I've taken my truck in 3 times now. The 1st time I had a EGR Valve code, incorrect oil, and fuel level sending unit. I had the EGR Valve replaced and an oil change. Not too worried about the fuel level sender until I need to change the fuel pump. Since then my truck is running like crap it feels like it is misfiring real bad at cruising speeds. The engine ling came on again and the code was for incorrect oil again. So I took it in told the guy exactly how it runs, even test drove it with him, and the codes. After he diagnosed it he couldn't find anything, but told me that I needed to go back to stock exhaust for him to further troubleshoot it. He says that the resonation of my muffler could be throwing the timing off. After I called him an idiot, I got my keys and left. HELP!!
Need serious help!!
jwberry
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I've taken my truck in 3 times now. The 1st time I had a EGR Valve code, incorrect oil, and fuel level sending unit. I had the EGR Valve replaced and an oil change. Not too worried about the fuel level sender until I need to change the fuel pump. Since then my truck is running like crap it feels like it is misfiring real bad at cruising speeds. The engine ling came on again and the code was for incorrect oil again. So I took it in told the guy exactly how it runs, even test drove it with him, and the codes. After he diagnosed it he couldn't find anything, but told me that I needed to go back to stock exhaust for him to further troubleshoot it. He says that the resonation of my muffler could be throwing the timing off. After I called him an idiot, I got my keys and left. HELP!!
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529 Posts
ok for one the dealerships are called stealerships for that reason... you got the egr valve replaced and oil changed when was your last spark plug changed??? dont worry about the mufflers there full of crap... if you have any questions hollar at me...
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529 Posts
can you give me a break down of whats going on now??? i have to get all info to get a good trouble shooting for you...
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18,376 Posts
Exhaust has nothing to do with it so it still missing at cruise and only throwing the 1521 oil code now
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18,376 Posts
Don't know if the mechanic told you but there is a flash update for the p1521 code and for egr also
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20,323 Posts
Quick question, You said tune-up, but also said the dealer said the spark plugs looked good. Did they replace the spark plugs? Did you look at the plugs? Spark plugs gap opens .001" for every 2000 miles. I doubt seriously they removed all the spark plugs and then reinstall the same plugs which makes me think they pulled one and didn't see anything unexpected so called them all are good. When they changed the oil, was there any unusal debris found? What are they basing their assumption on? codes? You called it right when it came to the exhaust system mods diversely affecting perormance. My guess is Charged392 is on the money. Good luck...
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Yes it still sounds and feels like it's missing at cruise speeds. The oil code is the only one I got last time.
No they didn't tell me there is an update to that code. In fact he said there was no updates out for my truck. He did show me that.
No they didn't tell me there is an update to that code. In fact he said there was no updates out for my truck. He did show me that.
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130 Posts
When I am at cruising speeds my truck feels and sounds like it is misfiring. Give it some gas and it goes away, sometimes right away other times it takes a second. I had three codes EGV Valve, Incorrect Oil, and Fuel Level Sending Unit. I had the EGR Valve replaced and oil changed about 3-4 weeks ago. Still getting the Incorrect Oil code and Fuel Level Sending unit. When I get the codes the truck seems to smooth out and run fine. I clear the codes and it runs like crap. That is the basics of it.
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18,376 Posts
I almost bet when the codes set the mds is disabled and running v8 all the time and when the codes not there one or more of the 4 mds cylinders is either not lifter locking correctly and the fuel is being cut to that cylinder but the valve is still opening casing a pumping misfire and physical drag on the eng
Normal operation of the mds locks the lifter down so the intake valve doesn't move creating a compressor like comp helping push the piston back down even without the fuel ignition in the chamber the system is very good when it works correctly
This is a common issue with these mds lifters and is very tricky to diagnose
Normal operation of the mds locks the lifter down so the intake valve doesn't move creating a compressor like comp helping push the piston back down even without the fuel ignition in the chamber the system is very good when it works correctly
This is a common issue with these mds lifters and is very tricky to diagnose
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20,323 Posts
Makes good sense to me, good call. So the check would be to disable the MDS using a tuner and see if it solves the problem?
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18,376 Posts
Disabling the mds would be one way or unplug the the mds plug in the rear on the intake should be an 8 wire plug
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20,323 Posts
Good info, does it throw a code when unplugged?
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19,751 Posts
A worn spark plug with the gap way too big will cause a miss while cruising. Even at idle.......
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18,376 Posts
It's not a plug that would throw a cylinder specific code esp at idle from what we have described here its enough of a miss to notice but not harm emmisions or the light would flash
What I believe is happening is the eng is shutting the fuel down to the cylinder and instead of disabling the valve it still opens and closes so you actually loose power to a noticeable amount on the affected cylinders I wish I and this truck In Front of me
What I believe is happening is the eng is shutting the fuel down to the cylinder and instead of disabling the valve it still opens and closes so you actually loose power to a noticeable amount on the affected cylinders I wish I and this truck In Front of me
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130 Posts
I wish I had my truck in front of you too. Sounds like I would have a good running truck a lot sooner.
If you don't mind I'm going to copy this and take it to the shop tomorrow. I found a retired Marine that everyone is telling me to take it to. So hopefully I can show him this thread and he can have a better starting point. Even though I know he'll want to diagnose the whole thing. :thumb:
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18,376 Posts
Hey any info can help people out if it helps him good I hope he figures it out for you let us know what you find out
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