So finally got the car back together and took her on the first shakedown cruise which ended in a pull home due to a bad coil and a bad ignition relay (both replaced) but I'm still having a problem aside from those , at around 2k rpm the engine is nearly shutting down then picking up again when I back off the throttle. I've already re checked the fuel pressure, which looks okay, I also replaced both the distributor cap and the rotary button today as well so I'm now wondering about the WOT switch. Anybody have any ideas?

 

We ALWAYS need the info on the car. MY, USA/RoW, five-speed/auto, etc.etc.

Did you replace the coil with the exact part number?

 

Yes need full model details for pertinent advice.

But can discount throttle position switch as you talk about problem around 2000 rpm. Faulty idle switch will give problem idling with no throttle. Faulty wide open switch will mean less snappy downshifts (if it's an auto?) and reduction in top end power I believe

 

Sorry guys its an '84 us automatic an Wally to answer your question No I used a coil from a vw as that was the only thing I had laying around and it seems to work okay after I installed it i took the car out again and it seemed to function okay which was a vast improvement over the stock coil which was getting incredibly hot and shutting down (like it looked a little melted on the bottom end) after the drive it was warm but no more than I would expect with its location that close to the engine block ( has anyone ever relocated one away from the engine?) anyway back to the problem at hand the symptoms are similar to fuel starvation but I've pretty well replaced the entire fuel delivery system aside from the hard fuel lines new damper and both regulators as well also pulled and cleaned the injectors and replaced the hoses that feed each of them I have brand new plugs and the fuel filter and pump are good also as is the in tank screen. I do have one question though on two of my injectors the plastic(?) collar around the injection valve (don't know if that's the proper name or not, where the fuel comes out) were gone, I've already ordered replacements, but could I be getting some kind of a short there? My Dads says the problem seems more like an ignition issue than a fuel problem and we are getting 35-40 psi of pressure at the rail.

 

While the coil may not be your only problem, the Factory Workshop Manual, Page 28-44 says, "8. Never replace specified ignition coil with a different ignition coil."

 

Believe it or not my dad and I actually found the problem by accident today! The fuel pump relay kicked the bucket and when I replaced it and started the car we noticed it was behaving oddly at idle but hadn't been a few minutes before when dad jumpered power directly off the battery to the fuel pump so I reasoned that there was a problem with the relay itself and pulled it out dad jumpered it again and the car fired right up and was running smooth as silk (with NO relay in), unhooked the jumper,replaced the relay and the problem was back, pulled relay and jumpered and the problem disappeared again,so, we did the only logical thing we could've done at that point hopped in the drivers seat and took her for a spin (still no relay!) and all I can say is WOW! they're a ton of fun when they're running right ! The relay is good as far as we can tell so I assume there is a short in the electrical between the relay and the pump that was causing the pump to lose power sporadically which would've caused all the symptoms we were seeing. Now all I have to do is track it down...or wire in a new line to the pump completely!

 

If the system works with a jumper in the relay socket, but not with the relay installed, the problem is with the relay.

 

well I'm pretty sure that's the problem anyway Wally but we had jumpered off the battery directly yesterday I found a heavier relay (40amp)and put that in and the car behaves fine except when I get on the throttle pretty hard then the symptoms return though not nearly as pronounced as before. Let me ask this though since I have no one to ask locally , should there be a noise coming from the relay when the car is started like a buzzing sound and it is definitely coming from the relay which doesn't seem like it'd be normal to me I've never had any other car have a noisy relay so I'm reasoning that Porsche would've found that to be unacceptable but am I wrong?

 

OK, may be a problem here.

The '84 is the last year for the complex and expensive fuel pump relay - P/N 928.615.113.01 - which is triggered by the electronic ignition system. It has an electronic control unit inside the relay that receives pulses from the ignition system, and the control unit closes the fuel pump supply contacts inside the relay.

I don't know where you would have found a 40 Amp version of that relay. If you have a standard relay in socket XVII, it might well be buzzing from the ignition pulses, and might well be your problem.

Porsche list on the correct fuel pump relay is $144.36.

Jeannie has just received a shipment of OEM relays, and she will sell you one of those for $29.93 plus shipping - give her a call at (828) 290-9280. You will probably need to leave a message - she is in and out at the moment.

 

That's awesome Wally I didn't actually find a 40 amp version of that relay , the 40 amp one is also wrong but all I had to go on was the relay that was in there to begin with and the one that advance had previously sold me which matched it it never occurred to me that both of them were wrong I just thought maybe advance sold me a bad part (like that would be a first!) an went to Oreilly where they told me they didn't stock that part I told them to match it to one that had the same pin out but with a higher rating that's how I ended up with one rated for 40 amps. The first one that went out was rated for 30amps and was in the car when I bought it. I notice the correct relay is only rated for 16 but who cares as long as it works! Thanks so much for the help and the right part is already on its way!

 

I don't think that the amp rating of the relay contacts is the problem, rather the power source that operates the relay activation coil. The correct relay uses an electronic circuit that monitors an ignition signal. The improper relay might well be loading the ignition circuit and causing ignition failure, and might be dropping out because the ignition circuit doesn't furnish enough power to keep the relay pulled in.

Let us know what happens.