I have a customers 996 with a hot start issue.
Brand new engine, IMS failure that was shut down in time and is now a LN 4.0, engine runs perfectly, about 950km on the break in.
Cold it starts good, wouldn't crank the fresh engine but luckily I live on a hill and it fired right up, now it starts fine cold. But hot the best I get is one stroke, half a revolution, and that's the best it does, starts up fine if I bum it. It will start, slow to crank if left for 1.5-2 hours.

Replaced, new correct size battery, new starter, new engine starter harness and the alt is only a couple years old charging correctly. Each repair the starter has a bit more grunt cold, but hot start remains.
Getting to the point where I'm thinking of yanking the whole power cable and running a heavy welders cable. I may try booster cables front to back first to see if it helps before I try the welders cable.

The 996 C4S is a 2003, 265,000 KM on the clock, came to me as non operational, it has no codes, had a couple of low voltage codes with old battery but nothing now. Like I said other than hot start the car runs perfectly, the 4.0 pulls like a rocket, a joy to drive other than looking for a hill everytime I shut it down.

Any thoughts?

 

Y cable (part 21)? This is a well known issue in the 996. There are several ground points that get corroded. There's one near the passenger side rear wheel that gets super dirty and corroded (part 29). It seems you've already replaced everything else, so pull these connections off and clean them up (throw a little dielectric grease on them - If this doesn't do it, replace the cable if need be (or at least the ends). Good luck
Parts; 21 & 29 here: http://www.autoatlanta.com/porsche-p...section=902-05

 

Y Cable would be my first check and it's easy to test. If the cable passes the test I would recommend contacting LN and inquiring about fuel injectors used on your engine. JR mentioned that bad injectors can produce the same hot start symptoms on his Rennvision Youtube channel - and since you have a rebuild I'd be curious if you have incorrect injectors installed. Incorrect injector selection was an issue on a rebuilt 3.6 (former 3.4) that I purchased - the 3.4 injectors were reused and created a rich-running scenario.

Best of luck!

 

I had the same kind of issue with our old 1985 Toyota Mini Van. lol

It ended up being the ground cable. Ever since then, that's the first thing I always check when I have starting issues.

 

Cable has been replaced.
Original injectors, seem to be fine, Do you have a link I don't want to be replacing parts I don't need too.

 

On the 914 we have a hot start issue, turn the key and all you get is nothing or a slight click.You just put a relay on the keyed wire.
But this doesn't seem to be the same issue, as this will catch but not turn over.

 

Since you have already replaced the battery, y-cable and even the starter, that sounds like a wiring issue to me. Ideally you want to do a voltage drop test between the battery post and the starter. However, the starter terminal is hard to access.

Some easy tests: when it happens again, use a jumper cable to connect the negative jump bolt on the airbox and the engine brace/exhaust. That will bypass the ground cable. Similarly use a jumper cable between the battery positive post and the positive jump start lug above the a/c compressor. That will bypass a good portion of the postive cables.

 

Are you a mechanic or a DYIer?

 

Might also consider replacing the ignition switch. All sorts of gremlins come from that. Other than that, I had a reman Bosch starter (to save some $) and it crapped out. Would lag on start then it broke the starter bendix housing. Sounded like all hell when I hit the starter. Replaced with a brand spanking new Bosch starter and no more hot start issues for many years now.

 

I remember reading here years ago that someone solved the issue with a heat shield of some kind.

 

Are you sure the battery is fully charged?
Are you sure the new starter is good? Is it rebuilt?
You should be able to bypass all external electrical issues and put a jumper cable from the red terminal of the battery to the smaller terminal on the starter. The starter should engage & turn. If it doesn't look at the starter again.

 

I think I found it, salt damage to the lug/wire crimp connection under the car.
I'll test it tomorrow.

 

Update?

 

Brian996 is giving advice.

 

LOL!!