sensor question

[1mattrichert]

What do the IMAP sensor and Delta P sensor measure exactly?

[Matt]

IMAP is boost pressure and the delta P or EGR Differential Pressure sensor measures EGR pressure into the intake.

[Rawze]

Like mentioned above, the IMAP (Intake manifold Air-pressure temperature sensor) measures both boost pressure AND intake air temperature. The accuracy of this sensor is absolutely critical towards efficient engine operation. The less accurate it is, the more it will throw off cylinder pressures, fuel-air mixture, timing, and a bunch of other stuff all at once. It also effects how the turbo operates. If it gets bad enough, it results is fuel mileage loss, power issues, excess soot, incorrect cylinder temps, etc. -- leading to repeating emissions issues and can cause turbo problems too.

The Delta-P sensor lets the ECM know how much EGR gas is being put into the intake. When it reads wrong, the engine uses too much EGR and makes for excess soot, lower fuel mileage, egr valve problems, repeating emissions issues, etc. It can also cause derates, power loss, and hesitation in throttle response.

The sad part is when considering what they do and the problems they can cause, is that almost no OEM repair shops will even bother to replace them as a preventative measure when someone complains about dpf and other emissions and/or power related issues. Instead, they will replace EGR valves, turbochargers, and DPF cans, because that is how they are trained. They are trained to sell you the most expensive components and patch the problems only long enough to get you out of their shop short term. There is no money in the cure, but only the treatment.