Outer Limits 4x4 Board

Howdy,

Since fitting a Turbo boost gauge (unfortunately I have one that also measures vacumme) the needle has been rock solid, in that at idle the guage sits at zero, accelerate and boost goes up and so on.

Today, out of the blue, start the engine and at idle the boost guage oscillates some plus & minus 2 PSI but stabalizes when the engine is reved. Rev a little and the needle sits still at 0, under load I am sitting at about 9 PSI.

Back off and the needle go bezerk!! The guage is a good quality VDO hooked into the pipe beteen the inlet manafold and turbo. If the guage is accurate it appears that at idle there is fluctuating pressue which was not there before

Any ideas?? Hopefully not a turbo problem... anyone see this issue?

Cheers

Rainsey

Rainsey,
I take it youve plumbed this into the line that goes from the inlet manifold to the boost aneroid on the fuel pump?
Go and have a good close look at the full lenght of the tubeing from connector to guage,and from the T piece to the aneroid, check all connections etc , for damage, splits worn areas etc.
Check T pieces for splits/damage etc.
How much boost was it putting out before this problem started?
Or failing that what was the last thing adjusted/played with?

Also
check all the clamps , hoses and pipes from the turbo to the inlet manifold, all seating correctly and all clamps tight.

Guzzi,

Last thing I played with.... other than parts of my anatomy, the suspension... or acrurately lifting the body.

Re the tube, that was my thought as well. I have gone over it as close as I can for the moment... and yep you are correct as to the hose that goes to my fuel pump... placed a Tee in line with it at the manafold.

I am up to my eyeballs with work at the momenet so I will not have time untill the weekend, but I am considering replacing the tubing. My only thought was that if it was a minute split in the tube, it may be where it goes into the pump as prior to body lift, this pipe was rubbingon my seconday battery housing, post lift, there is 2 inches of clearence.

Re the boost.. still getting the same top end boost.... just the oscillations at idle.

Will let uyou know how I go.

Cheers

Rainsey

I have a MU with the 4JB1T engine.

My boost gauge does the same thing. Has since I installed it.
I know of another MU owner at least with the same issue.

I have to date not considered it something to be worried about.

It has got me thinking now though.

Jimmy.

Hmmm the plot thickens.

Happened to be dragged down to Sydney for a meeting so I stopped by Olymic Intruments and bought the correct boost gauge.. a 0 to 15 PSI unit.

Replaced the suspect guage and what do you know.. no oscillations of the guage.. but the same sound vibrations coming from it that the previous unit had.

My thoughts.... either something i have done or somthing with the donk is screwing with my manafold pressue. The fluctuations are still there as I can hear the poor boost gauges dampening mechanism having a hearnia. I beleive that my past guage gave up the will to live... I am waiting for the new one to do the same.

Not being a mechanic.. I am trying to figure out what could cause such variance in the manafold pressure.... stuffed valve maybe. Some time ago I had some preignition ( if you can call it that on a diesel) then it stopped as soon as it came. My original thought was that my oil rings were leaking and the leaking oil may be igniting... I have had no probs since then.

The guage issue has only appeared in the last 15,000K.

Watch this space ..

Cheers
Rainsey

At idle on my 4JB1T's Boost Guage it is sitting at about 1PSI all the time....When you rev it and it hits boost it goes all the way to just past 11 but not all the way to 12...

I never did end up seeing your problem Jimmy.

Kurt.

Gobbles,

At idle I have 0 PSI. No load and reving the engine I get probably 4 PSI. Driving with the engine under load I max out at 9 to 10 PSI.

Rainsey

I got the same issue as you gobbles

The gauge shows about 2 psi at idle the when under load on boost shows around 12 psi thinking this was a problem with the turbo (replaced 17k ago) i took it to the mechanic who said that the guage hasn't been set properly from the factory

my gauge also makes a vibrating sound... it was as annoying as hell until i got used to it over time. I plumbed mine into the alloy bridge across the top of the engine though.... i just drilled and tapped it 1/8" BSPT I bought a Pricol gauge, which is apparently Smiths budget line..... it works/worked great.