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A few maintenance questions: TPMS issues and difficulty starting.

3K views 24 replies 11 participants last post by  racergreg 
#1 ·
Hello all. I have a couple questions concerning some maintenance issues on my car I thought I would run by you fine folks.

First, my TPMS system has a bit of an annoying issue. Namely, it is reading about 3 PSI lower than reality, as determined by two separate pressure gauges, and thus giving me low pressure warnings when the tire pressure is actually dead on. This only is an issue with the front wheels, but they are set at 32 PSI cold, and I'm still getting a low pressure warning all the time. When I start the car, it reads typically reads either 28 or 29 PSI on the guage cluster, and gives a warning. Checking the pressures shows them to be set correctly though. Any advice here? is there a way to recalibrate the TPMS sensors, or do I just need to overinflate the tires and deal with the horrible ride quality if I want to get rid of the error message? Also, why in the world are the rear tire pressures recommended to be 37 PSI? That seems really high. Never had a car that recommended over 32 before.

Second, I'm having an issue with the car being slightly difficult to start at times. It's especially true when it's hot, and I stop the car for a little while then attempt to restart it. It does actually start, at least so far, but it feels like the starter can barely turn the engine over and it takes 3 or 4 revolutions for the engine to fire. I checked the battery last night, and it reads 13.8 volts with the car off. 14.4 when the car is running at around 2k RPM, so it seems like the battery and charging system are working. the battery itself is less than 2 years old according to the maintenance records. Any thoughts on what might be causing this issue?
 
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#3 ·
How old are the tpms sensors? I have one that is intermittent now and they're about 5 yrs old. I plan to just replace next time I need tires. You can reset the sensors through the onboard computer- it's in the manual. Mine show about +1 psi vs. my gauge. Presume your car is a 987.1 (05-08). Like the 986 the factory spec for the rears is quite high- 36 psi on the 986. Have never heard reasoning for such high pressures. I tend to run the rears on my 986 a couple psi lower. On track 36 cold is way too high. I run them close to the same F/R when hot.

Can't really help much on the hard starting. Only times I've had issues it was the battery. Do you have access to another battery, just to try a jump to see if it makes a difference?
 
#5 ·
I keep forgetting that you guys can't see what my car is. Previous message boards I have participated in have had that info displayed next to your handle, and I forget it's not there anymore. Sorry about that. I will put it in my sig in minute here.

The car is a 2007 Cayman S 6MT with Sport Chrono and the 19" wheel option.

The TPMS sensors have all been replaced, the oldest one being from 2012 and the newest from 2014. It appears the rears were replaced first and the fronts second, but each was done at a different time.

Is there any way to change the notification PSI in the system? If the sensor just reads 3 PSI low and you know that, you could theoretically just change the 4 PSI down point by 3 PSI in the system if that were possible. Ideally I would prefer to be able to recalibrate the sensor, as they are all functioning, it's just the front two read 3 PSI lower than actual.
 
#9 ·
The rear tires were at 34 PSI when I checked shortly after I got the car. I brought them up to 37, and immediately noticed a negative impact on ride quality. I don't track the car, so I'm really only concerned with street applications.

One other thing I did notice when I went through the service records is that the battery is actually quite new. It was replaced in February 2016, so it seems unlikely to be a dying battery. Honestly it feels like the starter motor is having trouble overcoming the compression of the engine. Could the starter motor itself be going bad?
987.2 19" pressures are F32/R34. The weight is about the same so there must be some suspension differences taken into account.

Feeshta, maybe someone erroneously used the Gen 2 specs to 34PSI.
 
#8 ·
The rear tires were at 34 PSI when I checked shortly after I got the car. I brought them up to 37, and immediately noticed a negative impact on ride quality. I don't track the car, so I'm really only concerned with street applications.

One other thing I did notice when I went through the service records is that the battery is actually quite new. It was replaced in February 2016, so it seems unlikely to be a dying battery. Honestly it feels like the starter motor is having trouble overcoming the compression of the engine. Could the starter motor itself be going bad?
 
#11 ·
The TPMS computer can be told whether it has summer/winter tires and wheel size (17/18/19) through the onboard computer. I would try setting to 17"/winter, then reseting to 19"/summer. Were the TPMS factory replacements? They strike me as too far out of spec. Non factory can usually be reset by dropping by 5-10psi and leaving for 30 min, then inflating back to spec. Worked for me.

Starting problem sounds like bad starter or bad battery. Cheapest to try a new battery first.
 
