Having read the guide on buying a Z it appears my car has a problem! :(

When I accelerate the boost guage blips to -3 then goes up to +9 (normal)

I did this about 20 times on the Mway yesterday and I got the same thing.

On idle the needle sits at 0!

When I take my foot off the accelerater after boost the guage reads -5 and the goes back to 0! remains at 0 on normal driving, again on acceleration the guage blips to - then to +psi.

My engine runs smooth with no whines or funny noises, no smoke, no turbo noises, starts first time, oil pressure +50 running to +15 at idle.

The guide says Ive got a problem! :( :(

Engine replaced in Aug 03. I have had no problems with engine.

Can someone give me a clue please.

Arthur

I presume your gauge is in psi ?

 

It sounds like you have a vacuum problem somewhere.

However this could be as simple as a small crack or puncture in the small hose that runs to the MAP sensor that is used for the gauge

Any hissing sounds when idling ?

 

-Eric

Hi Eric

No nothing. Where is the MAP sensor?

Arthur

Excuse me if I'm talking b*****ks, I'm not an expert on the z turbo plumbing. But most other road / race cars I've come across this is normal. When you open the throttle the compressor represents a constriction in the inlet tract until it starts spinning, so you get a negative pressure (a vacuum) then positive boost as the compressor starts to do it's thing. Turbo chargers spin on load, not on rpm. Zero boost at idle is normal too. The -5 on lift-off I am not so sure about, but I have seen a similar thing if you lift off abruptly. Is it a standard boost gauge you are running? I had an undamped aftermarket boost gauge on a Mitsubishi that danced around like nobody's business when you went on and off the throttle aggressively. Just my two penneth!

Most boostgauges also show vacuum..

during idle the boost gauge should be indicating at least -9 psi (on a psi scale).

 

 

anyway..the MAP sensor (aka boost sensor) can be found on the passenger side near the bulkhead. (see section EL, page 109 in the service manual.)

 

the hose runs from the balancetube to a t-piece and then along the bulkhead to the MAP sensor.

 

-Eric

 

 

Excuse me if I'm talking b*****ks, I'm not an expert on the z turbo plumbing. But most other road / race cars I've come across this is normal. When you open the throttle the compressor represents a constriction in the inlet tract until it starts spinning, so you get a negative pressure (a vacuum) then positive boost as the compressor starts to do it's thing. Turbo chargers spin on load, not on rpm. Zero boost at idle is normal too. The -5 on lift-off I am not so sure about, but I have seen a similar thing if you lift off abruptly. Is it a standard boost gauge you are running? I had an undamped aftermarket boost gauge on a Mitsubishi that danced around like nobody's business when you went on and off the throttle aggressively. Just my two penneth!

Will check this out tommorow Eric

Will check the manwell and get an idea of it!

Arthur