Hello - i recently bought an 85 automatic corvette and am working thru some rough idle and no power at speed issues and i had some basic questions -
1 - Should the motor while running at idle shut off when i disconnect the MAF sensor at the MAF sensor? mine shuts down when i pull this plug.
2 - i think that i need to replace the fuel pressure regulator, but i am wondering what issues can be seen with the fuel pressure at #32 and the engine is idling? when the engine is off it is near 34 or 36 and it holds pretty well ... over ten minutes it went to maybe #32. I will replace the fuel filter first to see if this gets me to the #36 i think i need at the fuel rails. but i am wondering if #32 of pressure at the fuel rails will show up as an obvious idle issue or if it is rather insignificant. From what the manual is saying i should see #44 prestart and #36 while running.
3 - What is meant by having the timing 180 degrees off? Just found a post that i think explains this to me .. sounds like 180 off means that the timing is set so that pistons TDC is on the exhaust stroke vs the compression stroke which i dont see how an engine could run like this?
Anyway thanks for any information to help me understand more what i am describing here.

 

I think your engine should run with the maf disconnected.......FP needs to be checked with the vacuum to the regulator disconnected and vac line blocked...I think it should idle fine at 32 psi but you should replace that filter. Your FP leakdown test sounds good....if you are still low on the FP you might check the electrical, such as fuel pump relay, fuse and connections. Clean the connections and check voltage to fuel pump. There is also a sock on the fuel filter that can get clogged. The fuel pump is easy to access on these cars. It is under the fuel filler. As far as the maf thing goes, someone else should chime in on that one. Oh, and your right about the 180 off thing...engine will not run.

 

The engine should run with the MAF disconnected.

 

Thanks - I was pretty sure i had read many posts here saying that the MAF can be troubleshot by disconnecting it, so it seemed logical that it should stay running.
I am beginging to think that maybe the engine has the wrong Harmonic balancer or timing cover. Something isnt right but i am just guessing atm.
Some history - I bought the car with the engine cranking but not being able to even partially fire up. My initial solution was to redo the spark plug wires to the correct firing order and the car started right up but it idled very rough. I then changed out the spark plugs and wires and found the plugs covered in dry oil/soot(though they looked pretty new) and this made the car idle better(less missing) but the main issue is that when i try to drive it a block or two there is almost no ability to accelerate. If i let it idle it will limp up in speed but if i press the gas peddle at all it shudders hard and loses speed. I am not seeing any ECM codes except when i do something on purpose like stop the fuel pump or remove the EST connector.
Here is a tread where Joe C describes my problem to the T in the first paragraph - the main difference is i have not done any engine rebuilding like he has done. Maybe i bought his car .. haha. I have pm'd him but am waiting on a reply.
http://forums.corvetteforum.com/c4-t...like-crap.html
I am gonna give the advice in that thread a try and see if it resovles my problem.