[MrSeabass]

this happened in the past week but ramped up in severity due to my extended drive this weekend.

130K mile 35i. Started noticing early last week that under *hard* acceleration around 3K RPM, the car would jerk as if it were misfiring but would go back to normal when I let my foot off the gas. I've had coil #1 go bad on me but engine-wise there were no problems.

Thursday I left to visit friends a 5 hours drive away, an almost constant interstate drive with speeds averaging 75 MPH, normal driving. When I got off the interstate after about 3 hours to fill up with gas/take one of the back roads, I accelerated to pass a vehicle, and around the same 3K RPM range as last time, ha hard misfire/shudder happened and the car went into limp mode. Drove it for another mile before I could find a space to pull off, plugged in the OBD reader I keep in the car... no codes. Turned it off, checked again, nothing came up. So I cleared them anyway, started the car, and it was back to normal.

Yesterday I started the return drive, same driving patterns, same journey. two hours in I'm on the backroads again, tried to accelerate up a hill - malfunction. Pull over, reset, get back on the road. 20 minutes later, again. Get onto the interstate, and it happens again. I pull off, check the code, and *this* time I get P0301. Thankfully there's an auto parts store that had a (generic) coil, so I swap it out.

... malfunction again with nearly *any* acceleration beyond Buick level. Can cannot function in auto mode at all, so I have to use manual gear changing the remaining 3 hours back. Downhill/flat the car is in 8th, but on the slightest gradient to stay somewhat with the flow of traffic, gotta drop to 5/6/7 or the car will shudder. So something went from bad to worse.

Today, casual drive around the neighborhood. Car in D, 2/3 gear, under 20MPH and the shudder happens. So I head right back to the garage and park it.

Right now after reading similar problems across the board, most everything point to changing the transfer case fluid - ordered last night and it will be here tomorrow. However, I am fairly worried about the rapid deterioration of my drivability and fear something else might have gone wrong. So let me bulletpoint all the aspects surrounding the components in case someone else here has an opinion.

• 130K miles, transmission fluid and transfer case fluid have never been replaced (yet)
• Valve cover recently replaced
• All coils but the 1st one are original
• Spark plugs are original (inspected #1 and found nothing 'wrong')
• Vehicle is 99.99% driven in normal city/highway conditions, comfort/auto
• Only one malfunction generated a P030, no other malfunctions created a code
• Have not yet checked the vehicle with Rheingold(?) for hidden codes.
• No shuddering with normal driving/cruising, no difference if driving straight or turning
• Will shudder in manual mode (not an gear shifting issue)

So does this sound like the transfer case, or something way more expensive to fix?

[pungo]

Since it's nearly ready for a 2nd trans fluid change and the transfer case should have been changed at least twice already and they're both original, it's way overdue so I'd start there, though damage may have already been done. No mention of diff fluids, so who knows about those.. Not sure why people don't change the drivetain fluids which are the lifeblood of the vehicle, they're not lifetime fluids

Not sure what scanner you're using, but maybe ista+ will show some codes and give you a better clue?

[MrSeabass]

I've used ISTA+ in the past for registering a new battery, in the process of reinstalling it as we speak to check it.

I'll plead guilty for not changing the 'lifetime' transmission fluid, but I have never heard of replacing the other fluids until yesterday, especially the diff.

[MrSeabass]

Okay, ISTA+ showed the following that was in line with the mileage yesterday today:

133E10 - Valvetronic system: deactivated, adjustment fault too frequent

Existent - yes

And the three things to perform:

- Check wiring harness between DME and Valvetronic servomotor.

- Perform the Valvetronic activation with the automatic deletion of the stiff movement counter.

- Replace Valvetronic servomotor and eccentric shaft.

I'm gonna check the first two and report back if anything changed. Does my issue sound like a Valvetronic failure tho?

[MrSeabass]

Well... I'm stuck in this cycle here and it won't progress. Using an Enet OBD cable.

Also recorded the sound with my phone in the engine bay of what I assume is the valvetronic motor: https://recorder.google.com/share/c2...9-f0a67d2a3dc2



Any help?

[MrSeabass]

OK, pretty sure the valvetronic motor is burned out now. Gonna attempt one more ISTA calibration/reset before calling around for a replacement quote. Just not in the mood to do this myself since I *just* had the valve cover off a month ago...

[MrSeabass]

Wait... is this a failed VANOS solenoid and I'm misdiagnosing this?

[najnad]

Very possible. Replace the vanos solenoids, clear codes, try again. They need to be replaced anyway if they are original.

[najnad]

Plugs and coils should be replaced as well.

[MrSeabass]

Alright, took the solenoids out, cleaned them and letting them soak in gasoline for a bit, then I'll reinstall them. Will likely order new ones later today regardless of the result. Same for coils and plugs.

[MrSeabass]

Oh I am also reading conflicting opinions regarding an out-of-car electrical test. Is it OK to connect the solenoid to a 12V/2A car charger to see if the solenoids move, or is that a bad idea?

[Bdavi011]

I'm not going to lie, it's hard to help to diagnose when there is alot of maintenance that needs to be done and the lack of it makes it hard to see if the problem is one or the other.

I would replace the valvetronic eccentric shaft actuator first and then erase codes and adaptations. I would try to do the differential, transmission, and transfer case services afterwards.

Some people have had luck spraying the solenoids with cleaner. Not too sure on how to get them to activate though to do a more thorough clean. I usually run some mild engine cleaner before an oil change to ensure solenoids get cleaned out every now and then but that's just me.

[MrSeabass]

Put the solenoids back in, drove it for a bit. Car responded a lot better but still has some low end RPM shudder, so I'll replace them.

Fluids for the other items will be replaced as the parts arrive.

[MrSeabass]

Valvetronic test - finally - was reset and 100% successful for 450 cycles according to ISET+, so that can be ruled out now.

[MrSeabass]

Problem has been completely resolved by replacing the spark plugs.

[pungo]

Originally Posted by MrSeabass

Problem has been completely resolved by replacing the spark plugs.

Good you got if fixed, but 130K on the original plugs and you were complaining about it "shuddering/jerking on acceleration"

Really can't understand people not performing basic recommended maintenance. I feel sorry for your neglected vehicle

[MrSeabass]

Originally Posted by pungo

Good you got if fixed, but 130K on the original plugs and you were complaining about it "shuddering/jerking on acceleration"

Really can't understand people not performing basic recommended maintenance. I feel sorry for your neglected vehicle

I've replaced the charge pipe, the thermostat, the water pump, the radiator, the valve cover, the oil filter gaskets, the intercooler, and the fuel injectors all myself. Oil is changed regularly. Yes, my vehicle is totally neglected. Thanks for your commentary.

[pungo]

Originally Posted by MrSeabass

I've replaced the charge pipe, the thermostat, the water pump, the radiator, the valve cover, the oil filter gaskets, the intercooler, and the fuel injectors all myself. Oil is changed regularly. Yes, my vehicle is totally neglected. Thanks for your commentary.

With the exception of oil changes, those are all items that failed, so you do reactive repairs. There's also basic maintenance, i.e. sparks plugs, transfer case/trans/diff fluids, which when not changed, are neglect.