Hey guys so of course new issues arise with the h3
So had it in last week for a check over because i get some rough idle and when breaking the rpms jerk around and there scanner showed a ton of codes,They ended up clearing them all and i went back today and there all back.

BCM shows up, 3 radio codes,something about losing circuit or something i cant exactly remember. Ecm, onstar,phone communication,passanger airbad loop open, 12 codes in total Lol.
random misfire p3000 (This same code was back in the summer and dealer changed out spark plugs and said it was fixed) Its back though and maybe never even left.
Shop was looking at engine and noticed the exhaust manifold had a broken bolt.

Now would the bcm cause all these random codes to pop up? Only dealer can replace this?
Would the broken bolt for manifold cause rough idle or heavier on fuel ?

Its 07 hummer H3

 

With this much stuff happening your best bet is to have the exact codes. Print em out and post em.

 

Step #1. If you have the original OEM battery connectors replace them with a high quality connector before you do anything. They are the source of many electrical gremlins.

 

Sorry, but we do not know what year H3, which model H3, how many miles, if any recent work was done, and we would need the actual codes that show up.

Yes a broken exhaust manifold bolt can lead to fuel use inefficiency, possibly even contribute to rough idle, but you should be hearing and exhaust leak before that happens.

The BCM controls/monitors the body function, not powertrain. The PCM (you said ECM) controls/monitors powertrain function. I can't tell from your vague description of what the codes are, but sounds like you have issues with both.

When was the last time you cleaned the MAF and Throttle Body?

 

2007 h3 3.7 auto 200,000KM
Had transmission service done,filter oil.
in the last 3 years its had new rad,new hvac,new window switch.then probably a few other things im forgetting but nothing really to do with this./

maf and throttle body have not been cleaned i will be doing that in a couple weeks hopefully it stops snowing.

Spark plugs were done last summer and only 2000km done on them but then i think only regular cheap ac delco plugs were installed but i could be wrong im checking this week when it goes back in.
Battery terminals are stock but i have new stinger's to install Hopefully in a week or so.


Yes i will get them to write the codes down for me im bringing it back this week. The only code i got was the P3000 cylinder misfire.He just told me what the other items were but not the codes.

 

Small update after going to 3 shops with the broken bolts. 1 shop said they would have to pull the head and $1400 for labor and parts because i would need new head gasket kit along with manifold gasket. I said no thanks.
2nd shop saw 2 rear broken bolts one of each side and said to do a job like this on a nightmare vehicle it would be $800
3rd shop said no problem at all, Said i may need to have it machined if its warped at all blah blah and half the price of second shop.

So its going there in a couple days hopefully all goes well.

Ill update about the rest or any comments about the rest is appreciated thanks yall

 

If that's the case you may as well put on a different head / gasket so as to have all new and avoid possible revisit with valve seat / spring or such later down the line.

 

The broken exhaust manifold bolt would not cause these issues. I know because I had two on rear port that took me almost year to finally get drilled out. Was real pain but once I got right tools was able to do myself. With head on engine. I continued to drive between attempts to repair. No codes and I drove probably 30k miles in that year.

The comm errors could be several things. Also simple things like bad grounds and crappy battery cable clamps could cause most of the codes you mentioned.

 

Yea i wont be getting the head pulled just to have the manifold done thats crazy so this shop im going to laughed and said no head stays.

For battery terminals i just replaced them yesterday with stinger ones.

 

Broken exhaust manifold bolts. No problem, most or the time. I have actually done this and it works. Take a die grinder and clean the broken bolt as well as as removing a little of the threads from the head. Put a nut over top of the bolt and weld the two together. Let everything cool. Start working the bolt out. you may have to repeat a few times to be successful. Drilling and extracting is time consuming and frustrating. Here is a video to show basically how it's done. Not saying you want to attempt this yourself, but this might save some time at the shop and save you some cash.