p38 4.6 engine wont stay alive after starting.

Dorset Ranger · Aug 21, 2018

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.

wammers · Aug 21, 2018

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

Dorset Ranger · Aug 21, 2018

Tried that no dice

Dorset Ranger · Aug 21, 2018

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

wammers · Aug 21, 2018

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.

Is that with MAF connected or disconnected?

Dorset Ranger · Aug 21, 2018

Both!

wammers · Aug 21, 2018

Dorset Ranger said:
Both!

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

Dorset Ranger · Aug 21, 2018

No, symptoms are the same with it connected or disconnected

Saint.V8 · Aug 21, 2018

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

Dorset Ranger · Aug 21, 2018

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

wammers · Aug 21, 2018

Saint.V8 said:
Idle Air Control Valve??? Split induction pipework/ducting???

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

Dorset Ranger · Aug 21, 2018

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)

wammers · Aug 21, 2018

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)

That will be the idle control unit.

Dorset Ranger · Aug 21, 2018

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

wammers · Aug 21, 2018

Dorset Ranger said:
Would make sense to me given the fluctuations. Easy fix to replace?

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

Dorset Ranger · Aug 21, 2018

Just swap it out then?

wammers · Aug 21, 2018

Dorset Ranger said:
Just swap it out then?

You could try cleaning it.

Dorset Ranger · Aug 21, 2018

Thanks guys, will give it a go

Dorset Ranger · Aug 21, 2018

Any idea how to undo the hose clips?

Dorset Ranger · Aug 21, 2018

Done it, bravery!

p38 4.6 engine wont stay alive after starting.

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