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9K views 28 replies 8 participants last post by  pfkaiser 
#1 ·
Trying to get my Seville past Cali Smog test and have 2 issues:

1) After changing spark plugs with AC Delco's (which, btw, is a miracle cure for rough idle) and cleaning EGR valve, got the HC #'s from 1200-1300's to 150-200's. Wondering what else I can do to get the HC #'s down to 100 or lower. Mechanic says the cat converter is probably shot after running that high for so long. Possibly, but would rather try something else cheaper than a cat converter. PCV perhaps?...I don't know.

2) Keep getting a P039 code that causes the SES light to come on and automatically fail the Smog test. Read here that there may be a software upgrade for this as I dont feel any problems with the tranny. Called the Caddy dealer and the service tech I talked to wasn't aware of any software update for that year. Havn't yet tried cleaning the sensor connector to the tranny but is on my to-do list. Will let you know how that turns out after I figure out how to get my fat butt under the car. :)

I've been impressed with everyone's input here after a week of reading/researching....lets see how y'all do with this problem!!
 
#4 ·
Thanks Ranger for your reply....

The only reason I'm having a hard time wrapping my brain around your answer is that the tranny seems to be fine. Nothing noticeable by driving it anyways. And just curious about what you said; are you saying to leave it in 3rd and drive on the highways, etc and what does this do after a week before testing?
 
#5 ·
... Mechanic says the cat converter is probably shot after running that high for so long...
umm... What?...

Hydrocarbons = fuel
More of them = a rich condition
Cat converters die out faster in lean conditions than rich conditions
Lean makes it hot, even red hot. Have you ever spilled fuel on yourself. It feels cold right? That's how it feels to the cat converter too. Even when the fuel burns in the cat (which is what the cat is for), it burns at a cooler temp when its rich in fuel.

So to sum it up;
More hydrocarbons = a longer life for your cat converter
Too little hydrocarbons (a lean condition) = a shorter life for your cat converter
The mechanic might be trying to get some moolah from you. However, your cat converter might just be old and becoming less efficient. It's job is to burn the leftover hydrocarbons, so there should be close to 0 out of the end of the exhaust.
 
#6 ·
You won't notice much difference. An automatic transmission has a little slippage unlike a standard trans that locks the engine to the trans. The TCC does just that. It locks the two to stop the slippage and give a little better mileage. Hold your speed steady (above 41 MPH) and just touch the brake pedal as if to disengage the cruise. The tach should jump by 200-300 RPM when the TCC disengages (if it is working). If you do not see the jump, then it is not engaged and in the failure mode. It will cost you about 1 MPG. It should only engage in 4th gear so leaving it in 3rd does not reset the DTC and give the PCM a week to pass all the readiness tests. If you clear the codes and go right in for a test, they can tell and you'll fail because the readiness flags will set. Uncle Sam already figured we'd try clearing codes before the test.
 
#7 ·
Awesome explanation Ranger...thanks again! Will do.

Krashed...Im still at a loss as to what would be causing the hc's to be high. Ohm'd out the coils...(with ohm meter in 20k position...dont know how to decipher/translate) 2/5 @ 5.79, 8/3 @ 5.78, 4/1 @ 5.77 and 6/7 @ 5.91. Spark plug wires ohm'd out between 1.32 and 4.06. Not opposed to replacing wires but at this point dont know if thats gonna help burn the gas anymore.

Any ideas?
 
#9 ·
Just got back from 2nd gear WOT to 70...blew a bunch of smoke out the tail pipes...couldnt tell which color because it's dark. But in the process threw a P042, which seemed to clear after normal driving. Maybe that points to the cat converter after all?
 
#10 · (Edited)
P042 = Left (towards the front of the car) bank O2 sensor signal lean.

That could be why you're getting more hydrocarbons. If the sensor sees that it's lean, the PCM will make the injectors stay open slightly longer to give it more gas.

Let me see if I can get you something for that code.

Edit: Here ya go:


PD32 is in the "PCM DATA?" menu in the on board diagnostics.


 
#11 ·
Just finished troubleshooting....

PD32 fluctuates above .3v. Referring to NOTE and checking Snapshot Data Parameters, PD38=160 and PD39=113. Dont know if that determines both banks were lean or not or how to check condition that would cause lean engine operation.

I mentioned last night that the SES seemed to clear itself after returning to normal driving patterns. While checking the above parameters at idle, the SES light came back on. (I never cleared the p042 code last night or today)

I dont know if this is an apples to oranges comparison but my wifes Ford Windstar required replacing o-rings under the valve cover to eliminate a p071 and p074 code (left/right banks running lean). My SLS has a nice oil leak going on in the back (1,3,5,7) and Im assuming its a valve cover. When I pull the spark plug on #5, it has oil around the threads... Your thoughts?
 
#13 ·
Thanks Sub..thats good to know. I guess my question is if the valve cover gasket/o-rings are leaking oil, will that cause a lean condition? I'm debating replacing the gasket/o-rings anyways, just to eliminate the drops in the driveway, however, my ultimate goal is to get this thing pass the California Smog test so I can sell her.
 
#14 ·
No, the cam cover gaskets or O rings shouldn't cause a lean condition. They are not as easy to replace as you might think. No room to lift the rear one so the engine has to be lowered or tilted. Front one has the water pump drive pulley attached to the intake cam and has to be removed. On a '93/'94 I'd look closer at the intake manifold cover gaskets. Those could cause a lean condition and are MUCH easier to change.
 
