long term problem C4
Thread Starter
5th Gear
Joined: Jan 2005
Posts: 5
Likes: 0
long term problem C4
I have owned my 1990 C4 for around five years now and have had several mechanical problems all of which I have been able to correct, untill now! For the last six months my 1990 has had an engine miss which I have not been able to track down or correct.I did the obvious things first, changed plugs (bosch +4) plug wires (accel 8mm) distribitor cap (accel) and rotor also accel and still the engine miss persists.I have next to none of the diagonstic equipment needed to go any further witht his problem so I consulted a friend of mine who is an excellent GM mechanic.We did some diagnostics on the car (hooked it to sun machine to check ignition system also checked computer to see if any codes were showing, visual check for vacum leaks etc.) all to no avail. Everything checked out OK.Later on I took the 1990 to a GM mechanic with more sophisticated testing equipment and he came up with nothing.Now I am at my wits end! I do not like dirving my C4 with this stuttering miss which is prevelant it seems through all rpm ranges.Anyone have any ideas on where to go from here?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
To start with, I am not a big fan of the +4 plugs. I would recommend NGK's of some sort.
As for the miss, it is quite possibly fuel related. You don't mention if the injection system has been tested. Fuel pump/filter/fuel pressure regulator/injectors themselves, etc.
Also, with a 1990, it is not impossible for a wiring problem to exist. Older wires are not as durable, nor are they as resistant to heat and such, I would think it is quite possible that wire(s) inside a harness are damaged.
As for the miss, it is quite possibly fuel related. You don't mention if the injection system has been tested. Fuel pump/filter/fuel pressure regulator/injectors themselves, etc.
Also, with a 1990, it is not impossible for a wiring problem to exist. Older wires are not as durable, nor are they as resistant to heat and such, I would think it is quite possible that wire(s) inside a harness are damaged.
