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P1128 (again) and Porsche IMSB "solution"....

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The P1128 error came back. Difference this time -- vs. the time before -- is the error data appears to indicate some kind of intake air leak. The long term fuel trims show "big" positive numbers which is the DME *adding* fuel.

After I got the car back after the tech found leaves in the air box and up against the plastic screen just ahead of the MAF the car was running better. And the P1128 stayed away. I drove the car some over the weekend and it was fine.

Then Monday I drove it to the office. Just a few miles from the office the CEL came on. P1128 error. Verified no other active or pending codes, logged the freeze frame data, etc., and then cleared the code. Drove the car at lunch time and it was fine. But that evening in just a few miles the CEL was on again. Same error code. I followed the same process as before. Talked to the Porsche service manager and tech and was told best to bring the car in with the CEL on. So I drove the car Sunday quite a bit and finally got the CEL to come on. I double checked it was the same code and wrote down all the details.

Dropped car off and the tech has been on and off working on a diagnosis.

Got a status update this AM. The tech says he can find no smoking gun to account for the error. Double checked the intake for leaks. None found. Engine vacuum is right on the money which eliminates AOS.

All Porsche diagnostics computer telemetry from the engine doesn't flag any thing. No exhaust leaks. Tech says essentially the error arises because of what the O2 sensors report. O2 sensors are "new" having been replaced at 305K miles which is less than 20K miles ago.

But tech thinks one might be "lazy". He swapped them around and tonight I'll pick up the car and drive it like I always drive it and see if I can cause the CEL to come on and see if the error follows the sensors or stays put. The tech admits this is a real puzzler.

So that's the update on the P1128 situation.


Now about that Porsche IMSB "solution"...

Don't quite remember how the subject of IMSB came up -- it is *not* considered a possible explanation in the case of this persistent P1128 error code -- but the tech mentioned that Porsche now offers an IMSB "solution" well, not solution maybe but a "kit". The kit includes a new (obviously) bearing an improved bearing along with a new end flange, bolts, etc. Parts cost is just a couple of hundred dollars but that's not an official number. The parts department manager was not available when I was there so I was not able to ask for a quote. The old bearing comes out the new bearing goes in. Since the engine can't accept the larger diameter bearing used in the 2005 and newer engines either the new bearing is a dual row or it is a much better grade (?) of a single row bearing.

I don't know the labor cost, but of course it requires dropping the transmission to install the new hardware.

The tech said the kit comes with a warranty, which if it is the standard warranty it would a 2 year warranty on parts and a one year warranty on labor, but I have not gotten confirmation of this yet.

Before learning of this kit I was clearly on the side -- this is for me and my car -- of leaving the IMSB alone. The engine is over 315K miles and counting.

But the tech did mention some vibration around the 3K RPM area -- I just remembered it was in the middle of this portion of our discussion the IMSB came up -- which could be attributed to a number of possible causes one of which could be due to a clutch or a dual mass flywheel (DMF) problem. While the clutch doesn't slip, engages with no shuddering, I do notice once in a while a "clunk" like there is some kind of slack in the clutch. (My WAG is that is the dual mass feature of the DMF probably if not dead nearly so.)

It is just a matter of time really if I intend to keep the car (and so far I do intend to keep the car) before the clutch (and probably the DMF) will need to be replaced. At this time I might (might!) consider having the tech apply the Porsche IMSB to the engine. Really this would be driven as much by curiosity to see in what condition the factory installed bearing in after all the miles than to address any real concerns the bearing was about to blow.
re: IMSB and 3k
grant - Thursday at 2:05:24 pm
note that ~ 3k is also the resonant frequency of the M96 motor. i had a bearing "nearly" fail and there was no degradation of that resonance - its was always there.

Furthermore, my experience is that one, un-named replacement IMS bearing made of harder materials, lasts worse than the factory. Those hard balls just chew the crap out of the races. Mine was a mess - astounding that it held together. Pedro's answer - a new same old bearing and an oil feed, makes the most sense to me. There are a couple other lubricated solutions too.

As to the P1128. Good luck. Troubles with "no trouble found" and intermittent are maddening. You might elect to just ignore it.

My car continues to take gas perfectly. what did I fix? Nothing that I know of. I mist have fixed something, but it was mainly an accident (or it was slightly clogged and i did not detect the clog).

G

Grant gee-lenahan-at-vee-eff-email-dot-net
Re: re: IMSB and 3k
MarcW - Thursday at 4:03:57 pm
Quote
grant
note that ~ 3k is also the resonant frequency of the M96 motor. i had a bearing "nearly" fail and there was no degradation of that resonance - its was always there.

Furthermore, my experience is that one, un-named replacement IMS bearing made of harder materials, lasts worse than the factory. Those hard balls just chew the crap out of the races. Mine was a mess - astounding that it held together. Pedro's answer - a new same old bearing and an oil feed, makes the most sense to me. There are a couple other lubricated solutions too.

As to the P1128. Good luck. Troubles with "no trouble found" and intermittent are maddening. You might elect to just ignore it.

