Low Power Upon Starting Up

thompsondrew · 09-08-2012, 08:54 PM

I have a 2005 Boxster S (46,000 miles) which has a worrisome problem. Every once in a while, when accelerating away from a stop the car seems to have reduced power. If I press the accelerator down more, not much more power. If I then put it pedal to the metal the cars gets up and scoots. This worries me as I am afraid to pull out unless I have adequate time in case I need to react to this.

thompsondrew · 09-09-2012, 09:34 AM

Forgot to mention that I have Tiptronic. Whether I accelerate normally or with reduced power, the red indicator light shows 2nd gear which I think is normal.

mikefocke · 09-09-2012, 01:38 PM

The start in second is a fuel saving design but you can always shift manually via the buttons on the steering wheel down to 1st if you want the most acceleration in the first 50 feet. You do this at the price of an extra shift but the first gear is what we used to call a "stump puller" so it gives you greater torque to the rear wheels on startup. I probably did this only several times a year as any time I needed it I was probably better off just waiting till I had more room to start out normally in second.

thompsondrew · 09-09-2012, 05:40 PM

Mike,
I understand the ability to shift into 1st, however my problem is that the car always starts in 2nd, as it should, but once in a while it starts in second but with significantly reduced power. It's like starting in too high a gear, which I know I'm not.

mikefocke · 09-10-2012, 06:09 AM

Is there anything about the type of stop you did before you try to accelerate that would give a clue? Hill? Abruptness or length of stop? Warmth of day or engine? Any start to accelerate, brake, decide to start again sequence? Looking for a pattern that would help the diagnosis.

Only maybe twice in 6-7 years did my Tip ever get confused and it was always in an abnormal situation where I made two many decisions in a short time one involving hard braking and I ended up needing to shift out of what I was stuck in. And never felt the engine wasn't putting out, only the trans logic got confused maybe switching between the patterns it has as well as the gearing got it.

thompsondrew · 09-10-2012, 11:06 AM

I have not been able to see a trend. Originally I thought that I was trying to accelerate away too soon after stopping and the transmission was confused. Not so. It happens even if stopped for a while. It happens about every 15-20 accelerations. Just often enough to make me leery to pull out in traffic unless I have plenty of room. Not fun. No CEL codes.

thompsondrew · 10-27-2012, 09:21 PM

Mike,
I have spent the last several weeks trying to find a trend for my problem. Most of the time it occurs within the first 3-4 starts from a corner after starting the engine, e.g. engine cool. It has also happened several times after restarting a hot engine.

mikefocke · 10-28-2012, 11:24 AM

At this point, the only suggestion I have is to get the code reader on it and see if there are any clues.

thompsondrew · 12-03-2012, 06:36 PM

The car is now at the dealer. I asked them to check transmission codes. No engine codes as of today.
A new similar problem has cropped up. With the engine hot, I stopped off at a store for about 20 minutes. I came back, started the car and no power, just kept idling when the accelerator was pressed. Power eventually came back. Then drove to a second store and it repeated itself. No problem since.
Could the MAF need cleaning? Any other suggestions?

mikefocke · 12-05-2012, 06:22 AM

Sounds engine control related and I wonder at the link between the accelerator pedal and the ECU...its as if there is a spot in the pedal travel that isn't registering an "I wanna go faster" signal and when you mash it it gets by that spot. It's electronic and not mechanical by your model year I think. Don't have any diagnosis manuals for the 987 so can't suggest much beyond asking the dealer if he has any way of checking that signal path. That he didn't see any codes would seem to me to say there is no code throwing diagnostic circuit but there may be some other tool or probe point the mechanic can use. Though if intermittent it will be elusive.

thompsondrew · 12-05-2012, 09:30 AM

As luck would have it, the technician, working on my car, has experienced the same problem on one of the dealers 911's. When I came in to pick up the car he asked me if I drive with two feet, which I do (Tip). He said he has noticed the power loss if the accelerator is pressed before the brake pedal is released. Sounds like the right solution to me. I haven't tried to intentionally create it but I will.
The dealer said that he has never seen an MAF problem without codes.
I knew this wouldn't get solve if I didn't find someone who had experienced it.

mikefocke · 12-06-2012, 07:11 AM

That explanation sounds odd. Think of sitting on a hill. You press the accelerator before you release the brake and you generally do it with two feet in a TIP. And I never experienced any power loss there.

thompsondrew · 12-06-2012, 08:37 AM

Yes, it does sound odd but I am grasping at anything right now. I'll try and recreate it and let you know.