General STS thread

[kevm14]

I am going to put this here until and if I need to take action. For now this is for information and discussion.

For a recap, recall that the MIL came up like 1 day after I reset the P0430 which itself was gone for a whole month after 2 bottles of Techron. I had (mistakenly it turns out) assumed that it was a P0430 again (cat inefficiency, bank 2). My generic tool had no idea what was going on. So I scanned it with the Tech 2. 8 codes. Here we go.

This is supposedly in some priority order so I will maintain the order in which they were listed.

EBCM (brake control module)
C0250 symptom 71
Passed last ignition and this ignition (so fixed forever)

EBCM again
C0249 symptom 71
Passed last ignition and this ignition (again...fixed forever?)

IPM (instrument panel)
U2100 symptom 72
This is a comms code and I seem to get these U2100 every single time I scan with the Tech 2. I have not figured out if there is an actual problem or if it is some kind of by product of, perhaps, the clone scan tool. I have never seen these cause a problem that I am aware of.

IPM again
U2100 symptom 00
Again, I will look these up but I don't know what to say...

ESC (suspension module)
C0630 symptom 55
Passed this and last ignition cycle
This corresponds to an issue with the right rear ride height sensor. I did have to replace a right front sensor a year ago so maybe it needs a right rear now. Not sure yet. A Delphi right rear sensor is $122.79.

EBCM again
U2100 symptom 00
See above for comms codes

ECM (ahh, engine module)
P0174 symptom 00
Passed last ignition, MIL commanded (no idea why my generic tool couldn't read this)
Lean on bank 2. Interesting. It passed last though.

ECM again
P0171 symptom 00
Lean on bank 1. Oh wow, lean on both??

So...I reset all and rescanned and they are all gone...as usual.

I will monitor. It is worth noting that there have been no drivability changes.

I will need to read up on all codes just because I should. Curious about the top two EBCM codes. Hopefully that is not anything serious. The right rear ride height sensor may be on its way out. And lean on both banks is....weird and a little concerning.

Now it did get a MAF at some point. Lean on both, if true, could suggest some kind of air metering issue with a resulting fueling miscalculation. I could clean the MAF though I certainly cleaned it at least once. 140k or so. With 25 modules possible (it may have 22 of them), it is not shy about throwing codes.

There is a silver lining...the P0430 didn't come back. lol. Maybe the Techron actually did something! So maybe I have that going for me.

[kevm14]

Some quick research reveals many threads on the lean codes. Here are 4 threads. At least three of which indicate the presence of both codes.

https://www.cadillacforums.com/forums/c ... p0174.html
https://www.cadillacforums.com/forums/c ... p0174.html
https://www.cadillacforums.com/forums/c ... p0174.html

https://www.cadillacforums.com/forums/c ... -lean.html

Ah look at this. It's been cold recently.

Had these codes on my '05. Cleaning the MAF didn't cure it. Ultimately I ended up replacing the bellows after swapping the MAF first, which didn't stop the codes. Ultimately I ended up with a two fold problem because once I peeled the old bellows off I could see a couple slight lines where it must have been leaking. Either wouldn't stop the codes but once botr were replaced they stopped. Mine was only on certain cold days and would not do it once the car was warmed up. Drove a caddy tech I know and myself up a wall trying to chase it down.

If you don't have any visible leaks, you could try cleaning it first, then replace, and dig deeper from there. Using a mirror to look at the underside of the bellows can't hurt. It isn't uncommon for them to split on the underside where you can't see.

BMW syndrome?

I have no idea what this part is.

The rubber boot that goes from the throttle body to the plenum. I'm drawing a blank as to what the cadillac term was, but it's a $40-50 piece. You could always try tightening the band clamps first.

The downside to this is the plenum needs to come off to remove it. Not a bad job but was disappointing to throw a code after it was done. Once I reinstalled the new maf that previously hadn't worked, there hasn't been any codes in roughly 15k mi.

