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Vacumn problem? (VS Ecotec)

Dan VS 231

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Ok so my car is running again after many hours in the shed and a bunch of new parts.

Now there seems to be a problem with a vacumn unit that mounts to the back of the manifold. The unit has two vacumn pipes that run under the manifold, one runs to the pollution canister up front and the other runs to the throttle body. The car is running rough after it idles down and seems to be pulsing on idle too. This unit is also pulsing and ticking something like an injector does normally (which are just reco'd so it shouldnt be them).

What is that unit and would it cause the car to run rough and what is it worth to replace? The revs intially were spiking badly when changing gears in the shed too but that seems to have calmed down now.

Cheers.
 

EREXON

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Id say the MAF (mass air flow) sensor. just before the air filter.
Dunno if this is a problem with holdens but alot of high performance vehicles seem to have MAF problems and this causing rough idle and the needle just keeps trying to settle down but just keeps jumping up and down running very rough.

Try pull the codes and see if anything is wrong and go from there?
 

hako

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That pollution canister you mention will be the purge solenoid - it 'may' be locked open allowing air to be sucked into the throttle body upsetting the idle. This should give a code 97. Gregorys has a test procedure which I can forward.
 

Surfwagon

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If you still have the original factory elbow where that vac line from the purge solenoid goes to the TB it may be cracked as they invaribly do with age.
The tube between the purge valve and TB is plastic (good) with rubber at each end and it's these rubber parts that perish.
 

Dan VS 231

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We did check all those pipes and changed the unit to tb line as we felt it was a bit short. A mate with a diagnostic unit came over last night and plugged into the port under the steering wheel dash but couldnt get a reading. He think it might only read certain model cars.

Also after more investigation we are thinking it might be the throttle position sensor as the revs still spike when changing from neutral to drive. Hopefully we can get the car in at his workshop today an run it up for a diagnostic. Because without computer help we are just looking and pointing and possible problem areas right now.

Thanks all for the ideas. Will soon find out more. Cheers.
 

Surfwagon

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The TPS is self positioning so even if you had changed your TB the TPS resets its idle and full throttle value once you restart the engine.
To make sure it is reset, turn on your ign without starting the car and push the pedal all the way to the floor and if someone is with you check that this is full throttle on the TB then release the pedal back to idle position and the TPS is reset.
 

Dan VS 231

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I guess we could check that one out tonight. Other than that it rules it out and its back to the drawing board.
 

hako

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Dan VS 231

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After much searching I finally found some wire to act as the paperclip and found the codes: 12, 64, 65, 76 and 97. The 12 came up first but I stuck around and got the others.

Code 64 - LH Oxygen Sensor Lean (O2)

Code 65 - LH Oxygen Sensor Rich (O2)

Code 76 - Air/Fuel ratio variation between left and right banks

Code 97 - Canister Purge Solenoid and/or Circuit.

Now the 64, 65 and 76 would explain themselves as if the LH O2 sensor is running way off like it is then there air/fuel mix would be different between banks.

The 97 is my original problem and now its confirmed. Any ideas on the cost of the unit from Holden and would I need to replace the canister or just the unit at the back of the manifold?

I have wanted to get new O2 sensors just because for a long time and it has been a bit rich lately. A new purge unit will also sort out the other code. Cheers for the advice all.
 

hako

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Try pulling it off and wash in a solvent - maybe petrol or injector cleaner and also double-check all vacuum lines and elbows as Surfwagon suggests. No use buying a new one when the old one can be cleaned. The Gregory manual outlines an electrical test on the actual solenoid.
 
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