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White Diamond '03 DHS (with DTS floor shift)
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Run the engine to heat the exhaust system. The thermal expansion might help loosen it.
 

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2004 Deville base
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15 Posts
Discussion Starter #23
The oil fill cap is on the clean air side (atmospheric) of the PCV system. The rattle valve or orifice is the dirty side. Regardless, a smoke test pressurizes the entire inside of the engine - remember that the cam covers have wide open drains to the oil pan, so the PCV dirty air line is equalized between the crankcase and the cam cover - it's restricted only into the intake manifold full vacuum line.

The old rattle valve slammed shut in the event of an intake manifold backfire - and the Northstar has an intake manifold overpressure valve built-in.

View attachment 573676
Great! good to know I don't have a mysterious passage somewhere inside.
But, another question:
1. The vacuum system (above) appears to have some stuff my car doesn't have:
Item 3 and associated hoses. I seem to have electric (relay on firewall) controls to the secondary air injection valves (items 2 & 8). My car started life in California and they always do emissions differently than federal. Does that account for the difference?
2. I have an electrical sensor/actuator/switch on the top front corner of the throttle body. It's held in place (loosley) by an extension of the metal bracket for the accerlator & cruise control cables. I've noticed an accumulation of dirt around the base of that device, suggesting oily fluid might be seeping out providing a sticky spot for dirt. I can wiggle and turn and slightly raise that device because the bracket doesn't apply much pressure to hold it down. What is that thing and could it be a potential vacuum leak source?
3. I can find item 2 but not item 8. I'm guessing it's somewhere on bank 2 exhaust manifold?
4. Where is sensor 1 bank 1? Just in case I have to replace that one. I found only 1 sensor 2 because the car only has 1 cataytic converter.
Thank you.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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67,179 Posts
The thingy on the top of the throttlebody is the MAP (Manifold Absolute Pressure) sensor. Manifold vacuum signal.

#3 is the AIR system vacuum - secondary air that sends fresh air to the exhaust manifolds in order to quickly light the cat on cold start. You (should) have it. The relay is clipped to the right strut tower - blue connector.

#2 is the AIR valve for Bank 1 - the right (rear) bank, on top of the cam cover. #8 is the AIR valve for Bank 2 - the left (front) bank, near the lower radiator hose.

B2S1 is in the left bank exhaust collector - left bank mixture sensing
B1S1 is in the top of the right bank exhaust manifold - right bank mixture sensing
B1S2 is the after-cat sensor - exhaust/converter total mixture efficiency sensing

Click to enlarge, use the < > to scroll pictures, click the little grid right lower for full view.

Front O2 sensor B2 S1.gif CMP-VSS-B1S1 locator.gif B1S2 sensor.gif Butt plug & air box 2 notes.JPG
 

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2004 Deville base
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15 Posts
Discussion Starter #25
The thingy on the top of the throttlebody is the MAP (Manifold Absolute Pressure) sensor. Manifold vacuum signal.

#3 is the AIR system vacuum - secondary air that sends fresh air to the exhaust manifolds in order to quickly light the cat on cold start. You (should) have it. The relay is clipped to the right strut tower - blue connector.

#2 is the AIR valve for Bank 1 - the right (rear) bank, on top of the cam cover. #8 is the AIR valve for Bank 2 - the left (front) bank, near the lower radiator hose.

B2S1 is in the left bank exhaust collector - left bank mixture sensing
B1S1 is in the top of the right bank exhaust manifold - right bank mixture sensing
B1S2 is the after-cat sensor - exhaust/converter total mixture efficiency sensing

Click to enlarge, use the < > to scroll pictures, click the little grid right lower for full view.

View attachment 573707 View attachment 573705 View attachment 573706 View attachment 573708
Thank you! Nice lookin engine!
Ok, I found #2 but no #3 or #8. Looked where you said for #8 and, while it's pretty crowded, I could not find a shut off valve on bank 2 exhaust manifold and no vacuum solenoid valve (#3). To help me identify what I was looking for, I checked Rockauto's web site for a picture of the part. They list only 1 AIR check valve for the 04 DeVille, but 2 for the 02 Seville. The pictures show a port for vacuum lines on the 02 parts but only an electrical control connection for the 04 part. Who knew? But then, Rockauto also lists a PCV valve for the 04...(they don't show where to put it).
I do have the relay that operates the secondary air system and an air pump in the left front fender that's notorious for collecting water. The replacement came with a different inlet hose design to eliminate that problem (so far, it has). I also found a broken wire leading to the relay.

Anyway, I'm gonna put a shim on top of the MAP sensor to see if my P0174 goes away. Really don't want to mess with the O2 sensors ulnless I have to....If that works, I can blissfully go off to SEMA without stranding the wife (be no bliss if that happened). I'll let you know if that works... Thanks
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Your 2004 may have a slightly different AIR setup - and slightly different emissions equipment - from my 2002.5. It happens in these forums every day. One reason you need the GM/Cadillac/Helm service manuals for THAT model year car and model.

