Another 986 Not cranking

[Greg Moirous]

Hi guys,

I'm at a loss here...

For a couple of years my beloved Boxster started to developp the infamous "not starting when hot" symptoms. Engine would start right up when cold but crank and not start when hot (at a gas station...after a short stop etc..).

I dealt with it for a while and this year after getting her out of storage for the summer I ran out of battery because I drained it trying to start too many times on the grocery store parking lot (engine warm)...that was enough for me to decide to change the CPS.

After a short battle, the CPS bolt is stripped and I decide to put everything back and enjoy my Boxster as is.

 

Before putting the wheel back on, I checked and the engine fired right up (glad I didnt screw up anything).

Now the car is on the ground on its wheels and she wont even crank!

I read a lot of things about clutch switch, ignition switch, even fuel pressure...

before starting to throw parts and time at it I wanted to make sure it's not something else I missed!!???

 

It would be real bad luck to have a switch fail just within 5 min of putting the wheel back on? 

 

What can I diagnose before starting throwing $$$ ??

 

[Yikes]

A similar situation at one time with my 986s.

i noticed you said the no start would occur at gas stations. Does this occur after adding or filing your gas tank? If yes I would offer one thing to check for Sure. The Regenerative Valve located under the intake on the 4 ,5 , 6 cylinder side or left if your behind the car looking forward. It is stuffed under there about midway back and has a plastic line going to it and a 2 wire connector. Get a stethoscope or a small metal extension and listen to the valve if it’s not clicking away with ignition on or running...???Well that valve when failed or failing causes you to sit at the gas station cranking away like till people are staring. Holding your gas pedal to the floor will usually get it started with a Redline people R staring again startup....best of luck!!

Mine is killing me.! Cracked cylinder head most likely.

Oil in coolant known good oil cooler new O-Rings and now Smoke like crazy last time I started it while trying to flush cooling system after installing new oil cooler.

I guess my crack has merged an oil galley to combustion chamber still runs like a top..I just put like 12k in it in parts!! Now I am trying to figure if I sell it.. I mean give it away Yikes! Or just wait for$$???... ah sorry for that rant I’m venting..I’m so pissed !!

I dream of LS-3 crate motors and adapter kits...!

Edited May 29, 2018 by Yikes
Poor typing

[Ahsai]

Check fuses C1 to C4 and E1. Then jump the clutch start lock microswitch and retry. Also try another key if you have one. Next is checking the power to the start lock relay.

[Yikes]

I somehow missed you are now not even cranking. I’d start with basics is the  battery up to snuff, A quick check with a volt meter to battery and try cranking it should drop a bit in voltage if it’s getting to the starter. Put a test light to the starter check to ensure your getting voltage, check for voltage in the run position to be sure it’s there. And by all means see above answer and thousands more all over regarding no crank heh...

[mikefocke]

A classic cause of not starting when hot is the crank position sensor.  If it is not working the tach will not bounce even a bit when the key is turned. Repeated attempts could have killed the battery. Good luck.

[Greg Moirous]

20 hours ago, mikefocke said:

A classic cause of not starting when hot is the crank position sensor.  If it is not working the tach will not bounce even a bit when the key is turned. Repeated attempts could have killed the battery. Good luck.

Hence the beginning of the story and try to change it...when it was cranking but not starting...

[JFP in PA]

22 minutes ago, Greg Moirous said:

Hence the beginning of the story and try to change it...when it was cranking but not starting...

 

Did you change it but with a stripped bolt?  Reason I ask is if the CPS is left loose, the sensor can back away from the flywheel enough to not see the trigger teeth and the car will act like it has another dead sensor…...

[Greg Moirous]

Yes I tried to change it but stripped the bolt.

The head is still attached to the bolt, just the hex is stripped (was hexagone and is round now).

I tried restarting it after replugging and it started right away.

 

You have a good point... would the car not even crank if the sensor was bad or too far from teeth or even unplugged? or would it crank and not start?

[JFP in PA]

It would probably just spin over as the DME would not see the engine turning and shut off the fuel and ignition systems.

[Greg Moirous]

1 minute ago, JFP in PA said:

It would probably just spin over as the DME would not see the engine turning and shut off the fuel and ignition systems.

Thanks.

In this case its not even cranking/spinning anymore.. ?

[Greg Moirous]

Well...all fuses seemed fine.

I even swapped all of them for same Amp ones.

Jumped the clutch switch, still no crank. :(

There is a buzzing sound when you turn on the ignition (something is waking up) to pos 1 of the key.

