When my car idles, there is a small miss that I can only hear every 10 seconds, then when I rev the car to 2000 rpm, there is a miss every 3-5 seconds all the way until I hit around 4000rpm, but it only does this when i'm not in gear (only in neutral or park is when it will do it). I have new spark plugs, spark plug wires, and a new distributor that were all professionally installed along with the fuel pressure regulator, rebuilt motor, rebuilt tranny, no problems with the fuel pump. Is it just a normal thing for a turbo vehicle, or is there a spark plug that is fouled out?

 

A miss is not normal on any vehicle.

Are you sure that the plugs were gapped properly upon install? Also double check all the ignition work that has been done on the car. Might just be a loose connection somewhere.

 

Fuel injector may be clogged.

 

Sounds like a misfire from the ignition. Where as the each fuel injector fires twice per revotolution, each spark plug only fires once. If you're estimated time between misses is fairly accurate this would dictate a miss from the ignition rather than a fuel injector not firing. But that's just if it's a misfire. If it's something else then I don't know. A missfire is really hard to diagnose if you're not there. What you should try doing is pulling each plug wire from it's plug one at a time and checking to see if you got spark. If each sparks accordingly then its probably not ignition related. If that checks out, remove all the metal retainers from the fuel injector clips. Then one at a time, pull the injector connector slightly off its injector and see if that changes anything. If all this checks out ok, then its probably not a misfire at all.

 

Try replacing the miles of vacuum lines that Im sure your turbo has (if its anything like my N/A) When I did mine, I found more that a few that were on the verge of failing. Getting rid of vacuum leaks and electrical hiccups (fuel injector pigtails) has made my Z purr at idle, even when its cold.

 

Ya know... My car has had a little stumble in it for months now. I haven't been able to pin it down. It's mostly at idle, but it still seems to be running a little lean. All the vacuum lines are new, Fuel pump, regulator, Injectors were replaced about a year ago, plugs, cap, rotor, wire, distributor are all new. Maybe I should take all those brand new pigtails I bought a year and a half ago and actually put them in the car. For some reason I just haven't yet found the motivation to do it, but I have new connectors for the injectors, tps, etc... You might be on to something. Maybe I'll change them out and see what happens. They don't seem to be doing me any good stowed away in the passenger side cubby.


Rod.

 

Just make sure you solder all the connections and pack the back side of the connectors with dielectric grease before slipping some shrink tube ofer the back half of it and shrinking it. Clean all the contacts on the injectors and put more dielectric grease on them the keep the most destructive force on earth (water) out.

 

I forgot to say, I have all six new fuel injectors, new fuel pressure regulator. I believe the car is running a little rich, and where the tps connector is supposed to be, there is three prongs that are supposed to be connected, but instead there is two small little connectors that connect to only two of the prongs.

 

fix the throttle position switch first, the way its setup now its probably too rich or too lean because the computer either doesnt know the car is idling, or worse yet, the wires for full throttle are on the idle terminals of the switch and its way too rich.