Cyberpunky

Have had to push start car last few times it has sat in sun for a few hours
Or all day. Ok in mornings or when left in shade, as it starts first time so it is just when really hot. Just tried a jump starter/booster but it just cranked faster
Anyone had a similar problem
BTW it is summer here and temp is 35C
peace
Cyberpunky

JohnKoaWood

DME relay....

PerceptionProblem

My guess would be something electrical as well. Sun might provide *just* enough heat to make things connect improperly.

But would only be a guess, in the end. I'd be totally stumped.

Paulyy

Okay so i went up and had a look. put in my spare working DME relay and it didn't start.
i took off the plug from the coil to the cap and tried to make it arc with the cap prong and i couldn't get it arcing. i put it as close to possible and i couldn't feel an arc between the 2, you usually can feel the arc happen.

to make sure it turns on we tried to push started it and it starts. For the life of me i couldn't work it out.

Bruce was on the phone to his mechanic (word has it he's one of the best P-car mechanic in melb) and he diagnosed through the phone it could be the ignition switch.

Cyberpunky

Thanks for coming over to work today Pauly. Was good to eliminate the DME relay. I think my mechanic is on the money with this one. It makes sense considering how easy it bump starts. Hopefully I can get it over to him in next cpl of weeks and get it fixed, although I am tempted to just fit a new switch myself. Has anyone done this ?

Makis

Looks to me problem is electrical. When cranking voltage gets too low and ecu/ignition amplifier do not generate enough power to produce good spark. When you push start this is not a problem as the power is good. I would check ground connections around the car and try to freshen them with a bit of wd40 and turning the bolt around a bit to get wd40 to work its way behind the bolt.

Paulyy

Anytime mate

http://www.clarks-garage.com/shop-manual/elect-25.htm
That's for an older 944, but i think it could be the same,
http://www.clarks-garage.com/shop-manual/ign-04.htm use this link to check your coil

mytrplseven

Have you tried letting it sit in the hot sun and then putting jumper cables on it instead of push starting? I'd be thinking of a marginal battery or battery connections. Give it a shot and see what happens. good luck

Paulyy

i'll aster this for him. He used a jump pack to start it and all it did was make the engine turn over quicker, but didn't start.

Cyberpunky

Yeah the jump pack just made it crank a little faster. It happened again today, so I drove it backwards a little on the starter, and tried to bump start it, which didn't work but then when I retried it, she started up like normal.

Paulyy

did you try the turning the ignition key slowly?

peanut

weird !

I can only think of two ways that bump starting essentially differs from starter motor starting and that is 1. the engine turns over faster when bump starting and the other is that you probably put your foot on the gas when bump starting whereas on the starter motor normally it should start without touching the gas pedal.

i'd maybe check how fast the engine turns over on the battery ,(it should be 200+rpm for the ECU to activate the DME relay ) secondly I might look at the AFM .

Try bump starting without touching the gas pedal and see if it still starts ? Just curious as to what happens.Everything else must be working ok ie fuel delivery and ignition spark or it wouldn't start at all.

Did you try wiggling the ignition key when cranking the engine as others suggested? The ECU and the Coil are supplied with 12v+ from terminal 15 on the ignition switch when the ignition is switched on. When you turn the key to cranking position you may be losing an essential supply connection within the switch

Cyberpunky

well today I had an *induction* session for work that went for about 4 or 5 hours. Much to my horror I saw that I had left parkers/running lights on the whole time, and car had been in the sun. I was thinking that not only wouldn't the car start, but I wouldn't have much cranking left in battery. I thought I was going to be stuck for sure but car started like normal, so battery is not an issue.

When car wouldn't start, the day before, I tried turning key lightly but no way I tried worked, although I didn't jiggle it.

OK here are my thoughts. Battery clearly OK as demonstrated by the fact I can crank and crank and crank some more,and with what happened today.
Coil must be OK as car runs so well when it runs. DME relay is fine as swapped with another, while in fault condition and no change. DME ok as again car runs like a dream normally. If it was fuel pressure I would think bump starting, wouldn't work. Starter motor must be fine.
So ign sw makes sense but am wondering if there is anything else it could be

peanut

Have you checked to see if you still have 12v+ at terminal 30 on the DME relay socket when you are actually cranking the engine ?
if the ignition switch is faulty you might actually lose your 12v+ supply to the DME relay, the coil and the ECU ,when the key is in the cranking position.
.

Paulyy

That would make sense. Try that. when you turn the key in the "start" position on the 944, everything else turns off except the DME, KLR, Fuel pump and Starter motor.