ticking and groaning noise

superfans · 05-10-2005, 10:49 PM

Dear everyone,

Hi, I am a newbie to this board. I understand that many people from this board are experienced Porsche technicians/owners and hope that you will have the answers to my questions. Actually I am encountering some problem with my 996tt and am wondering if you guys can help me to find out what was wrong with my car.

Problems:

1. Ticking noise from the dashboard area (it seems that the noise will go away if I turn off the air con);
2. Groaning/Moaning noise from front of the car (I think the noise is from underneath my car);
3. When I start the car in the morning, everything seems fine at the begining. However, once I put the gear into D and step on the gas a little bit, the rpm of the engine will drop and the car wants to stall as if it does not have enough fuel.

I shall be grateful if you can let me have your views on the above. Thanks in advance.

Best regards.

AFJuvat · 05-14-2005, 08:36 AM

Welcome to the BBS.

Ticking noise under dashboard: Insulation pulling away from airbox and making contact with the blower fan.

Groaning noise: Could be several things unfortunately. When does it happen? When you turn the wheel? when driving?

Stalling: I'll bet it runs fine after the car warms up. You probably have a contaminated mass flow sensor.

AFJuvat

superfans · 05-14-2005, 06:31 PM

AFJuvat, thanks for your views.

1. Ticking/clicking noise from the dashboard area - It is some kind of electrical noise. It seems that the noise will go away if I turn off the air con. This intermittent clicking noise is not continuous. It usually will appear only after I¡¦ve warmed up the car. This noise is separate from the groaning/moaning noise referred to in item 2 below.

2. Groaning/Moaning noise - This groaning/moaning noise is from the gas filling area at right front. It sounds like ¡§Won ¡K. Won ¡K. Won ¡K. Won ¡K.¡¨ and will not stop. The noise will not stop even when the car is parked/stationary (with engine on). Do you think this could be the sound of a bad fuel pump? Do you think a faulty fuel pump could cause the clicking noise mentioned above (eg from a bad fuel pump relay)? Moreover, I can fill the gas filling area of the car is particularly hot. Is this normal? Could that be because of a bad cooling fan (I am not sure if there is any cooling fan at the front of the car)?

3. Stalling problem - Your are right on. The car runs fine when it is warmed up. If I drive the car at around 50 mph or 80 kmph before the engine is warmed up and slam on the brakes, then the rpm of the engine will drop quickly to below 500 and the engine would almost stall as if it does not have enough fuel. Besides the possibility of a contaminated mass flow sensor, do you think a bad fuel pump or a bad oxygen sensor would possibly
cause the stalling? By the way, the car was kept in the garage and not driven for about three months.

AFJuvat · 05-15-2005, 07:16 PM

1. Ticking and clicking: I would still bet it is related to your blower fan. Your relays are above your fuse panel in the drivers side footwell. Additionally, there is a second relay pack under the sound padding where the rear seat would be on a non-turbo.

2. Groaning\moaning noise. It can't be your fuel pump. Your fuel pump is located right in the center of your luggage compartment - that black dome in the top center. Fuel pump problems will cause all sorts of drivability issues regardless of engine temperature. There are fans at the very front of the car on either side for the radiators\oil cooler\AC condensor. However, by your description, it doesn't sound like that would be the problem. I wonder if it is a faulty drive axle for the front differental or a bad bearing somewhere on that side. Unfortunately, you will probably need professional assistance with this problem.

3. Rough idle on cold start: Still most likely your mass flow sensor. The sensor, by virtue of its location, is vulnerable to dirt contamination from the air filter (ironic, isn't it) The Mass flow sensor is the oval shaped plug located on the pipe leading from the airbox to the splitter pipe (see attached photo - the MAF is part #3) You can remove teh MAF and see if the sensor plate is dirty. You can try to clean it with alcohol and a cotton swab. This may or may not correct the problem. In roughly 50% of the cases, it has worked, and in the other 50%, I had to replace the sensor.

AFJuvat

AFJuvat · 05-15-2005, 07:17 PM

Forgot to post the image.

