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Hello Everyone, My 98 Deville has been doing some werid things lately, When i turn key to start, it acts like its not getting any gas, sometimes takes 5-6 sec of cranking to start, when it finally starts it runs very poorly for about another 5-6 secconds. Once all that is over it seems to be fine, I have also had the car stall on two occasions, i was able to put in Neutral and re-start. I took my baby to auto zone and they pulled my codes, we came up with a bad egr valve, being the DIY kind of guy i am i went home to install it and after removing the two bolts i noticed the fule lines run right over the center bolt, making it impossible to remove the EGR valve. the fuel lines are soldered on to a piece of metal that also uses the egr's bolt to secure it, My question is can i remove the fuel lines right there at the egr valve, with the batt dissconnected of course? I could pull the fule line fastiner up past the bolt, but there is no where to move it so i can get that last bolt out. I hope i described this good enough. I am going to try to tackle this again bright and early tomorrow morning DEC 4th so if anyone can reply tonight i would appreciate it greatly> Thanks in advance fellow cadillac lovers
 

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I'm havn't worked on a Deville but you should be able to move the fuel lines a pretty good amount once you take the bolt out.
The car should be designed to be able to remove the EGR fairly easily.Fuel lines are pretty strong, that doesn't mean you can take a crowbar to pry them out of the way but you can put a reasonable amount of pull on them.
 

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Discussion Starter #3
zonie77 said:
I'm havn't worked on a Deville but you should be able to move the fuel lines a pretty good amount once you take the bolt out.
The car should be designed to be able to remove the EGR fairly easily.Fuel lines are pretty strong, that doesn't mean you can take a crowbar to pry them out of the way but you can put a reasonable amount of pull on them.
Awesome! Thank you Zonnie77, i was being fairly easy on it fearing the worst, ill go give it hell tomorrow morning. Thanks Again
 

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Now I get to tell you why the AutoZone zombie didn't do you any favors.

The EGR 'code' that he so eagerly pulled from your Cadillac's PCM doesn't necessarily translate into a part that needs to be changed. Don't blame him, though... he just sells cheap auto parts. :bouncer:

Your Cadillac's PCM decides if an EGR fault needs to be set by momentarily commanding the EGR valve to open, and then watching the MAP sensor to see what kind of change there is in manifold pressure. If there isn't a change, or what change there is isn't large enough, then the PCM sets an EGR **system** fault.

The EGR passages in the intake manifold may be clogged. The MAP sensor may have had a hiccup. There might be a small particle of carbon stuck between the EGR's pintle and seat (easily cleaned). There are a few other possibilities, too.

Northstar's before 2003 had outrageous problems with carbon. EGR vales rarely fail (which isn't saying that they don't fail ever).

Believe it or not, there is actually some merit in having a qualified technician (instead of an AutoZone part seller) do the diagnosis.

If your EGR valve is really bad (bad, naughty EGR valve)... then your risky venture in having a free diagnosis has paid off in spades. Consider yourself lucky. :cookoo:

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Elisss
 

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Discussion Starter #5
ellisss said:
Now I get to tell you why the AutoZone zombie didn't do you any favors.

Believe it or not, there is actually some merit in having a qualified technician (instead of an AutoZone part seller) do the diagnosis.

Ellisss, you were correct. I managed to get the egr vavle in with some help from friends, and its doing the exact same [email protected]# thing. It is much worse when its cold. but it still take 5-6 secconds of cranking to actually start. tomorrow i will replace the o2 sensor , now i have heard that i have two o2 sensors that i could replace and have also heard its best to replace the one AFTER the cat. I thought these cars have two cats?? If anyone wants to know how i got the EGR valve off the bolt. you have to hold the throtle open so it makes room for the gas line holder to slide over (towards front of car) If anyone has an opinion on which o2 sensor to replace first or im sure im missing someting else i can replace, or check. Thanks for the feedback so far guys, i need to solve this before a road trip i have planned to Vegas next weekend.
 

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CognLac said:
Ellisss, you were correct. I managed to get the egr vavle in with some help from friends, and its doing the exact same [email protected]# thing.
:banghead:

No no no no no. Do not replace an oxygen sensor.

While you may indeed have an O2 sensor that needs replacement, I can assure you that the symptoms you describe do not correlate to a slow, weak, or failed O2 sensor.

