Rough Idle, miss, dead spot in fuel feed....help

[paulmiller_98]

OK, I am no mechanic by far but I have worked on my own vehicles so far and just about have tackled everythhing even built my own engine a couple times, but here'e the trouble. My C-4, 1985 TPI Vette is giving me fits, I have changed the fuel pump, fuel filter, distributor cap, rotor, plugs and the TPS (which was giving me an error code by the way) cleared the codes and have a clean read out, but I still have a strong miss, (coughing) back when I try to accelerate, then the engine will kind of suddenly pick up and take off but still with the miss, sometimes, and it is becoming more frequent it will run smooth, but still only for a short spurt. There is a tap in the distributor, I am sure it is there, but I have checked for bad wires, and I think if it were the coil or the control module I would have a no run situation, am I right?
Anyone have this problem before, and where should I start? I did scribe where the TPS was but am going to check the voltage tonight after work, to insure it is correct. I know it can't be very far off though.
I have run a can of Seafoam through the fuels system as well (thought it could be water since I am in Florida) (and we have had plenty of water lately).

 

[MoeJr]

I believe 85 had a Mass Airflow Sensor. Try disconnecting it and see if it runs better. These tend to go and make the car run terrible. U can always tap on the MAF and see if the engine stumbles. If it does it is no good.

 

[paulmiller_98]

OK, tried the Mass Air Flow sensor, the idle did get worse. What if you cannot get .54 volts out of the TPS, I turned it as far as it would go and I could only get .50 volts. Then I ran the car and took the computer readout again and got a 33, 34 which is the MAF and MAP. Does this mean I ECM?

 

[bradfordsvettes]

the tps will probably fly but is slightly low sounds like it may be time for relays or a maf sensor steve

 

[MoeJr]

If you can only get .50 out of your tps the either it is too far back on the perch or the idle air screw is not set correctly. Sounds like it needs to be set up for minimum idle air rate.

 

[paulmiller_98]

Yes, I did try and reset the idle, just to get it to run. One thing, I did forget to clear the codes after unplugging the MAF so that is where I got the codes for the other reply. sorry. After clearing the codes, I got the three 12's then nothing but three 12's.
Thing is this morning, I decided to drive it to work so I might get a pro test on the emmissions, as I was leaving the drive, I barely made it to the road. Stopped at the golden arches for breakfast and pulling out... full power, full throttle, and on the highway, screamed! Like 80 to 110 in seconds! I don't get it, this might be an intermittent problem here.
Still I can't ignore that tapping sound in the distributor, never heard that before. Maybe the coil arcing, I'm not sure at this point.

 

[CaptainBlue]

Hello, Just some thoughts, you can check your coil with an ohm meter, but have you check your fuel injectors specifically your cold start valve?

 

[vette-dude]

Have you changed the sparkplug wires? They may be arcing to ground causing the tapping sound and susequent miss,dead spot. My was doing this and the plug wires cured the problem.


Randy