What makes you think P0172 means rich fuel mixture?
It actually means rich fuel TRIM, that is : It is adjusting rich because the mixture is lean or the #1 O2 sensor thinks it is lean.
The computer can only control the amount of fuel not the amount of air, the MAF meters the air then the computer gives enough fuel to get the mixture right. If more air is hitting the #1 O2 sensor than was metered you get the P0172. (layman explanation, somebody want to correct something)

170F is too cool, the t-stats job is to keep the temp ABOVE180F. The fan turns on at about 217F and cools it down to 180F.
The t-stat is closed below 180F and open above 180F it is the fans job to keep the temp below 217F
The temp sensor is on the t-stat housing.
It is remotely possible for the low temperature to cause fuel ratio problems since the air density can be affected and the MAF measures volume/sec. And the O2 sensor measures percent of unburned O2.
The MAF also measure the air temp.

Could be the computer, so many mechanics will suggest that as a fix. OOh, those nasty/scary computers, they are out to get us!
Could be one of the sensors, innocent coils of wire encased in epoxe.
More likely raw air getting to the #1 O2 sensor via a leak or hole in the exhaust .

 

Well the shop that did my timing chain two years ago drained the coolant so it’s still good as barely put any miles on it anyhow.

That’s what I’m wondering and I will have to wait till I have some help to recheck the exhaust again next week will drive it to work. Like I said if I have a exhaust leak wonder why I don’t smell it? Strong smell went away with air filter, plugs. Doesn’t run any louder. Should throw a code just for the #1 O2 of it was bad. Yep it’s says system bank 1 rich. To me that meant engine is running rich but guess it means the computer is making it rich trying to fix something.

You guys both dismiss bad fuel?
also the flexfuel engines needing alcohol level in the computer zeroed out and fuel trims?

One thing I don’t want to do is throw parts at this and shops will do the same at a higher cost for everything. I have some freeze frames from my little scanner I have from a drive a few mins ago…
Would either of you be able to look at any of that and tell me anything? My buddy’s is better but won’t see him till Monday.

 

Also why am I not getting a code for the thermostat unless it won’t tell you because it’s not overheating with a dash light.

 

It’s not over heating , but it is running cooler then programmed, if it warms up within the parameters of the ECM then it won’t show code P0128

if it’s running cold then it’s running rich, so change the thermostat first!
please don’t go cheap in the thermostat, the $14.00 AC isn’t the correct one, just the same retail name.
So, reuse the Dexcool, be sure to burp the coolant

 

Yeah I know it’s not overheating, was just saying I guess it doesn’t tell you if the engine runs cold the thermostat is bad. Well dang that’s a easy fix if that’s the issue! I learned replacing the vapor canister buying a Amazon one and it didn’t fix the code. Got a name brand one and fixed that code.

 

I get a hookup from Advanced Auto here and they don’t have offer that one and worried to try Amazon stuff. Already found a fake Acdelco part I was sent from a vender.

 

Nope, it says "fuel trim system rich, bank 1" Nobody seems to see the "TRIM" part.
If your reader does leave out the "TRIM" don't rely on anything beside the code numbers it says. I don't trust talking code readers, anyway.

 

Then order the thermostat from RockAuto, don’t forget the discount code!

 

Okay we checked over the exhaust again and it’s good. Went over the engine for vacuum leaks. Hear nothing. We pulled the hose off the valve cover and I gave it gas. Engine didn’t act any different as we’re looking for a pcv and Google said our engines don’t have one. So we took the hose off and no cracks. But if we cover up the little plastic elbow it sucks air into the air tube for throttle body and bogs engine. I gave it gas a few times then we connected the hose back up. Go to turn the engine off and check engine light is gone and has not returned. But when I started the engine today it idled horrible and after a second fixed itself. But seemed like it was out of breathe. So sure seems like the hose to the valve cover and that elbow must have something to do with this issue. Is the plastic elbow hollow or is there a valve in there?

 

The elbow is not a valve. A common source is a crack in the rubber tube from the air cleaner to throttle body, or a loose connection on either end. Might be a bad electrical connection to the MAF or a bad mechanical connection MAF to tube.