#15 · (Edited)
Just got back from having it Smog Tested. Failed...but not by much. I guess they don't require it to be dyno'd....they just do emissions. Here's the results:

RPM....%CO2....%O2................HC (PPM)..................CO (%)
.......................................Max....Ave...Measured...Max....Ave....Measured
649..........13.0......1.8........100.....17.......112........1.00....0.0......0.27 Failed
2432........13.5......1.0.........130.....12........24.........1.00...0.10.....0.35 Pass

So its just at idle that my HC's are too high...Im stumped
 
#17 ·
After talking to the mechanic about a possible vacuum leak, he's still leaning towards a bad cat. Not heeding the advice of the mechanic, I've tried to identify vacuum leaks with a can of carb cleaner (disengaging the tps sensor first..dont ask) but Im afraid I couldnt tell between a vacuum hose or any other hose so may be missing something...otherwise, not able to find a leak. Wouldnt a bad cat get some kind of error code if it went bad?
One symptom/issue not mentioned before; if I fill the tank more than 1/2 full, a strong fuel smell permeates the cabin...eventually going away. Problem with the evap? And would that cause the HC's to be high at idle?
Another "issue" is intermittent hesitation at various accelerations, like a cylinder cuts in and out whenever it wants to. Even though I ohm'd the coils and all seem to be in range, after lifting the hood and staring at things like a deer caught in headlights, I notice a rapid clicking sound coming from the 6/7 coil. Idle's smooth...not necessarily "cadillac smooth" but smooth enough for the girls I go out with.
I've had a p030 and a p070 code, but cleared them and they havn't come back yet. The p030 came back once after some above average driving, cleared it again and it hasnt come back since. Could either of these codes (I know what they are) have anything to do with high HC's at idle?
 
#19 ·
... Wouldnt a bad cat get some kind of error code if it went bad?...
Not on a 94. The 94 is OBD-I and only has two O2 sensors (one on each exhaust manifold). 96 is when they started putting a Post-cat O2 sensor to monitor the cat-converter efficiency.

he might be right that the cat converter is loosing efficiency. But if it is, it's just because it's getting old and not because of the explanation he offered.
 
#18 ·
One symptom/issue not mentioned before; if I fill the tank more than 1/2 full, a strong fuel smell permeates the cabin...eventually going away. Problem with the evap?
These cars have been known to rot out the fuel filler pipe. That could cause the gas smell as well as an EVAP problem as the tank would no longer be air tight.
 
#20 ·
Hey Ranger...

Saw you involved in another post on another site called Caddyinfo.com. The conversation went something like this:

"The rest of the EGR must be cleaned out, too."

"REST of the EGR? All that needs to be cleaned is the pintle valve."

"This is a 1994, with the EGR passages under the intake manifold through trenches in the heads. Over about 100,000 miles they fill up and clog. In the 1995 and up Northstars the EGR passages are metal hoses external to the heads but they still need to be cleaned out once in a long while."

"Oh! The "mouse holes". I thought you where talking about the valve, but Angela's is a '96"

So I cleaned my EGR's pintle valve, but knew nothing about mouse holes. Is that something I should have cleaned out to reduce the H/C output? And if so, how does one clean out the mouse holes?
 
#21 ·
You see those black rivers of carbon in these pics. Those are the EGR passages on a 94 engine. The "Mouse holes" are in between the EGR valve and these "rivers." It might be a pain in the butt to clean them out. It took me almost 2 whole cans of carb cleaner and some pipe brushes to do it.


 
#23 ·
Finally got the car smogged and passed with flying colors. After avoiding a new cat converter the whole time, it turns out the old one was just dust inside the case. After the mechanic took it off, he came over, tipped the cat converter on its end and "ash" just came out. Installed a new cat, took it to get it smogged and the hydrocarbon output went from 112ppm (max 100 allowed to pass California smog test) to 5ppm. Roughly $320 out the door. Now its time to replace the front hub/bearings. Lets see how cheap I can do this....
 
#24 · (Edited)
I'm glad this thread is over... :lol:

'94 would be a "ASM" or dyno test, codes don't matter as long as the stuff out the pipe is clean.
If it fails for HC and CO both it is usually a weak cat, especially when the numbers are that close.
Most things that would cause it to fail a dyno test will be noticeable driving like a misfire. When people get failed emissions tests it is amazing to watch how many parts they just throw at the thing trying to get it to pass.
Vacuum leaks won't usually create an HC problem, it will drive the engine lean. HC is unburned gasoline which only shows up when you don't have enough oxygen to burn the Hydrocarbons.

Oh and EGR is for NOx, or oxides of Nitrogen. It has little to do with anything else unless it sticks open then it can cause some gas reading problems but most of these have pintle position sensors and would set a code for EGR position error.

Glad to hear you got it through, what kind of cat did you put on it?
 
#25 ·
In the 21 years that I worked on emissions in a Caddy/Olds dealship I've found that when cars 'JUST FAIL' by a little on both H/C & C/O it was the CAT. I know it's not what you want to hear but that's probably what you'll find at the end of all your other solutions.
 
#28 ·
pfk, you need to buy your converters somewhere else.
The installer is required by law to warranty that catalyst to work for 5 years.
See EPA regulations.
They are installing the wrong one, or a cheap one.
 
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