Thread: TD5 Inlet Manifold pressure

hoses are new, as is turbo boost modulator, MAF and loom. Sensors all seem to be ok as is wastegate valve...

Originally Posted by QLDMIKE

Mine did this on Fraser just recently. Spent $6 and replaced the three little hoses that go from intercooler hose, intake hose, wastegate modulator and all go back to that little modulator/sensor.

Problem solved.

Turned out one of them had a fine crack and was letting pressure out resulting in not enough pressure passing through to open the wastegate.

Originally Posted by B-A-S

For reference/advise.

The ambient pressure sensor is fitted in the air box to give the ecu the atmospheric pressure .
The inlet manifold pressure sensor is to give the ecu inlet pressure.

The ecu calculates the difference between the 2 and it then knows what the actual charge pressure is for injecting the correct ammount of fuel to match and able to alter/change with the boost modulator if fitted on some cars easy lol.

It ECU cant just relie on a sensor in the inlet manifold if it does not know what the outside atmosperic pressure is to take away from the actual seen manifold pressure so it uses both to calculate it.
It also uses this calcualtion for adjusting fuel and others maps depending on altitude which it can work out from the seen pressures.

There is abit more to it than that but from this you get the basics and my fingers are hurting now lol, and i dont type or spell to well either

Boost cut for the ecu is actualy 242Kpa, if you are hitting this then you have a charge pressure problem in most cases, or it coud be a bad raading sensor.
Normaly it is when the wastegate has been tampperd with it will give boost cut if over done.
Remember you can drive normaly one day and the next under some different load and ambient pressure you an hit boost cut.
So an ideal reading to see on th inlet side is actualy 220-225kpa as a mximium on a standard car.


Also its worth making a log of the car and see if there are any other sensors hitting a limit, the problem with nanocom is that it does not im my opinion record live or log as fast as some other tools so it can take time to work out the cause of a problem.

Pete

I know this post is old now, but normal inline and rotary injection pumps use an altitude valve to do the same thing, both turbo and non turbo.
One of the most common is in the Toymota 1HZ. You find them on just about every trayback Cruiser that does underground work or up in mountains etc.
For most general everyday hacks, they never really actuate and in most cases get removed if the pump gets overhauled as the diaphrams cack up and go hard from no use.
Basically it trims the overall fuelling to compensate for the loss or gain in ambient pressure.

Andrew.