(begin humorous ranting...)
What you are doing is called playing baseball with your car. You're standing on the pitcher's mound with a pile of expensive parts. One by one, you throw the parts at your car, in the hope that one of the parts will fix your problem. If you have time and money to waste, then I promise you that eventually... one of the parts may (or may not) fix the problem.
(end ranting).

Oxygen sensors today are all heated sensors. They don't work until the internals reach about 600 degrees (f). Used to be that a car would remain in open loop (no on-the-fly control of fuel injection) until the exhaust gas would heat the O2 sensor enough so that it would function properly. With a heated O2 sensor, as soon as you turn the ignition key on, the internal heater in the sensor brings it up to proper temp within a few seconds.

Now, is it possible that the heater on your upstream O2 sensor is bad or week, causing poor drivability for a few seconds until it's hot enough? Sure. Is it possible for your heater to be faulty and not have an O2 sensor-specific fault code set in your PCM? No, not likely. Do I think you should replace the upstream O2 sensor now, without a proper diagnosis? No.

Do you need a proper diagnosis to determine the problem? No, of course not.

Let's check the basics first...

Fuel filter. Is it clogged? Don't just replace it if you're not sure. Save the money and remove your current fuel filter. Hold the filter vertically so that the inlet (marked on the filter) is pointing down. Does fuel readily and easily drain from the filter? Wipe the inlet nipple with a clean rag, while holding the inlet side up (pointing towards the sky). Apply your lips to the nipple and blow. Aside from the laughter going on at the thought of this... if you can easily blow through the filter, put the old one back on the car as it still has life in it. If, on the other hand, you can't easily blow through the inlet... you have a clogged filter. Replace it. Is that definitely the problem you are having? No, not definitely. Will a clean filter prolong the life of your very expensive fuel pump? Yes, definitely.

Okay... next...

Let's check for fuel injectors that are leaking fuel into your cylinders when the motor isn't running. Hook up a fuel pressure gauge (you have one, right? :lildevil: ) to the schrader valve on the fuel supply line. Turn the key to the on position without cranking the motor. Wait 5 seconds. Turn the key off. Watch the fuel pressure gauge. If you see anything like a significant drop in pressure during the first 10 minutes (like more than 10 or 15 psi), then you *may* have one or two injectors leaking gas after the motor stops.

This will possibly cause slow cranking, but will more than likely cause really poor running for the first few seconds of engine operation.

An alternative to the fuel pressure gauge watching thing is this: After letting the car sit overnight, turn the ignition key to the run position (do not crank the motor). A few seconds after that, turn the key off. 30 Seconds later do it again. Repeat a few times, and then start the motor. Look for a puff or plume of black or dark colored smoke from the exhaust. If you see the dark smoke, then that's probably the fuel leaking from an injector or two.

Okay... next...

Is there an exhaust restriction? Remove an upstream O2 sensor, and install a backpressure testing tool. Don't have one? Hmmm... do you have a vacuum gauge? Install it on a manifold vacuum port anywhere on the intake. Warm the engine to operating temperature. In Park and idling, note the vacuum reading on the gauge. Now rev the motor to 3000 RPM exactly while watching the vacuum gauge again. At 3000 RPM, you should see a minimum of 1.5" of vacuum more than you did at idle. If not, then you have a restricted exhaust.

I'm really at a loss to think of any other possibilities. Hopfully, one or two of the other qualified technicians residing at these forums will chime in with an opinion or two.

Is it any consolence that with a decent OBD2 diagnostic tool, a qualified mechanic will probably be able to diagnost the problem while sitting in the driver's seat? :lildevil: :lildevil:

Hope this is helping. Quit playing baseball with your car.

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Ellisss
 

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Discussion Starter #7
ellisss said:
:banghead:

No no no no no. Do not replace an oxygen sensor.

Hope this is helping. Quit playing baseball with your car.

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First off, I want to thank you Ellisss, you have been most helpfull, and I have noticed you were the first to respond on other people's questions also. I will try the blowing the fuel filter test first, sounds fun too, free buzz ;) If this dosent work I will dry my eyes and then pony up the bread to have a Pro look at my baby. If i remember correctly, the FF should be under pass side about mid car? Also what is your take on trying a tank of mid grade instead of the usual premium, it seemed to work for another 4.6L owner. I dont think it will do any damage for one tank, just to try, or am I mistaken?
 

