I have a 2006 H3 with 175,000 miles on it. It’s frequently reluctant to start, but most of the time it’ll start on the second attempt. I typically feel a very short, slight drop in acceleration a minute or two into a trip, especially first thing in the morning.

I need to get the check engine light to clear since my inspection is due soon. The local auto parts store pulled the code for me and it’s P0171, bank 1 system too lean.

Recently I put on a new Air Cleaner Intake Duct to replace an old cracked one and can’t see any other cracks/leaks between the air filter and the throttle plate. The air filter was replaced last month.

I cleaned the MAF sensor with some CRC Mass Airflow Sensor Cleaner. The MAF sensor seems to be working. When I unplug the wire harness from the MAF sensor, the engine dies. Is there a way to test the MAF sensor beyond that?

When I was replacing the spark plugs last month, I noticed that the soft rubber breather hose that runs from the breather port at the rear of the valve cover to the resonator box was gummed with a yellow gunk like mentioned in this thread. I managed to clean that line before replacing it, but I was wondering if there’s anything that can, or even should, be cleaned inside the resonator box itself. I’m guessing the gunk that was in the hose also ended up in the resonator.

Also, the two bolts that hold the resonator box in place can’t get any purchase when I try to tighten them again. Is there something I can do to get those bolts to tighten in the threads again? I’m not crazy about them not being tightened and wonder if that’s not causing a vacuum leak with the breather hose.

Ran a bottle of GUMOUT - Regane Fuel System Cleaner through the gas tank for good measure. Haven’t noticed any change in performance as a result.

Any input would definitely be appreciated. I’d love to get that code cleared.

 

Sounds like you've covered quite a bit.

So,
Recap...

Bolts holding resonator are loose?
Rubber hose at back of engine under resonator box was replaced?
You cleaned MAF?
You completely cleaned TB??????
You made certain that there are no O2 sensors malfunctioning?

 

_____

 

You need to clean the TB, ain't no reason to go spraying stuff in the intake. Remove the TB when you do it.

Have you checked that the intake manifold bolts are tight?

You have enough miles to consider investing in new O2 sensors. Best way to test the O2 sensors is to put the vehicle on a scanner, start and watch what they do as the engine warms to full operation temperature. That will require a scan tool, not just an OBDII reader.

 

Thanks for the input. I spent some time under the hood last weekend cleaning the TB and replacing both O2 sensors. Attached a few pics below. The old O2 sensors look like they've seen better days.

Put everything back together and drove 80-100 miles. Check engine light didn't go off and didn't really notice a measurable change in performance. Still having problems starting. Usually takes at least two attempts. Again this week I had one instance where it took a few minutes of trying.

Took it back to AutoZone to see if the codes were any different. Still getting the P0171 code. This time though, it's also suggesting that I replace the O2 sensors, which wasn't suggested the first time I pulled the codes.

I used Bosch sensors in the replacement:
15131 (upstream)
15159 (downstream)

From what I can tell by searching the interwebs, those should both work with my vehicle. From other forum posts, though, I know that spark plugs are sensitive as to which manufacturer's parts are used. Is there a similar issue with O2 sensors?

I did notice on the upstream sensor, that while the connector was the same, the cable was a little shorter than I needed to run it properly. I had to use a bit of wire to keep it pulled up and away from the engine block rather than routing the cable as it originally was.

Any suggestions would be appreciated. Call me optimistic, but I feel like I'm really close to getting this resolved. I just gotta figure out which puzzle piece is out of whack.

 

A quality O2 sensor should be fine, not the same issue as spark plugs.

 

I had to change my O2 sensor and it was hard to get off. I took out my MAF and cleaned it. Yours looks good but take it out and check the inside if you have not done so already. I stuck in iridium plugs. I cleared P0171 which I understand is a common code. For me the O2 sensor was the crust of my P0171 issue.

 

Those O2 sensors were indeed a challenge to remove.

Yeah, I did clean the MAF sensor with CRC MAF Sensor cleaner. Twice in fact. It looks like there's another sensor similar to the MAF that's downstream from the TB. Is that something that needs to be tested/cleaned?

 

I re-read your threed and the responses. I have the same issue with inspections in Colorado, the engine light needs to be off. Doc says to check the manifold bolts. He also is not sold on worrying about plugs. The scanner procurement is a great idea. If you cannot afford to get the expensive scan tool he recommends, get an OBD II that will at least clear the code prior to inspection. I use and Actron CP9125. Also if your state has those automatic emissions test units that they set up along the freeways, go find one and drive by it a few times. You may get lucky. "No admissions test required."

So far as the resonator goes, I have one that you can have. I changed over to a K&N CAI and my old one is in my way. (I could not find a Volant and did not feel like making one. So I settled). I would have to hunt for the screws. You pay shipping only.

re-cap:
1) Check the manifold, screws especially.
2) Get a scan tool. A good one will allow you to watch the problem and isolate. And ODB II will clear the codes and turn off the engine light.

 

Thanks 2, I'll take you up on that resonator. I'll send you a PM to sort out the details.

I disconnected the battery to clear the codes. After about 15 miles, the check engine light popped back on, simultaneously triggering my @#^#%*!%* response.

I've rechecked all of the screws, everything looks snug. I was finally able to get the ones on the resonator box to tighten after some repositioning when I did the TB cleaning.

I figured I'd spend $10 and replace the soft rubber breather hose (I've seen it called a crankcase ventilation hose or an air cleaner intake hose - the highlighted part #11 in the pic below)


From poking around in the forums, it looks like it should be part number 15123628, but the interwebs want to tell me that it's not compatible with my base model '06 H3. Anybody have any thoughts on that?