Engine misfires?

You might as well give it a major tune-up and see what happens-if not come on back and we''l get into the fuel and ignition system.

What I would do is complete the tune up as change the wires cap rotor and check the coil
which design u have for the coil is it in the cap or out
look for an oil leak in the distributor and the cap

distributor may be at fault too check it out

Hi frank1235,

Thank you for the donation.

The symptoms are consistent with an intermittently failing PGM-FI main relay. I would suggest removing it and resoldering the circuit board, this is a known issue.

Hi there,

When you say a dead cylinder, yes. It would make a huge impact on a 4 Cly engine, a faulty engine mount will normally show up during engine accelerations the torque of the engine will cause it to move on the fault mount, if the engine is running poorly (due to a faulty Cly) it will tend to shake a bit more, but this will depend on how bad the mount is.

Mark (mhpautos)

I would think so. You will see the engine jumping up and down when accelerating if engine mounts are worn out.

Have one of those exact autos. Had that same problem.

Replaced the IAC valve with no success.
Checked for low level on coolant.
Bled the coolant system of air.
Fiddled with vacuum lines.
The problem was resolved with a new intake manifold gasket.

Now your problem might be stemming from a different cause but I would wager than a look into those areas might fix the problem.

The manifold can be checked with a smoke bomb as they use in furnaces. Find the escaping smoke and you found the leak.

In order to do the work that they had to do, it was necessary to disconnect the motor mount. Did they get it hooked back up properly or was it bad? Another question along those lines is the motor mount bad on any other part of the car? Check the mounts out. I assume that they got the misfire fixed?

Two that come to mind are so simple that they should be very obvious. If fact, they are so obvious that you probably won't try them, but here goes. It is easy to put in new plugs but it is also easy to crack a plug. It will fire but not all the time. Another is a bad wire. They can look great, but manhandling wires can cause them to fail and they can fail such that it idles terrible but seems to run fine at high speed. It could be a valve but I would doublt that.

Once the belt was installed that is failed to fire? As I said no one believes the two areas. You would be surprised how often this happens. It has to be simple. The wrong person pulling on a plug wire and that wire will fire but not right. Installing and cracking a plug is easy, a lot easier that burning a valve. Did they get everything reconnected properly again after the install? The answer will be yes but to the next person that looks they will spot something that was not reconnected.

A misfire can be caused by a ignition or fuel problem. You haven't said the check engine light is on so I will assume it is not a engine management issue. Since you have change the most commom causes here are some things to look into. The coil, faultly ignition module. On the fuel side check for Dirty injectors, low fuel pressure, faulty injectors, and clogged fuel filter. Also check for a vacuum leak and a faultly ERG valve can cause misfires. If all of the above checks out then this leaves a compression problem due to burnt or bent valves or leaking head gasket. FYI a spark plug that has heavy ash deposits may indicate a coolant leak from the head gasket or a cracked head. A misfire can also be caused by weak valve springs or worn cam lobes, This can be detected through the use of a vacuum gauge.
Good luck Backyardmechanic?