
 

thanks Mike that would be great ! i have not seen many carbon issues yet , it would be nice to tool up for when the opportunity comes I’ll be ready

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Jürgen Owner
Mexico
Jürgen Default
 

Thank youMichael for these captures... The "before"capture shows what could be described as hash due to the restriction of the carbon builtup. Furthermore I notice that every other intake pull on the "before" capture is slightly less than in the "after" capture. Usually I would attribute this to some degree to where the pressure sensor is connected to or to a mechanical issue. I "assume" the…

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Michael Owner/Technician
Pennsylvania
Michael Default
 

The one pictured was probably the worst one.

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Eric Owner/Technician
Wisconsin
Eric Default
 

Is the before picture the poorest condition cylinder you saw? If the other cylinders were the same I'm not sure this was your problem. I've seen valves with a larger amount of carbon buildup that didn't have any effect on the engine's performance. Was the sensor connected to the same port on the engine and the engine run under the same conditions, rpm, engine temp, etc? I'm not saying you…

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Michael Owner/Technician
Pennsylvania
Michael Default
 

Thanks for your input, Eric

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Eric Owner/Technician
Wisconsin
Eric Default
 

That's not the type of reply I was looking for, I was looking for a discussion about what happened to this vehicle. Does anyone have any experiences similar to this one, or different from it? I really would like to learn what to look for since I'm seeing these vehicles in my shop too.

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Michael Owner/Technician
Pennsylvania
Michael Default
 

The intake pulse took like 5 mins to set up and capture. What I do know is you can see turbulence in the "before" and it's gone in the "after" It can't be more clear that there was a correction. The sensor was connected at the same location pre and post repair. Clear flood was used to get these captures. I have not ever seen an intake gasket leak on a GM with the 3.0 or 3.6 DI engine and they…

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Eric Owner/Technician
Wisconsin
Eric Default
 

Wow man, calm down, I'm not ragging on you, I'm trying to better understand the problem and your repair. Your initial post was vague and I had some questions and random thoughts. Defensive much? I just asked some questions and wondered some things out loud. The vehicles I've seen with similar problems and similar carbon buildup were caused by injector issues and not by the carbon buildup. I've…

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Michael Owner/Technician
Pennsylvania
Michael Default
 

Eric, maybe you're the one that needs to calm down? You didn't hear my response or my tone you're only reading it. It can easily be taken out of context. I was merely explaining some points on my end. Sorry if you thought it was "vague" I run a busy shop and was excited to post results so I may have rushed it a little. Hopefully no harm, no foul. If this vehicle comes back with the same issue…

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Edward Owner
Texas
Edward Default
   

Eric Diedrick Michael, stumble on a curious idea I didn't think of using a pulse sensor to determine valve coking. In the past months I've been reviewing several forms and postings and the information so far justified to start performing testing and see for myself if it checks out, as to Michael post there are to many variables to explain over the net. I personal like testing my self and coming…

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Agree
Interesting
Thanks
Kevin Owner/Technician
Georgia
Kevin Default
 

Edward, Can you tell me where you purchased the intake valve cleaning adapters you posted a picture of in your post? I have not seen many of those and most kits only have adapters for BMW and Mini. Thanks!

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Edward Owner
Texas
Edward Default
 

Kevin eBay​.​com there are several of them in different makes and models also universal... Thanks for the response...

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Kevin Owner/Technician
Georgia
Kevin Default
 

Edward, Thanks for the info and quick response! Kevin

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Dmitriy Analyst
Ontario
Dmitriy Default
   

Michael, certainly, the "after blasting" waveforms looks perfect. Now, if comparing the captures by putting them on top of each other using the sync traces... it looks like one of them is inverted? Is it possible in your setup (for example, if using BNC-banana extension leads), or there must be some other explanation? Thank you for performing the experiments! diag​.​net/file/f1gyh5t4d… ​

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Michael Owner/Technician
Pennsylvania
Michael Default
 

Both captures were utilizing the same pulse sensor, location and leads. I'm a little green with this type of testing so I'm interested to hear more.

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Dmitriy Analyst
Ontario
Dmitriy Default
 

The only other variable I can think of is throttle blade position. Picoscope guys recommend to use closed throttle, and even disconnect the throttle motor to be sure: picoauto​.​com/library/automo… Of course, for that fuel delivery needs to be disabled too...

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Michael Owner/Technician
Pennsylvania
Michael Default
 

This was done "clear flood"

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Eric Owner/Technician
Wisconsin
Eric Default
 

When you have some free time, try checking a good running vehicle with the throttle in both the closed and wide open position. Then try a poor running one, one with a bad intake valve would be best, with the throttle in the closed and wide open positions. I find I get better results with the throttle closed.

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Michael Owner/Technician
Pennsylvania
Michael Default
 

Will do, Eric

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Eric Owner/Technician
Wisconsin
Eric Default
 

This post is a good example of why a case study of one vehicle doesn't always provide good results. I'm not saying these aren't good results but there are more questions left than answers given, at least for me. We, the collective we, went through this a lot in the early days of iATN. we would spend hours after work on an idea only to find out that the thoughts we had in theory didn't work out…

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Edward Owner
Texas
Edward Default
 

Eric 10-4 absolutely agree....

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