AFJuvat

superfans · 05-16-2005, 12:47 AM

AFJuvat, thanks for the help. I'll probably take the car to the dealer for them to have a look.

By the way, one more question - will a faulty front axle for the front differential or bad bearings make a continuous groaning/moaning noise around the right front wheel even when the car is stationary?

MMBRAZIL · MMBRAZIL's Garage

The ticking/clicking could be an air conditioning filter miss placed. I changed my filters a couple of months ago, and one of them I did not place it correcty, and it made that type of noise.
You can see an article here on how to reach your filters ( 2 per car ).

superfans · 08:24 PM

Two more questions for you -

1. Will a faulty front axle for the front differential or bad bearings make a continuous groaning/moaning noise around the right front wheel even when the car is stationary?

2. If the car was not driven for approx. 3 months and the battery was almost dead, do you think moisture can build up inside the fuel tank which may cause the idle/stalling problem?

superfans · 05-22-2005, 01:22 AM

Hi, everyone:

Some additional info. - I've tried starting the engine this morning and I've heard a pretty loud "clunking noise" from the engine and noticed some white/grey color smoke coming from the exhaust pipes and the smell of gasoline. Could there be some sort of leakage? Do you think that this could be the cause of the stalling problem that I've been encountering lately?

AFJuvat · 05-22-2005, 03:03 PM

Take the car into a dealership. A little bluish white smoke on startup is normal. However, if it continues for a significant period of time, it could be indicative of more serious engine problems.

It still sounds like the maoning noise if coming from the front drivetrain.

AFJuvat

superfans · 05-23-2005, 05:06 AM

AFJuvat,

Sorry to bother you. I have one more question. Problems seem to keep on coming. Today when I start the car, there is a loud plastic rubbing noise from the right side of the engine area (could this be from a bad alternator? belt tensioner? bad pump of some sort?)? Any idea as to what that is? It goes away after driving the car for a couple of mins? In fact, I am a little disappointed with Porsche reliability.

AFJuvat · 05-23-2005, 05:37 AM

Plastic rubbing noise.... well, if it is coming from the right (passenger) side of the car, it can't be the alternator - that is on the drivers side. Al of your rollers and tensioners are centrally located on the engine. are all of your hoses and the like in their proper positions? How many miles are on the car?

AFJuvat

superfans · 06:23 PM

AFJuvat,

I've checked for the rubbing noise again. It is actually from the middle of the engine area. It sounds like "Poo...Poo...Poo...". It happens only at start-up and will only last for a couple of seconds. In the circumstances, could this be the engine belt noise? My car has around 7500 miles on it.

As to the stalling of the engine when braking, what actually happened is that when braking to stop (during the first 5 mins after start-up), the idle will drop to where the car is about to stall, then bounce up and around until it finds the idle. Someone suspects that it may be because of a vacuum leak in the brake booster vacuum line. Do you think a leak in the brake booster vacuum line can cause the rpm to run low and thus stalling the engine? When the car is warmed up, the stalling problem will go away. Do you think it is possible that the seals expand from the heat and therefore reducing the leak? Will a vacuum leak in the brake booster screw up the way the engine runs? However, I do not think there is any problem with braking.

I suspect that the A/C may be the culprit. Acutally if I don't turn on the A/C, headlights and radio (with the battery level slightly below 14), then the rpm will only drops a little (still above 500) and stalling will not happen even when braking. Only when I have all the electrical items turned on (especially the A/C - with the battery level drops to slightly above 12), then the problem will appear. I am wondering whether the stalling has anything to do with a possible faulty A/C fan (which draws a lot of electricity from the battery) coz the ticking noise from the instrument panel area seems to be from a faulty A/C fan. Yesterday, when I have the A/C turned on, the ticking noise appeared after the car is warmed up. Once I turned off the A/C, the ticking noise also disappeared. I've tried a couple times (ie turn on and off the A/C) and the same has happened so I guess the ticking noise must be A/C related. Furthermore, I also heard a loud squeaking noise from behind the instrument panel when I turned on the A/C. Any views?

