My truck is a 14 5.3. Well I recently filled up with a tank of E85 because I wanted to compare track times from my passes with a tank of 87 octane. A few days after filling up, the truck threw a CEL. My scanner revealed it was P050d, Cold Start Rough Idle. It did throw the code in the morning when the temps were a little cool and it was after the truck had sat all night. I already had an appointment with the dealer for two recalls so I left the code in and asked them to look at it. The dealer reset the code and said it was due to my AFE intake. AFE used my truck for testing and the intake has been on since February with no issues so I doubt that. Anyway, the truck kept throwing the same code every few days in the morning, so once the tank was at 1/4 I filled it with 87 octane. It seems the problem is solved. Truck idles better on cold start and no more CEL's. Has anyone had the same issues with E85 or would it be something else causing this? BTW the truck ran fine and seemed to pull hard on e85, it was just the cold starts.

 

Possible carbon build up on the valves.

 

With only 7000 miles?

 

It's unlikely but possible. The tech would need to do some good diagnosis work to figure out the problem.

 

Diagnostic Instructions•Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
•Review Strategy Based Diagnosis for an overview of the diagnostic approach.
•Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC DescriptorDTC P050D
Cold Start Rough Idle

Circuit/System DescriptionDuring a cold start, the engine control module (ECM) commands dual-pulse mode during Open Loop operation to improve cold start emissions. In dual-pulse mode, the fuel injectors are energized twice during each injection event. As with misfire diagnosis, in dual-pulse mode the ECM monitors the crankshaft position sensor and the camshaft position sensor to calculate crankshaft rotation speed. In normal operation, optimum fuel delivery during dual-pulse mode produces a steady crankshaft rotation speed. If the variations exceed a calibrated value, the code will be set.

Conditions for Running the DTC•DTCs P0010, P0011, P0016, P0089, P0090–P0092, P00C6, P00C8, P00C9, P00CA, P0101–P0103, P0106–P0108, P0112–P0114, P0116–P0118, P0121–P0123, P0128, P0192, P0193, P0201–P0206, P0222, P0223, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0315, P0335, P0336, P0351–P0356, P0628, P069E, P1248, P1249, P124A, P124B, P124C, P124D, P1258, P135A, P135B, P150C, P163A, P1762, P2122, P2123, P2127, P2128, P2135, P2138, P2147, P2148, P2150, P2151, P2153, P2154, P2156, P2157, P216B, P216C, P216E, P216F, P228C, P228D, U0109 are not set.
•The catalyst temperature is less than 300°C (572°F).
•The engine coolant temperature is between 17–43°C (62–110°F).
•The barometric pressure is greater than 75 kPa.
•The engine speed is between 550–2000 RPM.
•The engine is running less than 100 seconds.
•Accelerator position is less than 1 %.
•DTC P050D runs once per cold start.
Conditions for Setting the DTCThis DTC will set if the engine control module detects variations in crankshaft rotation speed caused by the lack of adequate fuel delivery during dual-pulse mode.

Action Taken When the DTC Sets•DTC P050D is a Type B DTC.
•The engine control module disables dual pulse mode and energizes the fuel injector as it would for a warm engine.
Conditions for Clearing the DTCDTC P050D is a Type B DTC.

Diagnostic Aids•This DTC may be set with a misfire DTC, however the existence of this DTC is a higher priority and indicates the condition to diagnose is related to fuel and/or injectors, not the ignition/spark system.
•A restricted fuel injector may cause this DTC to set.
•High resistance in the circuits of the fuel injectors could set this DTC without setting an injector DTC. Test the fuel injector circuits of the affected cylinders for a high resistance if you suspect a condition. Refer to Fuel Injector Diagnosis.
•A drop in system voltage during cold start may set this DTC.
Reference InformationSchematic Reference
Engine Controls Schematics

Connector End View Reference
Component Connector End Views

Description and Operation
Fuel System Description

Electrical Information Reference
•Circuit Testing
•Connector Repairs
•Testing for Intermittent Conditions and Poor Connections
•Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference
Control Module References for scan tool information

Circuit/System TestingNote: Circuit/System Testing requires cold start. Do not start vehicle prior to connecting scan tool and preparing to evaluate the condition during engine crank.

 1. Start the engine and observe the Cylinder 1–8 Current Misfire Counters during the first 500 engine cycles. The Cylinder 1–8 Current Misfire Counters should not be incrementing.
⇒ If the misfire counters are incrementing on one or more cylinders
1.1. Ignition OFF.
1.2. Verify that the following conditions do not exist:
◦Fuel pressure that is too low or too high — Refer to Fuel System Diagnosis.
◦Contaminated fuel — Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
⇒ If a condition exist, repair as necessary.
⇒ If none of the conditions exist, replace the Q17 Fuel Injector(s) as indicated by high misfire counts.
⇓ If the misfire counters are not incrementing
 2. All OK.
Repair InstructionsFuel Injector Replacement

Repair VerificationNote: Repair Verification requires cold start.

 1. Ignition ON, engine OFF, clear the DTCs with a scan tool.
 2. Start the engine.
 3. Verify the DTC does not reset.

 

So yes the e-85 could have caused your problem

 

Thanks for the info, thats what I'm thinking as well.

 

You are welcome

 

I meant to post the same thing and forgot. Lol

 

Snooze you lose! hahahahahaha