Fuel Trim, Rough Idle & P0301

[Brian]

So I’ve got a very rough idle. Sometimes feels like it wants to shut off. Been getting the P0301 misfire code and I’ve changed and clean a bunch of parts already but nothing has worked so far. Checked fuel trim last night and LTFT bank 1 went as high 16.4 and bank 2 went as high 7.8. When holding at higher RPM’s bank 1 went down a little bit, but bank 2 went up a little bit. What’s that all about?? That doesn’t seem normal. Shouldn’t both values go up or down at the same time??

Topic

[none]

Year, make, model, and engine (V6 or V8?) will help us help you.

What are all these parts you’ve replaced or cleaned?

[Brian]

Sorry about that. 2006 Dodge Charger 3.5L V6.

Here’s a complete list of what I’ve done so far since first getting the misfire code:

– New Gas Cap
– Change spark plugs & PCV Valve
– Change ignition coils
– change fuel injecter on cylinder 1
– clean throttle body
– Seafoam via vacuum line
– Clean short and long run actuator (Cleaned with carb cleaner)
– cylinder compression test (looks good)
– swapped spark plugs 1 & 2
– Clean IAT and MAP sensors
– New cam and crank positions sensors
– Vacuum test (looked good also)
– New plenum gasket
– New EGR valve & gaskets
– New Evap purge solenoid
– New o2 sensors (upstream)
– Removed and checked the vapor/charcoal canister and the hoses look good and the
canister itself did not have any cracks either. I took a hand vacuum pump and
pumped a bunch of air in there to see if maybe it’s clogged and could possibly
loosen it up a little.

So, I have probably done way more than I should have but since I have 112,000 miles I figured I might as well change some of this stuff just for preventative maintenance anyway.

When I first start the car the STFT percentages are in the negatives and the idle feels good. Then they gradually work there way up to the positives and that’s when the idle gets rough again.

[Allan]

Hello 🙂

Have you check fuel presure?

[none]

Considering all the parts you’ve thrown at it, it’s probably time to do some circuit testing. You can find wiring diagrams here: http://www.revbase.com/BBBMotor/Wd

A scope would be ideal for testing the injectors and the coils, but it wouldn’t hurt to at least verify good powers and grounds to both on the number one cylinder with a voltmeter.

[Brian]

[quote=”allhan” post=150827]Hello 🙂

Have you check fuel presure?[/quote]

I haven’t checked fuel pressure because I would have to buy a special tool just to connect up to the fuel rail. This car doesnt have any shrader valves or any ports to test pressure.

[Author]

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