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EGR bits and pieces

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Old 03-19-2017, 01:57 PM   #1
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EGR bits and pieces

Hello all.

I have a 1989 2.8MPFI in my Triumph TR7 that Im getting ready for summer. The engine was acquired minus a bunch of bits such as the vacuum harness.

I have on the coil bracket a device that Im unable to ID. Its black plastic, about the size of a deck of cards, 4pin connector to the ECU, plus a couple of other black wires and with a single vacuum port.

I _think_ its the EGR solenoid vacuum sensor but Im not having a lot of luck identifying it much less knowing how to plumb it in to everything else.

If someone has a stock 2.8MPFI I'd appreciate some help identifying this thing and how to connect it to the rest of the car. The research Ive done has variously identified the unit as EGR vacuum sensor, EVRV and even MAP (and I know it cant be a MAP). I cant seem to find a good diagram showing where the vacuum port and various wires need to go.

Can anyone help?

Thanks!
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Old 03-19-2017, 07:26 PM   #2
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Re: EGR bits and pieces

Posting a picture of what you have will help us help you identify the part in question.
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Old 03-20-2017, 06:34 AM   #3
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Re: EGR bits and pieces

Sure.
A bit of explanation:
A) 4 pin connector goes to what the mnual says is the EVRV connector; pink/black, grey, white, black/white.
B) I joined these wires. They come from the transducer in the housing and to the circuit board in another part of the housing. They were sheared and needed soldering.
C) 2 black wires (cut). Dont know where they go but I suspect it was the EGR solenoid.
D) The one vacuum port. I suspect this goes to the throttle body, possibly via the EGR solenoid.

The backside of the unit is plain with no features. The unit is about 50mm by 30mm by 25mm (2in x 1.25in x 1in).

The screws are not standard.
I had to crack the unit open to make the soldering connections.

There are no distinguishing marks other than "made in canada 'G'" and A0309B. There is a semi-distinguishable other number ending in 89B but I suspect thats a date stamp since it came from a 1989 donor.

Ive seen diagrams where the EGR operation is all described in one diagram but in may case I appear to have three distinct components:
1) the usual "mushroom top" EGR itself, with one vac input
2) the usual EGR solenoid with a couple of wires and vac lines
3) this thing

I _think_ the vac to line D and wires C attach to the EGR solenoid and the EGR solenoid has input from the throttle body but Im piecing this narrative together from a bunch of sources. I would rather get this right first time than try various combinations each with a warm-up/cool-down cycle.

Thanks
Attached Thumbnails
EGR bits and pieces-thatbit.jpg  
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Old 03-20-2017, 11:52 AM   #4
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Re: EGR bits and pieces

With out going to look at my motor I have no idea? It looks like nothing I've seen !
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Old 03-20-2017, 12:03 PM   #5
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Re: EGR bits and pieces

Hey man how are ya.

Going from what Ive pieced together if you look at the right bank you will see 4 components in this order from left to right, sitting above the right bank exhaust manifold:
I - II - III - IV

Where I is "the widget" with the connector facing you, II would be the coil, III the EGR solenoid and IV the EGR valve.
The widget would be mounted kind of upside down right next to the coil on the bracket. You might have to dig around amongst loom and HT leads to get a good look at it.

The engine came from a kinda beat up and neglected donor car. Im more than happy to believe the component in question isn't stock. Any help you can offer would be brilliant.

The engine will run and not too shabbily either thanks to new O2 and MAF. However she's throwing EGR codes and I'd rather get it sorted.

Last edited by carltr7; 03-20-2017 at 12:07 PM. Reason: typo
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Old 03-20-2017, 01:12 PM   #6
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Re: EGR bits and pieces

Yeah man ok, i remember it now !




i tried to get some helpful pics ? The 4 pin connector goes into my main harness , the vac went to the egr solenoid you can see that in the pic (didnt know that was the egr solenoid ) two black wires come out of the box and back in ? Other two went ........
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Old 03-20-2017, 01:16 PM   #7
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Re: EGR bits and pieces

Into that solenoid , just double checked. Do you have the wiring diagrams to help ?
My car is running no egr system and never throws a code, however as you can see I do have the sensors still connected .
That widget fixes poorly to the coil bracket, hence the zips tie somebody put around it .
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Old 03-20-2017, 01:59 PM   #8
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Re: EGR bits and pieces

Hey z, I think ive figured it out thanks to your pics.
Please refer to to the diagram "egr.png" below.

