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1990 Renix XJ EGR question. Auto 4.0

90XJ_Seth

NAXJA Forum User
Location
California
I tried searching this site and the internet and couldn't get an answer.

I passed smog (California)! Last time only took me 7 tries and all of your help.

However my Nox is still pretty high, close to failing.
Max at 15 is 711 mine was 448
Max at 25 is 613 mine was 567.

I have my transducer with label egr connected to the front egr tube. The vacuum side goes to the solenoid and the bottom port for backpressure goes to the TB side of the egr.

The EGR diaphragm doesn't appear to move in this format. However, if I connect the transducer in reverse (vacuum to egr and egr to solenoid) the EGR diaphragm moves during throttle increases. When connected firectly to vacuum and bypassing the transducer the egr shuts down the engine so the diaphragm is working.

Questions
1-is my transducer installed in reverse?
2-does the diaphragm hardly move the egr or not at all normally?
3-is my transducer just bad?
4-are either of the two transducers that look functionally identical on Amazon able to be swapped in?

Hope that was all clear.
 
The egr should not shut down the engine as far as I know.

Your catalyst maybe close to dead also. The california cats are are expensive, but should do a good job at cleaning up the NOx HC and CO. it would be wise to also replace the O2 sender when the cat is changed, a bad O2 sender can ruin a cat.

I got a Magnaflow Cat, Calif. type. Go to Planet Magnaflow website and buy from them using the internet coupon they offer, I paid about 300 bucks for mine ... this was the best price I found for the magnaflow cat.

https://www.partshopper.com/?s=3390...eep+Cherokee&type=ca&model=Cherokee&make=Jeep
 
If you rapidly open and close the throttle getting the rpm to about 1500 RPM, you should see the diapham and even the pintle move.
 
The EGR solenoid is controlled by the ECU, a certain RPM and vacuum and the ECU *stops power to the EGR solenoid* the solenoid *unpowered* is normally open.

I don't have a transducer handy but seem to recall it is marked either with a flow arrow or in and out.

The solenoid vacuum comes from the intake manifold.
 
The EGR solenoid is controlled by the ECU, a certain RPM and vacuum and the ECU *stops power to the EGR solenoid* the solenoid *unpowered* is normally open.

I don't have a transducer handy but seem to recall it is marked either with a flow arrow or in and out.

The solenoid vacuum comes from the intake manifold.
 
I had a bad EGR a few years ago. The replacement I got from Autozone had the transducer connected in reverse out of the box.

Also, not sure what the prices are today, but a year and a half ago I bought a Walker CA cat for about $150. I went from just failing (high NOx) to easily passing here in SD.
 
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