jdk1

As the weather has gotten warmer in Chicago I have started having trouble starting my '99 C4 (76k miles) after the engine is fully warmed up. It isn't the battery or starter. It will just keep turning over like there is an absence of fuel. Eventually it will start after enough tries, but even then the idle is all over the place and it will frequently die. After driving the car a very short distance it is fine.

There are no codes to report. Any ideas? MAF? Fuel filter? I ran Techron though the tank last week and it didn't seem to make a difference.

Thanks in advance for the help!

Jeff

99firehawk

put a fuel pressure guage on it see what it reads

Porsche_Smile

when was the last time it had a tune up?

1999Porsche911

Have you checked the MAF? Cleaned it? Idle is effected by a dirty MAF. Is it a 99 C2? If so, remove and clean the idle control valve. Do you have a scanner?

jdk1

Thank you very much for the replies.

I have to admit that I'm past due for plugs. They haven't been changed since 30k.

I have cleaned the MAF a few times along with the throttle body. It is a C4 so I don't believe that I have an idle control valve.

I do have the durametric tool if any of those readings would come in handy.

Brad - I don't own a fuel pressure tester but could easily run over to Sears and pick one up. At what point in the fuel system would you suggest testing? What kind of reading am I looking for?

99firehawk

ON A C4 the test point is at the fuel filter in the engine compartment
i would try autozone or similar see if you can rent one its cheaper then buying one and you may never need it again.
I notice that you said no faults, what are you using to check for faults ?

1999Porsche911

Hook up your scanner and, on a warm engine, take the following readiings at idle, no A/C:

MAF
STFT (both banks)
LTFT ( both banks)
Look at the before cat O2 sensors and make sure they are moving regularly between high and low
2 after cat O2 sensors
Calculated load
Timing