500

I think this is a great summary of where to start (assuming all critical maintenance, such as timing belt, is up to date):

Measuring fuel delivery and compression are pretty fast to do. You already have evaluated vacuum. Ensure each injector is firing and that you have spark present at each plug.

Aside from being less powerful than expected, how does the engine run? Is it smooth?

944Speedy944

all maintenance has been upkept, timing has been done aswell as replacing basic items such as the fuel pump.

as for the fuel pressure however, I am unsure what the pressure looks like since I don’t have an adaptor for the early fuel rail.

I also have not measured compression in eons but to my best knowledge I have rather good compression because it was rather tricky to hand crank the engine when the sparks where still in.

As for my fuel delivery however. No clue whatsoever. Not sure what my injectors look like not sure how much fuel is being delivered etc. all I know is fuel is being delivered and timing ( I believe ) is good. If anyone has the pressure amounts that’d be wonderful to see.



additionally, just to throw this in here. Not sure if this could attend to poor performance or not but my pistons aren’t exactly in great shape. However theoretically this shouldn’t be an issue ?


Piston number 1 as from the spark plug, either corrosion or carbon build up

944Speedy944

after a bit more research and some testing in this topic I have isolated the issue, thank you to this text because I wouldn’t have checked the sparks.

It’s running incredibly lean, the sparks are chalk white on the tips and my fuel rail has super high pressure because the injectors simply aren’t doing enough

jeyjey

That would certainly explain it falling off at higher revs....

V2Rocket

what is the pressure on the fuel rail? When running it should be around 30psi at idle, 37psi at WOT.

Quick test- unplug the DME coolant temp sensor (blue plastic connector at front of cylinder head) and see if it runs better. Disconnecting this will make the DME default to full-rich tuning because it thinks the engine is extremely cold.

944Speedy944

I will try this as soon as a figure out a solution to my new issue, I went ahead and replaced my injectors and swapped my fuel rail because I had spare of both, however the fuel rail I put in is a late so the pressure regulator is at a different spot so now I’m trying to find a way to reach the new pressure regulator location lol.

( p.s before anyone says you should’ve had your injectors cleaned etc, witch hunter is permanently closed and the previous owner swapped the originals out for Autozone ones anyways, so I went ahead and swapped them out for some more Autozone ones )

Jfrahm

You might test the DME temp sensor and maybe the AFM temp sensor to see if the DME has the correct info to set the fuel mixture.
If there are part numbers on the injectors please post them also, maybe they are not correct.