p38 4.6 engine wont stay alive after starting.

Hi guys,


My 1999 4.6 v8 (Thor) starts but almost immediately dies. here are some details, please help if you can!


1. The amount of time it stays alive for can vary from one to ten seconds.

2. The engine seems to run lumpy as I’m experiencing a lot of shake particularly as it dies.

3. The revs fluctuate and it runs below normal idle speed.

4. The battery is fully charged.

5. It has fuel!

6. Trying to increase revs once it fires seems to impound the problem.

Unplug the MAF sensor then start. If it runs and does not cut out MAF sensor is duff.

Tried that no dice

If its starts and stays alive, when i try to pick the revs up from idle, it kills it alomst straight away.

Dorset Ranger said:

If its starts and stays alive, when i try to pick the revs up from idle, it kills it alomst straight away.

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Is that with MAF connected or disconnected?

Both!

Dorset Ranger said:

Both!

Click to expand...

Does it stay alive with MAF disconnected until you press throttle? If it does the MAF is duff.

No, symptoms are the same with it connected or disconnected

Idle Air Control Valve??? Split induction pipework/ducting???

Just noticed a humm and vibration from the throttle body unit and adjoining manifold with the ignition on

Saint.V8 said:

Idle Air Control Valve??? Split induction pipework/ducting???

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Yep if the MAF checks out looks like he has a bit of work to do.

Actually it’s coming from the round cylinder that has the two hoses connecting to either side of the TBU (green BOSCH sticker on it)

Dorset Ranger said:

Actually it’s coming from the round cylinder that has the two hoses connecting to either side of the TBU (green BOSCH sticker on it)

Click to expand...

That will be the idle control unit.

Would make sense to me given the fluctuations. Easy fix to replace?

Dorset Ranger said:

Would make sense to me given the fluctuations. Easy fix to replace?

Click to expand...

Does it look like this? https://rimmerbros.com/Item--i-ERR6078P

Just swap it out then?

Dorset Ranger said:

Just swap it out then?

Click to expand...

You could try cleaning it.

Thanks guys, will give it a go

Any idea how to undo the hose clips?

Done it, bravery!