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2003 Deville DTS
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Discussion Starter #1
Hopefully I will connect with someone who was unfortunate enough to share my Cadillac Issues! And perhaps Help :confused:

Will start with this: I have a 03 Deville DTS with 142,000 miles on it. It ran absolutely perfect until about 300 miles ago.

1) Check engine light came on with P0300 and P0507. Car was bucking and idling very high with power loss. I took it to a friend
who was not afraid of the Northstar. Though I discovered later he was not interested in working on it at all
He was trying to convince me that I have a headgasket issue without even diagnosing it.

a) Not the headgasket
b) He completely cleaned the MAF and throttle body
c) Car ran fine for 8 miles. Check engine light came back on, bucking became more wild. I parked it for a week.

2) Took it back to my mechanic to replace the plugs, coil packs, serpentine belt and valve gasket covers

a) He first told me I had excessive blow by
b) I asked him to replace the plugs, coil pack, serpentine, valve gasket covers AS DISCUSSED.

3) He then tells me that my timing chain is loose, that it is most likely the chain rails and that was the reason he saw things in the oil
pan. Says that I should scrap the engine/car

TO ME, that's crazy.. the car's body and interior is MINT, I just replaced all the shocks, struts, tires, rotors, pads, fuel pump, etc....

4) Then quotes me a price of $3,000 just to replace one part of the chain and tries to convince me to replace the head gaskets while
he is at it, even though they are not broken

5) I call the Cadillac dealer and they said at most to replace the timing chain in its entirety would be $2,400 and not to mess with the
head gasket.

ENTER MY CURRENT SITUATION:

My mechanics DID replace my plugs, packs, serpentine and valve gasket covers but gave the car back to me with the following codes:

- P0101
- P0121
- P0507

Idle hovers over 1,000, but is consistent and not jumping

He said the timing chain needs replaced

From what I've read, the idle could be : The IAC Or the Mass Air Flow OR the Plenum Or the Throttle Position Sensor.

QUESTION 1: Has anyone trouble shot this successfully before? If so, please help

QUESTION 2: Has anyone replaced their timing chains before and if so, can you share your experience?

Thank you everyone so much in advance.
 

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Super Moderator
2010 DTS
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87,318 Posts
Re: 2003 Deville DTS TIMING CHAIN/HIGH IDLE/BLOW BY

1. Always post the code definitions along with the codes. We don't have them all memorized.

2. Find different mechanics.

3. You have no HG symptoms.

4. Northstar rings and cylinder walls last forever with very little wear. Blowby is a real stretch.

5. A loose timing chain is also a stretch. The tensioner shoes will last forever.

6. These guys have no idea what they are talking about and are just trying to get into your wallet.

7. I do recognize P0101. That's a MAF sensor code. You might replace that to start with and see what happens.

8. A ripped plenum duct will usually set a P0171 & P0174 code, but it is easy enough to check. Check all the other possible vacuum leak points while you're at it.

9. Find different mechanics.
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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20,005 Posts
Re: 2003 Deville DTS TIMING CHAIN/HIGH IDLE/BLOW BY

1. Always post the code definitions along with the codes. We don't have them all memorized.

2. Find different mechanics.

3. You have no HG symptoms.

4. Northstar rings and cylinder walls last forever with very little wear. Blowby is a real stretch.

5. A loose timing chain is also a stretch. The tensioner shoes will last forever.

6. These guys have no idea what they are talking about and are just trying to get into your wallet.

7. I do recognize P0101. That's a MAF sensor code. You might replace that to start with and see what happens.

8. A ripped plenum duct will usually set a P0171 & P0174 code, but it is easy enough to check. Check all the other possible vacuum leak points while you're at it.

9. Find different mechanics.
====================================:yeah: with emphasis on #2 and #9 -

your codes point to MAF sensor and TPS -
both will affect idle -
and both are relatively inexpensive - and easy to change -
 

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Administrator
2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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70,416 Posts
Your engine has 3 timing chains. I doubt there's anything wrong with them, although the nylon guides and slippers will have some wear by now. Not normally a problem. (Picture courtesy of Ranger)

You can check for blowby - but you must plug the PCV dirty air line while doing this. Remove the PCV clean air line from the laft (front) cam cover and plug the hole into the cam cover. Now carefully remove the (high vacuum) line from the right (rear) cam cover and plug the rubber connector - the vacuum line. Idle the engine and hold your thumb over the PCV orifice fitting. Does internal engine pressure build up quickly and significantly ??? If not, blowby is not your problem.

More pictures and info in my albums. Click the Commmunity tab up there ^^^ - 2 albums, the red Seville.
 

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2003 Deville DTS
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Discussion Starter #5
Thank you for your responses. A part of me is thinking the mechanic was trying to make some fast money off of me because he knew me and knew I could afford to repair this and was himself going through financial difficulty. Maybe that is why he took offense when I said I was going to take it to a Cadillac Dealer.

