Slow to turn over when warmed up

I'm new to rennlist. It looks like a very informative site. My 1999 996 is slow to turn over after I drive it a bit. It starts well in the morning, but then will start sluggish if I drive it for just 30 minutes. It's not the battery. Anyone had this problem? It seems weird that it's sluggish when the engine is warmed up. Any ideas as to what it is? My only thought is that it's the starter. Thanks. Matt

Miles/ year would be of help. Mine does this. I blame the starter at 135,000 mine is prolly tired. But I have heard they go bad at any given time. Mine always sounds kinda lazy actually. But when the car is warm it is a tad slower to turn the car over.

I had this problem and completely checked out the electrical system. The weak link was the battery so I replaced it. Problem greatly improved but then after a period of time the starter again dragged intermittently when warm. I replaced the starter. That was the problem.

The problem is the positive cable that goes from the middle of the transmission to the starter/alternator. An over-crimped connection from the factory makes the cable transfer less electricity once it gets hot from the engine bay. I'm testing now to replace my cable with the 997 version to see if I can get rid of the slow start. My alternator/starter/battery are new and the problem still persist. You will get better start once they replace the starter, because the new/fresh connection to the cable, but it will degrade with time again. joel

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+1 had the same problem, replaced the cable, solved.

Thanks very much to all for the information! The car has 65k miles, but I'd assume the starter could go bad at any time. Matt

My starter went out of business at 51k miles....

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And both of my cars have their original starters. One has over 244K miles on it and the other around 68K miles. In the OP's case I suspect the battery. My 03 Turbo exhibited the same slow to crank symptom just a bit slower than normal too and I took the car in. CPO car. The Porsche tech checked the battery first thing in the AM and it checked out ok but he checked it later in the day -- after about 6 hours of the car just sitting -- and the battery had lost some power, considerable power. A new battery had the engine cranking right over and starting right up, cold or hot. I know starters fail but it just occurred to me I've replaced more batteries in my Porsches (1 in the Boxster and 1 in the Turbo) than starters. Two batteries. Zero starters. Sincerely, Macster.

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. Mine does it to. 11.3 compression is lot for the battery. Just make sure your battery is full charge when you go out and you should be ok.

Suggestions. Many of the auto parts places test battery under induced load and decent alternater analysis free of charge. Check connections including ground connection. Once those influences are eliminated, its almost sure to be the starter (not unique to Porsche). Hot engine tired starter is common. Finding a capable wrench to replace faulty component(s) - might be preferable to a rebuilt unit. If it's approaching the doubtful phase, fix it...peace of mind vs. $. Good luck with remedy!

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Compression doesn't really matter all that much. The cost in energy to compress the charge in the combustion chamber is almost completely recovered by the initial spring back/push back from this compressed charge and then there's the additional push of the charge when it burns. (Those of us that have experience kick starting motorcycle engines can attest to the pushback from the pressure of the compression stroke even when the charge isn't burning. Give a motorcycle engine of any size (a 500cc 4-stroke for instance) kickstart lever a half-hearted kick and when the thing kicks back.. oh my!) The starter motor is geared way down too. The gear wheel the starter motor gear engages is the flywheel which is 'huge'. The starter gear by comparison is a tiny pinion gear a bit larger in (pitch) diameter than the starter motor shaft. The starter as a huge mechanical advantage. The downside is the engine turns not very fast. The upside is the engine doesn't need to turn very fast to start and begin running. Sincerely, Macster.

Had the same problem. Replacing the cable from the starter to the alternator to the positive lead in the engine bay fixed it. http://www.renntech.org/forums/topic/31797-strange-low-voltage-problems

Ok the slow starting when warm has become very frustrating. To date I’ve installed another new battery bringing the total to two batteries in two years. I’ve had the electrical system checked by two service departments and I’ve pulled the starter and alternator off the car and had them tested individually and everything past. The ground strap from the battery to car and the ground strap in the rear have zero corrosion and the starter wires in the engine are not corroded. The voltage readings taking at the battery and then at the starter are only off by less than .2volts using a Fluke meter for testing. To say the least…I’m confused at this point. One theory I have is the starter once “heat soaked” by the engine loses its ability to perform. I’m open to trying anything at this point.

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Ground is negative not positive. I have no issues with my starter when hot with 100K+ miles.

