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[feeutfo]

I'd prefer a more aggressive servo anyway, if anyone has a sensible suggestion.

I realise this is not everyone's taste, but mondo levels of servo assistance suite me fine.
(ie, loads).


(sits back and waits for Markdtm's response . )





Relevance to the op might mean fixing his problem, if I understand things correctly.

[Andy H]

I'm by no means cirtain, but I think this is normal.

Is it to do with engine load? If knocked into neutral, there's less load, so less tick over throttle is needed to keep the same revs. Therefor less vacume in the plenum and vac pipe to servo, so less servo assistance. Or at least there's an effect on servo assistance, , my simple brain can't work out which way it would affect it ATM, as i'm knackered, but I often wondered what caused the pedal feel to change.

Normally less load means throttles closed therefore more vacuum in the intake plenum. If engine is being used for 'engine braking' then you get maximum vacuum. Knock it into neutral & the engine has to open the throttles a little to maintain idle so the vacuum will be less.

The servo should store enough vacuum for 3 or 4 brake applications (if the non-return valve is working).

[Lizzie_Zoom]

I'd prefer a more aggressive servo anyway, if anyone has a sensible suggestion.

I realise this is not everyone's taste, but mondo levels of servo assistance suite me fine.
(ie, loads).


(sits back and waits for Markdtm's response . )





Relevance to the op might mean fixing his problem, if I understand things correctly.

[Lizzie_Zoom]

I'm by no means cirtain, but I think this is normal.

Is it to do with engine load? If knocked into neutral, there's less load, so less tick over throttle is needed to keep the same revs. Therefor less vacume in the plenum and vac pipe to servo, so less servo assistance. Or at least there's an effect on servo assistance, , my simple brain can't work out which way it would affect it ATM, as i'm knackered, but I often wondered what caused the pedal feel to change.

That is interesting to me Chris.  You have confirmed what I thought was happening to mine during the problems I had recently with a missing "top hot" 'O' ring on my plenum, along with mis-firing.  I had a very noticeable drop in braking power, with the pedal needing to be depressed a long way down before the brakes bit.

I didn't know for sure if the leak in the plenum/drop in engine power would have that effect, but now I do. Thanks Chris

[Kevin Wood]

Normally if coasting in gear the engine is developing no power (overrun) so throttles closed and maximum vacuum. Suddenly put it in Neutral and the ICV will open to stop the revs falling, so it's plausible that you'd get a little less vacuum in this instance. Moreso if there's a defect causing a misfire or intake air leak.