Skip to main content ↑ ↓
Topic: NoX excessively high..... (Read 1931 times) previous topic - next topic

NoX excessively high.....

1984 5.0 EEC3

The CO and HC are wonderful. NoX levels put it above california gross polluter levels.

If I put vacuum by a hand pump to the egr valve at idle....it works fine....it stumbles and dies. But if take egr line and disconnect it from the valve and put it to a vacuum gauge, it fluctuates rapidly at less than 5psi and then drops to zero as the throttle is opened. If I put my finger over the vent port on the throttle body on he left side there, then it will show full vacuum at the egr port until I release the egr vent port.

If I put vacuum to the top of the vent port on the tb, then the car will die and won't restart worth anything and takes a second person to start it while I hold the throttle open to get it started. Releasing the throttle and the engine dies. If I put vacuum back to the vent port with it running in this "" mode then it will die again but restart and run like a champ.

Is this some kind of "test" mode? Also, how does this egr system work? Thinking the egr vent/solenoid is maybe no good, being as how the valve and passages are clean.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

NoX excessively high.....

Reply #1 –
When I had the 5.0 with CFI in my '83 one of the ports the EGR was connect to on the intake would build up with carbon deposits.  I would remove the EGR and basically have to take a screw driver and chip away at the carbon build up until I had it all removed.  The EGR would also be plugged and I would have to do the same thing to it.  I never figured out what caused this but after the first time I would just remove it about every six months and clean it really well and prevented the complete blockage that I found the first time.  I am not saying this is your problem but I would check it out.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

NoX excessively high.....

Reply #2 –
On the 3.8 the pasages below the CFI get plugged up with carbon as well.  It may be the same situation on the 5.0.  If I remember right the EGR is mounted to the CFI base plate so if the EGR has carbon so does the area on the manifold below the CFI.
Armed Forces Car Club
Eastern Sierra Chapter, California
WEB:  armedforcescarclub.com

NoX excessively high.....

Reply #3 –
The car dies when you open the egr valve manually with a vacuum pump.

Off idle with the vac line connected to a vac gauge, it fluctuates at about 4 psi extremely rapid then drops to zero.

The problem is somewhere between the position sensor or the egr solenoid assembly below the coolant bottle I think. But both of those parts are kinda pricey to just throw at the car.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

NoX excessively high.....

Reply #4 –
The 5.0 I pulled out of my cat had the ports in the heads completely clogged with carbon (could't even get a screwdriver in there).  Not sure if that helps though.
My car is a gravity hybrid.  The gasoline engine gets me up the hills, and gravity gets me down.

NoX excessively high.....

Reply #5 –
Quote from: Smkn600ctd;357840
The car dies when you open the egr valve manually with a vacuum pump.
The valve lets exhaust into the intake, so that works like it should.

Quote
Off idle with the vac line connected to a vac gauge, it fluctuates at about 4 psi extremely rapid then drops to zero.
This says the EGR control solenoid and the EGR vent solenoid are both working.

Note: If you replace the vent solenoid it will probable have a little air filter built on it. This replaces the vacuum tube that runs back to the throttle body for "clean air".

If this is an 84 I would expect it to be an EEC IV. If there is an ignition module on the side of the distributor, it is EEC IV.

I think the EGR controls NOX by reducing the combustion chamber temp. Maybe it's too hot for some other reason. Lean fuel mixture for instance.

If it is EEC IV have you run KOEO and KOER self tests?

NoX excessively high.....

Reply #6 –
It's a early 84 with EEC 3.

What is it that makes the car run totally different when you vacuum to the vent from the TB side?
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

NoX excessively high.....

Reply #7 –
Quote from: Smkn600ctd;357852
What is it that makes the car run totally different when you vacuum to the vent from the TB side?
I can't guess what that must be doing.

NoX excessively high.....

Reply #9 –
Took the position sensor off and it tested good.....but it's the wrong part. It's a grey one instead of the black one that belongs on the 85 and older. Was reading that the resistance in them are different. Ordered up a new one from rock auto, should be here in a few days. The car wouldn't even run with the sensor unplugged. Should be interesting to see how it runs with the right part.
1984 T-Bird Elan 5.0 (sold)
1994 T-Bird LX 4.6
2009 Dodge Charger Daytona 341/400
2013 Camaro SS

NoX excessively high.....

Reply #10 –
Wow!  I did not think you could pull any codes on an EEC III...I thought they were just a bit slow:pbb:

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp
 

NoX excessively high.....

Reply #11 –
Never mind.
2002 Honda Civic EX

1984 Ford Thunderbird Elan
5.0 CFI, T5, Dual Exhaust