weird starting problem
 

ok, problems.

Today after a long relativley easy drive from Slough to Croyden (via M25) had a problem. 2 hour drive ? top down, not racing, top speed prob, 80 mph. perfrmance fine, all gauges fine and normal.

got to my destination, stopped the car, then decided to park car in shade (litearlly 10 sec's after switching off) and click "nothing"

so gave it 30 sec's for all the secuirty stuff to reset. put imoby key in, 2 beeps (fine), put key in ignitioon, turned to 1st post, switched off alarm from key fob, igntion lights and a beep (normal), turned key to start and "nothing", no click (as far as I could hear)
mmmmm...

now niside of car was damn hot as was under the bonnet (fans come on fine!) so pulled dme relay and fuel relay (past fix) still no joy, pulled all relays, tried again, still no joy, (all the relays as hot as hell!)

so left car for about 30 mins, bonnet open) pulled all relays again, made sure all fuses were in fine, started !

now last time I had a similar problem I changed the DME relay, this cured problem, however that was a car would turn over but not fire, this time (as makis thought) was like a dead battery.

so thoughts

1> weatehr was very hot (heat wave), under bonnet and in car temps was VERY hot
2> possible electical problem with alarm, immoby, fuse board, relay,

disconcertying, as I could have been in a very embarrasing problem with a non-starting Porsche ;)

this weekned I'm going to crawl all through the electrics and see if I can reproduce the fault.

also would fitting a small fan directed at the alarm brain uder dash help,
and another fan ? to lower the very hot under bonnet temps ?

ideas gents ???

Sounds like your starter solenoid is not throwing out the gear to turn the flywheel. Check your battery connections, especially ground and power to starter. If all checks out, may need a starter solenoid (or new starter all together, if you don't have a starter/alternator shop around who can repair it)

Good Luck,

hmm. with a bad solenoid, the starter should still spin with the exception that the gear would not engage (as you said). however, sounds like adrian wasn't getting anything. and that sounds more like a deeper electrical issue.

the problem is that you have the alarm/immobilizer to consider as a potential culprit. perhaps, if the alarm could be totally disabled and taken out of the loop, you could then try to duplicate the fault and if it does not return, you could be reasonably sure that the problem was with the alarm/immob. if the problem persists, then you could at least eliminate the alarm/immob as a possible source and concentrate on the engine management instead.

HI ronin,

I think your right.

problem is, working out how to take out the alarm/bypass it,

if you remove the alarm, siren goes off and car stays in immobylisation mode ! Sometime ago I had a look at the cables and it's all well wired in,

not looking forward to it, but its going to be a bit of a slog

cheeers

A

adrian, this might sound stupid, but check to make sure that the wire connecting the ignition to the distributor is attatched on both sides.

I speak from experience.

hey CJ,

will do

cheers

A

Where is the alarm immobilizer? I am having some no-start problems and I have thought the alarm or bad wiring might be the culprit.

if you have a stock one, it is a key-lock just aft of the driver's side door. if you don't have the key-lock then any alarm/immobiliser on the car will be aftermarket and you'd have to do some investigating. btw. list your car year and model in your sig. makes it easier to help :)

and location
as uk cars have different set-ups from us

ronin, adrian:

Thanks for your input, it tells me exactly what I needed to know. According to your posts I don't have a factory installed alarm (no key at driver's side door quarter panel) and have already removed the after market alarm, so that rules out alarms as the problem.

I will also update my sig!! BTW, I have an 86 (mildly modified) and an 87 (restored stock) 944 na--U.S.

Again, thanks for the help.

my car (uk spec - all of them as far as I know)

does not have key in door,
all uk spec cars have/had porsche alarm armed/disarmed via door key.
also immoboilser on a separate key tag (pos. on steering wheel panal)

I've still got the porsche immoby, but had the porsche alarm replaced with a Thatcham catagory 1 (remote key fob) alarm

now that you have eliminated the immobilizer, we'll focus on the electronics. has the problem persisted with no change? fill us in on what's been happening so far.

agree, doesn't sound like the immobiliser...they usually allow the engine to crank...just not start…(or to start for about 5 seconds)

btw.. immobilisers in Europe are great, very smart, rare for them to go off falsely…over and over which the cheap/crap ones (with blowing horns and sirens) here States tend to do.

this sounds like a poor connection from the battery to the starter motor…yadda…yadda…could be the solenoid, or a battery terminal/cable connection that so many of these old cars experience…just that your problem is showing up with the extra heat you have been experiencing…don’t let that fool you

hey guy's

I'm going to do some investigating on the weekend, however I think it might be the alarm, as the alarm (I believe) gives 12 to the starter, if it doesnt then it could feel like a solenoid problem,

though with a didgy solenoid I'd expect t hear a click and I'm not.

the igntion lights come on (when you press the key fob - ie disable the alarms own immoblisation circuits) but turn the key and npthing.