So I mistyped, my bad. This issue excluding the typo (negative vs positive ) is still the same, and several searches on this forum and renntech point to a few possibilities that include the starter as a possible fault. Any suggestions CHSU74 you have are greatly welcomed. Even speculative banter is welcome

On the roof of the transmission well around the transmission bell housing there is a small black box that is a junction point for the positive lead going to the main fuse terminal behind the battery. The cable coming from the positive jump lead on the engine connects to this junction point. There is also a positive lead that forks off to the DME and relays/fuses behind the rear seats. I've read a few posts where this positive terminal can get filled with junk and corrode the cables or connection point. Also how do you know that the main battery cable on top of the engine isn't corroded? Just for fun, have you replaced it? It is not an expensive part. What is the condition of the main battery positive cable coming from the main fuse box (you have to remove the battery tray IIRC) to the battery. If your drains are clogged up in the front this area can see/fill with more water. Have you cleaned the terminals or replaced the ground straps (one from engine to body and another from battery to body). Any other excessive draw on the system during start? I.e. stereo, amps, speakers, lights, etc.

If you've eliminated the wiring (and your replacement cables are as good as or better than OEM including the crimp/soldering/gauge) then I would agree and guess your starter is getting tired even if it passes bench... just live with it until it dies? And then just for kicks whack it with a hammer a few last times before it gives up the ghost... then just bump start it until...

"Also how do you know that the main battery cable on top of the engine isn't corroded? Just for fun, have you replaced it? It is not an expensive part." I replaced this cable with Monster cable and connections as well as the cable and terminals at the battery. "What is the condition of the main battery positive cable coming from the main fuse box (you have to remove the battery tray IIRC) to the battery. If your drains are clogged up in the front this area can see/fill with more water." Drains are clear and sliced into the cable to inspect then re sealed with heat shrink. ”Have you cleaned the terminals or replaced the ground straps (one from engine to body and another from battery to body).” Replaced these at the same time in preparation for amplifier/stereo upgrade. Connections: Heated wire with mini touch to imbed solder them mated it to the connection terminal via crimp. 4AWG "Any other excessive draw on the system during start? I.e. stereo, amps, speakers, lights, etc." Nothing extra during start, but when cold the car fires right up...no issues at all. 've read your post over on Renntech and your findings lead me down the paths above. Good posts you have with alot of explanation. Thanks for taking the time to respond.

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I gree The one part I didnt look at was the connections on top of the transmission well. I will replace it as well. I have plenty of 4AWG at the house...

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IIRC the OE cable gauge is 2AWG or 3AWG. Pretty quality solid core low strand cable. Also, since you made your own it's important that the crimps are done properly, otherwise the strands can break down the road due to vibrations. The crimpers that just clamp down on two sides are inferior to the ones that do it from all sides.

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Well if it looks OK, I wouldn't touch it... unless you want to replace with OE part... since it is fairly well protected from the elements...

Update: After having the starter tested and many, many threads later I decided to replace the starter. During the R&R the oil filler tube broke, the alternator removal was a pain again (3rd time R&R), several broken hoses for the SAI. All and all it was a good project, replaced the starter and all is good and the car drove fine for three days and then... CEL. Now I have a SAI CEL. I did notice right before the CEL popped on I had just completed a 45min drive to cars and coffee and the engive was at proper operating temp. The SAI pump turned on then off and the light popped on. I thought the SAI pump only ran during initial startup when the engine was cold. Could this be an indication that the sensor which tells the SAI system to function is going bad or giving false information? Thoughts? Side question: Is there a process that we can use to "program" out this system?

Good choice, glad to hear that solved the problem. It's perfectly normal for the SAI pump to run at other times too, not just cold startup. What is the CEL code? Guessing a gummed up check valve or a misplaced vacuum tube. You can re-flash your DME with a RoW program and it will ignore the SAI system (and several O2 sensors and perhaps bank 2 CPS), but it won't pass emissions if your state requires a smog test.

I'm more inclined to think it's a misplaced hose or one that has become loose. The CEL was off prior to the starter R&R and I did knock a few hoses off and found one baldly cracked. Anyway, I'll dig into it later in the week.

You can buy that plastic tubing by the foot, it's really cheap. And the little rubber connectors are cheap too. Don't ask me for part numbers though. That whole thing is a big headache. I replaced all of mine along with the check valve and a good cleaning. Should be trouble free for another 100k..

I'm going to replace the 2 check valves, the front change over valve, and the shut off valve.There is one hose from the change over valve mounted above the alternator that dissapears into the rear of the engine by the rear intake righthand side. Any idea where that hose connects?

Into a tube into the resonance flap located in the rear intake plenum cross over. The hoses are 19-21 in this diagram going into the flap: http://www.autoatlanta.com/porsche-p...-05/107-10.php

Life is good. CEL is gone, slow starting....gone. Car is solid and I'm driving the dream. Thanks Logray for all the help.

I doesn't sound like you replaced the transmission to starter ground strap as suggested by Joel. I would do this even if it tests good and is not corroded--electrical gremlins are transitory and difficult to pin down.

