consistant starting issue

[comicbook8@gmai]

yeah did alll the leakdown stuff passed no prob . have come accross another possiblity testing at the mo , but not saying nothing yet i will know by sunday night. i will hopefully post a conclusion then. im close, i can smell a fix !!!!!

[comicbook8@gmai]

ok , so i tried jumping the 944 from my v.w t.d.i and she starts first time every time when jumped with the v.w engine running !! so i reckon my 12 month old new ? batt is dodgy .
but when i jump without the v.w running it still the same a whole lotta cranking going on , i cleaned the grounds on the engine block and batt and changed the batt"S around . when its jumped with the vw engine running the voltmeter in the dash reads almost 14 v , and starts first crank every time. with v.w batt installed(defo good 1) the voltmeter reads 10v same as my porsche batt did and still cranking . so i am convinced its a weak voltage getting to spark plugs but what could cause this? alarm sys immob maybe ??
anybody any ideas im running out of steam on this one.

[jmd_forest]

Sounds like you have bad ground. The standard battery and jump without the engine running is not enough to overcome the bad ground. With the engine in the vdub running you are getting the 14V to the DME and the car will start.

Clean up all the ground points in the car and I bet the problem goes away.

The other possibility is a corroded battery/starter/alternator cable.

jmd_forest

[comicbook8@gmai]

yeah has to be a bad ground does'nt it ? the engine block ground back of block tight to firewall thread seems damaged wont tighten properly , going to try putting in a new ground on intake manifold and block and check every connection alt/starter at the weekend .
any other not so obvious ground point's to check ?? im going to bypass the immobiliser aswell see if that makes a differance . i'm getting closer narrowing it down slowly but surely !

[Outback Porsche]

Originally Posted by comicbook8@gmai

firewall thread seems damaged wont tighten properly

I had the same problem. A 'Heli-Coil' fixed it. Bugger of a job. Had to remove the intake manifold to get room to work on it.

Glad to hear your almost there.

Cheers,

[comicbook8@gmai]

cleaned all grounds i could find , not really any improvement that i could tell . been away for a while then the weather has turned bad gone cold now it starts great every time !! but i know the prob will return when the ambient temp picks up , havent got to do much with her lately because of bad weather semi hibernation for the winter me thinks .talked to a starter motor expert recently he mentioned checking a hard start connection on the starter , so i will do that over christmas .

[mallard ducks]

you know I have pretty much the same problem. The warmer it gets the worse it starts; the colder it gets the better it starts. So in November, December, Jan, Feb, March I have perfect starting. In Oct, April it's pretty good - within 1-3 tries. May and September could be 2-4 tries. June, July August it's just a PITA to start.

Everything is good/checks good on my car except for a vacuum leak that I haven't gotten round to fixing yet. It is fairly substantial, e.g. design idle speed = 850rpm +- 50rpm, but I have a hunting idle between 1,000/1,100 rpm.

I'm almost positive once I get the vacuum leak taken care of, the starting issue will go away. what I'm guessing is that the leak is not large enough to cause a consistent year round starting issue - but it is just right to mess up the mixture at starting beyond certain temperature points.

Re-reading the thread I don't think I see that you've confirmed about checking for vacuum leaks(?) What do you idle at? Do you have a hunting idle?

[comicbook8@gmai]

yep we have same prob except the idle , mine idles textbook 850/900 steady as a rock all year round .as for vacum leaks i have no other symptoms to suggest a vac leak .im sure its elec going to strip the starter next .described it to a associate last week the guy is a bit of a guru made a lot of money from designing starters alternaters ,he reckon there could be air getting in to the chamber somewhere or the bosch starter has a hard start connection which goes bad and drains excess power from battery during cranking which gives a weak spark ,this we get away with during cold days because the mix is much richer takes less to ignite or something like that .worth having a look at .if i dont have any luck i am goanna get him to have a look at it , he more or less retired though so would prefer to get it sorted myself .i have some time off at chistmas will get stuck into it then , i will post if i find aything
"HAPPY CHRISTMAS "

[Pops944]

I just got over the same problem. Mine would crank for up to 25 seconds at a time, then rest for a minute then crank again maybe two more times before it would start; but then it ran great. In the process of looking for the gremlin I found several vacuum lines loose (just got it back from a shop having the clutch replaced) and fixed them and replaced the coil (it was low on the secondary resistance scale), and finally found by pure luck a hole in the fuel supply line (looks like it was drilled through the crimp connector base) that was leaking gas onto the engine. I did a temporary repair of the hose while awaiting my new ones, and now my car comes to life within 5 seconds even at freezing temperatures.

[gtroth]

I'd probably use a volt meter and the schematic and trace down that big voltage drop myself (I suppose the drop might be to the gauge so the 10V you are reading might be a lie).