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Discussion Starter #8
QUOTE : Is it any consolence that with a decent OBD2 diagnostic tool, a qualified mechanic will probably be able to diagnost the problem while sitting in the driver's seat?

How much is a decent - good OBD2 tool cost? if this is any indication on whats to come with owning a caddy, is it worth the initial investment ?
 

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Decent OBDII reader for a Cadillac? $0. With the ignition on, push and hold either OFF and WARMER, or OFF and PASSENGER WARMER, whichever applies. When the displays all light up, you can let go and your car will scroll the codes on the Driver Info center. When it is done, it will display PCM?. At that point, you can just turn the ignition off.
 

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Where is the fuel filter on a 97 STS? And could anyone give me step by step instructions on how to check and replace if necessary. Thanks
 

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Discussion Starter #11
DaveSmed said:
Decent OBDII reader for a Cadillac? $0. With the ignition on, push and hold either OFF and WARMER, or OFF and PASSENGER WARMER, whichever applies. When the displays all light up, you can let go and your car will scroll the codes on the Driver Info center. When it is done, it will display PCM?. At that point, you can just turn the ignition off.
Sweet, is the "off" referring to display off or temp/hvac controls off?
go caddy huh, can i bank on what ever it tells me is correct?
and thank you Dave

Also is my fuel filter under pass side about mid car?
 

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Looking at the original post...it actually sounds like a leaking fuel pressure regulator. Common for these to go bad on the Northstars and Auroras....and cause hard starts/stalls.

Logan
 

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Discussion Starter #13 (Edited)
Logandiagnostic said:
Looking at the original post...it actually sounds like a leaking fuel pressure regulator. Common for these to go bad on the Northstars and Auroras....and cause hard starts/stalls.

Logan
OK wow, well, i went ahead and replaced the fuel filter anyways, I honestly thought i was going to die about twice, and burn down my friends house while i was at it. I had no clue how to get the filter holder off. Anyone who will be doing this on their own for the first time, do yourself a favor and remove the little black clip from the other lines BEFORE you remove the gas lines. and the holder comes off WITH the filter (ahh) also there is a washer on the OUT side that is very small and fell off, pay attention. :( so now im stinky and my car does the same thing. LOGAN is there an easy way for someone like me to check that pressure regulator.and aproximate cost for a new one? I took the advice given (BY DAVE thanks) and checked my codes, to my suprise i had about 13 history codes but none current, at the end it scrolled through the 3 letter codes and all said NONE,
 

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The fuel pressure regulator is easy to check. Start the car up, and look for something that looks like the top of a small EGR valve thats by the fuel rail. It will have a vacuum line going to the top of it. Pull the vacum line off, and if gas comes out, the diaphram inside is leaking.
 

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Discussion Starter #15 (Edited)
where can i find the crankshaft position sensor? i was poking around looking for prices on a fuel pressure regulator and found this site. http://autos.msn.com/research/vip/Reliability.aspx?modelid=349&src=vip

Also because i just picked this car up 3 months ago and do not have its past history. should i just replace the spark plugs anyways? at lunch i will go out and try the fuel pressure regulator test. is it the small piece that the fuel lines go into? about the size of a quarter? I looked for the FPR and could not find it, do i have to remove the Beauty plastic cover? first
 

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The crankshaft sensors are in the center front of the engine...above the oil filter assembly. There are 2 different ones. A tan and then a black one.

I would check for a leaking regulator first. Easy and fast to do. Its also a common problem. The regulator should be mounted near the drivers side rear fuel injector.

Logan
 

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Discussion Starter #17
Logandiagnostic said:
The crankshaft sensors are in the center front of the engine...above the oil filter assembly. There are 2 different ones. A tan and then a black one.

I would check for a leaking regulator first. Easy and fast to do. Its also a common problem. The regulator should be mounted near the drivers side rear fuel injector.

Logan
got ya Logan, do i have to remove the plastic cover? first, thanks for responding
 

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Discussion Starter #19
Logandiagnostic said:
Yes...it would be easier to see if you pull the top cover.

Logan
OK fuel pressure reg is cool. i removed vaccuum line and nothing came out, had it off for about 10 sec, i pulled #4 spark plug and it looks werid, i asked around and people think its bad, carbon build up and right where the spark should come from on the little finger (scientific huh) looks like ther is a gray spot, above filiment. Is it as hard as it looks to change the rear plugs on this car?
 
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