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Pontiac Firebird 1995
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Discussion Starter · #1 ·
Hi Guys its me again,
when I bought my 1995 3.4l V6 Firebird a few months ago, I´ve noticed on the way back home that the SES-light had turned on.
I was kinda suprised that the light did come on, because before buying that car i did a 40 Minutes test-drive on nearly every circumstances and the light stayed off as it should be.
Back at home Ive fixed some other Problems that the Car had like an Valve-Cover leak and an Transmission-Seal leak, ive also changed the Engine Oil and Filter as well as the Transmission Oil and Filter as well as the Air-Filter and the Gas Filter.
While working on the Intake Mainfold and changing the gaskets ive noticed that an Vacum line was broken, so ive replaced that and the PCV-Valve line was missing too so i build an new one connecting it to the Intake as it should be.
Ive also resetted the SES-light and did some Test-Drive and the SES-light stayed off so ive thought that the Problem was solved.

This weekend i went to an Restaurant with my Girlfriend and took the Highway, Ive noticed that the SES-light always turns on when im driving for longer then 10 Minutes or so 60 Mph or more then that. After turning the Engine off and restart, the SES-light stays off as long as you dont drive over 60Mph or more, for some time.
The Engine runs greats and Idels normal, only sometimes when the car is cold and you start the car and rev it in neutral or Drive it sounds like the Engine stalls but then it gets it self together and everyting looks normal and it dont stalls again while reving it up.

Ive looked into that Problem here in the Forum and some say its maybe the EGR-System so ive thinking about taking it apart and maybe clean it if its clogged up?
Also ive been thinking about to scan the Car for trouble Codes but the Guys here wants 100€ just to check for codes so maybe im going to check them by myself if possible?

I would really appreciate any help from you Guys!

Thanks a lot!
Acelino :)
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Scan the PCM for codes to determine what turned on the SES light. It requires an OBD-1 scan tool, or GaryDoug's free scanning software.

The 1995 V8 has an OBD-2 style 16-pin DLC (data link connector) and requires a hybrid cable to connect. I don't know if the 1995 3.4L V6 is the same.

The factory service manual (FSM) describes the various codes, and provides a step-by-step logic table to help identify the source. Have you downloaded a free copy yet - courtesy of GaryDoug ?

 
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Pontiac Firebird 1995
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35 Posts
Discussion Starter · #3 ·
Hi Fred and thanks for the fast reply,

no i did not download GaryDoug´s scanning software yet but going to do it this afternoon. How does the software work? I mean i need a connecting cable from the car to my Laptop right?

Thanks a lot!
Acelino
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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14,355 Posts


With regard to the cable, you need to verify the design/number of pins in your data link connector, as noted in my post above.

If you need help with the software or cable:

@GaryDoug
 

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Pontiac Firebird 1995
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35 Posts
Discussion Starter · #5 ·
Hey Fred,
thanks a lot!
going to look into it this weekend!

Have a nice day!
Acelino :)
 

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Pontiac Firebird 1995
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35 Posts
Discussion Starter · #6 ·
Hi Guys,

this Weekend I’ve looked into my EGR System and I found out that something is broken, I don’t actually know how to name that thing but I guess it’s an electromagnetic valve or something similar to it. Anyways that thing is broken so I’ve ordered an new EGR System from Rockauto, could that be the problem causing my SES-Light to turn on?

228841

228842
228843
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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That is the EGR valve. It consists of three electronically actuated pintle valves that are operated in various combinations under certain engine operating conditions to reduce combustion chamber temperatures. Exhaust gas is introduced to the combustion chambers to displace part of the air/fuel mixture, and reduce combustion temperature. High combustion chamber temperatures promote the formation of NOx - various oxides of nitrogen. These gasses promote the formation of chemical "smog".

A problem with the EGR system can be the cause of the SES light only operating under certain driving conditions. Combustion temperatures elevate when you place the engine under heavy load at low RPM for example Cruising at low RPM in a high gear, pressing the accel pedal to climb an incline, without downshifting = "lugging" the engine.

The diagnostic for exhaust gas flow is looking for small changes in intake manifold absolute pressure (MAP) to confirm the valve has opened and exhaust gas is flowing. The diagnostic can only be run if speed, throttle position, and engine RPM are relatively steady. And, EGR is not used at wide open throttle, or above a certain RPM. That might explain why you only saw the SES light come on under limited driving conditions.

The only way to know if it's actually the EGR system that turned on the SES light is to scan the PCM for codes. Replacing the valve in this case, without the codes appears to make sense, since it appears to be "broken". But there is no guarantee that will solve the SES problem. My approach strongly favors using the diagnostic tools BEFORE buying parts.
 

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Pontiac Firebird 1995
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Discussion Starter · #8 ·
That is the EGR valve. It consists of three electronically actuated pintle valves that are operated in various combinations under certain engine operating conditions to reduce combustion chamber temperatures. Exhaust gas is introduced to the combustion chambers to displace part of the air/fuel mixture, and reduce combustion temperature. High combustion chamber temperatures promote the formation of NOx - various oxides of nitrogen. These gasses promote the formation of chemical "smog".

A problem with the EGR system can be the cause of the SES light only operating under certain driving conditions. Combustion temperatures elevate when you place the engine under heavy load at low RPM for example Cruising at low RPM in a high gear, pressing the accel pedal to climb an incline, without downshifting = "lugging" the engine.

The diagnostic for exhaust gas flow is looking for small changes in intake manifold absolute pressure (MAP) to confirm the valve has opened and exhaust gas is flowing. The diagnostic can only be run if speed, throttle position, and engine RPM are relatively steady. And, EGR is not used at wide open throttle, or above a certain RPM. That might explain why you only saw the SES light come on under limited driving conditions.

The only way to know if it's actually the EGR system that turned on the SES light is to scan the PCM for codes. Replacing the valve in this case, without the codes appears to make sense, since it appears to be "broken". But there is no guarantee that will solve the SES problem. My approach strongly favors using the diagnostic tools BEFORE buying parts.
Hi Fred,
thanks for your reply.
Its always amazing to see how much you know about these cars.

Since one of the valves is broken, I will have to replace the EGR-System. In addition, someone has already screwed around the EGR-System and torn off a screw. There were also missing seals which led to the system leaking and the smell of exhaust gases in the engine bay.

I am also in favor of reading out the codes first and the replacing/repairing parts, but here in Germany it is not so easy to find a company that can read out the codes.

In two weeks I have an appointment with a company that can / will read out the codes for me. Before that I will install the new EGR-System and see if the error still occurs.
The Company that can read out the codes is unfortunately 1.5 hours away :)
 

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1994 Firebird Formula 381ci LT1 / TH400+GV O/D
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Free scanning software specifically for your car, written by GaryDoug, our resident electrical engineer. You just need to build or buy a cable.


You record the data, I interpret it for you. Note “DTC” tab for diagnostic codes.
 
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Pontiac Firebird 1995
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Discussion Starter · #10 ·
Free scanning software specifically for your car, written by GaryDoug, our resident electrical engineer. You just need to build or buy a cable.


You record the data, I interpret it for you. Note “DTC” tab for diagnostic codes.
Hey Fred,

definitely going to do that as soon as i get an Diagnostic Cable!

Thanks a lot! :)
 
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