That buzz stops as soon as I try to crank (pos 2 of the key)..not sure if it was already like that before???

[Ahsai]

You need to do some low level troubleshooting. E.g., check if you get power on the start lock relay.

 

The buzz you hear sounds like the fuel pump priming, which shoild last for a second or two in pos 1. That's normal.

 

Do you have a Durametric?

[Greg Moirous]

OK Relay 7 is Start Lock relay. Which pin should I get power to?

You're right that sounds just like the fuel pump getting started.

Also the fuel pump stops when I turn the key to pos 2 (trying to crank) and resume when I come back to 1 (after not cranking) a few sec later. Like it is disabled on pos 2??

 

I have various OBD readers... ELM327 etc..

[Ahsai]

The sound is nornal. Non-Durmaetirc scanners are not going to be useful in this case.

 

Check out the circuit diagram I drew here. Remove the start lock relay and check if you have +12v at pin 30 on the socket when you turn the key to the cranking position.

 

Then with key in the last postition before crank and clutch fully depressed, pin 86 should have +12v also. You should also get 12v between pins 85 amd 86.

 

 

 

Edited June 1, 2018 by Ahsai

[Greg Moirous]

well I dont get anything on the starter relay.

Nothing on 30 when trying to crank and nothing on 86.

where is the 80amp fuse? 

[Ahsai]

The 80A fuse is in the power distribution box under the dash passenger side but it sounds more like the ignition switch to me because that 80A also controls a lot of other electrical parts too such as the wipers.

 

[Greg Moirous]

weird..never had an issue with it. key turns freely no hard point or issue...

[Greg Moirous]

Could it be an issue with the key? Rfid? 

[Ahsai]

You said when you turn the key to the cranking (momentary) position and you don't have 12v at pin 30. As you can see from the wiring diagram 12v from the battery goes to the 80A fuse, then the ignition switch then to pin 30. No voltage at pin 30 when you turn the key to crank can only mean the 80A fuse or ignition switch.

[Greg Moirous]

Just find it odd that the ignition swift brakes with no sign (key turns freely, never had an intermitent issue before)...

But again if the fuse was bad other stuff wouldnt be powered.

Where is it located exactly? could be an easy check.

 

Could it be the key itself? not answering to rfid for ex??Unfortunately cant seem to find my spare to try it.

And could it be the alarm/lock system not giving me the 12V?

[Ahsai]

Yeah, I agree it's odd and I can't explain it either.

 

The start lock relay is controlled by the DME and immobilizer. If your RFID is bad, the DME will not power the start lock relay. However, note that the test you did was with the start lock relay removed so DME and immobilizer were not even in the picture. If you put a very fat wire to jump pins 30 and 87, you should be able to crank the engine. If it does crank but not fire up, it means the ignition switch is fine but somehow the DME is not firing the ignition coils (a bad RFID or a bad crank position sensor can cause that).

[Greg Moirous]

Since I dont even get 12V at 30, jump wire will not do anything between 87 and 30 right?

From your schematic, cranck switch is really just the physical switch? ( I was under the impression it would be all the imobilizer etc..).

If it's the case, and the DME is only controlling the feed between 85 and 86, then the issue is fuse or ign switch...

[Ahsai]

Yes but it's another test to confirm you really have a problem with the ignition switch/fuse

 

Yes, the switch in my diagram represents the mechanical ignition switch.

 

Yes, the DME/immobilizer control only pins 85 and 86.

 

The ignition switch induces the RFID signal from your keyfob, sends it to the immobilzer, which tells the DME to activate the start lock relay. Once the engine starts spinning, the crank position sensor will generate signal to the DME so the DME will activate the coils for sparks and also keep the fuel pump running.

[Greg Moirous]

The Boxster is alive!!

Here is what I did: 

changed the battery (I tried to start, but she still didn't crank)

jumped 30 and 87, tried to crank: nothing.

put 12V on 87 (15Amp power supply), tried to crank: Nothing

put 12V on 86 and 87, tried to crank 1 time, nothing, tried a 2nd time....and voila, it cranked and even started!!

Weird thing, the starter "sticked" for a few sec after I switched the power supply off.

 

Put the relay back on, she starts right up. I even let her get up to temp and took her for a spin.

Stopped the engine, waited 5 min and started right back!

 

Not sure what happened??? like something was stuck and forcing the 12V helped??

or a 1st sign of Ignition switch going bad (the replacement is on its way).

 

Thanks Ahsai for the schematics and answers!!

[Ahsai]

Glad you got it sorted. I can't really explain what happened though. Probably an intermittent ignition switch or starter solenoid.