Engine stalled when running low speed and rough idle

[steveltx]

Hi all,

This is a 1999 Boxster. The car always starts with no problem. Driving high speed is OK.

The problem happened when driving low speed such as stopped at the stop sign, the engine then stopped.

After that it's very difficult to start again and I need to wait for a day and the car will start again with no problem.

I have replaced the crank position sensor and the problem still persists.

I am starting to suspect it's the fuel pump or fuel pump relay. But the car always starts with no problem which puzzles me.

Also there was no check engine light, no OPB code.

The next area I suspect is the throttle body. May be it's too dirty and needs to be cleaned.

Any suggestion is appreciated.

Steve

[Duram]

It could be the idle speed adjuster or the throttle position sensor. Both of these are located on the throttle body. Other things that come to mind are a vacuum leak. If you have access to a diagnostic tool that can read factory fault codes there may be an informational code that OBD2 tools will not see. It may also be useful to clear the faults (Even if none are stored) using a non-OBD2 system. As this will clear the idle adaptation values from the ECU and force the ECU to relearn the idle values. After clearing the codes let the car idle for 10 min to be sure it relearned values.

Since the problem appears it may be temperature related you may look at the IATS (Intake Air Temperature Sensor) actual value as well to see if it is a realistic value.

[JFP in PA]

Hi all,

This is a 1999 Boxster. The car always starts with no problem. Driving high speed is OK.

The problem happened when driving low speed such as stopped at the stop sign, the engine then stopped.

After that it's very difficult to start again and I need to wait for a day and the car will start again with no problem.

I have replaced the crank position sensor and the problem still persists.

I am starting to suspect it's the fuel pump or fuel pump relay. But the car always starts with no problem which puzzles me.

Also there was no check engine light, no OPB code.

The next area I suspect is the throttle body. May be it's too dirty and needs to be cleaned.

Any suggestion is appreciated.

Steve

If you suspect the fuel system (pump. etc.), it is a 5 min. test to attach a fuel pressure gauge to the test port and check it . A quick scan with either a PIWIS or Durametric system should also tell you about any pending codes that might be related, as well as test just about everything else you have mentioned............

[steveltx]

Hi,

It's been a few months since I posted the problem on this thread.

I have replaced the fuel pump, cleaned the idle control valve and the throttle body.

I have also replaced the MAF and even the crank position sensor.

The problem still remains. My mechanic tried to help out but he couldn't find the problem.

I am running out of idea and need to stop replacing parts. It's expensive.

Does anyone have the idea that what I should check next? Thanks so much.

Steve

[logray]

What is the condition of the electrical system.

Main leads, generator, battery, starter.

I've seen under-performing electrical cause this issue before.

Also I would focus on fixing rough idle. Could be bad variocam, bad intake leak, fuel delivery issue.

Are there any codes?

Edited April 4, 2013 by logray

[steveltx]

Hi,

There was no code at all. The battery is very new. I think the electrical condition is good.

Alternator is good.

Is it possible that fuel injection was causing the problem?

Also is there any better way to check the vacuum leak?

Thanks.

Steve

[JFP in PA]

Vacuum leaks are often a pain to locate on these cars as there are so many places, some nowhere near the engine, where they can occur. Often, a test with a smoke machine is the only real option.

[steveltx]

Hi,

I am suspecting the cracked oil filler tube. AOS was also replaced recently.

I searched the internet a little bit. Many people had broken oil filler tube and

was having the rough idle problem especially for older Boxster.

They also said that if you had a bad AOS earlier, the tube is very likely broken.

Anybody knows how how to hard it is to replace the cracked oil filler tube?

Thanks.

Steve

[JFP in PA]

Hi,

I am suspecting the cracked oil filler tube. AOS was also replaced recently.

I searched the internet a little bit. Many people had broken oil filler tube and

was having the rough idle problem especially for older Boxster.

They also said that if you had a bad AOS earlier, the tube is very likely broken.

Anybody knows how how to hard it is to replace the cracked oil filler tube?

Thanks.

Steve

It is a bit "fiddly' and time consuming, but not overly hard; DIY discussion here: http://www.renntech.org/forums/index.php/topic/30329-oil-fill-tube-q/?&p=160714&hl=%22tube%22&fromsearch=1#entry160714