Outer Limits 4x4 Board

Weird thing, doesn't happen always, seems to miss as if on 3 cylinders, leads are ok, plugs are new, coil and dizzi cap changed. Can start it and runs great, go to put the foot down sometimes and it happens, may not happen, for half day, then as I select a gear down it may flutter & miss, whilst cruising all is fine, just seems to experience ignition or fuel problems sometimes when under load. Compression is good on all cylinders, motor in good condition. Maybe someone has experienced same....One guy recently mentioned Fuel pump regulator, not even sure where it is.....

I would pop the lid off your TPS (Throttle Position sensor) and see if its adjusted correct - don't make adjustments until you know how it works, its basicially just two switches in the form of skinny contacts.

When you are at idle, one switch is closed, it tells the ECU that you are indeed at idle (no pedal input) and to idle w/o using o2 sensor input - if this is adjusted incorrectly it can make your idle "hunt" (unstable idle).

The other is for full throttle - it tells the ECU the pedal is pushed to the floor or thereabouts - if this is adjusted incorrectly it can make your engine to weird things, cutout, overfuel.

Easy to adjust, but easy to break. You can get Bosch direct-fit replacements from old Euro cards (BMWs, Volvos, Saabs). A multimeter (one with a beep function is great) is needed to check continuity at the TPS sensor plug. It should be closed at idle on two contacts, and when you manually pull the throttle cable the other 2 contacts should close.

I will check out the TPS and make sure it's operating properly, will take time to study & learn more about how the TPS operates, many thanks for providing such a great reply.

TPS error will show as hunting at idle.....

Basically the ECU does not know its at idle and so hunts on the Lambda probe say...... +/- 200 RPM every couple of seconds.

Apart form unstable idle youy symptoms would be difficult to explain from a TPS error.

p.s. the TPS units are crap quality.