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2001 seville sts 219K
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156 Posts
Discussion Starter #1
I'm getting a P0300 at idle and it's idling rough too. I replaced the plugs and boots/wires with AC delco and the code will not go away. A guy here at work has a scaner but I have never used one before. From my understanding this is the only way to tell which coil bank is bad correct?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,004 Posts
Yes, some aftermarket scanners will enter an individual coil reading. Not sure how. Any other codes besides misfire in the DIC ?

You replaced all the plugs (#41-987 ?) and boots.......How did the coil cassettes look ? Clean and no carbon (spark) tracks ? What about the ICM connectors and the cassette ground spring - Tight ? Coil boots centered on each plug and pushed flush with the cam cover ? (I got sneaky with mine and stretched the internal springs a bit......).

www.rockauto.com still has a few OEM DELPHI coil cassettes with ICM for a decent price.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #3
I did the plugs first and put it back together. Then that didn't fix so I took it back apart for the boots. I got all the parts from rock auto. After doing some research could it be my injectors? P0300 is the only code I'm getting.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,004 Posts
Pull the beauty cover and check the PCV vacuum side - the plastic pipe from the rear cam cover to the intake manifold, and the other vacuum fittings at the throttlebody casting top. While you're in there, shoot a tad of choke cleaner at the base of the rubber connector - the plenum - between the throttlebody and intake manifold. Any idle quality change ? Reach down (engine off) behind/below the p/s pump area to the CMP (CaMshaft Position sensor) connector in the front lower part of the rear cam cover and give it a few wiggles and tugs. Re-check the coil ICM connectors.

Other than that, you're probably in for a GM dealer diagnostic.
 

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04 Deville, 11 DTS Premium, 00 Deville (sold), 02 Deville (sold)
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2,688 Posts
Clean the throttle body and check the plenum for leaks both of these are covered in detail in the Caddy tech Tips section of the board. Has your N* ever stalled or just cut off for no apparent reason... if so suspect the CKP sensors.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #6
I replaced the CKP sensors and checked that plenum awhile back. Since the coil packs are interchangeable I'm probably just pick one up as spare anyway.
 

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1997 Seville STS, 2000 Seville STS
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1,694 Posts
Coil packs on a 2000+ engine are not interchangeable, there is one for the back and one for the front. They look the same (other than one is black and one is silver), but the spacing of the coils is is different and I'm sure the ICM wiring is different due to the firing order on each bank.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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71,004 Posts
Except for color, the coil cassettes are identical. The ICM's are both the same part number and ID sticker on the ICM itself.

If necessary, I can post other pictures. (The black partner.........) Each ICM is held in by a pair of T15 Torx and a snap tab - pull the screws and carefully lift the cassette snap tab hole off the ICM barb and it will slide out the slot - the inner connector is sealed by a triple silicone seal oval - (very similar to most other engine connector seals) - make sure it goes back in correctly.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #9
This P0300 is strange. I cleared all the codes last night when I got home from work and then on ride to work (20 miles) this morning no code. It's acting like when its cooler outside (60 degrees) it doesn't get the code. I could see a coil acting intermittent like that but not and injector. I need a scanner.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #10
I sprayed about half a can of carb cleaner on every vacuum line, plenum and hose I could find with no change in idle speed. I unhooked the cam position sensor and plugged it back in, it seems OK. I then made up a homemade stethoscope and listened to each injector and they all sound the same to me. I then shut off the car and measured the resistance of each injector and got 14.2 ohms on each. I did score a used OEM coil off E-bay for $60 so I guess that’s the next step.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #11
I had some time last weekend so I replaced both coil packs and the entire fuel rail, injectors and FPR with new OEM. Then I fired it up and what do you know I still have the P0300 at idle so I must have a vacuum leak somewhere I just can’t find it. On the plus side my throttle response is much better and I’m up 4mpg on the highway.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Take a look at these 2 diagrams and pull the EGR (Exhaust Gas Recirculation) valve to clean its pintle and passages. At the same time pull the EVAP solenoid which is stuck into the "driver's side" of the throttlebody casting. That valve and its associated vacuum lines can be a source of a nagging miss.

After that, get a 20 oz jug of Chevron TECHRON gas additive, dump it in and fill with 93 octane Chevron, Texaco, or Shell. (Google "top tier gasoline" for info). Go for a long drive and do a couple of WOT runs.

Here's my carbon-cleaner procedure: On a long, straight stretch of quiet road, from a slow rolling start, put the stick in 2. (From here on the transmission and engine WILL NOT let you break anything.) Turn off Traction Control if possible. All clear ?? Punch it ! Stick your foot through the firewall. The 1-2 upshift will come at about 6,300 rpm - redline - and you'll continue up to close to redline again, about 75+ mph. Flip your foot off the gas and let the engine pull the car back down to 20 mph, no brakes. (If you miss the foot-off-the-gas at 2nd redline, don't worry: the transmission will upshift to 3 and continue happily on up. Back off anyway. The transmission WILL NOT downshift until vehicle speed is safe for engine speed to increase in the downshifts.) Lots of black crap out the tailpipe ?? Calm down and do it again..............Why ?? This procedure heavily loads the pistons and rings, breaking down carbon deposits. On engine pulldown, the cylinders unload and go to high vacuum, allowing the piston rings to rotate in their grooves and shed carbon deposits. Couple of times a month. If you're uncomfortable doing the Full Monty the first time, ease into it with maybe a high rpm first gear run to get the feel of your car.
 

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2001 seville sts 219K
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156 Posts
Discussion Starter #13
I cleaned out the EGR a while back but I can do that again since it’s so easy to get at. The EVAP solenoid I have never cleaned so I will try that this weekend. The carbon cleaning procedure is also overdue I better try that today.
 
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