Question:

My vehicle is vibrating and exhaust is puttering out while in park????

by | earlier

I hooked my scanner up and got a trouble code of P0400 ??? what could be the problem. This happened yesterday after we go off the freeway. My vehicle is 95 Mercury Grand Marquis V8.

Tags:

Report

Answer The Question I've Same Question Too

Follow Question

4 ANSWERS

Sort By: Date | Rating

A P0400 code indicates insufficient EGR flow. This could be caused by several things: restricted or carboned up passages, sticking pintle on EGR valve, or a problem with the vacuum supply to the EGR sensors.

The computer commands EGR operation and the Backpressure Transducer measures the pressure (or lack of it) to determine how well the EGR valve did in allowing EGR flow. The Transducer has several hoses going to it and this seems to be a common failure point in getting a P0400 code. So before you automatically assume that you have a bad EGR valve or carboned up passages, take a minute to closely examine the hoses going to the Exhaust Gas Backpressure Transducer. If you find on cracked or in bad shape, replace it. Also check to make sure all the hoses are attached to the proper port.
Report (0) (0) | earlier
Mileage? Color again White, Pinkish-Brown? Smell; Oily, Sweet, Oily Sweet? Oily Sweet & Pinkish-Brown= Transmission Fluid (Modulator Valve), Oily= Blow Head Gasket or Head. All will clog the EGR Valve.
Report (0) (0) | earlier
turn the tickover up a notch.

basically, your engine is HOT, so the air fuel mix is particularly weak, which leads to lower revs on tickover (park)

or its caused by a blocked / dirty air filter, and your poor engine cant breathe properly, coz on tickover, the induction is minimal, put your foot down and the induction sucks gallons of air, and everything is OK...

it could even be a dodgy oily plug, on a V8 you wont notice its on 7 cylnders until you put it in park, the revs drop and it splutters..

so, basically, give your car a service... ive been driving automatics for 25yrs, and we own a garage.
Report (0) (0) | earlier
EGR flow fault. Bad egr, bad vac line, clogged up intake, some possibilities. will give you the drivability problem you just described, as well.
Report (0) (0) | earlier