My car continues to take gas perfectly. what did I fix? Nothing that I know of. I mist have fixed something, but it was mainly an accident (or it was slightly clogged and i did not detect the clog).

G

Told the tech the car has always had some kind of a vibration harmonic at 3K. It was not severe -- at least to me -- and I never really thought much about it. The vibration/harmonic isn't present all the time. I really don't pay it much mind but I seem to recall it is often most noticeable the smoother the road. Oh, and when in the higher gears.

Trying to get some info about the Porsche IMSB kit: cost, contents, the bearing supplied, etc.

For the P1128 error code I really don't have the luxury of ignoring the code. The car will almost certainly require a smog check next time it is due to be registered and I would prefer to not have to "dance" around clearing the code and driving the car enough to get the readiness monitors all set to complete but short of the CEL coming on again in order to squeak the car through its smog check. I got real tired of that when bank #2 converter was acting up.

So, I'm kind of hoping the tech finds the source of the error code.


Grant gee-lenahan-at-vee-eff-email-dot-net
Update....
MarcW - Friday at 12:34:31 pm
Test drove the Boxster last night putting around 50 miles on the car driving the car very similar to how I drive it to work. Some surface street time, then mostly freeway, ending with some surface street time again.

No CEL. Spoke to tech today and told him this. He said he drove the car around 30 miles earlier in the day and with a good mix of surface roads and freeways and no CEL either.

If the problem is a "lazy" O2 sensor it ain't that lazy.

So I picked up the Boxster today and it will go back into "service" this weekend. Oh, no charge for the diagnostics time. Yay!

What I can do is just keep my trusty OBD2 code reader in the car and on the drive to work when I get close to work or on the drive home when I get close to home use the OBD2 tool to trigger some O2 sensor tests to see if the testing can flag a weak or bad O2 sensor.

But the dealer is kind of sneaky... I needed a shuttle driver to follow me home as I drove the Boxster home and then bring me back so I could continue to work in my other car. Only one of two shuttle drivers near and the near one had two riders to drop off already so the SM got a tech to drive a car and follow me over to my house so I could drop off the Boxster then bring me back to the dealer and my other car.

Guess which car the SM have the tech drive to follow me home and bring me back to the dealer?

A slightly used (<4K miles I think) late model (I don't know the year but a 2016/2017 at least) Cayman GT4 in I guess Carrera white. I'm not up on the various GT4 variations but this car has a 6-speed manual, the large fixed wing, roll bar (painted yellow), heavily bolstered seats (with I was told limited adjustment of the seat's positon/shape). There was even a fire extinguisher under my legs in front of the passenger seat. I remembered a year or so back the dealer offered me some special Cayman model and it was tempting but it lacked A/C. (And my info is the dealer had a tough time selling the car because of this.) With this GT4 I made sure to check and this car does have A/C. Didn't think to check but it may have PCCB's, too.

The car just came in and has less than 4K miles and looks to be in pristine condition. Hasn't even been prepped for sale as a used car yet.

A pretty nice car and in even just a mile or two ride in the car from my house to the dealer I could tell the car has plenty of get and go. Wow!

So what's holding me back? A couple of things -- the car is a bit raw to use as a daily and too expensive for a toy and as my Turbo is expensive to service/repair the word I get is GT4 is as bad maybe worse in this regard -- but mainly prior to today's exposure to a GT4 I've done a bit of research on GT4's and the prices are way high. Surprisingly there is a large supply of these cars. I don't quite understand how prices can remain high in this case but of course while the asking prices are high what the cars actually sell for might be something less. Or they could sell for the asking price. IOWs, the prices remain high because people are willing to pay the asking price. I haven't bothered to track examples to try to learn how long they remain on the market and when the sell what they actually sell for.

Sorry, but no pics of the GT4. I was in a hurry to get the Boxster home and while I had the presence of mind to recognize the car for what it was -- one would have to be dead not to -- I didn't have the presence of mind to grab my iPad and take a pic or 3. But the car will almost certainly go up on the dealer's web site (Porsche of Livermore, CA) and I'm sure pics will be posted.
Just curious Mark. What are the issues that make the GT4 expensive to service/repair?

Steve
Don't know for sure...
MarcW - Friday at 3:52:02 pm
but I can guess it is because GT4 is a high performance car and all its hardware is packaged pretty darn tight which makes for more time to get at, swap, replace things.

Kind of like the difference between my Boxster and my 996 Turbo. While the Boxster is a pretty nicely packaged car the Turbo has some pretty impressive packaging especially in the engine compartment, and around the rear transmission/diff, etc.

The differences in the cars how all the hardware manages to fit makes for more expensive servicing. And Turbo parts are generally more expensive. Things like coils, air filter, there's a fuel filter (the Boxster has a non-serviceable filter in the fuel tank), fuel pump, water pump, etc.

Regarding the packaging my Boxster's 5-speed transmission fluid change requires just 0.3 hour labor and nearly 3 liters of fluid. My 996 Turbo's 6-speed fluid change requires more time (but I don't recall the difference now) -- due to the fact the Turbo transmission has plastic panels under it that require removing before one can actually get at the transmission --- but just about the same amount of fluid.

