bfly

My '04 CTT has a hesitation/jerkyness after it sits over night. It happens at part throttle and only for the first 1/4 mile. I replaced the plugs and coil packs recently so I am guessing that is not the issue. I also checked the voltage at the jumper posts and cigarette lighter one morning and they both look fine (I figure the jumper posts are the starting battery and the cigarette lighter is the other one).

Any ideas? Throttle position sensor?

a17322a

I noticed the same thing in my cayenne S when cold, the transmission goes down to 1st gear and it makes acceleration jerky and very sensitvey to the throttle. Normally the transmission is set to start on 2nd, which is why you only feel it for a 1/4 mile after the transmission warms up it doens't downshift all the way to first.

ltc

TCU update and/or valve body assembly....

mudman2

This is the cold start procedure. It holds 1 for about 1/4 mile to warm up the cats for emissions reasons after that its back to start in 2

Its normal.

bfly

Thanks for the replies but it is not an issue with the car starting out in 1st. The hesitation happens in 2nd as well. I am pretty sure it is an engine issue not a transmission one.

mudman2

If you are saying that the car goes into 2 for and then after the 1/4 mile its ok then my response is applicable if its way after the first 1/4 mile then LTC "TCU update and/or valve body assembly.... " is applicable

bfly

When cold, in second gear, I have had times it felt like a bucking bronco. In first gear, barley moving with VERY light power, you can feel the engine lose all power for a brief second. If it were the transmission you would see the tach jump when this loss of 'power' happened.

mudman2

The linkage betweent he EGAS system and the Transmission Control Unit can cause all sorts of issues

It could well be a reset of EGAS and a reflash of the TCU will cure the problem. Does not sound like engine to me apart from the throttle and the transmission having an argument

Hesitation is the middle name of 03/04/05 model years = Porsche Hesitation Cayenne

If you do a search you will find volumes

yeldogt

I know that when I had the problem I figured I had the EGas problem -- then I was told that it did not affect the 06's. When i had this problem they really did not have a solution -- they just told everyone to wait until the car warmed up.

Mine ended up being a defective second set of coils - I had not expected they would have failed.


I still don't particularly like the way the car first starts out when it is cold. Especially when an occasional driver takes it - everybody dislikes the way it operates. Very sensitive throttle when in 1st gear

Fuzzi

Hi there. I reviewed this post to see if I could find the solution to the problem that I am having, which is similar to last post - when it is cold in the morning, my car lurches. I have an automatic transmission. Also in the morning when I stop at an incline, even though the gear is in "D" - Drive, the car has started to roll backward. I almost had heart failure. I have to put the car in Park and then in Drive to avoid rolling back.
Does anyone know what the problem could be and a possible fix?
Thanks Fuzzi

Fuzzi

Meant hesitation not desitation!

mudman2

Well number one is that your transmission is not hill-holding so I think your valve body has problems, anything else happening when the gears change like clunks and bumps ? It could also be the transmission control unit which could also explain the lurching.

Can you get a read of error codes ?

rting

2004 Porsche Cayenne S - about 45,000km on the Odometer.

I have the SAME VIBRATION PROBLEM! Replaced with a new set of spark plugs a few weeks ago and the vibration / lurching problem went away BUT came back today.

Symptoms:
1. Begins with a cold start - or cold start then short trip (say under 15min driving) - then restart the car after engine turned off for about 45 minutes to 1 hour.
2. Lower engine idling revs with vibration.
3. At city speeds the vibration would get worst as driving speed increases. Take it onto the highway it will vibrate more.
4. "Emission Control Warning Light (Check Engine)" warning light would come on.
5. Cannot repeat the problem consistently.
6. Replaced all 8 spark plugs and now the problem came back.
7. Since day 1 I own this car, I have the "lurching from cold start" issue but never resolved or mentioned.
8. Switching off and then switching on the PSM seems result in the PSM stuck electronically at off resulting in an increase in the gear change rev speed regardless if the PSM is off or on.

I have a trusted mechanic so would like to help him narrow down the issues.

So I should ask him to look at (already a new set of NGK spark plugs):
1. EGAS System (what is it??)
2. Transmission Control Unit / TCU
3. Other possibilities?? It seems that DURING the process of replacing the spark plugs the electrical system resets? Thus resetting both systems above.

HELP!!!!!!!!!!!!!!!!!!!!!!!

mudman2

OK first of all it sounds like your Indy is going to need a PIWIS since resetting the TCU for instance cannot be done any other way.

1 - EGAS is the proportional learning system which tries to match throttle response to your style of driving. In effect it can make the car feel like a dog when you want to drive aggressively sometimes. resetting it helps but it will always adapt to your driving style. You can help it by turning off PSM and driving like a loon for 30 minutes or so.

2 - The TCU on 04's were problematic and many were replaced. He can talk to it using PIWIS, he can reflash it also using PIWIS.

3 - Check all the coils for cracks

4 - Get a list of error codes

Changing the plugs does not reset anything but you might have damaged the coils when you took them off or even put them back in different places so a crack moved to a more sensitive location

Post error messages when you get them

JFR-

While not a response to the OP problem, to those regarding the 1st gear roll off when cold... just tap the Tiptronic +.

Cars should warm up before the revs get escalated. It even says something to this affect in the owners manual about no high revs when cold... then they program a 1st gear roll off!?

I baby the throttle and Tiptronic upshift my CS at ~2k rpm when it's cold.