engine turning over constantly

[AlexH997]

hi all

this evening i went to the petrol station to fill my tank up before I went out. The station is only 2 miles away so the car was running at optimal temperature. The car hasn't been used for 4 days.

When i came back, I put the key in ignition to start but it kept turning over constantly. I stopped, waited a few seconds and then started up. This time it still kept turning over but eventually started.

I've had this experience before a few times but it's always started. Tonight it took 2 attempts to startup.

Is there something I should have checked out or is it the mixture of the weather, not being used for 4 days and not running at optimal temp.

Car is a 997.1

thanks

Alex

[crisisjez]

Don't know wether this is the case but the old v8 engines in the XJ/K8 models with the nickasil bores suffered the same issue when stopped shortly after first start when cold.
The symptom was a really fast crank like there was no compression and no start.
The cause was petrol washing down the bores and destroying the oil seal between ring and bore that gave the compression.
Usually the only way to start was plugs out and pour oil down each hole.
No way are you at optimal temp after 2 miles. Do you get any black smoke? ( except at start up)

Edited by crisisjez on Wednesday 16th October 21:34

[Wozy68]

Short trip, start/stop, cooler weather, car still running rich on choke, I'd never put my 911 through that.. If it was an RX8, you'd have been calling the AA out.

[AlexH997]

crisisjez said:

Don't know wether this is the case but the old v8 engines in the XJ/K8 models with the nickasil bores suffered the same issue when stopped shortly after first start when cold.
The symptom was a really fast crank like there was no compression and no start.
The cause was petrol washing down the bores and destroying the oil seal between ring and bore that gave the compression.
Usually the only way to start was plugs out and pour oil down each hole.
No way are you at optimal temp after 2 miles. Do you get any black smoke? ( except at start up)

Edited by crisisjez on Wednesday 16th October 21:34

No, no black smoke.

[AlexH997]

Wozy68 said:

Short trip, start/stop, cooler weather, car still running rich on choke, I'd never put my 911 through that.. If it was an RX8, you'd have been calling the AA out.

I didn't have much choice, the car needed refuelling before I went out. Car normally does 50 miles a day so warms up plenty.

so you reckon its rich on choke?

[supersport]

No, it shouldn't do that. Maybe once in a blue moon maybe. But it sounds like you have an ongoing issue.

[AlexH997]

Mine does it when the weather or car is cold/damp.

[crisisjez]

Plan better so the cars not empty on a cold engine, it takes a good 10 miles to properly warm up the engine.
If it still does it I'd be considering a leak down check.

[markiii]

ground strap

[Pickled Piper]

I didn't understand the initial description. Did the car crank but not fire? or was the starter motor just spinning without turning over the engine?

pp

[BertBert]

What on earth is a choke?

To the problem, it's not normal behaviour, so there's something wrong somewhere and prob hard to diagnose.

Bert

[edc]

BertBert said:

What on earth is a choke?

I'm not sure if you are being sarcastic or not. The choke was a manual way to adjust the mixture. With modern cars it is all automated now. But at start up the car runs 'rich'. In days gone by you would start the car with the choke pulled out and bit by bit push it back in to adjust until the choke was all the way home.

[Rockster]

AlexH997 said:

Mine does it when the weather or car is cold/damp.

Reads like a temp sensor (coolant or intake) is giving a bad reading, a reading that is warmer than actual.

As a result the engine is fueled too leanly and the engine cranks a while before finally firing. (The engine might spit back through the intake if this the case. If the engine was being fueled to rich the engine will backfire through the exhaust. In both cases you might have trouble hearing this.)

Because the engine cranks a while it sounds like it is cranking with no effort because we are not used to hearing the engine crank without firing almost from the start of the cranking phase.

Once cranking the compression helps in that the compressed air returns almost all the energy it required to compress so the engine can almost sound like it is cranking with no compression.

This happens at engine start and does not affect emissions so there is no CEL.

You might be able to observe the bad temp reading using an OBD2 scan tool and monitoring intake air temp and engine temp (coolant temp) before, when, and after this happens.