Tarago 1986 4Y-E Engine EFI, Rough Idle, stalls on acceleration.

[Crisby]

Hello,

This problem just appeared one morning upon starting. Idle is rough. Giving it the accelerator quickly, the engine stalls briefly, before reving up. Engine lacks normal power. Have checked all the plugs, and they are giving spark.

Is this a problem with air supply, or leaks?

I have recently installed a new cylinder head, and had the motor running fine, but the idle speed seemed to need adjustment. I could not set it to right idle speed and have the motor return to that speed after normal engine speeds. Then this new problem appeared.

Any ideas?

Cheers...............Crisby

[litldv8]

just 1 - 1uzfe

but i am betting on a air leak

[Crisby]

It may well prove to be air leaks, or a rat's nest in the air filter box!

What has also come to my attention, with this problem, is a very noisy "swooshing" sound from the fuel rail, when I have the ignition on, and hence, the fuel pump working. I have never noticed noise there before. I have done a lot of work on the fuel system, previously, and usually I have to strain my ear to hear if the fuel pump is working (engine off but ignition on). Could air be in the system? Or water?

Also new is an indication of a fault with the Oxygen sensor circuit, according to the Self Diagnosis Mode.

Can these things be related to my problem?

Crisby.

[Crisby]

Hello, More Ideas...

Would a defective Coolant Temperature Sensor be affecting the Idle, and the low engine power? Anyway, I broke the Sensor off while trying to fix this problem, but maybe it was rotten anyway?

[Hen]

It sounds like it might be a vacuum leak. That'd be what I'd check for first.

I strongly doubt the coolant temp sensor would cause such a problem, it's old school EFI after all.

Hen

PS - you can also try crimping off any suspicious vacuum hoses and see if things improve when you block one. Just be careful if they are old and brittle.