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I have a 2012 Chrysler town and country and it recently popped the code of a p0175. I took it to a mechanic and they gave it back saying they couldn't detect where the problem is. He said he had checked the MAF sensor, the O2 sensors, the fuel line, thermostat etc.. and he couldn't figure it out. I am hoping someone on here might be able to help. I also didn't know to use E85 on the 3 years I have bought it and was wondering if that might help whatever is going on? Yes I am dumb for thinking E85 was just regular 85 fuel FOR 3 YEARS!!!
 

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What's the mileage? Is it over 100k? If you haven't done the spark plugs on it, you're more than likely due.
 

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My opinion, unless E85 (85% ethanol) is $1.50/gal below regular unleaded (typically E10 - 10% ethanol) it is not worth it dollar-wise. You mpg will drop by 40% (e.g. 20mpg down to 12mpg) so E85 needs to be 40% cheaper to break even.

I agree with Sienile regarding the spark plugs. Have them replaced with proper NGK or Champion.
 

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More likely is the "mechanic" that can't figure out your issue installed them and he didn't gap them properly and just put them in with whatever gap they had on them. A lot of younger mechanics think everything comes ready to use out the box, which isn't always the case. I've even chewed out a younger boss of mine because he thought I was wasting time on spark plug jobs. He changed his tune on the next one when I showed him that the new plugs straight from the box were almost as gapped out as the ones we were replacing. And it's not just the young ones, but it's more common amongst them.

For a P0175 there has to be an issue with the front half of the engine. That code is for too rich, which means either too much gas or not enough air. A coil or spark plug can cause it by not making enough spark to burn all the fuel. An injector can cause it by leaking or not spraying correctly (clogged and dripping). On these engines another possibility is the rockers not opening the valves enough. That would normally have a loud ticking to go with it.
 

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We did the spark plugs about 6 months ago but maybe I will check and see if one of them is faulty.
Well we have already determined your mechanic doesn't know what he's doing.
Could have used the wrong plugs, could have failed to gap them properly, likely failed to replace the coils when doing the plugs.
Also very likely they failed to properly torque the intake manifold back down properly after the plug change and now you have a vacuum leak on front cylinders from an improperly torque mainfold.
 

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Discussion Starter · #10 ·
Step 1, Find a new mechanic.
If your mechanic thinks these have a MAF sensor he clearly knows nothing about these vans.
More likely is the "mechanic" that can't figure out your issue installed them and he didn't gap them properly and just put them in with whatever gap they had on them. A lot of younger mechanics think everything comes ready to use out the box, which isn't always the case. I've even chewed out a younger boss of mine because he thought I was wasting time on spark plug jobs. He changed his tune on the next one when I showed him that the new plugs straight from the box were almost as gapped out as the ones we were replacing. And it's not just the young ones, but it's more common amongst them.

For a P0175 there has to be an issue with the front half of the engine. That code is for too rich, which means either too much gas or not enough air. A coil or spark plug can cause it by not making enough spark to burn all the fuel. An injector can cause it by leaking or not spraying correctly (clogged and dripping). On these engines another possibility is the rockers not opening the valves enough. That would normally have a loud ticking to go with it.
Okay he did tell me there was a leak somewhere on the front of the engine so I am gonna try to replace the injectors and check the spark plugs today. I am leaning a little more towards injectors because of the fact that he put in the E85 gas in the van and now the check engine light will turn off and on every now and then.
 

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Okay he did tell me there was a leak somewhere on the front of the engine so I am gonna try to replace the injectors and check the spark plugs today. I am leaning a little more towards injectors because of the fact that he put in the E85 gas in the van and now the check engine light will turn off and on every now and then.
I would put money on improperly installed intake manifold causing a vacuum leak at the manifold causing it to run rich.
 

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Oh, yeah. If those plugs have never been changed, they are 100% a contributing factor to this.
 
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Oh, yeah. If those plugs have never been changed, they are 100% a contributing factor to this.
She said earlier that the plugs were changed 6 months ago.
Knowing that, I'm betting the mechanic failed to properly install the intake manifold, or reused the old gaskets and they failed, either of which would cause a vacuum leak that would cause a rich condition on that bank.
 

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Ooops, I had forgot she said that. So plugs shouldn't be an issue unless they were done wrong. You may be right about the intake gaskets.
 

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ECM tries to compensate for the excess air, in turn flooding itself.
Not really. Two things happen. The manifold pressure may drop slightly, causing the PCM to think the load is a little higher. This adds a little fuel, but really just speeds up the engine. The O2 sensor still adjusts fuel trim. It takes a big leak to affect manifold pressure very much.

The other is that one cylinder a little lean can make the PCM add a little fuel in response to a lean O2 sensor indication, causing neighboring cylinders to run a little rich (since they share one O2 sensor), but the O2 sensor sees roughly the average of all and it’s not going to drive the average mixture super rich. To set a rich code the feedback system has to be at its limit of ability to compensate for a rich mixture, which isn’t what’s happening here.

If it’s bad enough a vacuum leak can cause a lean code or a misfire, but not a rich code.

With one caveat — if the MAP sensor has a vacuum hose and IT leaks, that can cause a rich mixture because the sensor thinks load is a lot higher than it really is. But ours don’t have a hose. Maybe the 3.0 does — don’t remember.
 

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Chrysler PCMs don't always behave the way you expect them to. I had a Durango in the shop that would die within a minute and throw a lean code. The problem was a fuel soaked vapor canister. PCM would see the rich condition caused by the purge flow and lean out to the point it couldn't run. Doesn't seem impossible that a vacuum leak could cause a rich code.
 
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