Turbo spark plugs require the rear bumper be removed along with the exhaust system and some of the intake system. Thus the labor is about twice that for a Boxster plug change. To refit the Turbo exhaust system metal o-rings have to be replaced that seal the turbo to the exhaust system. This adds to the parts cost.

Just about every service, every repair (water pump, fuel pump are two that both cars have required) is more expensive in terms of labor and parts for the Turbo vs. the Boxster. In the case of the Turbo every time the transmission has been out (once under CPO warranty and once on my nickle to address an RMS leak) considerable other hardware (like bumper, exhaust, some intake) have to be removed. Even if the clutch is otherwise ok -- and so far it has been -- some clutch hardware in the bell housing has to be replaced. Hardware like the needle bearings that support the clutch control shaft. I mentioned the turbo metal o-rings above that have to be replaced every time the exhaust system is taken apart.

When I was told the GT4 was more expensive to service/work on the above is what came to mind and I was thinking the GT4 would be more like the Turbo in servicing and repair rather than like the Boxster.
GT4
grant - Saturday at 7:55:11 am
The one new Porsche that calls to me and might open my famously closed wallet.

Terrific car, once one tames the front end plow (alignment and rear roll stiffness fixes). As usual Porsche dialed the agility out for "safety".

I am not aware of it being substantially worse than other new model Porsches, specifically Caymans in terms of maintenance. In fact, its really not all that different from the 981 v1 Cayman S it is derived from. The suspension is different (mostly coil-overs, rates don't affect maint), tune of motor, wing (no maint there), seats (ditto), control arms (ditto), safety stuff (more dittos). The 6-speed (GT4 are all 6 speeds BTW) does have an issue - most track users have broken 3rd gear at least once. I know one guy on #4 - all courtesy Porsche, but woe to he who has one without a warranty!.

So yes, new = harder to work on, but i just cannot see the GT4 being all that different from a run-of the fancy mill Cayman_s, with 5 out of 6 gears in service.

I'm told the latest revisions fixes the gearbox.

G

Grant gee-lenahan-at-vee-eff-email-dot-net
Re: GT4
MarcW - Saturday at 11:33:11 am
Quote
grant
The one new Porsche that calls to me and might open my famously closed wallet.

Terrific car, once one tames the front end plow (alignment and rear roll stiffness fixes). As usual Porsche dialed the agility out for "safety".

I am not aware of it being substantially worse than other new model Porsches, specifically Caymans in terms of maintenance. In fact, its really not all that different from the 981 v1 Cayman S it is derived from. The suspension is different (mostly coil-overs, rates don't affect maint), tune of motor, wing (no maint there), seats (ditto), control arms (ditto), safety stuff (more dittos). The 6-speed (GT4 are all 6 speeds BTW) does have an issue - most track users have broken 3rd gear at least once. I know one guy on #4 - all courtesy Porsche, but woe to he who has one without a warranty!.

So yes, new = harder to work on, but i just cannot see the GT4 being all that different from a run-of the fancy mill Cayman_s, with 5 out of 6 gears in service.

I'm told the latest revisions fixes the gearbox.

G

No direct experrience with the GT4 service/repair costs but I was cautioned by those that should know the car is more expensive to service/repair than the less exotic Cayman models. The plow I think comes from the very wide rear tires. I haven't bothered to look into if slighly narrower rear tires can be fitted or if it takes other mod's to address the plow. 'course, I haven't even driven one yet and maybe the plow only appears when the car is used on the track. If I bought one -- and it ain't going to happen -- I'd not track it so maybe the plow behavior would never come up.

Did a little research and there is a 3rd gear problem. I don't have any real details but gathered from my research this is a known problem and Porsche is pretty good about taking care of it.
3 rd gear and understeer
grant - Saturday at 7:37:40 pm
Porsche is very aware and very good, but still......

As to the plow, as I said the fix is well known. Way more negative camber in the front, reduced dynamic roll stiffness in the rear.
There are a bunch of competing methods to achieve this, from programming the dynamic suspension, to replacing it, to anti-roll bars.... The best is a race shop in Maryland that sets up several of the campaigned cars. Randy Pobst raved about it and several folks I know took their cars there.

Dealers are way behind the curve on that stuff, btw. They don't cater to the hard core crowd. The "plowing" is not rally noticeable until you';re at 9/10s. Its also very temperature and tire dependent. Under normal circumstances you would not necessarily anticipate what happens when you go 11/10ths. Admitted;ly driving style can help or hurt - had i known i would have been on the brakes harder and earlier **while initiating turning** and then off to allow the fronts to do nothing but steer but with the weight transfer. Monday morning quarterbacking - it was less fun in the moment :-)

Fabulous car. I'd buy one (if money were not an object), and i simply don't accept the maintenance concerns. Is it more? Sure - its a bit more complex. Is it vastly different? - no, it can't be; and from what I've seen and herd (note: GT4s are like locusts at the track, i talk to dozens of owners) they are in fact reliable. Most problems i see are from "less then well though through" aftermarket mods.

G

Grant gee-lenahan-at-vee-eff-email-dot-net
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