Ultimately there must have been enough of a leak (not much) before the plenum and the maf throwing off just enough. There was a good amount of oxidation on the sealing surface of the tb which was odd considering the exposed surface and all other aluminum on the car isn't oxidized, but I could see little lines running in that weren't oxidized and I think that's where the air was getting in.

Huh? I will have to look...there's a rubber boot between the intake manifold and TB?

I guess it is just a matter of inspecting for post-MAF air leaks, which is a pretty normal response to a lean code on both banks. That is not a sophisticated diagnostic technique.

I believe I've solved my issue. I replaced the rubber ends of those two PCV lines on top of the engine, although only a couple of them showed a tiny hint of cracking. Generic 3/8" fuel line & elbows from the auto parts store work great for these. I also went ahead and replaced the MAF sensor as well as the throttle body, although the TB was unnecessary; but it's a surprisingly inexpensive part. The "aha" moment came when I made the problem worse instead of better -- turns out the larger rubber hose that goes to the brake booster was loose, and I inadvertently knocked it off when I was monkeying around with the vacuum line that runs behind the intake manifold. The engine ran like hell and would not idle correctly until I figured this out. Popped the brake booster hose firmly back in place, cleared the trouble codes, and it's running good as new So if you are getting random System Too Lean codes, that hose back there is another one to check.

Or it needs another MAF. It's probably the MAF or a post-MAF air leak. Just need to find it. Not a big deal.

[kevm14]

So a GM MAF is $75.79. LOL. So cheap.

And if that is too much, I can get a GM reman for $50.79 after a $45 core (which is MORE than the new MAF if I keep the core).

[kevm14]

OMG

Are you ready for this?

Guess how much the electronic throttle body is. Go ahead. I'll wait. Don't scroll down.











Did you guess?




























$57.79. That's AC Delco. I have no idea how it can be that cheap. I bet most non-electronic throttle bodies are way more than that, especially when you add up the other parts that this completely replaces. It performs idle air control functions. And throttle position sensor. There are definitely some NOT overpriced parts for the Northstar. I would have guessed $400 for the TB, seriously.
https://www.rockauto.com/en/moreinfo.ph ... 36&jsn=436

It is tempting just to replace this as I wonder if it would fix that lazy tip in response that I've complained about since buying the car. And forget cleaning the damn thing - just replace every 50k!! lol

[kevm14]

Other relevant prices:
- GM O2s around $92/ea for front wideband. I probably don't need these anyway.
- GM rear O2 $52/ea.
- CARB-certified cats on RockAuto. $398 per side for Eastern Catalytic. That is an integrated exhaust manifold and cat. That isn't bad actually. I believe I have CA emissions which is annoying. But if I didn't, Walker sells a right for $402 and a left for $325. I would not entertain this one due to the labor, not the parts cost.

[kevm14]

Ok so C0249 and C0250 is a comms code, which I guess goes with the U2100. I really don't know what to say about this so I am inclined to ignore it.

I have also uploaded U2100. Really not planning on chasing this as I get it every time I scan with the Tech 2...

For the suspension...

Action Taken When the DTC Sets
• Stores a DTC C0615, C0620, C0625, or C0630 in the ESC memory.

• Command speed dependent damping system default AND command normal force signals to default state.

• Sends a message to the instrument panel cluster (IPC) to display the SERVICE SUSPENSION SYSTEM message.

Conditions for Setting the DTC
• The ESC module senses position sensor output voltage under 0.35 or over 4.75 volts.

• The condition must be detected for 1 second in 4 consecutive ignition cycles.

• No activity on the position sensor when activity detected on 2 or more other position sensors.

Never saw service suspension. But then when the right front sensor failed, I never saw it then, either. Wouldn't be surprised if I need to do a sensor and I am sure it is easy so whatever.

EDIT: I was able to see the sensor through the wheel actually. It looked normal, as opposed to totally broken and hanging in two pieces like the front one was when it failed. So I might ignore this for a bit.