A question about the battery level. I just have my battery changed. When the radio, headlights and A/C are off, the battery level will be around 14. But when the radio, headlights and A/C are on, the battery level will drop to slightly above 12. Do you think this is normal? Will a leaking brake booster line or faulty A/C fan draws a lot of electricity from battery than usual?

superfans · 05-25-2005, 08:10 PM

Quote:

Originally posted by superfans
AFJuvat,

I've checked for the rubbing noise again. It is actually from the middle of the engine area. It sounds like "Poo...Poo...Poo...". It happens only at start-up and will only last for a couple of seconds. In the circumstances, could this be the engine belt noise? My car has around 7500 miles on it.

As to the stalling of the engine when braking, what actually happened is that when braking to stop (during the first 5 mins after start-up), the idle will drop to where the car is about to stall, then bounce up and around until it finds the idle. Someone suspects that it may be because of a vacuum leak in the brake booster vacuum line. Do you think a leak in the brake booster vacuum line can cause the rpm to run low and thus stalling the engine? When the car is warmed up, the stalling problem will go away. Do you think it is possible that the seals expand from the heat and therefore reducing the leak? Will a vacuum leak in the brake booster screw up the way the engine runs? However, I do not think there is any problem with braking.

I suspect that the A/C may be the culprit. Acutally if I don't turn on the A/C, headlights and radio (with the battery level slightly below 14), then the rpm will only drops a little (still above 500) and stalling will not happen even when braking. Only when I have all the electrical items turned on (especially the A/C - with the battery level drops to slightly above 12), then the problem will appear. I am wondering whether the stalling has anything to do with a possible faulty A/C fan (which draws a lot of electricity from the battery) coz the ticking noise from the instrument panel area seems to be from a faulty A/C fan. Yesterday, when I have the A/C turned on, the ticking noise appeared after the car is warmed up. Once I turned off the A/C, the ticking noise also disappeared. I've tried a couple times (ie turn on and off the A/C) and the same has happened so I guess the ticking noise must be A/C related. Furthermore, I also heard a loud squeaking noise from behind the instrument panel when I turned on the A/C. Any views?

A question about the battery level. I just have my battery changed. When the radio, headlights and A/C are off, the battery level will be around 14. But when the radio, headlights and A/C are on, the battery level will drop to slightly above 12. Do you think this is normal? Will a leaking brake booster line or faulty A/C fan draws a lot of electricity from battery than usual?

In addition to the above, there is always a loud plastic rubbing noise from around the centre of the engine when I start the car. It will last for about 5-10 seconds. Do you think this may be the sound of a faulty alternator or bad alternator belt?

If the battery is running low, then will it affect the engine rpm? Is it possible that when applying the brakes, more electricity will be drawn from the battery to operate the vacuum pump, brake booster, etc. which sort of causing the engine to cut-off?

MMBRAZIL · MMBRAZIL's Garage

This sounds more of an faulty alternater or a voltage regulator.

superfans · 06:02 PM

I have a feeling that there may be a leaking vacuum brake booster plus a faulty alternator (not to mention that there may be a faulty A/C fan) which cause the rpm surge when the engine is cold. Once the engine is warmed up, the leaking may not be as bad and thus draw less current from the battery which therefore allow the engine to run a bit smoother even when applying the brakes. Any views?

superfans · 05-30-2005, 06:03 PM

Yesterday, I placed my foot on the brake pedal when starting the engine but the brake pedal did not depress or drop. Does it mean that the brake booster is not functioning properly?

AFJuvat · 05-30-2005, 06:12 PM

It could indicate a vacuum leak on the brake booster or a faulty check valve at the booster. A good vacuum leak can cause drivability issues.

Have your alternator checked. The alternator seems to be an issue on these cars.

AFJuvat

superfans · 06-01-2005, 06:39 PM

AFJuvat,

Thanks again for the tips. As a matter of fact, I do feel the braking time/distance is a bit longer than usual especially when I push the car hard.