Hi All,

Well over the past few months I have had this strange issue happen with my 1993 ED Falcon GLi 4.0. Say If I don't turn it over and take it around the block for at least 24hrs when I do half way through the drive it starts missing really badly, it doesn't stall and gets me home. When I start it up later in the day and drive it again it doesn't miss a beat and runs perfectly. I have no idea what it could be, new leads, new plugs, new dizzy and rotor as well. Could it be the coil? Or could it be a vacuum problem? Considering it only happens when i have not driven it for a day or so its rather confusing. I only do about 5000kms a year in it to get me to work and back. Any advice would be great thanks.

Cheers,

MH

Its possible it may have a blown headgasket and water is seeping into the chambers whilst its sitting. As you drive it , it clears out..

No sign of oil in the water, no sign of water in the oil. Doesn't blow smoke. If I drive it everyday and it starts straight away (doesn't crank) then it drives perfectly....

Narrowed it down to the MAP sensor.....now to replace it and see how we go.

A MAP sensor usually causes idle and performance issues, not so much missing. If that doesn't fix the issue then read on.

If it is missing under acceleration it could be a number of things. As you basically already replaced most of the ignition, I'd say coil would be the next bet, although it is common for the coil to fail once warmed up, rather than after start up. This is the same for the TFI module.

It could also be fuel related. Check the fuel filter, a severely blocked fuel filter will cause issues with fuel pressure AFTER the filter...ie pump is pushing fuel through blocked filter and dribble comes out the other end...this will cause the line to take longer to pressurize, meaning miss firing under load as more fuel is demanded on a non pressurized fuel line. It could also be a stuff fuel pump unable to pressurize the line quickly.

Another issue could be electronic/battery/alternator related.
If a battery is dropping cells it can cause the electronics to go haywire. An ECU would require a certain amount of voltage to run properly.
Alternator could also not be charging properly. Slipping belt/stuffed alternator/broken rectifier can cause low voltage output. This could mean the alternator has enough to charge a battery OR run the electronics of the car, but not both. Lets say your alternator is stuffed and only putting out 13V, battery is semi flat (but not dropping cells) with enough juice to start the car. After using whatever is remaining in the battery, the car is relying on a stuffed alternator to run properly. Since the alternator will try and charge the battery AND run the electronics, things might go a bit weird in the electronics department until the battery has enough charge to help out the alternator.
You can also have a short some where causing a faster drain of the batteries, coupled with a bad alternator can cause electronic issues.
So check the battery, alternator charging output and if you can, connect a multimeter in series with the battery to see how much current is drawn when the car is just sitting (ie engine off, no keys in ignition, all doors/boot closed, no radio, etc).

Well hopefully that is a little useful...mind you I could also be talking out of my a***. To me though, it sounds reasonably logical!

Thanks phongus...I did forget to mention that it only runs on LPG so that could throw in a few whammies as well. Hopefully all will be good by Friday afternoon so will advise on how I go.