Those dang fpr issues....

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Codido187

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Dec 4, 2017
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Hello duramax lovers,mechanics,enthusiasts. I am having some minor issues after installing my fuel pressure regulator on my 2004 chevy 2500hd lb7.
So my problem is when I am in drive the truck shutters and it has a higher idle then usual. Also when I put the vehicle in reverse it does the same dang thing. The truck has power like a beast there is no white smoke. I am not tuned I am bone stock. Also when the truck is in park it idles normally. I recently did an oil change fuel filter change and I always keep diesel kleen in the tank every fill up. When I replaced the fpr it took me roughly two days because my auto parts store didnt have the parts I needed and I left the wire harness unplugged. My question is should I give my truck some time to relearn everything or what direction should I take.

Thank you in advanced
 
IOWA LLY

IOWA LLY

Yes, its really me
Feb 23, 2007
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You forgot to plug in the ECT sensor. It's located right beside the alternator. If you didn't forget to plug it in then you might have pinched a wire.


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Codido187

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Dec 4, 2017
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Thank you I appreciate your response I am on shift right now I will get back with you in the morning thank you.
 
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Codido187

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Dec 4, 2017
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Dang good to know gents I will borrow my girlfriends grandpas soldering iron. What size of heat shrink would y’all get? I would suppose when I removed the alternator I yanked on the already bad wire connections. Why would the truck idle wierd in park and drive is my question. I don’t understand how the ect works as this is my first diesel truck.
 
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IOWA LLY

IOWA LLY

Yes, its really me
Feb 23, 2007
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The fuel tables and idle rpm will vary with coolant temperature. And if the ECT sensor is disconnected it will think the coolant temp is very cold. (-40f) So the idle rpm will be raised and all sorts of other strange things will happen because the ECM is trying to compensate for the extreme cold.


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tsd_billy

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Apr 5, 2016
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oklahoma city
IOWA LLY said:
The fuel tables and idle rpm will vary with coolant temperature. And if the ECT sensor is disconnected it will think the coolant temp is very cold. (-40f) So the idle rpm will be raised and all sorts of other strange things will happen because the ECM is trying to compensate for the extreme cold.


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Click to expand...



Well said sir


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Codido187

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Dec 4, 2017
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Very interesting thank you for the explanation. I will sodder everything up in the morning. Thank you both for your quick responses I’ll let you know if it changes the roughness. I am sure it will y’all know what your talking about
 
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Codido187

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Dec 4, 2017
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Ect is buttoned up still surging in reverse and drive. I wonder if I got a bad fpr when I replaced it? Or I have a bad ect but I am not popping any codes
 
IOWA LLY

IOWA LLY

Yes, its really me
Feb 23, 2007
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What were the symptoms before you replaced the FPR? Where did you get your new FPR from?

Surging and erratic idle can be caused from a whole host of things.....


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Codido187

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Dec 4, 2017
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Ok the symptoms were surging slow surging at idle rpms would move by 500 at a time. It was a duralast they didn’t have Bosch. I am untuned. I am at a total loss. Ok I’ll disconnect the fpr and see what happens it idles normal in park but reverse and drive it goes into high idle the truck is bone stock
 
DAVe3283

DAVe3283

Heavy & Slow
Sep 3, 2009
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Boise, ID, USA
Do you have any way of logging the truck? I would do a log of desired rail pressure, actual rail pressure, ECT, MAF, IAT, FRP command, mainrate (fuel command), and pilot quantity.
 
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aashton1206

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Sep 3, 2015
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Gotta order a fpr online, has to be Bosch


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, Rick Fletes Dsp 5 on v2, 33x12.5 nitto at on 20 inch American Racing 20x10 wheels, Stage 5 Built Transmission by Mike Cole with triple disc billet low stall converter, 4 inch Injen cold air intake, Profab Intake Horn, Batmo Wheel, PPE Race Valve, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust axle dump, lbz cp3 pump, Dual Platinum AGM Duralast, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Upper Contol arms, Drilled and Slotted Rotors on all four Corners, FED Y Bridge, Shantz Custom Fab Traction Bars.
 
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aashton1206

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Sep 3, 2015
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6139ff600740a5c67488ff2291d97075.jpg


This is where I get mine


2004 Silverado Cali lb7, Airdog ll 165, fresh sticks at 325k, Rick Fletes Dsp 5 on v2, 33x12.5 nitto at on 20 inch American Racing 20x10 wheels, Stage 5 Built Transmission by Mike Cole with triple disc billet low stall converter, 4 inch Injen cold air intake, Profab Intake Horn, Batmo Wheel, PPE Race Valve, Full EGR Removed w/ fed belt, 3.5 inch MBRP Downpipe, Full five inch MBRP Exhaust axle dump, lbz cp3 pump, Dual Platinum AGM Duralast, High Output Alternator, Cognito Pittman and idler w/ support kit, Cognito Upper Contol arms, Drilled and Slotted Rotors on all four Corners, FED Y Bridge, Shantz Custom Fab Traction Bars.
 
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