SARGEPUG

First time since I've owned the car since 6/11, that she won't start! All is cranking fine, just won't turnover. I cranked it for about 10-15 sec a few times and it just won't start. Temp outside is in the 40s and I would say gas is a few months old. I can't remember if I put stabilizer in it or not. Strange thing is, is that she cranked right over a couple days ago, after sitting idle for past 2 months. I then drove her for a good 20 miles, with no issues. Car currently has 78k on the clock. Always garaged and never sees rain / snow. Any ideas!?

Steve Weiner-Rennsport Systems

Since I see several cars listed under your picture, may I ask which one you are having trouble with?

SARGEPUG

Hi Steve,
Since I posted in this forum, I assumed all would think the Targa, so that's the problem child here. I might have wasted my money, but I went out and bought octane boost, fuel inject cleaner, water remover, and starter fluid. All are on standby, if somebody has used them as a remedy for similiar problem and recommends I try it. Car has not been started in 2 days. However, like I originally said, she cranked right up after 2 months idle 2 days ago and drove and started back up while warm with no issue.

SARGEPUG

I did a search and found great troubleshooting items listed by theiceman!

I started troubleshooting with #1 and didn't hear a noise. However, I said screw it and let me try cranking her up again. She started up in a couple seconds as nomal!! Cranked 2 to 3 times and fired. I'm going to put in Octane boost, because the gas is at least 3mo old. What does the Dr. suggest now??

1. you should be hearing a whine coming from the back drivers side of the car with the ignition on .. that is good . that is your ignition module .. although it is not guarenteed to be good if you hear it , hearing it is definitely a good sign .. if you cant hear it you should get someone younger to listen .. if they cant hear it .. then you have a good place to start .

2. The Bosch Brazillian coils are known to be very weak ,, if you have one of those take it off and use it as a paper weight and replace it ..

3. You can take the cap off and see if the rotor is turning when you turn the key to start .. another good piece of info.

Fuel / Air

if the car is not starting does it always do it cold ? hot ? the accumulator is only used when the system is hot to maintain fuel pressure . if it doesnt start cold either thats not your problem so back to basics we go ..

1. with the ignition on take the air cover off and emove air filter .. stick your hand under and lift the throtle plate .. you should instantly hear the fuel pump run ( remember its at the front of the car ) it is very distinguishable tho . If it doesnt run there's your problem ,.. dont get fooled tho as it is an intermitent problem.

2. does the car have a pop off valve ? you would have seen it when you took the air filter out . if it does make sure the valve body itself is sealed well and and the flap is seated properly .. if this is letting air in . then no start for your Porsche.

3. is it the warm up regulator , cold start injector and are the air valves working ? sorry that's Porsche 102 ..

User 4221

Intermittent starting issues like this are often the DME relay failing.
The DME relay resides under the driver's seat next to the Motronic box. It controls the fuel pump and O2 sensor heater.

Without getting root-cause on what was not being provided for combustion, it is hard to guess.

I had a no-start issue recently and found the fuel pump had expired. In my troubleshooting I checked the following...... I'm lazy so I started with the easy stuff first.

1. With ignition in the run position, I felt the IAC valve and confirmed it was buzzing as it should be. This confirms the DME is sending the right signals.
2. With a spark gap, I checked that I was getting spark from the distributor

At this point, I knew I had spark (and air) just not fuel.

3. Checked power present at fuse 6 in the front trunk when cranking by using a cheap volt-meter
4. Raised front of car and confirmed power at the fuel pump when cranking..... Noticed fuel pump was not turning and found a replacement.


Hope this helps.

Shannon123

+1 on DME

Here's a troubleshooting checklist just in case.

Amber Gramps

Always, Always, Always have a spare DME relay in the glove box.

It happened to me and at first I panicked, then went hey, I got this handled. Swap took just minutes and fired at first tap.

Ed Hughes

If you haven't learned one of the cardinal rules of having a spare DME relay for a Carrera by now, I guess this is your watershed moment. It is often the primary culprit of a no-start issue, and is so easy to change, it is a quick diagnosis as to whether it is the problem.

SARGEPUG

Thanks all, I just ordered a DME relay from Pelican, once installed I will report back!

SARGEPUG

Another question, can a faulty DME relay, cause the car to stop running while I am driving?

User 4221

Yes. It powers the fuel pump.

If the car stopped running while driving and felt fuel-starved, the DME is the likely culprit.

theiceman

Sarge my starting tips are for an sc which has a completely different set of rules for starting. Sounds like you are on the right track tho

I dont think any of your chemicals are going to help
I think you have flakey dme relay, sensors, or fuel pump

SARGEPUG

Thanks, I figured it could, don't want to break down.

SARGEPUG

Thanks, realized it was for SC, but didn't realize would be a difference.

theiceman

yeah SCs dont have any of those fancy computer gimick things in them to fail .. i do hear they may be big one day tho