Bomba

I did a search but didn't come up with anything on this issue.....

Background:

• 2007 C2S with 108k miles.....
• I have the slow crank when engine is hot issue, so I know that I need to do the starter cable. I've just been putting it off because it's not an inexpensive job, that I'd like to pair with a new RMS and clutch when the time comes.
• The battery is 3 years old and I was planning on changing it this spring.
• No CEL ever and the car generally runs strong....
• A/C has been a bit weak over the last several days (I live in Miami, Florida, so yes, I use A/C in January).
• I daily drive the car, 5 miles a day, round trip to the office....
• No smoke, never had the bores scoped, never felt the need to.... No soot on the tailpipes.... Never really been worried about it....
• When the engine is hot, the car has always intermittently had the idle drop from around 1k RPM down to 800, which I thought was linked to the A/C compressor kicking in.... Never been an issue, and the car has done it since I bought it...

Issue:

• After a 40 minute drive in stop and go traffic, I needed to run in to an appointment quickly and the engine was hot....
• I found that my appointment was cancelled after I arrived at my meeting, and went back out to the car to start it. As expected, I got the slow crank issue because the engine oil temp was at the "hot" 200+ degrees...
• The car starts after 3 or 4 cranks (as expected) and I start my drive back to the office....
• 5 minutes after starting to drive, I come to a traffic light and the revs drop, and the car stalls.... (Cue panic because it might not start right away and I'm in at a busy intersection)
• The car starts, but now I'm hyper focused on the RPM drop and find that I need to give the car a little bit more gas when starting in 1st gear to keep the engine from bogging down.... A tiny tiny bit more gas, not much.... It could have been paranoia on my part about the car stalling again.
• The last 2 days, there have been no issues with idle or stalling on my usual 5 mile commute....

So my question to the group is the following:

1. Could this all be a result of a weak battery? The car cranks up fine when I first start it in the morning or after work....
2. Perhaps the alternator? These first two are easy ones, but I don't have any typical electrical issues when batteries start to go....
3. I don't believe I have a vacuum leak since I have no CEL's and the car runs strong for my short 2.5 mile each way commute?
4. Could it be the A/C compressor is going and straining the engine? I have no belt squeals or anything of the sort.
5. Coil packs? I don't believe they've been changed in 5 years, so it's probably time.
6. Dirty throttle body? This is an intermittent thing and again, the car runs strong so I'm baffled.
7. Fuel filter? Again, this only happens when the engine is fully up to temperature and after stop-go traffic....

I know that the car does NOT like extended stop-go traffic, which doesn't surprise me but outright stalling is a new one for me.

Any thoughts from the group? Your input is much appreciated before I drop it at my independent shop who *could* go on a wild goose chase of replacing parts.

Thank you!

Graufuchs

When was the last time the plugs were changed? Fouled possibly due to the short trips? (While you are in there the coil-packs also.)

Leaky/dirty fuel injectors is also a possibility as well.

A weak battery wouldn't cause the car to stall, although the constant short trips would negatively impact the battery life.

Bomba

Thanks for the reply. I'm fairly certain the plugs were done at around 90k miles. I haven't done them in my ownership so they're probably due. Interesting point on the injectors, but the car runs strong most of the time. This only happens when the engine is hot, in stop-go traffic, so it makes me wonder.

Petza914

Do the plugs and coil packs and clean the throttle body. The first sign of a failing battery is a PSM fault sonif you're not getting that, battery is probably ok, unless it's an AGM as they seems to work fine until one start they're completely dead (happened to the one in my pickup yesterday and the one in my 914 about 5 years ago). You can put one of those USB chargers that displays voltage in the cigarette lighter and see what the voltage is doing. I would also change the starter and cable. While you're in there, might as well do the AOS and corrugated plastic lines if not done in the last 30k miles. It's a decent list but could be banged out in a weekend.

frybear

Not sure if this will but somewhat similar issue. Started the car in the morning, went to the post office. Back in car after a few minutes, started up just a little harder than normal and went to grocery store near post office. came out a few minutes later, definitely a harder start. Drove to the gas station right near grocery store. After fill up, could NOT start car at all. Used a jump pack and started fine. Ended up replacing starter and starter cable and now it starts up like a Honda!

Optionman1

Check your starter. This happened to my 996.2 and is not an unusual issue. Cold starts no problem, hot starts just as you described.

8x57IRS

Any error codes? Durametric? Otherwise visit your indy to check that. Otherwise only guesswork.

Bomba

No error codes.

Wayne Smith

Stalling problems, not starting problems. Stalling when accelerating from a stop light could be clutch problems. Or is this happening while you're driving? A bit more detail might be helpful.

Bomba

It stalled when the engine oil was really warm and sitting at a stop light. Clutch not depressed and obviously not in gear. Revs just dropped and it stalled.

It doesn't happen while driving (IE: moving down the road) and the clutch takeup is "normal", even with 108k miles on the original clutch.

Wayne Smith

That clarifies things. Thanks. It does leave these questions ...

What is the idle rpm at?

Is the idle smooth?

When it drops down and stalls is this over a 5 second period or immediate?

Can you compensate by adding a bit of throttle?

Does the car start right back up when you crank it?

Sorry for all the questions. Just trying to get a full picture before jumping to conclusions.

Saaboteur

Crank position sensor is fairly inexpensive, and symptoms of a failing one would include hot start issues.

Bomba

Responses below. Thanks for asking more detailed questions because the easy answer is to start changing parts out and "jump to conclusions" as you said.....

Just to add.... No oil burning, no soot on tailpipes and no CEL's....

Wayne Smith

Just a few things ... fuel pump (low pressure), vapor lock, charcoal canister (overfilled tank when gassing up). The key to me is the extra cranking required to get it to start again (I'm assuming it's not slow to crank, but just required an extra amount of cranking).

Regarding the .1 cars there are many here l that are much better qualified to lead you further than I can based upon the clarifications you've presented. Good luck.

Bomba

It's actually slow crank, but only when the engine is hot.