WARM START - I hate my Porsche 911 Carrera 4S
03-03-2015, 04:23 AM
#1
Intermediate
Thread Starter
WARM START - I hate my Porsche 911 Carrera 4S
I had my Porsche 911 Carrera 4S for 4 years now and spent a fortune trying to get the warm start fixed. 28,000 miles on the clock
Problem..
Car fires up on cold start - Great Smile
Warm start say I drive for 10 mins park up and then restart its struggling like mad to startup, so bloody embarrassing pulling up in a flash car that sounds like a coughing dog when starting up.. wrrr wrror worrr worrr worr then starts and sometimes I have to turn car off then try again in 5 mins
These are the actions I have had done in order to get this fixed and failed.
1. Part number 997-607-019-03 ("alternator/starter harness", "alternator/starter cable loom")
All the below done by a indy
2. Battery Earth Cables and 996 607 030 00 ground strap
3. New Battery
4. Coil packs
5. New Starter Motor 2 months ago (helped for 1 week and problems back)
I just want to enjoy this 911 for the first time before my finance is fully paid...
Please help guys before I do this to it...
Matt
Problem..
Car fires up on cold start - Great Smile
Warm start say I drive for 10 mins park up and then restart its struggling like mad to startup, so bloody embarrassing pulling up in a flash car that sounds like a coughing dog when starting up.. wrrr wrror worrr worrr worr then starts and sometimes I have to turn car off then try again in 5 mins
These are the actions I have had done in order to get this fixed and failed.
1. Part number 997-607-019-03 ("alternator/starter harness", "alternator/starter cable loom")
All the below done by a indy
2. Battery Earth Cables and 996 607 030 00 ground strap
3. New Battery
4. Coil packs
5. New Starter Motor 2 months ago (helped for 1 week and problems back)
I just want to enjoy this 911 for the first time before my finance is fully paid...
Please help guys before I do this to it...
Matt
Last edited by mattblack; 03-03-2015 at 09:53 AM.
03-03-2015, 09:02 AM
#3
Rennlist Member
sorry you had to be the one but i was sort of waiting until someone chimed in with this - when all the "accepted" fixes don't work. interestingly enough, this kind of Murphy's Law usually happens to me.
by "earth cables" you mean the ones running from batt to trans?
maybe it's a bad ground somewhere?
by "earth cables" you mean the ones running from batt to trans?
maybe it's a bad ground somewhere?
03-03-2015, 09:05 AM
#4
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Are you doing your own work? Maybe time to find a trusted indy shop. Should take less than 4 years to be properly fixed.
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03-03-2015, 09:59 AM
#8
Intermediate
Thread Starter
sorry you had to be the one but i was sort of waiting until someone chimed in with this - when all the "accepted" fixes don't work. interestingly enough, this kind of Murphy's Law usually happens to me.
by "earth cables" you mean the ones running from batt to trans?
maybe it's a bad ground somewhere?
by "earth cables" you mean the ones running from batt to trans?
maybe it's a bad ground somewhere?
03-03-2015, 10:01 AM
#9
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03-03-2015, 10:17 AM
#10
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Thread Starter
03-03-2015, 11:26 AM
#13
Rennlist Member
Sounds similar to what happened in my pickup truck (started great cold and hot, but not warm), and here is how it can be related the the fuel pump and how to easily test it (or have it tested):
The vehicle's computer assumes that the fuel system will maintain a certain amount of pressure for a period of time. If it leaks down quickly when you turn the car off then you have a leak down somewhere in the system involving the fuel rail. All cars have a fitting that allows you to hook up and read the pressure in the rail. I bought a fuel pressure gauge for around $15 at Harbor Freight that hooked up to my truck's fuel rail test fitting (a schrader valve that looks just like the one on a bicycle) and sure enough, as soon as I would turn off the truck the pressure would drop down to zero within 20 seconds. It should hold pressure for at least 45 minutes or more.
Leaving the test gauge hooked up, you could see that when I attempted to start the truck there was no fuel pressure. The ECU assumed that due to the limited time the truck had been off, there was still pressure in the rail and it wouldn't turn on the pump. I don't know about our cars, but in the truck, if I turned the key off-and-on several times (without attempting to engage the starter), the ECU would decide to turn on the fuel pump (I could see the pressure ramp up on the gauge) and then the engine would start promptly.
Now that the fuel pressure problem was confirmed, it was one of four things.
1) An outright fuel leak - Easy to rule this one out if the car hasn't burst into flames and doesn't have a strong gasoline smell.
2) The pressure regular valve had gone bad and doesn't hold pressure. For the truck, this was the cheapest/easiest thing to replace. I replaced it but it didn't help. There are ways to test this but I didn't bother. The truck had 160k miles so it is time to replace some things anyway.
3) The fuel injectors were next to be replaced. Unfortunately even rebuilt ones weren't cheap... but I thought they were old enough so it was time anyway. But that didn't fix it either.
4) Finally, that left the fuel pump. Again relatively cheap on a pickup and due to miles and the desire to run the truck as long as I can, I went ahead a replaced it. Fixed!!!!!
It turns out that the fuel pump has a check valve to prevent back flow into the tank when the pump isn't running. That had gone bad so as soon as I turned off power the fuel would leak back down the line through the pump and into the tank. 7391420's suggestion to consider the fuel pump is solid.
The good news is that it is easy to test (or have tested) the pressure in the fuel rail. If the pressure drops to zero within seconds or even minutes then this is likely your problem. Then it is a matter of figuring out which of the above it is. The rule I used in this case is if there is no good or easy way to test which of the things it is, start with the cheapest/easiest thing to fix and/or the thing that is most likely to need updating first. I went ahead and replace plugs and coils while I had the fuel rail out the way, along with the oxygen sensors, and now the truck, at 164,000 miles purrs like a kitten. Hopefully now the truck will be solid for another 100k miles.
