2002 Boxsters S will not start when cold

jasund991 · 12-31-2006, 06:45 PM

I have a 02 Boxsters S that all of the sudden will not start when cold. I have had it towed to the dealer twice and been told it needs a new fuel pump. I get it home, it sits over night and won't start in the morning.

It's sooooo frustrating!

Does anyone have any ideas? Could this be an emmisions issue? Is there a cold air sensor or something that someone is missing?

Can anyone help????

Tool Pants · 12-31-2006, 08:17 PM

So, has the fuel pump been replaced?

AFJuvat · 01-01-2007, 05:09 AM

A bad MAF will make the car idle like trash when the engine is cold.

If the fuel pump was replaced and it did not fix the problem you can go after the dealer.

AFJ

jasund991 · 01-01-2007, 08:29 PM

The fuel pump has been replaced twice!

Is the MAF (Mass Air Flow sensor)? If they are screwing that up when they install the pump, could that prevent a cold air start?

The first time I took the car in, the guy I work with at Porsche North Scottsdale told me that later in the afternoon when he went out to bring the car in the bay after it had been sitting in the sun for several hours, it started right up. This was after the first fuel pump replacement. My theory is, that the car will start in warm air. Unfortunately, it hasn't been over 72 in Phoenix, so I can't get the car in the sun to warm it up to test my theory.

Let me give some more backgound.

This entire thing started when I noticed some stutterting in the engine power at high rpm. While cruising in 5th, I gave it gas to accelarate and the car stuttered. A couple of days later, I pushed the engine hard and it almost completely lost power at around 5500 rpm, although the engine rpm would still spin up. The problem quickly got worse with stutterting in lower gears and at lower rpm, but I was able to drive to the dealer. The dealer told me it was the fuel pump, which they replaced.

Next morning, cold in the garage, guess what, won't start.

Got it back the second time, fuel pump replaced again, left town for xmas and just got back and guess what, cold in the garage won't start.

The chances that two defective fuel pumps have been installed are so astronomically small. There has to be something else going on.

The car is going to be towed to the dealer again tomorow morning, for the the third time in three weeks, sweet.

I'll let you know what I find out.

So, what changes in the start squence when the car is started in cold air vs warm air?

I have read about about an emmisions pump that drives for about 30 seconds (that's the whine you hear when you first start the car). Could that have someting to do with it?

Believe me, I plan to go after the dealer. This is rediculous, very frustrating and time consuming.

AFJuvat · 01-02-2007, 04:29 AM

It sounds like a bad MAF - mass flow sensor. It isn't located anywhere near the fuel pump - it is in the engine compartment, right after the air filter. MAF failures are much more common than fuel pump failures.

Clogged injectors could also cause this, but that is very rare.

The Secondary Air Pump has nothing to do with this.

AFJ

jasund991 · 01-02-2007, 06:40 AM

Thanks, I should know soon.

Although, the dealer told me that if it was an air sensor, wouldn't the check engine line come on? On the other hand, if the MAF is bad and will not let the car start in cold air, I suppose the check engine light couldn't turn on!

OldTee · 01-02-2007, 07:28 AM

Just talking, I don't know anything about
Boxster fuel systems, so feel free to yell BS.

In both my 911SC CIS and 928 LH fuel systems there is a cold start system, kinda. The LH temp II sensor on the 928 can cause this kind of indication and I forget if it is "will run when cold but won't start hot, or the other way around." It sounds to me that you are going lean, lean. so it won't start cold and runs out of fuel when running hard. Get a loaner computer for a day or two and try that. Otherwise look for temp sensors. Beware the dealership who swaps parts at your cost to trouble shoot.

AFJuvat · 01-02-2007, 05:50 PM

Quote:

Originally posted by jasund991
...Although, the dealer told me that if it was an air sensor, wouldn't the check engine line come on? On the other hand, if the MAF is bad and will not let the car start in cold air, I suppose the check engine light couldn't turn on!

The MAF is quirky. It only seems to send a check engine light when it totally fails (i.e. no signal at all) or if it is sending such a screwy signal that the car cannot idle - then it will throw "mixture out of adjustment" errors.

I was replacing them at a rate of about 3 a month there for a while. There is a newer style that is supposed to be more durable.

FWIW, the problem seems to be dirt contamination of the sensor - isn't a hot wire like the older ones so it has a harder time "burning off" contaminants.

Old Tee - you are sort of on the right track, but the temp sensor is integral with the MAF.

AFJ

jasund991 · 01-03-2007, 08:45 AM

Well, they put a third pump in. They told me they ran the numbers, sent everything to Germany. Everything is where it is supposed to be. The car did start this morning, yea!

Three times even. So I guess we'll see. They did tell me that about three years ago they had the same problem with another Boxster and it took 3 pumps. They say they haven't had a problem since. I figure that means it worked or they took it to another dealer.

Thanks for everyone's input.

By the way, they did remove the pump and bench test it and it was indeed dead, would not work.