Also uploaded the lean code one, if only to look at the criteria for setting.

Conditions for Setting the DTC
• The combined value of the Short Term FT and the Long Term FT parameters are more than 25 percent.

• The above condition is present for more than 100 seconds.

Wow, ok. So this will need to be fixed even with it likely being related to the cold weather - obviously something is leaking unmetered air and given those threads, I have plenty of places to check.

So after 8 codes across 4 modules, I really have a clue that the right rear ride height sensor is probably on the way out and should either just order it or physically inspect the sensor which may be starting to come apart. And I have an intermittent lean condition that plenty of other people have reported and is well documented. I can handle that.

Also for what it's worth, and it may not be worth much, I had no light on my drive home last night. But, that doesn't mean it doesn't have codes - just no MIL commanded.

[kevm14]

Ah yes, there is a rubber coupler between the intake manifold and the throttle body...but it's not even the throttle body...it's just a body, which the TB bolts to on the front.

This is the SRX but it's the same obviously. It is a very short coupler and I guess you need to remove the intake manifold to replace it. The good news is, that is pretty easy on these.

WP_20181201_09_53_55_Pro.jpg

I thought he meant the air intake boot. Guess not.

WP_20181201_09_54_01_Pro.jpg

I will say a good investment would be a smoke machine. I guess I could just pump smoke into the intake (brake booster hose maybe) and monitor where smoke comes out. Pretty easy that way. Other options include old school methods like blasting an unlit propane torch around while it idles and see if the idle changes, or doing the same with something like brake cleaner. A little more scientific monitoring method is to monitor short and long term fuel trims while spraying specific areas. That seems to work decently.

The MIL did not come on during my short drive to Tire Pros.

[kevm14]

On the off chance I decide I need to replace this, here is some info. The description is "(525) Intake Manifold Plenum Duct."

[kevm14]

So the clunking I was dealing with seems to be gone. I think I am starting to hear my caliper rattle as I expected. But I'm so sensitized to this that when I hear ANYTHING I freak out because I just did all that work and I am afraid it will slip in the bar hole and start clunking again. I will continue to evaluate as I drive it.

I guess I am thinking about the surface of the bar where the link inserts. It was not flat, because I kind of screwed it up with the saw. So I am concerned that it could want to slip in some direction toward a "less tight" position and then start rattling in there. Which would suggest I may want to see if I can tighten the nut up in a week. But that will screw up my loctite. So much stress from this! I guess I am simply hoping that the brand new part with new nut, tightened down properly, will just clamp so tight that slip cannot occur, no matter what kind of road conditions prevail.

Quote was from Feb...

I think the clunking is starting to come back though I have not verified that it is the link slipping in the bar. Aside from simply attempting to retorque the nut, what I started to think about was drilling out the hole a bit (with my super awesome drill bits) and then "obtain" some kind of sleeve that would slip onto the end link stud, and take up the slop in the hole. Either that or close up the hole a bit with weld and redrill to the right size for the end link stud.

I like the sleeve idea though I don't know what the source for a sleeve would be, and it would be awfully short. Rather than a cylinder it would be more like a ring. I guess if it is sandwiched between the link and the nut it would stay put. For the sleeve/ring, I guess I could find something the right inner diameter to fit tightly on the stud, and then drill appropriately for the outer diameter. Or, could drill, and then weld a sleeve in. THAT would be better.

If replacing the bar wasn't so involved I would just entertain that but that's pretty much not happening.

Alrighty. Laid under the car and doubling up on wrenches I was able to tighten the upper end-link nut like 1/4 turn or something. 18mm. The center of the stud takes a 5mm allen but I did not seem to need to hold that this time.

Road test actually reveals no clunking. I will see what happens on my commute. It seemed like I had to break the loctite upon the initial turning of the nut then it was a little easier before getting tight again. I will take even temporary relief of suspension clunks. They drive me crazy.

[kevm14]

Definitely seems better on my commute. I am under no delusion that this is the last time I am going to have to deal with this.