My question is this: What would the real symptoms of a worn timing chain be and how could I tell? I ask this not to be repetitive, but because if I take it to the Dealer, I will have it towed rather than risk driving it and having it break. According to the mechanic it could break any minute.

So I have not driven it, except home to get away from his shop.

The only symptom I have now is high idle with codes point to the IAC or the MAF, which I will troubleshoot later.

Would there be codes thrown if the timing chain needed service?

Thank you
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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Timing components are purely mechanical and not able to be monitored by OBD.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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70,416 Posts
The timing chains are not worn and are not about to break. IF a guide or slipper was worn to the point of allowing some slop there would be either a distinct rattle or whine at the timing cover.

Even a worn (stretched) one of the 3 chains would not "jump time".

You have fuel, fuel mixture, vacuum or ignition problems.

Probably the worst consequence of driving the car for any length of time with fuel mixture problems would be to destroy the (expensive) catalytic converter.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Ignition - Coil cassette(s), ICM(s), spark plugs, plug boots, electrical connectors, CKPs, CMP - anything related to spark and spark control.

CKP ? CMP ? - use the Acronyms sticky on the main threads page.

MAF, TPS, IAC - all related to airflow measurement and induction control.
 

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2003 Deville DTS
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204 Posts
Discussion Starter #10
One more thing before I troubleshoot tomorrow: Because I have codes related to the MAF and IAC, would either of these, if faulty cause a hissing noise, or generally a loud air release sound? Prior to this, everything was nice and quiet.

Just by opening up the oil cap and looking at one little piece of the timing chain, it appeared and felt super tight. The mechanic said it was loose, but I know there are three chains and he had my coil packs off to replace plugs and valve gasket seals... perhaps he saw something in there. He was not very specific.

Thank you
 

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Registered
2004 DHS 53 K - 1997 STS 73 K - 1999 SLS 32 K
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8 Posts
The hissing noise indicate a major air leak between the throttle plate and the cylinder heads including the plastic intake. See if the garage that you are working with has a smoke machine to pin point the leak.

Nothing is wrong with the chains or guides etc. It is unfortunate that "the not well versed mechanics" immediately jump to crazy conclusions just because it is a northstar.

The northstar is a much better engine than the 4 camer V-8 mercedes engines 2006 to 2008, that chew up their chain idler gears causing the timing chain to jump at 50 K Miles.
 

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2003 Deville DTS
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204 Posts
Discussion Starter #12
Could the major air leak between the throttle plate and the cylinder head be any indication of over-excessive blow by or a bad ring?
 

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2001 Seville STS, 1990 Seville (RIP), 1972 Sedan Deville
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26,323 Posts
Any audible vacuum leak should definitely be causing lean codes.

The most common '00+ large vacuum leak is a torn intake plenum duct. The rubber bellow between the TB and intake manifold. To check it, spray brake cleaner on it and flex all 360 degrees of it with a tool, with the engine idling. Any change in idle speed or quality indicate a tear.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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The hissing noise indicate a major air leak between the throttle plate and the cylinder heads including the plastic intake.
The Plenum (GM term) is the flex coupler between the throttlebody and the intake manifold. The intake manifold uses 8 individual port seals at the cylinder head intake face.

More 00+ Northstar stuff in my 2 albums. The Community tab. The red Seville.

Click a thumbnail to enlarge, use your browser <-- to back out.
 

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Discussion Starter #16
You guys are all so well informed. Basically, it was determined that

A) The former mechanic was hustling me

B) I do not have the timing chain issue

C) It was a tiny valve that wears over time and mileage and was a simple $300 fix by dealer prices.

I just want to thank everyone who responded with precise knowledge and hopefully this thread helps anyone else who experiences the same issues.
 

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CTS
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Re: 2003 Deville DTS TIMING CHAIN/HIGH IDLE/BLOW BY

1. Always post the code definitions along with the codes. We don't have them all memorized.

2. Find different mechanics.

3. You have no HG symptoms.

4. Northstar rings and cylinder walls last forever with very little wear. Blowby is a real stretch.

5. A loose timing chain is also a stretch. The tensioner shoes will last forever.

6. These guys have no idea what they are talking about and are just trying to get into your wallet.

7. I do recognize P0101. That's a MAF sensor code. You might replace that to start with and see what happens.

8. A ripped plenum duct will usually set a P0171 & P0174 code, but it is easy enough to check. Check all the other possible vacuum leak points while you're at it.

9. Find different mechanics.
Agree w/Ranger on this, and would only add the PCV rubber fitting at the intake manifold (access from passenger side of engine) is usually disintegrating by now causing a sizable vacuum leak and symptoms you describe. Easy cheap fix. :thumbsup:
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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$300 fix for a rubber coupling ??? The same part is available on the Help! racks at parts stores for $1.49.
 
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