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Discussion Starter #1
I've noticed a weird symptom that occasionally happens. I think I've replicated it enough times to say when it happens.

2008 Redline w/ 72,500 miles and an automatic transmission.

When I am leaving my side street at a slow speed (25ish), and I let go of the gas pedal as I near the stop sign, I experience a harder downshift.
It nearly jerks the car for a moment.

The best info I can find so far is this:

Does this sound like what it could be?
I have to take out the transmission to replace the rear main seal anyway... so... how hard would it be to replace a downshift solenoid?
Are there any other recommended things I should do to the transmission while it is lowered?
 

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Yup. Seems as though ALL Kappa auto trans go through this at one point or another. Here’s what you’ll need to replace:

2 Pcs Intake & Exhaust Camshaft Position Actuator Solenoids for GM Chevy Malibu HHR Buick Pontiac 2.0L 2.2L 2.4L 12655420 12655421

Amazon.com: 2 Pcs Intake & Exhaust Camshaft Position Actuator Solenoids for GM Chevy Malibu HHR Buick Pontiac 2.0L 2.2L 2.4L 12655420 12655421: Automotive

Do a forum search for the above pieces and you’ll see a ton of posts on the subject. Easy fix.
 

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The full story: Auto transmission suckage

It helps to read that thread all the way through, depending on how fast you can read.

Long story short: It's the income and exhaust VVT actuators (solenoids) at the front, top, of the engine.

:thumbs:

.
 

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Discussion Starter #4
Yup. Seems as though ALL Kappa auto trans go through this at one point or another. Here’s what you’ll need to replace:

2 Pcs Intake & Exhaust Camshaft Position Actuator Solenoids for GM Chevy Malibu HHR Buick Pontiac 2.0L 2.2L 2.4L 12655420 12655421

Amazon.com: 2 Pcs Intake & Exhaust Camshaft Position Actuator Solenoids for GM Chevy Malibu HHR Buick Pontiac 2.0L 2.2L 2.4L 12655420 12655421: Automotive

Do a forum search for the above pieces and you’ll see a ton of posts on the subject. Easy fix.
Thank you! Those are super cheap. I don't understand how they impact downshifting. Would anyone be open to explaining?

The full story: Auto transmission suckage

It helps to read that thread all the way through, depending on how fast you can read.

Long story short: It's the income and exhaust VVT actuators (solenoids) at the front, top, of the engine.

:thumbs:
I appreciate the read. It quickly went into a rabbit hole and was hard to track.
The gist as I understand it, there are multiple likely causes:
  • Could be "normal" behavior
  • Could be low transmission fluid (I planned on doing a change anyway)
  • Could be can solenoids
  • Could be the transmission valve assembly
  • Could be the downshift solenoids
 

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Thank you! Those are super cheap. I don't understand how they impact downshifting. Would anyone be open to explaining?
........
When the cam phazing solenoid does not work properly the engine does not behave as expected by the ECM. This misbehavior can be interpreted by the ECM as a slip in the transmission, so it adjusts the shift pressure to maximum in an attempt to stop the "slip" that isn't really happening. The increased pressure results in the harsh downshift. In short, the ECM is confused.
 

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Discussion Starter #6
When the cam phazing solenoid does not work properly the engine does not behave as expected by the ECM. This misbehavior can be interpreted by the ECM as a slip in the transmission, so it adjusts the shift pressure to maximum in an attempt to stop the "slip" that isn't really happening. The increased pressure results in the harsh downshift. In short, the ECM is confused.
Yer a mechanical wizard! Thank you.
 

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Hi squilliam,

There are a rare few "doctor in a can" products that are worth trying, but this one might resolve your down-shifting troubles.

There is a product sold for automatic transmissions sold under a variety of brands, names and descriptions. The one that comes to mind is "Automatic Transmission Conditioner & Sealer" made by Gunk. You remove 12 ounces of auto trans fluid from the dip stick and pour in one bottle of the product. What it does is soften the internal rubber seals inside the transmission that lost some pliability with age. I have used such products in old automatic transmissions (not yet a Kappa) and they do work well in correcting the shifting behavior of the transmission. In a couple of cars, it took two bottles to make a difference.

Here is one I am thinking of, but there are many such products.
113768


BUT.......
If it is time to replace the auto trans fluid and filter, I would try that first.

About 6 weeks ago, I changed the automatic transmission fluid and filter on our 2006 Jeep Liberty at 85,000 miles. I did it once before in 2009 at 35,000 miles. I did not include any such conditioner/sealer. Afterwards, I was surprised to notice an improvement in the transmission's character. I was changing the fluid & filter solely as a preventative measure, surprised it actually made the transmission behave better.

My point to the story is....just maybe your trans will work better after a fluid and filter change, and keep the conditioner/sealer as your Plan-B.

If you recently changed your transmission fluid and filter, and you now have the problem, go right to trying the Gunk product or equivalent. If one bottle made no difference, try a second bottle.
 

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Just change the solenoids. 99% cure rate. Use premium engine oil and filter to reduce camshaft position solenoid problems. The solenoids can be sensitive to contamination.
 

