I have finally managed to get my 4AGE engine running, after sorting out the timing etc.

The problem i now have is that, when i start the engine it revs like crazy (estimated about 5-6000rpm). I have connected up all the various sensors etc but cannot get it to idle at all. It is as if the throttle is stuck open, but i have checked the big butterfly and it is closing properly. Some of the vacuum hoses are not connected, but i wouldn't have thought that would cause the engine to rev like that?

It is running smoothly enough, but with no exhaust apart from the manifold it is quite noisy at 5000rpm

Anyone got any ideas?

BTW - Has anyone got a design for a revised inlet plenum, to clear the bonnet line?

[Edited on 8/7/04 by albertz]

Check that the throttle position sensor is moving with the butterfly and that all connections to it are secure.

I'll have a think if there is anything else.

Don't know the 4-AGE, but if you have any connections that are open when they should be closed (e.g. vacuum hoses) then the various engine management sensors will be badly affected.

Good luck!

David

Albertz

If you have vacuum hoses etc. disconnected then there is a strong probablity that the engine is sucking un-metered air. This will have a similar effect to the throttle being stuck open hence the 5000rpm.

Thanks guys, i will try and block off all the vacuums. I did unscrew the throttle position sensor last night, had a little fiddle with it (the sensor!) and put it back on. When i took it off is seemed to be under a bit of spring i.e. it rotated from say 12.00 o'clock to 11.00 o'clock. I didn't actually check that it was moving with the butterfly but i will check tonight.

Any other ideas welcome.

Cheers

Albertz,

What sort of plenum do you have? If it's the later large port jobbie I might be able to get my Dad to Tig weld it for you.

Well i actually have both. But the engine that i intend to use is the TVIS version, basically because its the lower mileage one.

The scuttle/bonnet/nosecone setup that i have only requires me to lower the plenum by about 2". I was hoping to be able to modify the TVIS plenum, i know that it is tapered but i was hoping to make the alterations before the tapering starts - if that makes any sense. I havent really studied it too much yet.

The non TVIS plenum doesn't match up with the cylinder head on the TVIS engine(i have been informed), therefore this would require either an adaptor or changing the cylinder head as well (which i dont really want to do).

PS - paulbeyer, i have sent u a U2U message.

If it's reving high, even under zero load, it must be getting enough air to do so. Any problem with throttle pots or other sensors can only add additional fuel. This wouldn't be enough to give the effect you describe above.
As mentioned up the thread a bit, block off all the various holes in the inlet tract, because air is air - regardless of how it gets into the engine.

It's almost certainly the vacuum connections, we had the same issue with Bob's car when we first started it. You need to cap the tubes, not loop them together - some are open to the air and others open into the plenum. The bottom ones that pass air during a cold start, where the coolant hoses feed, are probably the culprit.

HTH!

Right, I now have a few definite things to check tonight. It sounds as if it must be linked to excess air.

BTW - Does anyone have a diagram showing the correct locations of the vacuum hoses? I have had most of them off at one time or another.

Thanks for all the help, i will give an update tomorrow.

Edit - I checked all the vacuum hoses tonight and it appears that the big hose to the servo was hanging open ended in the engine bay, so i clamped it with vice grips and started the engine.........success, it fires up and then dies down to a decent smooth idle.

Thanks for all the help. Result.

[Edited on 8/7/04 by albertz]