#3 - the vacuum porting solenoid - may be somewhere different and feed only to the right (rear) bank AIR check valve due to deletion of #8, the left (front) bank one.

alldatadiy.com or helminc.com
 

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What if your fuel pump pressure is low, or your injectors plugged? At idle, you should get sufficient flow, but as the engine requires more and more fuel, you should eventually run out of fuel trim adjustment. Other GM injectors have a habit of being sticky, pulse them open and they delay closing, setting P 0172 & P 0175 rich codes. These tend to set at idle, where the engine uses less fuel than you can prevent coming through the injectors. Fuel Trims show as -30, typically.
 

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2004 Deville base
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15 Posts
Discussion Starter #28
What if your fuel pump pressure is low, or your injectors plugged? At idle, you should get sufficient flow, but as the engine requires more and more fuel, you should eventually run out of fuel trim adjustment. Other GM injectors have a habit of being sticky, pulse them open and they delay closing, setting P 0172 & P 0175 rich codes. These tend to set at idle, where the engine uses less fuel than you can prevent coming through the injectors. Fuel Trims show as -30, typically.
Thanks for the suggestion. I'll have to get help for that one. My scanner only shows trouble codes, not real time pressure readings or trim levels. However, the car runs fine. I would expect hesitation, missing, or other symptoms if the injectors or fuel pressure were not functioning properly. I was getting @ 19 mpg in the city before I forgot to reconnect the MAF sensor before my last test drive. That senior moment caused mpg to drop to @15. Thought I finally fixed the "leak" issue because only 1 code came up (p0102). But, how could the pcm tell if the engine was running lean if the MAF was unplugged? So, fixed that, cleared the code and going for another test drive.... At least I was able to get a 30 day temporary registration while we sort this out...
 

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92 Fleetwood 2dr cpe - FWD, 96 Seville SLS, 02 Seville
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774 Posts
Late to this thread.

When chasing rich/lean, Need to focus on items that are common unique.

If you receive rich/lean for both sides of the engine, then focus on items common to both. Ie fuel pressure/supply, air supply/vacuum leaks, map/mag, throttle,

If on one side only, then focus on items unique to that side, plugs, injector, o2 sensor, cylinder mechanical, orings, seals.

For the O2, You can hook up the scanner, check that O2 is creating voltage cycles (reflecting the computer is constantly adjusting up and down), and then check the STFT/LTFT to see how the computer is resPonding to the o2 sensor.
 

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2004 Deville base
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15 Posts
Discussion Starter #30
Late to this thread.

When chasing rich/lean, Need to focus on items that are common unique.

If you receive rich/lean for both sides of the engine, then focus on items common to both. Ie fuel pressure/supply, air supply/vacuum leaks, map/mag, throttle,

If on one side only, then focus on items unique to that side, plugs, injector, o2 sensor, cylinder mechanical, orings, seals.

For the O2, You can hook up the scanner, check that O2 is creating voltage cycles (reflecting the computer is constantly adjusting up and down), and then check the STFT/LTFT to see how the computer is resPonding to the o2 sensor.
Hi Guys;
Happy to say my car is FIXED!
Sad to say I had to give up and take it to a shop and let someone else fix it.
As mentioned previously, my scanner only reads trouble codes, not real time engine operation. Of course, the shop had the tools to monitor engine performance, including lean/rich adjustments the PCM was directing.
The problem was a vacuum leak, but not where I was looking. Turns out, the vacuum powered brake booster was the source. And, I had used the hose leading to the booster to connect my smoke machine. So, everything but the booster was "Smoked" and slightly pressurized and showed no leaks. The shop simply pinched off the hose to the booster and watched the lean/rich range return to normal. Thought I'd pass this along because it's not the typical location for a vacuum leak on this engine.
The shop said the master cylinder had a slight fluid leak and that caused the diaphram in the booster to fail. So, at great expense, both parts are now replaced and I can pass the emissions test and renew the registration and expect many more years of happy motoring...
I appreciate all your responses and your patience with me. I also learned how to fix a few other things, like the right rear window not working and the right side blend door (didn't know It had failed) and there's a new design for the power steering high pressure hose. I've replaced that years ago but need to do it again.
Next, I'm gonna change the transmission fluid. The on board monitor system sez it's still good but it's been 70,000 plus miles since the transmission was replaced, so I figure it's due.
Thanks again!
 

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White Diamond '03 DHS (with DTS floor shift)
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WOW! Never heard of that on before. Glad you got it fixed and thanks for the feedback. It may help someone in the future.
 
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