My truck recently failed it's annual vehicle inspection, mainly emission tests (SMOG as you may call it) parking brakes and Parking Brake Foot Pedal.

causes were:-

• leaking CATS causing bad Lambda and HC emission readings.
• a bad bank 1 sensor 2 i.e. downstream Ho2 sensor, this actually threw a MIL during the first test and started misfiring of course affecting emissions.
• spark plugs pretty messy, probably due to bad lambda and misfiring.
• RHS parking brake was not engaging, out of adjustment (have no idea why, cables are good)
• The Parking Foot Pedal was not springing-back consistently, mechanism was corroded preventing its plastic tensioner to stick (roof leak)

fixes:-

• Replaced both CATs with RA Davico 19414 (bank 1 left) and Davico 19418 (bank 2 right) the old CATs were MAGNAFLOW which had rusted and eroded along their seems. 8.5 years ago I welded-in new Universal Magnaflows to replace the original "plugged" OEM CATs, this was hard difficult work with marginal cost benefit and possibly the wrong call in the long run.
• Replaced all Ho2 sensors but due to RA stock availability, upstream with Bosch 15282 and down stream with GM 2133867 i.e. done in matching pairs
• Replaced all spark plugs with ACD 41-110 (already in my spares box) think these have been superseded by ACD 41962
• inspected air filter, this was very clean, like new so didn't replace.
• checked MAF sensor, this was not dirty but cleaned it anyway.
• adjusted RHA parking brake, a real pain but of course necessary (not a cable)
• replaced the Parking E-Brake Foot Peddle mechanism with a new 2008 version, discarded it's new-style release lever and re-used the old one.

experiences:-

• The RA Davico CATs looked and seem great quality BUT beware their exhaust flange gaskets are smaller than stock GM gaskets by 0.15" Somehow the a gasket got lost in shipping, these are special and hard to get even directly from Davico - took 3 weeks, what a nightmare !!
• The previous sensors were all Bosch, however one new Bosch upstream sensors died on route to the test station costing yet another re-test. All credit to RA , they immediately shipped out a replacement,
• The old spark plugs gaps were good ( 0.040") one can only assume that running with bad fuel/air mix and misfiring caused them to foul-up.
• Found a great way to set the Parking brake gap to 0.026" (as recommended) using digital verniers, dead accurate, easy to do ✔️
• Replacing the Parking Foot Pedal mechanism was tedious but it now works as it should. Note there are no adjustments in the mechanism (ignore the manual) or the cables, everything is fixed (at least on an 05)

Prior to testing, there was no MIL, DTCs or any noticeable misfiring, however I did suspect the exhaust sounded "odd" even though it looked visually OK, only after removing the CATS could the hairline cracks along the Magnaflows be seen, very well hidden along the tops.

Also worth mentioning, this H2 runs on both LPG and gasoline (LPG vehicles need gasoline to start) however LPG contains no additives so a "valve saver lube kit" is needed (which it has)

The Tech2 now shows no misfires or codes and the truck has passed it's emission tests with flying colors, parking brakes and pedal are good so it's now back on the road after a long break - yeehaw !!

Everything is a challenge

 

Well, I would guess while a little long it was easier to do the great writeup then to do the actual work.
You've been busy and thanks for sharing

Neal

 

Indeed and apologies for the rather verbose descriptions, would you believe that's the shortened version 😁

 

Okay, I can't help it it's 4th of July weekend.

I live in a mountainous rural area, where we don't have the influences of the Nancy Pelosi types..... Living free in what the founding fathers envisioned, I find it appalling to hear what goes on in the large urban areas.

In the spirit of this holiday, I can only think if the founding fathers envisioned their government monitoring every man's horse and wagon.... A loose wheel spoke, and all xle squeaking and creating disturbing noise, passengers forced to be strapped in, your lantern at night doesn't meet the government standard for brightness and so on.

You sir, I would say are living behind enemy lines, in a community that has been taken over by the likes of North Korea, Cuba and other dictatorships. Hopefully the next three and a half years and beyond brings a lot of correction. (Such as just a few weeks ago, there's no more California EPA standards.... A huge win)

If the country continued down the path it was on, I'm afraid they would be coming for our Hummer keys within 5 years....

https://autos.yahoo.com/california-loses-set-own-emissions

 

@RobertDez

Hopefully the 4th July was a great day for all ...


It hard to remain detached from politics these days, however the American Constitution is enviable as is the country, Benjamin Franklin said "two wolves and a sheep voting on what to have for lunch" illustrates the idea that democracy can lead to the majority imposing its will on the minority, food for thought if you excuse the pun.

Very fortunately holidayed there last Christmas and New Year, starting from Vegas, driving onto Zion National Park, skied Park City and Jackson Hole, snow bused around Yellowstone, all totally amazing !!!

So hopefully they won't be coming for our Hummers any time soon 🫰🙏

 

A Brit making a flyover x2 without checking in @ the CLE?