Chucks928

Well....after chasing my tail with my 1982 928,I think its time to look at options. I have a few threads on here regarding this car and my getting it up and running and then chasing a rough running issue. I had checked compression originally and the numbers were not terrible...not great but still usable. That was last fall and on the advise of folks on here I re-checked my numbers again this past week. With a newer test gauge my numbers were not good.....120s to as low as 90 psi. Ouch...... verified timing and rechecked with same results. Adding a tbs of oil to each cylinder resulted in numbers rising to 160s to low 180s.....looks like the rings are shot. Soo... time to honestly look at my options....parts it out, suck it up and pull the engine and rebuild or hope to find a decent , affordable 4.5 that can just drop in and go.This car is solid but needs interior and electrical work....nothing extremely hard but add on the cost of an engine rebuild and the time to do all the work,then I have to seriously think this through. Any thoughts on rebuild costs on these engines? Or even the cost of a good,used engine? I,ve gone as far as rebuilt top ends,heads,cams and such,but never a Porsche or ever had to pull an engine. I guess i have the time and patience to do this but dont want to get way upside down on costs vs value. Any thought are appreciated. Chuck.
ps....car is an 82 US car with an auto tranny.

dzaprev

Hello, I have a 83 4.7 and 82 4.5 motors that have great compression. 850.00 PM me if your interested. How much would you sell yours for if you want to sell your car.

Kiln_Red

Have you checked the .4 and .6 ohm resistors at the left front of the engine bay? Temp II sensor and Aux Air Regulator? The AAR can be bench tested.

This one might sound nuts, but I have found it to be relevant for AFM 928 diagnostics. Pull the fuel pump fuse and start the car. Does it start and idle smoothly? If so, how long will it run this way?

docmirror

Unless the engine has 600,000 or more miles on it I seriously doubt you have a ring compression problem. If it runs, get it out on the road, and put 100 or so miles on it. Run it hard, run it long. I would be willing to bet your Comp test would show good again. You need to get some heat and circulation in the engine for a while. Then, after that if you still have low numbers, decide on what you want for the long run. If it's a 5sp, and an interesting color, I would say keep and restore. If an auto, and black, white, or silver then decide based on that lower value situation.

Chucks928

kiln, havent checked those resistors..not sure what they are? Temp sensor is good and I,ll be pulling the aar to check . I,ll try the fuel pump fuse and see what happens.
Chuck

Chucks928

Doc.. interesting. The car hasnt been on the road since purchased 2 yrs ago but tested fairly decent back then. Maybe some hard running will bring the numbers back to somewhat normal. Chuck

AirtekHVAC

Run it! They will pump back up! You would be surprised....my 78 sat for over 20 years, 79 for 12, 82 for 16....all 3 run good now and only getting better!

Kiln_Red

AAR Testing:
https://rennlist.com/forums/928-foru...ork-video.html

Ballast Resistors:

Chucks928

Thanks for the help folks! The car has pretty much been limited to idling since 2015 so a good stretch of running may be what the Dr ordered. With everything that I,ve checked and fixed or replaced it should be a nice running car. I,ll run it and see what happens. Chuck

Chucks928

found the resistors...apparently they are there as ballast resistors. What are the symptoms of 1 of them failing? On my old Plymouth,when the ballast resistor craps out, it doesnt start.

Kiln_Red

I haven't actually experienced failure of one or both of the ballast resistors. Some have reported that they will smoke from overheating. I have had experiences with bad and/or damaged connections, and expected performance issues. Stumbling idle, unburned fuel emission, inconsistent throttle response, bad fuel economy, sooty tailpipe, etc.

Make sure that all of the connections are tight and clean, and that the wiring is in good condition. Don't underestimate a bad or dirty connection at the coil, too.

997TTEQNY

Save it man!

Like someone else said, drive it like you stole it for a week straight and go from there.

danglerb

Taking cars apart is fun, selling the parts the opposite, so I would vote against parting out its not practical as a one time event.

AirtekHVAC

Resurrected your original thread. Don’t give up yet....I have been in your boat! You’ll get there!

Chucks928

Thanks guys.... Honestly,I dont think I have the heart to part it out....and it has become somewhat an obsession! I will drive the car and see what happens!