1970 914/4 resurrection help needed!, Poorly running F.I. 1.7 Options

[daveholiday]

Hello all, this is my first post on the forums, but have been "soaking up" information from here for a bout a year! This is a long post and perhaps a complex problem or multiple problems that I desperately need advice and guidance with. I am going to provide all the info I possibly can but if I leave something out please let me know! I will describe my problem first and then give a detailed history and specs of the car.

The problem:

My car will just not run smoothly across the rev range. I constantly have to give the car throttle inputs just to keep it running. When it does try to idle it is around the 400-500 rpm range. I can also hear pops through the intake if I try to hold the throttle open at a set point (hold the car at a specific rpm). If I am constantly moving/revving the throttle the engine will respond, but in exaggerated revving/deceleration. It also is very low on power when I do attempt to get it out on roads in the neighborhood. It also appears to be running very lean as all 4 of my spark plug tips are white.

Car/Engine specs:

1970 Porsche 914 1.7. The car is still fuel injection. I have most, if not all, of the service/repair records for the car including the bill of sale from when the car was purchased new. The car has the original engine (W004-9961). The car had a rebuild in 1977 that consisted of the installation of a HP camshaft (no description), 96mm big bore kit, lifters, rods, coil, seals etc. In 1980 the car had another major service consisting of: lifters, rings, lapped valves, and camshaft. This camshaft had a Porsche part number that matches the stock part number. The previous owner didn't have anything else major done to the car since the 1980 service. So the best I can tell the engine has a stock crank, cam, heads, F.I., distributor, but does have a 96mm big bore kit installed. The last time the car was running reliably was 1988-1990.

My service history:

-Engine removal for clutch replacement and flywheel resurfacing.
-While the engine was out, I replaced all the seals I could without removing the heads.
-Replaced all vacuum hoses, fuel lines, and clamps
-New F.I. and ignition wire harnesses (Thanks Jeff, they are gorgeous!)
-4 new fuel injectors with seals
-new points, condenser, cap, rotor, wires, plugs (NGK BPR6ES), and timed @ 3500rpm
with some help I was able to hold the engine rpms enough to time it.
- distributor vacuum advance tested and seems to be working
-AAR, CHT(new), manifold air temp sensor, TPS all test good.
-The MPS will hold 10in,hg for 30 minutes before dropping to 9.5 in. primary and secondary resistances are 89 and 349 ohms
-The cylinder compression is 160,160,155,150
- valves set to .006 at TDC for each cylinder
**edit** fuel pressure trigger points cleaned and tested, fuel pressure at 28psi

The bad news is the engine runs as poorly now as it did before I started working on it. I am out of ideas and could use some advice. I have religiously searched for vacuum leaks and have brand new proper metric sized lines. I have even gone as far as to use small spring clamps on the vacuum lines. The only other items that I haven't done extensive testing on is the MPS and the computer. My MPS holds vacuum and sounds like the internals are moving when releasing vacuum, but I don't know of any other tests that I can do without specialized equipment. I haven't stumbled across any references regarding testing the computer as of yet, but I hear it is rare for them to go bad.

Thank you all who have taken time to read this post, and thank you ahead of time for any advice big or small to help me.

Again, if I have left out any info that you think would be pertinent, please let me know and I will be happy to add it.

Thanks again!

Adam

[daveholiday]

Thanks for the replies...but it brings a question or two from me!

@Chris

When I pulled the engine I did replace both the battery cables and ground strap on the tranny. The connections are clean and tight and a new battery. I have a battery from another car that I can swap but it appears my current power is good.

As for the TPS the car runs a bit worse when unplugged, and I can hear 20 pulses/clicks when I slowly sweep the throttle. I am still going to rebuild it with a new board when i get the part as the orig. board does show a bit of wear.

As far as the displacement increase, that happened back in 1976. The car was driven regularly up until about 1991. So, as far as I know, the car was running fine with the 96mm kit and stock motor setup. I have been told that the stock system on these cars will handle a displacement increase provided no other mods are installed (cam). This is why I have been setting the car to stock 1.7 specs...including the new yellow injectors. I hope I have not been wasting time and effort! Hind sight is always 20/20!!

@Phil

As for the computer and MPS setup...Those are still up in the air. Neither the computer or the MPS have a Bosch part number so it is hard to verify them.

I have a friend who has a 1976 914 2.0 still running the stock fuel injection system. He has offered to let me try out my MPS on his car this weekend. Some folks have said his car will run on my MPS if it is good. Might not run perfect, but the system will still understand the MPS...if it is working properly. Perhaps I can get him to lend me his for an hour to try it!!

I appreciate all the help and suggestions and would love any more advice or links to topics about the 96mm kit and running different injectors/computer/MPS!!

For now I need a few days to rebuild the TPS and test out my MPS!

Adam