Few issues. P0171, p0301, and slipping trans?

6.2 · Jul 31, 2014

First off. 4.0 sohc motor. Automatic trans.

So. I recently got a code, p0301, misfire in cyl 1. No biggie. Check plug and wire. All good. Hmm. Switch plugs. And wire with another cyl just to confirm the code doesn't "follow" those items. It doesn't. Always cyl 1.

So I drove it a bit as I needed to haul some crap, then I got the p0171. Bank 1 lean.

Hmm. Ok. Cleaned MAF, cleaned my air filter (k&n) reset truck by disconnecting battery. Andddd no change.

Now. What really baffles me is when I punch it, it down shifts and once in a while it will start flashing the check engine light. And the truck sounds baaaaad. And a sometimes I'll give it gas and it will do nothing. Revs go up, speed goes down like I'm coasting no power.
I have a video I'll upload.

Once I let off the gas for a few seconds the cel stops flashing and and the truck returns to normal driving conditions. Only at idle, and the above mentioned situation, does it run rough. All other times its normal. Smooth. Etc.

Running out of ideas. Going to pick up a compression tester and check that. Can't find a vacuum leak, but I'm not a professional. May have to have a smoke test done.

Anyone have any other ideas?

adsm08 · Jul 31, 2014

Ignore the lean code for now and focus on the misfire.

Oxygen sensors give the info that sets lean codes, and oxygen sensors only see oxygen, they can't see CO2, CO, NOx, or HC, only O2, so to an oxygen sensor a lean condition from too much air/not enough fuel and a misfire where a bunch of raw fuel and oxygen get dumped down the exhaust look the same.

Since you ruled out ignition, more or less, and the issue is intermittent (flashing CEL means severe misfire happening right then, hence the rough run) I would say a base engine issue, such as compression or valve train issues are unlikely.

That leaves the fuel system. Swap the injector to a different cylinder and see if the miss follows it.

6.2 · Jul 31, 2014

Ok I'll try that then.

Have next week off work. Hopefully I can get it sorted out by then.

Truck isnt my daily anymore but I'd still like it to be running right.

Is there a how to somewhere for removing injectors?

adsm08 · Jul 31, 2014

Removing injectors is really easy. Unbolt the rail from the intake, or whatever it happens to bolt to, unplug the injector(s) you want, pull the rail up, if the injectors stay in it, check for clips and remove as needed, then pull on the injectors. They are mostly held in by just being clamped by the fuel rail bolts.

Most people hear "change fuel injector" and get intimidated, when in reality it's actually more difficult to do spark plugs on most engines.

It is advised to replace the o-rings on the injectors every time they are removed, but I have had no issues reusing them if they aren't torn or deformed.

6.2 · Jul 31, 2014

Alright cool. Sounds good.

6.2 · Aug 2, 2014

So I got around to doing the fuel filter today. Didn't have time to do an injector swap.

But, look at the fuel from the filter....

Pretty ****ed up.

I don't know much about fuel systems but I'd be willing to guess a plugged up filter would cause a lean issue at high rpm's. By not being able to get the fuel through fast enough. Just a guess.

And I'm guessing an injector (#1) is a little plugged up with shit from the filter. So I've got injector cleaner in the tank and will see if that clears it up.

Fingers crossed.

adsm08 · Aug 3, 2014

Are you sure that isn't engine oil?

6.2 · Aug 3, 2014

Hahahah right? My god it was brutal. Guessing it was never changed. Truck has 130k miles.

adsm08 · Aug 3, 2014

Yeah, and the front injectors are where all the crap settles in the rail of a 4.0 SOHC.

Sometimes it helps to take them out and soak them in some BG 44K for a few hours too.

6.2 · Aug 3, 2014

Will keep that in mind. Hoping injector cleaner will do the trick.

6.2 · Aug 5, 2014

Well, after burning $40 worth of gas just driving around with a new fuel filter and lots of injector cleaner its running pretty damn good. I cannot replicate the running lean, and the misfire code hasnt come up again. Before I touched anything it would come back after clearing about ten miles into the trip.

So I'm thinking its all good now. Will take it to work one day next week to see how it does on an extended drive. Fingers crossed.

adsm08 · Aug 5, 2014

Cool.

Few issues. P0171, p0301, and slipping trans?

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