I have a feeling ti might be to do with the brain connectors.

also the pas, door lock is acting up (same day), can lock/unlock oth doors from the pas door, but when useing the alarm fob, central lock button or drivers door, only the drivers door opens/closes. the pass door stays in what ever state it is left, "altough" the leds on both door locks works as normal

Adrian, it sounds like a classic case of starter heat-soak to me.

If an older, weak solenoid gets hot, it won't click, crank, or do anything.

The solenoid pulls back a plunger, the plunger hits a small "button" that completes the electrical cicuit and spins the starter motor.

Over time the bore of the solenoid can get corroded, add in the heat expansion, and it can actually mechanicaly "lock" the plunger keeping it from moving.

If you replace the solenoid, try wrapping the whole starter in some sort of heat reflecting wrap.

Good luck with it!

1> The linkage on the passenger door had jumped, (why it was'nt centrally locking!)

2> I removed all fuses/relays/and disconncted the battery ( to give the alarm brain and any other circuitry a full shut down.

I reomved the fuse board and looked underneath at all the connections and everything was fine, no botched soldering jobs.

removed the connectro from the brain, all looked ok, re-connected.

re-fit the battery, now, tried starting, despite having no relays/fuses the car tried to crank, obviously it wopuld not start,
so put back all the fuses and relays, cleaning all the contacts.

started car, bosh, fine !

now the alarm has been fitted very well, I think the alarm is connected to the battery via the ignition lock cabling, its all very tight up there so I could see th connection, but no failure there.

howevere, with experimenting with various things shut down, the "no click, no starting" scenario, seems to be the Porsche immobiliser and not the alarm. ie evebn with the alarm armed the car will still crank, not start, but with the immoby, armed and the alarm armed, it wont even click,

so I'm thinking the porsche immoby, "brain" was hot, now I found the fuse that controls the immoby, but cant find the brain, have got most of the trim and carpeting up. I'm planning on fitting a small fan to supply additional cooling, I was hoping the immoby and alarm, were under the dash but does not seem so...

ideas ?

well I think the problem is/was (with thaks to the makster!)

the Porsche immoby, is under the passenger seat, now the day when I had the problem, the top was down, and the interior was very hot,

not considering that the immoby was underneath and being cooked by the carpet and the seat, it all got very hot.

have prooved that pulling the fuse to the immoby wont stop an already running engine, but wont start an engine.

so if the unit got cooked, it would not have failed until I tried to re-start, which is what it did.

also the engine started after 30mins, when the top was back up (and the sunlight was'nt cooking the unit

so I'm going to get a cooling fan under the dashboard anyway.

but as for the seat I have and was thinking of doing thwe following.

1> we've cut the carpet out, and rasied the seat,
2> was thinking of fitting a low prifle fan to push some air under the seat

3> OR making a little heat deflector to place on the seat to deflect direct sunlght, was thining of using a polysteryne til wrapped with aly foil to deflect the heat away

ideas ?

also when if it fail next time will try pulling the fuse to re-set the unit

hmmm, sounds like a lot of trouble to go through to solve this problem. (if it is the immob) if the immob is being affected by the heat in this way, I'd say that it is a candidate for replacement as this should not happen if it were functioning properly. you shouldn't have to go through all sorts of mods to be able to make things work right. and it would be a bummer to make all these changes only to have the unit go bad later on anyway.

Yeah I hear ya,

thing is in this country, (and for the past 2 years) it has been the hottest heatwave since (76') as I said the interior of the car got cooked.

I think that the immoby THough a proper porsche install etc, in the uk was fitted by a snd user company, I'll ring up my OPC and find out anyway, its not too difficult to fit (now I know how)

but I really think it was ude to this amazing weather we've been having

will advise dooode

Ade

good luck ;) let us know how it goes