As we all know, EGR opens at cruise to allow some exhaust into the inlet manifold, thereby cooling the combustion chamber so as not to produce as much NOx pollution.

Let'a describe the components in the diagram.
"A" is "the widget" and I believe theyre calling it an EGR Diagnostic Vacuum SWitch. I have it mislabeled here as EVRV.
This has:
a) one port with vacuum from line AB (red)
b) 2 black wires A1 "going to itself" (actually they connect the vac transucer on one side of the mechanism to the circuit board on the other side)
c) edge connector A2 which connects to the loom and therefore the ECU with 4 wire colours as shown.
d) 2 additional black wires AB that command the solenoid B

"B" is the solenoid. When it gets 12V on black wires AB it will open a port to let vacuum through from throttle body D to EGR C.

"C" is the EGR valve. When it gets vacuum on line BC it will open allowing exhaust from the manifold into the inlet manifold (not shown).

"D" is the throttle body which has a port that can be used to connect its vacuum D to B.

I *think*, based on research, the vacuum on line DB gets through to the EVRV which tells the ECU that the engine is asking for air/fuel. The ECU, depending on other parameters, optionally replies, commanding EGR.

The command causes 12V to get to the solenoid which activates, routing vacuum to the EGR, causing it to open. It stays open for as long as its needed.

Now where Im not entirely clear is how (or whether) the EVRV is giving feedback to the ECU. In one scenario it may expect vacuum at its port to change after its commanded EGR solenoid activation.

In any case, the ECU knows how to set EGR codes and logically the only way it can "know" is by examining the signals its getting on the white and/or grey wires coming from A2 (pink and black are simply hot-in-run and ground, respectively).

Based on my research, there are various EGR configurations out there of which this is just one. Some EGRs appear to have everything in one module while this configuration splits the valve, solenoid and sensory components out into three separate units. Cheaper if you need to replace one of them I guess.

So I think the next step is to pop it all on the car and see. Handily the 2 black wires AB were cut staggered so I can see which is which.

I suspect the reasons you're not seeing codes is that there is enough vac/wire connection to fool the ECU into thinking EGR is being commanded and complied with. This is essentially what Im going for.

I hope this helps someone!

Kudos as ever to zs.
Attached Thumbnails
EGR bits and pieces-egr.png  

Last edited by carltr7; 03-20-2017 at 02:15 PM. Reason: clarification on EVRV vs EGR diagnostic sw
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Old 03-20-2017, 02:07 PM   #9
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Engine: 2.8 V6 MPFI 1988/89 Firebird
Transmission: WC T5 Manual
Axle/Gears: 3.08 Triumph TR7 5spd/TR8

Re: EGR bits and pieces

Armed with the new information I found this here:

http://repairguide.autozone.com/znet...528008e5d2.gif

I attach the GIF below under fair use for educational purposes.

Be aware this is for a 2004 2.2 Chevy Malibu so treat with caution.
However, based on what I am seeing it does describe the setup I have on my 2.8MPFI V6.
Attached Thumbnails
EGR bits and pieces-egr.gif  
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Old 03-20-2017, 02:47 PM   #10
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Re: EGR bits and pieces

I wanted to add this , you are right it is Electronic Vacuum Regulator Valve. Black white is ground. White is to ecm and is switched through to the black white ground. Grey is from ecm and is through to blk pink that is conected to air select valve, canister purge valve and fuses.
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Old 03-20-2017, 02:49 PM   #11
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Re: EGR bits and pieces

Sorry couldnt get focused with this tablet camera, had to get close enough to read but far enough to focus !
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