The vehicle's computer assumes that the fuel system will maintain a certain amount of pressure for a period of time. If it leaks down quickly when you turn the car off then you have a leak down somewhere in the system involving the fuel rail. All cars have a fitting that allows you to hook up and read the pressure in the rail. I bought a fuel pressure gauge for around $15 at Harbor Freight that hooked up to my truck's fuel rail test fitting (a schrader valve that looks just like the one on a bicycle) and sure enough, as soon as I would turn off the truck the pressure would drop down to zero within 20 seconds. It should hold pressure for at least 45 minutes or more.
Leaving the test gauge hooked up, you could see that when I attempted to start the truck there was no fuel pressure. The ECU assumed that due to the limited time the truck had been off, there was still pressure in the rail and it wouldn't turn on the pump. I don't know about our cars, but in the truck, if I turned the key off-and-on several times (without attempting to engage the starter), the ECU would decide to turn on the fuel pump (I could see the pressure ramp up on the gauge) and then the engine would start promptly.
Now that the fuel pressure problem was confirmed, it was one of four things.
1) An outright fuel leak - Easy to rule this one out if the car hasn't burst into flames and doesn't have a strong gasoline smell.
2) The pressure regular valve had gone bad and doesn't hold pressure. For the truck, this was the cheapest/easiest thing to replace. I replaced it but it didn't help. There are ways to test this but I didn't bother. The truck had 160k miles so it is time to replace some things anyway.
3) The fuel injectors were next to be replaced. Unfortunately even rebuilt ones weren't cheap... but I thought they were old enough so it was time anyway. But that didn't fix it either.
4) Finally, that left the fuel pump. Again relatively cheap on a pickup and due to miles and the desire to run the truck as long as I can, I went ahead a replaced it. Fixed!!!!!
It turns out that the fuel pump has a check valve to prevent back flow into the tank when the pump isn't running. That had gone bad so as soon as I turned off power the fuel would leak back down the line through the pump and into the tank. 7391420's suggestion to consider the fuel pump is solid.
The good news is that it is easy to test (or have tested) the pressure in the fuel rail. If the pressure drops to zero within seconds or even minutes then this is likely your problem. Then it is a matter of figuring out which of the above it is. The rule I used in this case is if there is no good or easy way to test which of the things it is, start with the cheapest/easiest thing to fix and/or the thing that is most likely to need updating first. I went ahead and replace plugs and coils while I had the fuel rail out the way, along with the oxygen sensors, and now the truck, at 164,000 miles purrs like a kitten. Hopefully now the truck will be solid for another 100k miles.
03-03-2015, 11:41 AM
#14
Rennlist Member
I went looking briefly online to see if I could find where the test fitting is on your car and I think it might by under the gold-colored cap seen just left of center on the fuel rail in this Pelican article's figure 6: http://www.pelicanparts.com/techarti...eplacement.htm. It is normally placed in a location accessible for testing purposes.
Be careful when removing as it may still have fuel under pressure and may spit out gasoline. If you aren't certain about what you are doing in this case it may be best left to a professional to test rather than risk a gasoline-related accident. In any case, please consult with a professional as to what fittings for a test gauge and where it wouldattach. You don't want to risk your testing spewing gas under pressure. In my case I had my son stand by to watch the fitting with an extinguisher in hand as I initially started the truck just for an abundance of caution.
Be careful when removing as it may still have fuel under pressure and may spit out gasoline. If you aren't certain about what you are doing in this case it may be best left to a professional to test rather than risk a gasoline-related accident. In any case, please consult with a professional as to what fittings for a test gauge and where it wouldattach. You don't want to risk your testing spewing gas under pressure. In my case I had my son stand by to watch the fitting with an extinguisher in hand as I initially started the truck just for an abundance of caution.
03-03-2015, 11:49 AM
#15
Rennlist Member
Nice video! LOL
While that was highly entertaining, I think a video of the actual cold start and warm start attempt would help with identifying the problem.
I just got an 08 C4s, and have stalled it a couple of times while driving (6speed car). It is weird, because it seems very easy to stall after temporarily stopping on any kind of incline, after the car has been running for awhile and warmed up. Then, when I try and start the car, the engine is VERY slow to turn over. It almost sounds like it has a dead battery. Of course, in heavy traffic with cars waiting behind me, this is just a bit stressful. I think people like to laugh (or honk) even harder at the guy in the stalled Porsche, compared to the average car.
It is as if the car is weak at idle, once it gets warmed up. Sounds similar to yours, so Ill try and replicate it on video when I get the time.
I was going to replace the battery, but it actually starts the car fine, even in the -20 degree celcius weather that we had around here this winter. Seeing your similar problem, I am wondering if my battery has nothing to do with it.
While that was highly entertaining, I think a video of the actual cold start and warm start attempt would help with identifying the problem.
I just got an 08 C4s, and have stalled it a couple of times while driving (6speed car). It is weird, because it seems very easy to stall after temporarily stopping on any kind of incline, after the car has been running for awhile and warmed up. Then, when I try and start the car, the engine is VERY slow to turn over. It almost sounds like it has a dead battery. Of course, in heavy traffic with cars waiting behind me, this is just a bit stressful. I think people like to laugh (or honk) even harder at the guy in the stalled Porsche, compared to the average car.
It is as if the car is weak at idle, once it gets warmed up. Sounds similar to yours, so Ill try and replicate it on video when I get the time.
I was going to replace the battery, but it actually starts the car fine, even in the -20 degree celcius weather that we had around here this winter. Seeing your similar problem, I am wondering if my battery has nothing to do with it.