Faster on part throttle than full

[Fenderer]

What does it mean when your chimaera seems to accelerate and pull better on part throttle than full ?

[bobfather]

Many things however my first thought would be fuel starvation, when was the fuel filter last changed?

[caduceus]

Also air filter, and the crappy OE hose (that can sometimes collapse) that feeds it. (If you have OE that is....)

[Fenderer]

That's got me thinking. I replaced the original disintegrated air filter with an aftermarket cheap cone filter, maybe that's restrictive. Good call on the fuel filter too, I don't think it's been changed in donkeys years.

[bobfather]

Cheap air filter could be the problem, these engines are known for drawing more air than standard aftermarket units can deliver. As said above, if the air filter is restricting flow then the long air pipe could be collapsing due to excessive vacuum

[Boosted LS1]

^ That's got me thinking. Vacuum is highest at closed throttle.

[bobfather]

Boosted LS1 said:

^ That's got me thinking. Vacuum is highest at closed throttle.

Normally aspirated induction is at highest air filter vacuum at fully open throttle. Engine drawing the greatest air volume through the filter, if the filter is restricted then the induction pipework will see high vacuum.

Vacuum in the plenum is highest at closed throttle. I guess it depends where you measure the vacuum

Edited by bobfather on Sunday 4th June 00:31

[Sardonicus]

Check your disintegrated original filter hasn't blocked the fine gauze in front of the hot wire sensor in the air mass meter itself easily checked

[Classic Chim]

The original air feed pipe can collapse just after the filter where it turns sharply in the nose of the car. Not easy to check on early cars and obviously looks fine when stationary.

[Boosted LS1]

bobfather said:

Boosted LS1 said:

^ That's got me thinking. Vacuum is highest at closed throttle.

Normally aspirated induction is at highest air filter vacuum at fully open throttle. Engine drawing the greatest air volume through the filter, if the filter is restricted then the induction pipework will see high vacuum.

Vacuum in the plenum is highest at closed throttle. I guess it depends where you measure the vacuum

Edited by bobfather on Sunday 4th June 00:31

Ah, yes. I see what you mean.