Dante924S

Hello guys i have had this problem with my 1987 porsche 924S for a few months now and i have been trying to track it down and am turning to you guys for your expertise and advice. when i turn and hold the key to crank the ignition, about 1 second after i turn it sometimes my car studders, i hear starter grind and the whole car shakes. i immediately let go when this series of events happen and i go for a second attempt at starting the car. most of the time when i try it the second time it fires right up. i have recently replaced the starter, spark plug wires, spark plugs (one was dropped and needed to be regapped to roughly .0029,which i gapped them all at) rubber like fuel lines which hang over intake manafold,( those were leaking a bit) another fuel line which goes from what i believe to be the fuel damper to the fuel rail, distributor rotor and cap, battery positive terminal, battery is roughly new aswell. I have done some troubleshooting and i have heard this may be a fuel delivery problem. perhaps something to do with a clogged fuel filter or weak pump. i am trying to remove the fuel filter and it looks like it has been on there for many many years due to how seized everything is. i cant even get the band clamp off, let alone the connections on either side of the filter. do you guys have any suggestions on what could be causing this suddering/grind noise?! i really appreciate your time in helping me track this down!

John_AZ

It would also be better if you mentioned you have a chip installed on the DME.

https://rennlist.com/forums/924-924s...l#post11721642

You are correct to get the fuel lines and parts replaced.
You can go OEM if you have to cut the lines or a couple of members will make the lines for you at the rear of the car from the pump to filter.

There is also a fuel tank screen filter that will clog and fail. It is screwed to the tank. Get a new filter gasket and short hose from the fuel tank to the pump.

Tank screen filter, gasket, hose to pump, maybe a new fuel pump, a hose from the pump to filter, new filter, hose to hard line, new FPD (fuel pressure damper), new FPR (fuel pressure regulator, new hoses from the hard lines to the fuel rail and finallly a new fuel rail jumper hose.
$600 to $700 or so.

Then go back to a stock DME chip and see what happens.

GL
J_AZ

Dante924S

Thank you for your insight, I will def work on getting all those replaced. All those hoses near the pump and filter are very dry rotted so its for sure a necessity. I will throw on the old chip and see what that does!! Thank you so much I'll update you when I get those replaced over the next few weeks!

drive135mph

I would also jumper the security module, It can be a bit of wild card when if fails, and it's pretty much free to check off the list as a potential problem.