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I agree with what others have said, it's the solenoids, change them both and by the GM part. You don't need a transmission additive you need new solenoids.

I'd had this myself as have a whack of us with autos and it's always the same thing.
 

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I have those two solenoids on my Base with manual transmission. Since they go bad frequently, what symptoms could I expect when failing?
 

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I have those two solenoids on my Base with manual transmission. Since they go bad frequently, what symptoms could I expect when failing?
A code will be set and the MIL will illuminate.
 

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Intake/exhaust cam solenoids have gone bad, on automatics before. Known fact and an easy fix. Not to expensive with short turn around time for you. Given the year of car and current mileage on your odo, a transmission flush with a new filter will improve this in the future for your car.

I have had one of these hard down shifts lately in my car.
Not a regular thing for my car, but it only does it under certain conditions.
Steep down hill grade, cooler temps under 30, first up shift after warm up-140 degrees,
let off on gas pedal the fuel cut off to the HPFP and maybe something in the trans module/ BCM idk logic for extra braking for the car if the HPFP is not in usage?
IF this hard downshifting occurs on frequent basis, change the 2 solenoids first, then see if results change for you?
IF not and since you are pulling your trans changing out the rear main seal, new fluid & filter for the long term life expectancy for your transmission is a positive thing here under 100k maintenance, can't hurt any except to your credit card maybe.

IF after both of these changes occur and you still have hard downshifts, it could be other unfound issues to the trans or the rear end, maybe the HPFP that is causing the harder than normal downshifting? I have not read that here on the forum that it is the trans or rear end, or the HPFP could be doing excessive hard downshifting mostly changing out the two solenoids fixes this for the owner.

LAC
 

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Discussion Starter #15
Hi squilliam,

There are a rare few "doctor in a can" products that are worth trying, but this one might resolve your down-shifting troubles.

There is a product sold for automatic transmissions sold under a variety of brands, names and descriptions. The one that comes to mind is "Automatic Transmission Conditioner & Sealer" made by Gunk. You remove 12 ounces of auto trans fluid from the dip stick and pour in one bottle of the product. What it does is soften the internal rubber seals inside the transmission that lost some pliability with age. I have used such products in old automatic transmissions (not yet a Kappa) and they do work well in correcting the shifting behavior of the transmission. In a couple of cars, it took two bottles to make a difference.

Here is one I am thinking of, but there are many such products.

BUT.......
If it is time to replace the auto trans fluid and filter, I would try that first.

About 6 weeks ago, I changed the automatic transmission fluid and filter on our 2006 Jeep Liberty at 85,000 miles. I did it once before in 2009 at 35,000 miles. I did not include any such conditioner/sealer. Afterwards, I was surprised to notice an improvement in the transmission's character. I was changing the fluid & filter solely as a preventative measure, surprised it actually made the transmission behave better.

My point to the story is....just maybe your trans will work better after a fluid and filter change, and keep the conditioner/sealer as your Plan-B.

If you recently changed your transmission fluid and filter, and you now have the problem, go right to trying the Gunk product or equivalent. If one bottle made no difference, try a second bottle.
Just change the solenoids. 99% cure rate. Use premium engine oil and filter to reduce camshaft position solenoid problems. The solenoids can be sensitive to contamination.
I agree with what others have said, it's the solenoids, change them both and by the GM part. You don't need a transmission additive you need new solenoids.

I'd had this myself as have a whack of us with autos and it's always the same thing.
Didn't want to quote everyone. I think the downside of a stop leak type additive is that it is a temporary measure, and does not fix seals.
On the plus side, I'm not leaking any transmission fluid.

I recently did a fresh oil and oil filter change, which exposed a small rear main seal leak. The filter looked as if it hadn't been changed in a LONG time.
I wonder if the oil change dislodged debris, which is clogging the solenoids partially. They're so cheap, I might as well replace them.

I figure when I do the transmission drop for the RMS leak, I will flush the transmission as well.
 

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Discussion Starter #16
A code will be set and the MIL will illuminate.
Hey John, I am having the toughest time finding the transmission filter/ gasket combo in the US.
Somehow only euro options are only showing.

I know our 5L40e was used in BMWs as well, but why aren't ours being treated similarly??
 

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Hey John, I am having the toughest time finding the transmission filter/ gasket combo in the US.
Somehow only euro options are only showing.

I know our 5L40e was used in BMWs as well, but why aren't ours being treated similarly??
Rock Auto lists three transmission filters, and it appears that all three include a gasket.
 

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The gasket will arrive like a ball inside the box along with the filter. Do yourself a favor. As soon as you get it, open the box right away and set the gasket on a flat surface, placing a board on top of it making sure it is not folded or distorted. When you are ready a few days later, it will be so much easier to align the gasket and pan together prior to the bolt-up.
 

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My 08 Redline (60K miles) occasionally downshifts hard, only just after a cold start, in the first half block from my driveway, when I'm slowing for the stop sign. No codes, level checks out, but fluid should probably be changed.
 
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