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EGR bypassed?

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Old 05-22-2016, 04:24 PM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
EGR bypassed?

Can someone of you guys tell me if is this the original wiring of this EGR? Connected Tunerpro, no 12V on it. When in closed loop the car wants to stall, even in gear or N. Can the EGR be the cause of this issue?
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Old 05-24-2016, 05:08 PM
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Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Those crimp connectors aren't factory. Looks like someone tried to fix a melted-wire problem.

An open EGR valve is usually more likely to cause an idle problem.
Old 05-24-2016, 10:43 PM
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Car: '87 IROC
Engine: LB9
Transmission: TH700R4
Re: EGR bypassed?

The EGR should have 12v on the brown wire with the key on. The brown wire is fused with a 10-amp fuse. If you're not getting 12v, I'd first check the fuse.

The way the EGR valve works is the ECM will ground either the brown/white wire, the red wire or the blue wire (or any combination of the three). This opens either one, two or all three of the valve pintles allowing exhaust gas to enter the intake.

I would unplug the EGR valve and see if the engine still stalls in closed loop. This would either confirm or eliminate the cause of the EGR valve being the cause of your problem.

If the problem still persists with the valve unplugged, you can always remove the valve and visually examine it to see if the any of the three valve pintles are stuck open.
Old 05-25-2016, 03:31 AM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
Re: EGR bypassed?

Thank you guys, I' ll check asap. Where can I find the EGR fuse? I bought a brand new EGR, the problem still persist. But checking the wires I noticed some strange things. I' m going to update you very soon!

How can I verify if the chip has been eventually re-burned?

Last edited by Firebird2011; 05-25-2016 at 10:22 AM.
Old 05-25-2016, 12:40 PM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
Re: EGR bypassed?

Ok, drove the car for about 20 mins, EGR disconnected. Stalls again. No code from SES. Funny how I get 12V from the D wire, instead of the brown on!!! Is this normal?

I think that someone rewired the connector badly, isnt' it?
Old 05-25-2016, 01:02 PM
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Car: '87 IROC
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Transmission: TH700R4
Re: EGR bypassed?

Originally Posted by Firebird2011
Ok, drove the car for about 20 mins, EGR disconnected. Stalls again. No code from SES. Funny how I get 12V from the D wire, instead of the brown on!!! Is this normal?

I think that someone rewired the connector badly, isnt' it?
I don't know what "D" wire is and color codes may be different year to year. As long as one of the four wires has 12V, I would say there's nothing wrong with the connection to the EGR.

If the connector was re-wired incorrectly, it would mean that as soon as the ECM demands EGR to open, it would create a dead short to ground and blow the EGR fuse. It might even fry the ECM.
Old 05-25-2016, 10:17 PM
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Re: EGR bypassed?

The attachment should help you.
Attached Files
File Type: pdf
electronic egr.pdf (84.3 KB, 103 views)
Old 05-27-2016, 02:27 AM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
Re: EGR bypassed?

Thank you for your help guys. Meanwhile I drove the car with disconnected O2 sensor and EGR. The problem seems to be "solved". I guess the O2 sensors seems to be the cause of this, I had no stalling and no hesitations from the engine. Going to buy a new Y pipe and a new O2 sensor. I' ll keep you updated!
Old 11-19-2018, 03:35 AM
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Car: Pontiac Firebird Formula
Engine: 3.1 LH0
Transmission: 700R4
Axle/Gears: Automatic
Re: EGR bypassed?

Ok, I' m updating the situation 2 years later: I recently drove the car with the EGR connector disconnected, the car runs much better than with. I first mad some tests, like unplug the MAP sensor connector, and code 32 - 54 came up. Once I reconnected the harness every code was cleared. Now I'm driving the car with rhe EGR connector disconnected, but the engine idle erraticly around 650/750 rpms. It didn' t stall so far, even at stop lights but the idle isn' t steady. I replaced the FPS and tested injector, all was ok.
The problem is that it seems very strange that the engine runs better without the electrical EGR connection!
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