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02 STS idling strange


95SevilleSLS

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I've had this problem since I bought this car. When I have it in park and just sitting there idling, it almost feels like it's missing. It's not really apparent, but you can feel a little bit of what I'd call a "chuggle" every once and a while. If I put it in drive, it idles smooth as can be. I've put it and drive and put load on it to see if there was a miss, but there wasn't. I just replaced the spark plugs and it's doing the same thing. I have a new air filter, fuel filter, and recent oil change. It doesn't seem to be affecting performance, but it's just annoying. Anyone else have this problem?

81K on 02 STS

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

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Hopefully all parts were AC Delco, if not let us know also any modifications add on's etc.

Start simple, you mentoned scince you got it .....Origional owner, helps to compare??... IS engine at operating temp, being cold can cause a rough idle, try a long drive and let us know, how many miles?? Always try a code check. next a injector cleaner I have had good luck with Chevron texron and Seafoam..

Not so simple .... with a scan tool, you can check the missfire monitors, looking for a problem cylinder.

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my 01 sls is having the same symptoms. after pulling the codes (SES is flashing btw..) i got

p0300(engine misfire detected) and

p0446 (evap solenoid valve control system)..

I havnt gotten around to correcting this problem yet..but does anyone know if the engine misfiring could be a result of the solenoid problem..? id like to get new plugs and check some other things under the hood when the weather holds up.

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I've had this problem since I bought this car. When I have it in park and just sitting there idling, it almost feels like it's missing. It's not really apparent, but you can feel a little bit of what I'd call a "chuggle" every once and a while. If I put it in drive, it idles smooth as can be. I've put it and drive and put load on it to see if there was a miss, but there wasn't. I just replaced the spark plugs and it's doing the same thing. I have a new air filter, fuel filter, and recent oil change. It doesn't seem to be affecting performance, but it's just annoying. Anyone else have this problem?

81K on 02 STS

I've had my 03 STS for 4 months now and it has 37000Km (23000mi). When the car is in park or in gear there is a very slight vibration and the tach fluctuates by about +/-25 rpm. There is no noticeable miss and acceleration is excellant. I showed the dealer and he said it is normal. is that what you are noticing?

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You've had the crank sensors replaced... right?

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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Everything I replaced was AC Delco. I have 81,600 miles on it. I bought it at 80,500. The previous owner, which was the dealer, had it for the past 20,000 miles. Not sure how they drove or what work was ever done. No codes have come up. I've added schaeffer injector cleaner and it didn't seem to make a difference.

03blacksts

I haven't watched the tach when that happens, but that is sort of what it feels like.

oynxsts

I don't know what previous work has been done, so I don't know if they have ever been replaced. I haven't done it, that's for sure.

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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I have the same problem on my 00 DHS. I took it to my mechanic and he looked it over and could find nothing wrong. My car has low miles (59000) so though it might be carboned up. I put in some heavy duty fuel system cleaner (can't remember the name right now, something like B44k) and this seemed to help for a while. I haven't run the entire tank through yet. I will let you know what I find. For now I still have the problem. Funny thing is somtimes she purrs like a kitten. Sometimes it is very noticeable. Even when the engine is up to normal operating temp.

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Everything I replaced was AC Delco. I have 81,600 miles on it. I bought it at 80,500. The previous owner, which was the dealer, had it for the past 20,000 miles. Not sure how they drove or what work was ever done. No codes have come up. I've added schaeffer injector cleaner and it didn't seem to make a difference.

oynxsts

I don't know what previous work has been done, so I don't know if they have ever been replaced. I haven't done it, that's for sure.

Step 1... off to the dealer, ask them for a service history on the car. They should give you a print out of this for free.

Step 2... Scan the print out for replacement of the crank sensors. if they have never been done, replace them. Crank sensors are a known and very common problem on all 2000-2003 N*'s. These cranky sensors cause all kind of problems, random stalls, lousy idle, etc.

If the crank sensors have been replaced then check and clean the EGR and TB... And then look for vacuum leak...

Injector cleaners, fuel system and oil additives should be used sparingly, if ever, they will cause more problems then they can solve.

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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I have a 1998 SLS with only 50k and I have the same issues. My car especially when cold has a bad shaking issue and it gets better when warm but still apparent. I used Seafoam in the fuel tank and sucked through a vacuum hose, been using 93 octane, cleaned the throttle body and IAC (Idle air Control) complete tune-up with plugs wires fuel filter etc. I was told now that it might be a problem with my TPS (throttle Position Sensor) which I will try tomorrow. It would be nice to get to the bottom of this one.

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replaced the TPS and problem still exists - I connected a OBD2 and it shows random misfire - although it wont show which cylinder and its not bad enough to trigger the MIL. Guess I'll keep looking

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Did you check codes through your DIC? Did that throw any codes?

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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More often then not a bad crank sensor WILL NOT issue a code... major PIA to track down.

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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How hard are crank sensors to get to/replace?

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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Not an impossible job after you remove the lower trim panel, the oil filter, and the oil filter adapter.

Typical symptoms of failed / failing crankshaft position sensors is random stalling.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Hmm, well I haven't had a random stall ever since I bought it.

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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Several things to check.

If your engine has a PCV valve, it will plug into the right bank (firewall) cam cover. Remove the valve and shake it; you should hear it rattle. Check the hose that connects the valve to the intake system.

Also inspect the O rings on the oil dipstick and the oil filler cap.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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Interesting...I've been told mine doesn't have a PCV valve, but I'm going to check all the stuff you just mentioned.

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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2002 doesnt have a serviceable PCV.

caddy.jpg

Easin' down the highway in a new Cadillac,

I had a fine fox in front, I had three more in the back

ZZTOP, I'm Bad I'm Nationwide

Greg

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That's what I thought. I'll check the oil fill cap and dipstick.

-Dusty-

- 02 Seville STS, white diamond

- 93 Sixty Special, Tan with vinyl top

- 79 Coupe DeVille, Tan with Tan top

- 06 GMC Sierra Z71, Black

- 92 Silverado C1500, black and grey

- 83 Chevy K10 Silverado, Black and Grey

b80385550.jpg

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