Questions and Answers

Finding Intermittent Miss Q. How are you doing? Hope you can help. 1995 Chevy ½ ton pick-up, 350 cid, automatic transmission, A/C, 115,000 miles infrequently experiencing a miss, rather large at times. Generally occurring when vehicle is hot and accelerating normally through 55 mph. has occurred other times too.

Changed cap, rotor, plugs and wires thinking about the coil or distributor. What do you think and since I have your attention any tips on changing the distributor?

A. The thing about an intermittent misfire is you can throw a lot of money and parts at it and hope you fix it. This is not a very reliable way of trying to diagnose a problem and is very costly to boot.

Most intermittent problems are caused by faulty electrical connections or wiring. You should perform a careful check of suspect circuits for poor mating of the connector halves, or terminals, not fully seated in the connector body (backed out). Improperly formed or damaged terminals. All connector terminals in problem circuit should be carefully reformed or replaced to insure proper contact tension. Poor terminal to wire connection. This requires removing the terminal from the connector body to check.

If a visual/physical check does not locate the cause of the problem, the vehicle can be driven with voltmeter connected to a suspected circuit. An abnormal voltage when the problem occurs, indicates the problem may be in that circuit.

The best thing to do is check to see if any DTCs are stored in the computer. If not, then a road test with the scan tool connected will reveal the cause of the problem. Even if you have a shop do the scan for you, it will be less costly than throwing money under the hood.

Additional Information provided courtesy of ALLDATA