Boost question

[framey]

Hi,
I just fitted a boost gauge (finally) to my car (92 3rd gen), and noticed that it spends most of the time in the vacuum(yellow) as opposed to the pressure side. Maybe up to 20psi. When I am accelerating, it goes to the pressure side.
Cant really comment on the vacuum side of things as I\'m still running in, but I have seen it going past the 5 psi position.

I ask this because I seem to have a terrible problem with some major hesitation at around 1/4 throttle position (irrelevant of rpm).

I\'m taking it to Pip in the new year, but wondered if anyone else may of had a similar problem.

btw it\'s an automatic.

Anyone help?
Thanks
here\'s a piccy of my boost gauge

[framey]

Just noticed the yellow range is in inches of mecury - what\'s that all about?

[Martiny]

mm of Mecury is the Standard way of Measuring vacuum.

I have the same gauge by the way.

Seem to me the gauge is behaving normally. When you are idling or even on part THROTTLE, thats exactly whats happening, you are THROTTLING the air intake to the engine. The engine is willing to suck in much more air, but we restrict it so we can control it!

Therefore, vacuum. Up to 20 is very good, it should be around 17 at idle ( in the yellow)

[framey]

OK - cool. So maybe the engine is behaving normally. I\'ll see what pip has to say about the other problem.

Thanks Martiny

[Martiny]

Yes I dont think the other problem is related to boost or vaccuum.

Actually, to expand on my previous post, the Vacuum, you can imagine causes a load on the engine, sometimes described as "pumping loss".

I think there are some ideas around to reduce this lost energy somehow, wasnt that part of the idea behind Mazda\'s "Miller cycle" engine, anyone?

I also think there was some technology to reduce it in the Rotary as well??  Anyone at all?

[zevans]

Hesitation on part throttle, cruising, is usually O2 / lambda sensors...

[Ricco_04]

Originally posted by zevans
Hesitation on part throttle, cruising, is usually O2 / lambda sensors...

Could these sensors cause the car to shudder when pulling away and accelerating at low revs (especially if crawling along, gear engaged (clutch already up) and then throttle - no matter how carefully it is applied)

[zevans]

Crawling in traffic you mean? Erm... dunno. Think so.

Do you have a standard flywheel?!

[Ricco_04]

Yeah mate, all standard. Except the back box which I had to get as some of the old one fell off and rolled down the road!!! :rollin