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Discussion Starter #1
Ok, I know this sounds crazy but.... the other day my truck did what I can best describe as a backfire or a miss. It happend twice, I was under a light load the first time it happend ( with a steady pedal) and thought I hit an open joint on the bridge I was on. I didnt pay it much mind. It then happend again about 5 miles further up the road, on flat road, 50 mph, steady throtle ( no load in the truck). All gauges showed normal and I couldnt get it to reoccor, o matter what I did.
Any thoughts on what could have caused this? And NO, its not the sparkplugs- I just changed those :D
 

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This response won't help you in the least but I had a Dodge/Cummins that did what you are describing. It always happened when I was cruising along at freeway speeds, about 100 miles after a fuel fill up. It didn't do it very often. I always referred to it as a burp. Couldn't ever figure out the cause. I just assumed it was a pinch of contamination finding its way to an injector. Changing the spark plugs won't help.
 

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kdcrockett;1575352; said:
Changing the spark plugs won't help.
You got that right. Our trucks don't have spark plugs... :D
 

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they dont i better stop paying the dealer to replace them then:eek: .i had bad fuel 2 differant times that at highway speeds it would hic up and smoke alot both times was from the same fuel station never went back.all is well now.now i gotta talk to the dealer about a refund:rolleyes: on my spark plugs.
 

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im not sure my friend my tractors do that alot!!!!
 

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Discussion Starter #7
RickDLance;1575425; said:
You do have the EGR disabled, don't you?
Nope. Havent got to that yet.
 

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what code are you getting
 

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smsdmax;1576258; said:
no egr blocked + boost stick = engine burps
Some trucks that have a functioning EGR system and boost stick will experience a momentary loss of power and loud "cough" noise during a sudden drop in engine rpm (ie: transmission upshift) and high boost.

If what you're experiencing occurs when in gear and low boost, it may be something else.

:)
 

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SOunds kinda like a turbo bark doesn't it>? Mine did this and then I put in a blocker plate. It worked for a long time. Now thought I am starting to hear it again., I thought the blocker plate fixes the bark. Thats what it sounds like you are describing to me...
 

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I just went thru the same thing on my truck. Took it to the stealer and it had kicked 2 codes. The tech cleaned the MAF and I drove it. Did it again. Took it back and got a new MAF sensor. Runs great now. When I posted this same thing, somebody gave me some other things that might have been wrong also. The throttle calibration might be off????? One other thing too but I can't remeber. My 2 cents.
 

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Discussion Starter #13
Thanks guys. I will put in the blocker plate and see if that cures it. No way its turbo bark, was only producing about 7 psi max while cruising ( probably less but i was going up a slight hill the first time).
Really odd how the EGR would be related to Boost though. I dont uderstand enough to relate the two.
Guess I will need the fingers stick now too, I was happy that I didnt have too so far. Oh well.
 

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SKLMotorsports;1577553; said:
Really odd how the EGR would be related to Boost though.
Fingers is the authority, and can explain this best.

Until then, here's my highly suspect, non-technical understanding:

1. The Boost Stick modifies the Manifold Absolute Pressure (MAP) signal, fooling the Engine Control Module (ECM) into commanding more boost. The increased boost pressure results in increased drive pressure; or in other words, greater exhaust pressure upstream from the drive side of the turbo.

2. When the EGR activates, the greater exhaust pressure results in increased EGR flow to the engine. On many trucks, the increased EGR flow results in a periodic "turbo cough" noise that occurs during transmission shifts under heavy throttle.

3. The Blocker Plate prevents EGR flow to the engine. Preventing EGR flow to the engine eliminates the turbo cough noise.


Wait. There's more.


4. The elimination of EGR flow results in increased intake air flow. The increased air flow at the MAF sensor is more than the ECM expects, which results in the ECM generating the associated Diagnostic Test Codes (DTCs), (P0401, EGR flow insufficient and P0101, MAF out of range) and on California emissions certification trucks, the Service Engine Soon (SES) light.

5. The Fingers Stick modifies the MAF sensor signal, sending the ECM the expected MAF sensor signal and preventing the EGR related DTCs.


I'm certain I've omitted several important points, but I believe that's the gist of it.

:)
 
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