insane_drummer

Hey everyone, I'm new to the forum, and I have a slight problem...

Alright to give a little background info:
My wife and I bought this 96 saturn sl2 about a year ago. Saturn has 114,000 mi.
About 3 months ago the car started acting kind of weird. I'm not sure all of what was going on at that time because I was extremely busy and my wife was driving it most of the time.
About a month ago time freed up a lot so I began looking into it.

The problem:
The car began to lurch and shake violently when accelerating. The car seemed to lose all kinds of power and could not get above about 60mph.
I was on another forum and they really helped me a lot, but they are stumped now too.

I replaced the EGR valve - no corrosion on plug
Check spark plugs - all good
Replaced ECTS
Checked ECTS connector with volt meter - good
Checked for clogged cat - good

I've narrowed it down to the problem being the EGR valve. When the car is running really rough - no power - horrible acceleration - shuddering and lurching - I pulled over opened the hood, without shutting the car off, unpluged the *note*brand new, electric EGR valve, got back in the car and all problems are solved.
With the EGR valve plugged in, any time you turn on the a/c everything just gets EXTREMELY crappy; however, with the EGR valve unplugged, acceleration is perfect, engine runs great, a/c works perfectly.

Any help/advice/suggestions anyone has would be much appreciated!
Thanks

bldegle2

sounds like it could be a short in the wiring harness, or..........

the computer is going bad......

this is one you may have to visit the dealer, or a very good independent repair shop.....

or you could attempt to try and do some electrical line testing, continuity check would be the simplest on the feed wires to the EGR valve....

other than that, maybe Ssicarman will drop in on your thread and offer some insight..

good luck.

laterz

__________________
97 SW2, sleeper w/tricks, 56mm TB, CAI, oil catcher, plasma booster, front/REAR strut braces, drilled/slotted front/REAR, Eibachs, KYB2's, 225/40/17, unorthodox underdrive, SPS short shifter. SPS poly suspension and True HID lighting the way....

scottyr94

First off are you throwing any codes? I would get those read first if you have the SES light on.

Sounds like an O2 sensor problem to me but I'm probably wrong.

insane_drummer

I took the car to autozone at the beginning and had them check for codes. None showed up.

nutjob

The ECM/PCM is receiving incorrect data to command the EGR valve to open at the wrong time. The question is what sensors are used by the ECM/PCM that determines when the EGR valve opens, length of time to keep it open, how far the opening, etc. Until you or someone can come up with a definitive solution you may be able to just block off the intake port of the manifold so there will be no interference of the EGR valve operating and drive w/o the erratic engine. Its a temporary band aid. There's quite few things going on to open the EGR valve with the built-in position sensor reporting the position of the valve to the ECM/PCM. Why its operating incorrectly must be from one or two other sensors incorrectly supplying data that in turn makes the ECM/PCM open the EGR valve. That will take some thought to come to some solution.

insane_drummer

Is there any methods of diagnosing what sensors could be causing the problem?
I'm open to doing some research, but I just don't know what direction to head in at this point.

nutjob

Here's a brief from one Saturn FSM; the ECM considers ECT, TP, MAP, IAT, RPM, and vehicle speed to determine an appropriate amount of EGR. You would have to examine and understand each components use, how it works, testing each individually or substituting, then driving to observe for any improvement to come to anything conclusive.

the Shaolin UWP

The EGR should never be opening under accelleration.

__________________

1986 RX7
2000 SC1
15.846 at 86.08 N/A
14.526 at 98.08 on the juice

Ssicarman

From the service manual. This is from a 98 but it should be (wiring etc) pretty much the same as your 96.

Exhaust Gas Recirculation (EGR) System Description

EGR System Operation
The exhaust gas recirculation (EGR) system is used to decrease the emission levels of oxides of nitrogen (NOX). NOX is a group of chemical compounds containing nitrogen and varying amounts of oxygen, which in large quantities, can have harmful environmental effects.

NOX forms during the combustion process in amounts that are dependent on the concentration of oxygen in the combustion chamber and the duration that the combustion process exceeds 822°C (1512°F). Decreased NOX levels are accomplished by reducing the peak combustion temperature through the dilution of the incoming air/fuel mixture with exhaust gas. Exhaust gas, largely non-reactive carbon dioxide and water vapor, reduces combustion temperatures because of lower oxygen content.

Correct amount of EGR depends upon the geometry of the combustion chamber and the operating condition of the engine. Too little EGR can yield:

• High NOX

• Spark detonation

• Engine overheating

While too much EGR can yield:

• Reduced engine power

• Engine stalling at idle

• Rough idle

The powertrain control module (PCM) regulates the amount of EGR needed under all engine operating conditions. The EGR system consists of the EGR valve and the PCM. The PCM bases EGR solenoid control off the following inputs:

• Engine coolant temperature

• Engine speed

• Intake air temperature

• Manifold absolute pressure

• Throttle position

• Vehicle speed

The EGR valve consists of a pintle valve that moves by the use of an internal solenoid and an internal pintle position sensor (potentiometer) used to determine pintle valve position. The PCM controls the solenoid by pulse width modulating ignition voltage whenever the EGR valve is commanded ON.

The internal position sensor is supplied a 5-volt reference and a ground from the PCM. The sensor varies resistance which changes signal line voltage used to determine actual pintle valve position.

Positioned at the top of the EGR valve are five terminals:

• A is solenoid ground.

• B, C, D are terminals from the PCM for the internal position sensor.

- B is sensor ground.

- C is sensor signal.

- D is sensor 5 volt supply.

• E is solenoid pulse width modulated ignition voltage.

EGR System Diagnostics


The PCM monitors the internal EGR valve solenoid (DTC P0403 and P1403) and position sensor (DTC P0405 and P01404) for low and high voltage faults. The PCM also monitors the EGR valve for a closed position error (P1404) and for a rational check of the valve position (P0404). A rational check of the valve position ensures the commanded duty cycle percent the PCM is commanding correlates to a correct position the sensor is indicating.

__________________
A lousy day in Paradise is still a day in Paradise.

insane_drummer

I just replaced the Engine coolant Temperature sensor a week ago.
Are there any sensors for intake air temp, manifold pressure, etc. that could be checked, or could this be a faulty PCM?