924 won't start when warm

[Guest]

My car starts fine when it's hot or cold (although it needs to run a mile or so so be going perfect). When it's warm, 15 minutes to 5 hours, it turns over and over before finally firing. Like it's flooded. I have checked all engine related things and all the settings are right.

I'm sure it's something to do with tiptronic ignition, which I confess to not understanding.

Does anyone have any ideas? Any suggestions would be very much appreciated.

 

[geoff Ives]

Does anyone have any ideas?
Join the queue.
In hot weather mine won't start afeter being left for one hour and less than two hours. It is amost certainly the hot start metering that is playing up. Talk to Bert Gear on 01271 866818 he has helped hundres of 924/944 owners in distress.

 

[Guest]

Thanks for that Geoff. Will give Bert a ring.

I bought off ebay a "hot start kit", doesn't seem to do a lot of good on my car but might work on yours. The scrap of paper I have says it comes from Club Autosport Ltd, Porsche House, Halesowen.Don't know if they still make this, but might be worth a phone call. The number I have here is 0384 410879. That looks out of date.

 

[924nutter]

There is an explanation of this phenomenum in the FAQ so this should help you understand why it happens. The warm start kit (I saw it on Ebay too) looks like it is just a couple of wires. A synopsis of it is; A symptom cure( not the disease) is to locate the earth wire from the coldstart injector and splice in another wire. Take it to earth via a switch. which should be located conveniently inside the passenger compartment. Turn the key and operate the switch. The engine will fire and catch after the third go.

go here http://www.porscheclubgbforum.com/tm.asp?m=78963 to view the answer.

 

[geoff Ives]

The problem is that there are two different injection systems. On the earlier version you can open the bonnet and pull out the plug to the 5th injector, push it back in and off you go. This can of cause be wired in to a flick switch on the dash baord. HOWEVER. This dosen't work on later cars (mine). As I said before, talk to Bert Gear. He is the Guru.

 

[924nutter]

There is one injection system on the 924 2.0, Kjetronic, which is a bit misleading as it isn't really electronic at all, and meters fuel continuously. I do agree with you Geoff that Burt Gear is something of a legend, and if tiptronic can't find the info he needs on the forum he should indeed Ring Burt, as I am really only proficient on the 2.0 litre, so if he has a 2.5 litre engine this info is useless. I have to respectfully disagree with your idea of pulling off the plug to the 5th injector, as when the coolant temperature is above a certain point, i.e. when the engine is still warm. the thermotimeswitch breaks the earth return and the 5th injector doesnt operate. Even if it did, it would only operate for between 7 to 12 seconds (from memory) as the timer in the switch cuts it out after that. My first 924 was an 84 model year car and this modifcatin worked for many years until the fuel pump packed up, and the problem disapeared with the new pump. I put this down to having fitted the new non-return valve which comes with the pump which greatly reduces the likely hood of vapour-lock, as the lines retain residual pressure preventing the fuel from turning to vapour, which I understand is the root cause.