There are two grounds at the back of the engine about 40mm apart - sounds like you found one? Watch out - I've read somewhere that very bad things can happen to your DME if you try to start with those grounds faulty (big currents sink into your DME through a wrong path).

[mallard ducks]

well it sounds like you'll get to bottom of it sooner or later comicbook8 - good luck and hope you track it down!

[C_Adams]

Check the plug above your flywheel sensor

[comicbook8@gmai]

Originally Posted by Pops944

I just got over the same problem. Mine would crank for up to 25 seconds at a time, then rest for a minute then crank again maybe two more times before it would start; but then it ran great. In the process of looking for the gremlin I found several vacuum lines loose (just got it back from a shop having the clutch replaced) and fixed them and replaced the coil (it was low on the secondary resistance scale), and finally found by pure luck a hole in the fuel supply line (looks like it was drilled through the crimp connector base) that was leaking gas onto the engine. I did a temporary repair of the hose while awaiting my new ones, and now my car comes to life within 5 seconds even at freezing temperatures.

nice one , glad you got it sorted
1. did she run fine other than the starting ? 2. when you sorted the vac lines did it make any differance to the starting,? 3. where was the hole in the fuel line that it leaked into the engine?, (that could be something i really need to look at) .
tks, sorry bout all the questions

[comicbook8@gmai]

Originally Posted by C_Adams

Check the plug above your flywheel sensor

is the the connection plug that goes to the ref / speed sensors ?
tks
hope santa brings you all something "porsche" nice at christmas.

[comicbook8@gmai]

well the car is starting first crank every crank ! im sure it has something to do with the cold weather , but even last winter she never started this good .she sat for 3 weeks unstarted went out turned the key fired right up , the only thing i did was put a new ground onto the intake manifold where the original at the back of engine block seemed threaded and loose so seems the new ground has defo made some differance for the good ! so fingers crossed im going to put this post to bed for now , and move onto the next issue " BACKLASH ON THE SHIFTER WHEN CHANGING DOWN " thanks very much for all your help guys you rule !!!!!!!

[Dtchy]

Alright...let's keep this thread alive. I have the EXACT same issue.

Easy start when cold and the warmer it is, the harder the start. I changed my FPR and have a check valve sitting waiting to get installed, but I think it's electrical related.

I have the issue too where I can crank for about 10 seconds and it sputters to life. Or I can crank a couple of seconds, switch ign off and crank again and it comes to life. Very weird...

Can anybody tell me what the volt gauge should read during cranking? Mine reads 10V with the red low voltage light on.

[comicbook8@gmai]

ok then we keep it alive for now !
I NEVER HAD THE LOW BATT LIGHT ON when starting but it would read bout 10v .
try jump starting it with the other car running see if she fire right up , if so change the battery for a stronger ampere one, i did defo made a differance check and clean all connections to starter motor spray with ac90 and check that ground at the back of engine block put a new 1 in from the intake manifold to the body.
they are the things i did that i could say made a differance.
how is she starting now in the cold air ?? mine starts as soon as i show her the key every time weird but i aint complaing for now

[Dtchy]

Still takes a couple of cranks, even when cold. But it's definitely worse when warm, or when the engine is warm.
I may go pick up a battery soon. It's that time anyway, since it's for sure more than 3 yrs old and put in by the PO.

[mallard ducks]

comicbook and every one else with same problem - I have an idea:

You've done fuel pressure checks and said it passes "with flying colours" - but are your fuel pressure numbers on the high side?

This could be a case of fuel pressure too high rather than lack of fuel. I have a wild guess that in cold weather the computer is specifying a richer mixture and opens up the fuel injectors to flow more (???) So this would alleviate the too high fuel pressure.

What leads me to the wild guess is that I have the exact same issue (see a few posts above) and I have higher than spec fuel pressure. It's not crazy high, but it is definitely above spec.

Now everytime over the summer that I had to do something with the fuel rail and it got emptied out - the car started first shot after putting things back together. If the problem was lack of fuel, it shouldn't start easier after emptying out the fuel rail.

So I thought, okay, maybe the vacuum to the FPR isn't strong enough: this past weekend I capped off the vacuum T where it goes one branch to the FPR and one branch to the EVAP valve (so now the vacuum line is intake manifold nipple -> "T" -> one branch to fuel damper, one branch to FPR with no branch to EVAP).

The car was doing the usual Fall temperatures 2-3 tries to start-up (i.e. getting better as the weather gets colder), but right now it's starting first shot from cold even though we're having a bit of an Indian summer up here.

Maybe I have some vacuum leaks sourcing from the EVAP hoses, or maybe just giving the FPR a bit stronger vacuum is doing the trick.

Anyway, guess I won't know for sure until next summer.