[GooliusBoozler]

2009 cts4 sedan auto, 119k miles

I just got my car back from the service center a few weeks ago with new timing chains (luckily covered under extended warranty) and everything seems good during casual driving but when I try to hit the gas a little harder the engine will get jittery and seem to blip off the power for a split second at random intervals resulting in acceleration that isn't smooth. This was never an issue before the service. I thought the service guys might've not put enough fluid into the trans but I can't check easily cus Cadillac decided they were too good to put a damn dipstick in there. My other suspicion is the spark plugs are old but since this started happening immediately after the engine fix I'm not sure. Anyone ever had this issue?

 

[HurstGN]

You might be on it with the plugs. I had the same problem after service and the plugs fixed my problem.

 

[Mullah88]

Any update on this because my wagon is now experiencing the same thing. Like the engine is misfiring when accelerating, it happens between 50-60mph

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[HurstGN]

Mullah, check your plugs. These engines seem sensitive to plugs not all gapped 100% spot on the spec.

 

[Mullah88]

Ok so this happens at or around the 1.5-2k rpm. The spark plugs, should I replace all or which one am I replacing? Also thanks for the head ups

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[tinman]

You're in there - replace 'em all

 

[Mullah88]

You're in there - replace 'em all

Go with oem or aftermarket?

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[Long]

Go with oem or aftermarket?

I vote OEM.

 

[Knobbz74]

Which ac delco plug do you guys recommend? A few sites i have been on list different part numbers. 41-988 vs 41-990 vs 41-110 etc.


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[Long]

Which ac delco plug do you guys recommend? A few sites i have been on list different part numbers. 41-988 vs 41-990 vs 41-110 etc.

It is listed in your OM, IIRC 41-990.
.043" gap, 15 ft/lbs. torque. (7.5 ft/lbs. for coil).

 

[CaddyFred]

If you want to upgrade, 41-988 for the iridium plugs.

 

[Long]

If you want to upgrade, 41-988 for the iridium plugs.

Correct.
OEM 41-988 (iridium) is about twice the price of 41-990 (platinum), but we're talking about ~ $20/set vs ~$30/set. Not a huge difference.
As shown in this chart, iridium scores higher in all categories.

 

[Mullah88]

So I have the plugs and Will be doing this today but the car does not have any codes or stored codes. What if it's the coils?

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[Long]

So I have the plugs and Will be doing this today but the car does not have any codes or stored codes. What if it's the coils?

A failing coil SHOULD set a code.

 

[Mullah88]

A failing coil SHOULD set a code.

Nice good to know

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[tinman]

So I have the plugs and Will be doing this today but the car does not have any codes or stored codes. What if it's the coils?

At least you will have eliminated the plugs factor and you will have new plugs!

 

[Knobbz74]

Correct.
OEM 41-988 (iridium) is about twice the price of 41-990 (platinum), but we're talking about ~ $20/set vs ~$30/set. Not a huge difference.
As shown in this chart, iridium scores higher in all categories.

I ask because I seem to be having this issue or similar AFTER doing plugs. I had a coil fail, replaced all 6 just for piece of mind and figured I would do plugs while I’m in there. Now it has slight misfire that doesnt set a code.


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[Long]

Personally, I would think plugs would set a code, but HurstGN's post says otherwise.
Plugs on the DI are easy & cheap enough to replace and will provide a good starting point, if not a solution to your issue.

 

[Long]

I ask because I seem to be having this issue or similar AFTER doing plugs. I had a coil fail, replaced all 6 just for piece of mind and figured I would do plugs while I’m in there. Now it has slight misfire that doesnt set a code.

Plugs OEM and gapped correctly?
OEM coil(s)?

 

[Knobbz74]

Plugs OEM and gapped correctly?
OEM coil(s)?

Plugs are AC 41-988 i believe and gapped and the coils are Bosch.


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