#14 ·
My $1.00 bet is the starter. However, to diagnose your problem, I would start with a load test on your (almost new) battery at your local friendly auto parts store. (Unfortunately, new doesn't always mean good). Once you have determined the battery's ability to supply the current needed (ie assuming it's good), then connect your voltmeter and get a reading during the fast and slow cranking scenarios. The voltage should be a minimum of 10.5 during all cranking. Generally, a cold engine should be a greater draw than a hot one. If the voltage is low and all your connections are good, I would say you can safely point to the starter as the problem.
Remembering way back to younger times, I recall starters on American stuff giving the same problem you describe. The issue was a worn armature bushing allowing just enough play for the armature to contact the stator and short the starter - but only when hot. Good luck!
 
#16 · (Edited)
Occam's razor is a bad battery causing your starter issues. Lead-acid batteries have a ~6-month shelf life which isn't always recognized; I've seen 12-month old batteries sitting on the shelf in auto parts stores. If the tests are only marginal, it may still be an issue. Batteries can simply be defective, too- it's not uncommon to have 1-2% DOA failure rate in bulk purchases, even on very high-end batteries.

There's often a calibration difference between different pressure gauges. It's not at all uncommon to see a few psi difference. Digital gauges tend to be a lot more accurate than analog, but still have a % tolerance; if ALL your TPMS gauges are off by the exact same amount, the test gauge is probably the one in error. Cold and hot pressure are going to be different, too. I run really stiff sidewall high performance tires (ZII* & RE-71R) and have found good performance at ~36psi hot. If I tried to autocross at OEM recommended 32psi, even with the really stiff sidewall tires, I get rollover onto the sidewall. Lower pressures may be more comfortable, but higher pressures are going to give you better performance, especially for softer sidewall max performance tires like MPSS or DW.
 
#17 ·
So I took the car in to an interstate battery center today, as that is the brand of battery that is installed. It tested fine from an output standpoint, but at a lower than normal voltage, meaning it appears to be undercharged, which would point towards a problem with the charging system. I guess I'm going to have to take it to the dealership. Thankfully it is still under bumper to bumper coverage on the extended warranty.

I guess I can also have them take a look at the TPMS system while it is in. To be clear, the rear tire TPMS sensor readings are almost dead on with the two mechanical pressure gauges I have used. Both gauges match each other, and match the rear sensors, but are off by about three PSI from the front sensors. Not sure why both front sensors seem to be off by about the same amount.
 
#18 ·
Can you please keep us updated with the hard to start issue. I have the same problem; car starts fine when cold but when its been running for a while it really struggles. 2006 Cayman S Manual.

So far I have:
- Changed the battery (didn't help)
- Changed the coolant temperature sensor (also didnt help) - I changed this out as per a thread on here to no avail.
 
#19 ·
I recall that it wasn't the coolant temperature sensor but an engine temperature sensor. I also recall they are different sensors but could be wrong. It seems to me the coolant sensor is in fact the coolant system thermostate and is only for allowing the proper coolant circulation. The engine sensor regulates fuel mixtures.
 
#20 ·
So, I have an appointment to have the car looked at on Wednesday at Porsche of Towson. It developed two more problems over the weekend. First, the headliner fell down, so I'm researching how best to fix that. Second, I got a low coolant light and a slight smell of coolant when I drove it to work this morning. The coolant issue may be related to the fact that the water pump was replaced when I purchased, but not telling.

I have also been having an issue with the 12V outlets in the car repeatedly blowing the fuse, so I am wondering whether that might be related to the charging issues.

I will keep you guys updated on how it goes.
 
#21 ·
By way of an update, I have to say I am extremely unimpressed with the service at Porsche of Towson. I'll explain in a minute, but first a couple notes.

I did refill the coolant up to the minimum indicator on Monday evening. It took almost 2 liters of coolant to do so, which is way more than I expected. My old BMW would warn you when the coolant was about 4 or 5 ounces low, so that was a surprise. I also was able to check the parking spot where I had been prior to the issue as it was unoccupied, and there was a large stain on the left side of the spot towards the rear of the car. The stain is not oil or water, but I can't say for certain it came from the car or was coolant as other cars had parked there in the meantime. If ?I had to guess, it looks like around 2 liters worth of stain though. Finally, the drivers side door handle broke Tuesday morning on the way to work, or more accurately, the return spring seems to have snapped. Good timing that it was before the trip to the dealer I guess, but mildly annoying.

