rpm's drop and idle is high

[lumberjak1984]

I have a lincoln ls v8 2001 99,000k and it runs smooth but occasionally at stops the rpm's drop to about 400-500 rpm's then goes back up and everything is normal like nothing happened. Also in park it idles around 700-800rpm's? i think it's kinda high Does anybody have an answer to my issues? Thank you.

[danielsatur]

How old is the EGR valve?

Check EGR gasket for leaks using statring fluid.

MCGIVER

[lumberjak1984]

Originally Posted by danielsatur

How old is the ERG valve?

i dont know. where can i find it on the car to check it out?...isn't it the egr valve???

[Quik_LS]

as your car ages the IAC valve wears. The IAC is the little valve the allows air to bypass the closed throttle plate so your car does not stall when sitting at idle. There is a little motor in it and it oopens and closes more/less as the PCM tries to keep the car at the target idle.

So the toughest condition it faces with when you are driving and then come to a stop - the IAC has to do a lot of work to compensate for the sudden loss of air intake. As it get older or is filled with the typical dirt and oil form the intake - the IAC reacts slower and you start to see stumbly transitions to and off of idle.

[danielsatur]

Thanks Guy!
I have cleaned my MAF,and all four oxygen sensors with CRC MAF cleaner.
I forgot the IAC control!

MCGIVER

[V Thompson]

I have a 2000 Pontiac fire bird and I'm experiencing the same problem. The RPM constantly goes up and down even with acceleration. I have changed the EGR value no improvement.

[danielsatur]

I would use Starting fluid,WD40 with straw to pin point possible Air Intake leaks,
if you find the leak the engine will tell you!

Hey! Quick LS ''his car runs''

Do you have simulator Oxygen sensors + Cats on this car?

I Have a blown cat on my S type JAG!

[V Thompson]

I'm not sure...I have someone working on my car and we are trying to pin point what's wrong with it. I had a diagnostic done it with the following messages. EGR VALVE STUCK OPEN..( I replaced it.
The PCm has determined that the catalyst sytstem efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank. (I have no idea what that means)

The PCM has determined that the voltage signal from exhaust gas recirculation sensor "A" is too low for the current engine operating conditions. (This sounds like I need to change or clean this sensor...any idea what this sensor is)

Last one...Malfunction indicator lamp circuit fault explanation: ECm has detected an improper voltage level on the MIL circuit with the light commanded on probable cause (1. Open or short circuit condition(2. Failed driver circuit in the ECM

Any Ideas?

[danielsatur]

V8 - Bank 1 = cylinders 1-4 (Passenger side)

Action taken:
1) Ramp/Jack-up Frnt of car.
2) On the passenger side crawl under car and pull both oxygen sensors out.
There's a pre + post sensor for the catalytic converter,and don't mix them up.
3) Tap on catalytic conveter - is it solid,or sound like a tin can?
4) Put a pieace of wire through oxygen sensor hole on the pre side.
5) If wire go's threw with no resistance,the brick is blown-out.

A bad oxygen sensor or bad cat can cause a low catalyst efficiency problem.

Are you still having a problem with EGR system?

Theres a Temp sensor for EGR system to tell how hot the car is.
The ECM will give the control signal to the EGR at the right time to Open/Close.
Theres also a feedback sensor that checks the EGR system.
Sometime the ports get block with EGR/PCV sluge. ''insufficient flow''

CAUTION -
If this car was running for awhile with bad EGR system,it could cause the
catalytic converter to go bad.

Aso a Hole in the Road or Speed bump can break down a CAT down too!

The suspenshion is very firm on Luxury Sport Sadans.

MCGIVER

[shorod]

It would help to know which engine your 2000 Firebird has to suggest the location of the EGR sensor, but probably more helpful would be to post in the Firebird forum. Let me know if you'd like me to move this post to that forum.

As for the cylinder bank identification, your v-style engine (either V6 or V8) has two rows, or "banks" of cylinders which form a V if you were to cross-section the engine block. Cylinder #1 will designate which bank is bank 1. Typically, if your engine is mounted with the belt and pulleys just behind the radiator like most rear wheel drive cars, cylinder #1 will be the cylinder nearest the pulleys on the left (as you are standing in front of the car/engine looking at the engine. On a transversly mounted engine (typical of a front wheel drive) bank one will be the bank next to the firewall.

-Rod

Originally Posted by V Thompson

I'm not sure...I have someone working on my car and we are trying to pin point what's wrong with it. I had a diagnostic done it with the following messages. EGR VALVE STUCK OPEN..( I replaced it.
The PCm has determined that the catalyst sytstem efficiency for bank 1 is below threshold for the current engine operating conditions. (Bank 1 identifies the location of cylinder #1, while bank 2 identifies the cylinders on the opposite bank. (I have no idea what that means)

The PCM has determined that the voltage signal from exhaust gas recirculation sensor "A" is too low for the current engine operating conditions. (This sounds like I need to change or clean this sensor...any idea what this sensor is)

Last one...Malfunction indicator lamp circuit fault explanation: ECm has detected an improper voltage level on the MIL circuit with the light commanded on probable cause (1. Open or short circuit condition(2. Failed driver circuit in the ECM

Any Ideas?

[V Thompson]

Hey,

Thanks for your replies they were very informative and I will pass this info unto the guy that's working on my car.