Alright. after a long day and 2 hours of engine install (I'm gettin good at this...good or bad?) I turn the key, and it roars to life. except one cylinder. alright. I thought at first, no big deal. could be just dirty contacts on the injector. so I clean them off, plug it in. nothin. I pull the injector out. squirt it with carb cleaner, thinking, maybe it's clogged. put it together, nothin. switch it around with another injector, still nothing. I know it's got spark.. I checked that. so WHAT THE HELL COULD IT BE!??!!??!?!?!?!?!?!? I'm hoping it's not a problem deep within the wiring harness...that would suck a lot. any help is appreciated. thanks.

 

The cylinders are fired two by two, I'm not sure where the split is in the harness is or if the wiring goes all the way to the DME before the two split. I'd have to figure out which cyls are grouped, I don't recall. ie, there's only two injector outputs for our cars. With it only being one cyl, I don't think it's a DME, therefore, a little cheaper. Really does sound like a wire tho, I'm thinking right at the injector hwere you plug it in at. Most wiring problems are at a connection or a spot that gets flexed alot(trunk harness). I'd check there first. Good Luck

 

I always thought each pair of pistons was 180ş out of phase.

 

Unless I missed it, it doesn't sound like you actually checked to see if you are getting current to that injector's plug on the harness. edit Unless that's what you meant buy it's got spark. I took that to mean spark plug.

Why don't you hook up a test light (noid light?) and check to see if that injector is actually getting any current.

 

USE A STETHESCOPE OR A LONG SCREWDRIVER AND LISTEN TO THE INJECTOR, MAKE SURE THAT IT IS PULSING, sorry for the caps. It should be making a ticking noise, and should sound like the rest of the injectors. The problem could be the injector itself. Do a compression test, if you don't have a gauge you can get some idea by disabling the ignition system and cranking the engine, it should sound even, not ragged. If it sounds kind of l "lopey" then you have mechanical problems.

 

#1 & #4 fire together, #2 & #3 fire together.

Is the injector working on other pistons? I know you said you tried other ones on it, but did you do vice-versa?

It is possible that the wire to the injector suffered damage, if it got bound up, bent, etc. But if it's abroken wire, and you can find it, you could conceivably replace the wire from before that point by soldiering in a new one. I have a loose injector (harness broke), and if it gives me any trouble, I'm going to do that. Already have another wire for it, but I'm not too keen to do it if it doesn't need it.

- Julie

 

I'm gonna check the injectors with the stethescope tomorrow. Never used a Noid light, might see about that. Also, gonna check the compression. if nothing shows up compression wise (that is if the #2 cylinder has no compression), I think it may be off to the junkyard for my 924S
but if it's something with the wiring, I'll be much happier. I may just end up towing it to my Porsche tech and having him fix it. Dad needs the garage for his M3. I hope I can get this fixed...and cheaply too

 

A noid light is just a test light that you plug into an electical socket. In you case you will unplug the suspect plug from the injector and plug the noid light into it (not the injector, duh). Crank the car and see if the light flashes. If it does then you are getting electric signal to fire the injector. If not, then something is afoot at the Circle K and you need to find the break in the harness.

 

well for some reason, when I did the compression test... all was well. the gauge read 150 PSI on all 4 cylinders. I put all the plugs back, and we were gonna listen to the injectors. we turned it on, and all 4 were firing. I was like, WTF??!?!?!??! so...I went for a drive. made up for the whole summer of the car in the garage. It seems that we may have one of the balance shafts a tooth off of where it should be...we have a mighty rattle (i felt thru the shifter) around 4000 RPM.

Also, the problem that we thought was a bad set of bearings, that is not fixed. we pulled the engine apart, the bearings were perfect. Now, I'm lookin at the camshaft. could possibly a bad cam bearing be a problem? or maybe (heaven forbid) a piece of the cam break off?

First thing tomorrow, I'm takin it to Todd, my local Porsche tech to have him take a look at it. well, I'm extatic. it runs. now, I just gotta have Todd figure out the prob. if it is the cam, I have a spare. so that makes it easy.

HAPPY DRIVING TO EVERYONE!

 

I can't sleep so I did some thinking to change the routine and decided to bring this thread back from the dead.

Given the rotor and cap ignition system, how can any 2 cylinders fire simultaneously? If they did, why would the zündfolge be 1-3-4-2 if 1-4 & 2-3 were firing at the same time?