Here is a good thread on it from the 997 forum. https://rennlist.com/forums/997-foru...w-voltage.html

I drove more than usual yesterday with some brief stops, and noticed it was very slow to start when the car was at it's warmest (after about a 1hr. drive). Is there a DIY on how to replace this cable? Anyone that has done it, any tips, etc.? Thanks, DS

I replaced the alt/starter cable. I got the replacement from suncoast, it was only about 100 bucks. It had a 997 part number so I'm assuming it was an upgrade. It took about 2hrs to replace. Its not bad at all. Disconnect the battery,remove air box,serpentine belt, and alternator. You can access the starter wires through the space the alt occupied. I ran the new cable outside the plelum on the pass side,from the jump start lug,then trough between the 2nd&3rd runner. I thought I had a thread about it but I can't find it now. Maybe search my name?

Mine did the same thing and I just changed the battery to the suggested beefy size. No problems after that. Old battery read good voltage but eh. From the front battery to the rear engine its a 2 piece cable bolted together under the car. Then the usual connections can be checked also. Hot metal has the surface expanded leaving less molecular structure to pass electrons in the skin effect. This effects all metal including the starter windings and cables. Good luck.

Eric, I found your old post...you don't happen to have a part number for what you ordered do you...I looked on Suncoast and didn't see anything fitting your description. Also, did you follow a DIY, or just go off of intuition? https://rennlist.com/forums/996-foru...-question.html Pac, if this doesn't work, I'll look at the battery route, but I have seen a number of people here and on RennTech that have had similar warm start issues and the cable resolved it. Thanks for both of your help! DS

Just went on intuition, was pretty straight forward. Try this link: http://www.suncoastparts.com/product...97HARNESS.html I couldn't find my reciept but this is what I ordered. Best 100 bucks I ever spent.

Great, thanks...after I posted I remembered you said 997, and surfed onto their 997 parts section and found it. Wow, that good huh? Thus far the motor mounts and Fister are the best mods I have done.

I'm with ya on the mufflers and mounts, but not having to cross your fingers hoping nobody hears you start it after fueling... Priceless!

Lmao, well put.

http://www.renntech.org/forums/topic...tage-problems/ Look at post #9 and #13 That crossover wire from the alt to the crimp at the starter has a bad habit of corroding and causing your problem.

Love that start of the Fisters in my garage. Scares the s$$t out of my chocolate lab.

I am having the same issue. I will order the part from Suncoast and change it it out this weekend. I hope this solves the problem. https://www.suncoastparts.com/produc...97HARNESS.html

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Try sunsetporscheparts.com instead. Much cheaper.

Oops, too many starter threads. I didn't realize this was the "already replaced the starter" thread.

They all help so no reason to apologize

Mine does this too - cranks over easy & strong in the AM or when heading home after work, but if I stop for gas, it is sluggish to crank. I managed to stall it at traffic light (I had been driving the GT3 for few days so the "light" clutch was still a novel thing). That was fun - the car was acting as if it was going to punish me for sitting a few days by not starting while the ever-increasing line of cars behind me grew less amused by the second. Battery is new (4-mo old AGM), so we will be looking at the starter and the cable this week.

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You can diagnose the starter cable with a multimeter and a long piece of insulated stiff wire such as one wire from a romex cable to reach the B+ at the back of the alternator. No guess work. What does your voltmeter in the cluster read when engine is hot with low beam and a/c ON?

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Is there a photo of this or is it obvious? I've got great cold cranking and 12.6 v at the battery. Getting a bit lazy when warm.

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A photo of the wire or the back of the alternator?

thx. i guess i need a review of the battery to starter current flow to understand. "My "secret weapon" for the B+ terminal A solid core insulated stiff wire hooking from the back of the alternator, with about 1/4" of metal wire exposed. Just connect it to your multimeter first, then probe the back for a quick reading..." that explains why there's no good photo i guess

Check this out https://www.renntech.org/topic/47504...arging-issues/

thx. I think this will help a lot. In the meantime what are the options if one is stranded? I haven't been stuck yet. I don't think a jump will help as the battery is not the problem.

this is good too. https://rennlist.com/forums/996-foru...ter-cable.html For now: Can you push start a warm car in a pinch?

buehler? all my searches end in push button or jump starts...am I the only one to ever roll start a motor? I'm a friggin dinosaur...

I've not push started a 996, but I've done it on other cars. Last one I had to push start was an 85.5 944. I would think that if it's a stick you can do it pretty easy. It's a lot more difficult with an automatic.

My son has this issue with his 99 c2m of not wanting to start after a "longer" drive, we've had to push start it twice. It actually starts pretty easily in 2nd gear

Good to know. I'm at a kids party. Parked on ahill just in case...