The car went in Tuesday evening for a Wednesday appointment, and I got a bad vibe from the service manager from the beginning. He seemed a bit perturbed that I had more than one issue to report/ask questions about, and practically rolled his eyes at me when I wasn't done after 2. He was also a bit dismissive of several of my concerns, particularly the blown fuse and TPMS issues, and didn't seem to take kindly to being asked about the horrible radio reception at all.

So, I leave with a rather poor impression right from the start. The following day, I hear nothing from them at all. I was busy all day at work, and away from the phone for a bit, but they did not even leave a message. It turns out they did not work on it at all, so why they wanted it on Wednesday is beyond me. They did finally call the following morning around 10:30 AM and stated that they could not replicate any of the issues save one, the broken return spring on the door handle. They asked a few more questions, and said they would call back in a little while once they check on a couple other things.

3 PM rolls around with no word so I start calling them to check, and the service manager is always on the phone. I leave a message, letting him know I live nearly an hour from the dealership given traffic and need to know soon whether to head that way to pick the car up before their 6 PM closing time. Nothing for another 45 minutes and I call again, same thing, on the phone. Secretary says he will call back in 5 minutes, which thankfully he does, and proceeds to lie and tell me he had called and left me a message. Grrr.

At this point, the service manager explains that they need to order a part for the door handle, but found nothing else wrong with the car. I ask how nearly 2 liters of coolant goes missing, and he says previous owner must not have checked it. I remind him for the third time that the water pump was changed by another Porsche dealership less than three months ago when I bought the car, and that there appears to be a stain from a spill where my car was parked, and he gives an excuse that it must have been a bubble in the system from the previous dealer. That seems really far fetched to me given the volume said bubble would have needed to be, and the fact that the car smelled strongly of coolant the day it happened. No explanation for the starting issues is given whatsoever.

Finally, he says that the part for the door handle needs to be ordered, will not be here before the weekend because it is so late in the day, but that they "should" be able to get to it on Monday. Why they waited until 5PM on Thursday to decide to order a part they should have known was needed by around 8AM on Wednesday is a mystery to me.

Finally, the cherry on top. Given that Monday is three days away, I ask whether I can have the car back in the meantime, as I am stuck in a crappy rental Kia that smells like wet dog. He says no, because the door card is not installed right now. I ask whether they could simply put it back so I can have my car for the three days that they will not be doing anything with it, and he hesitates, then states that the only way I can have my car back is if I pay the labor fees for putting the door back together and then taking it back apart again. Now, I can do this job myself, both in and back out, in less than half an hour, with nothing but a screwdriver and a plastic pry bar. A practiced tech probably needs about 5 minutes each direction, and you want to charge me an hour an half of labor to do it?

Sorry, but this dealership is not winning any repeat business from me. The only way I ever go back there is with a major issue when the car is still under warranty, and grudgingly even then.
 
#22 ·
^^ Sounds like a poor place to take your car for service, obviously they don't have much of an interest for you as a customer, I hope that there are options close buy?

Not defending the dealer about the coolant level, but these car do have a long-spread out system, it took me 4 heat/cool cycles to get mine to full after a front rad replacement, each time it took a little less coolant but all together it was nearly 4 liters.
 
#23 ·
Thank you for the heads up on the coolant system fill issues. It does make sense now that I think about how long the piping between engine and radiators is that there is a possibility of having a bubble issue. You would think that dealerships would have an effective method for countering that tendency though, as it was a dealership who changed the water pump.

Some other issues I had with the dealership were more troubling. I believe they tried to hit me up for a part that was not broken for one. I had a check airbag light on, so I asked if they could reset if if they had time. I made it clear that I was not interested in paying them to reset the light though, as I will eventually find someone with the durametric tool to do so.

The light was on because I had unplugged the console "passenger airbag" light when I installed my shift right solution. I mistakenly thought I could reset the light with my OBD2 tool, so I did not bother to disconnect the battery as the instructions state. Doh! Everything was connected properly when I put the interior back together, so it should work once reset. Well, the dealership told me that it was not possible to reset the light because they needed to replace the passenger seat pressure sensor module. I said if it was covered under my warranty, go for it, otherwise leave it alone. The warranty did not cover it, so they did not do anything with it in the end, but I honestly believe there is nothing wrong with that module. They probably would not have even replaced it, but simply just reset the light so it looked like they did. Time will tell I guess. Need to track down someone with a Durametric tool and try resetting the light to be sure, but I strongly suspect they were trying to take me for a ride there.
 
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