mgordon18

I'm still trying to pinpoint the reason my car is slow to crank when warm - to the point of sometimes failing to start at all until it cools down again.

I've brought it to the dealer and they could not reproduce the problem. It slow cranked once, but never truly failed, so they say there's nothing they can do.

In discussing the issue, I mentioned that both times it truly failed were after filling up at a gas station. Now the service rep wants to have the evap system checked to see if something in there might be causing the problem.

Is there any possible problem with an evap system that could cause a car to slow crank and not start? Sounds pretty far fetched to me, but I'll be the first to admit I don't know what I'm talking about!

Thanks in advance...

Macster

Slow crank does not read like an evap system problem, but a power supply problem.

Weak battery maybe due to an intermittently marginal alternator or battery/alternator cabling/ground problems.

Carrera997re

The alt cable IMO

Ptech1

It is possible. But there would more than likely be a purge valve fault due to a sticking condition, more common on Cayenne's after refueling. As most will tell you, more than likely an amperage draw problem due to starter/alternator cable and/or starter. Did the dealer bother to perform a draw test?

TommyV44

I have a great Porsche tech at my dealer that is a master at problems......I love this guy!

If you want PM me and I'll put you in touch with him/them.

Tom

kosmo

Cable?

Spiffyjiff

alt cable.

joelpirela

This is the test:

Drive the car around for a while. then stop the car and after 3 minutes start again. (do not refuel)
If the car has a slow crank, it is the Alternator/starter cable.

Now, drive the car for a while. Stop and put gas. Try to start.
If the car has a slow crank there (but not when you stop and go without refueling) is the evap purge valve on the left side of the TB/intake of your engine.

awrryan

There is a cable that should be replaced. I thought there was a TSB, but my mechanic heard about this. A cable that connects the batter to somewhere.

PhilD

Yup, I had my battery cables replaced by the dealer. The vehicle was out of warranty, but they did it as a "courtesy replacement" at no charge. The symptom was hard to start when warm, and the dealer seemed to know exactly what to do.

mgordon18

PM Sent - thanks Tom!

- M

mgordon18

I'm aware of the TSB and the alternator/starter cable issue. I brought the car to the dealership a few months ago with that specific solution in mind and they verified (in theory) that the cable is fine, or at least that the contact points have the proper voltage. That's what they told me. I'm not sure I believe they tested it correctly, but I don't know enough about the technical specifics to tell them they did it wrong...

I also brought it to my indy's attention. He also tells me the battery is "low, but fine," and that the voltages are within spec.

Meanwhile, the hard start problem still exists for me. So I'll try just about anything to get someone to figure this out before my CPO runs out in March.

Bijan

I would try to eliminate battery/cable issues first:
Measure battery voltage after being parked for a while, for example the next day after driving, without starting the engine. The voltage should be above 12.3 volts. This is an indication of battery condition.
Measure the voltage after starting the engine, it should be above 13.5 maybe 14 volts. This is an indication of alternator or cable issues.
Repeat above with warmed up engine, the readings should not vary by much.

CamsPorsche

Test the battery in isolation first.

Test the voltage of the starter second.

Test the alt cable to see if its losing power output third...

then test ignition switch last.

I've just had the same exact symptoms as you and replaced both the battery (it was getting old anyway) and the alternator cable. My car runs and starts like a dream now!

fskof

Per Porsche's technical bulletin:

Issue: Battery discharged and/or will not charge properly. Voltage drop due to alternator-starter-battery harness damage at starter terminal. This issue is often mis-diagnosed as a bad battery, bad alternator, or bad starter, and these parts are often replaced in multiple repair attempts before the harness is determined to be the cause of the issue.

Before ordering or replacing other parts, have the car professionally inspected. Check the voltage drop between the alternator and battery. Bring the car to normal operating temperature. Turn on as many power consumers as possible (AC, headlights, radio, defroster, etc.). Use the same grounding point for the following voltage measurements:
- Measure the voltage at the "B+" terminal on the alternator.
- Measure the voltage at the battery positive terminal.

If there is a voltage drop of greater than 0.5 volts between the alternator and the battery, and all of the connection points are tight, check the harness terminal at starter. It is possible that the crimps on the starter terminal where the two cables are joined together incorrectly, causing an excessive voltage drop between the alternator and the battery. This voltage drop does not allow the battery to charge properly, and as a result, the battery will continually discharge until it will no longer start the vehicle. There may be no visible damage to the harness, and more measurements may be necessary to determine which cable or part of the cable is responsible for the voltage drop.

http://www.suncoastparts.com/product/SKU997HARNESS.html

http://rennsportkc.com/porsche-997-a...t-kansas-city/

Start with post #53 http://www.6speedonline.com/forums/9...equinox-4.html


I did a search and found these pic's: