I'm trying to get my new-to-me FD to pass smog and I need to fix its EGR fault. I have the airbox/air pump/Y-pipe and rear-turbo-outlet pipe all removed. To do the relay EGR hack, I also need to remove the UIM. With all that out, should I also remove the LIM to replace its gasket? I have no idea if that gasket was every upgraded to the metal version, but I've had one fail on a prior car and that sucked.

I guess I could also fix the EGR sensor and avoid all that work.

 

To remove the LIM, the twins must come off. It's a worm bag if you choose to take that route. You can see the LIM gasket with it installed if you look of flange area just behind the water pump housing. It will be obvious which gasket you have.

 

Thanks. I didn't realize the turbos had to come out.

 

what is wrong with the EGR?

 

The switch that tells the ECU that the EGR valve is open has failed. I'd replace it, but Mazda no longer makes the part.

 

there are three ways to go with this:
the first is just to fix it, so the CEL is off and stays off for the test.
the second is that if the part is bad and NLA, sometimes you get an exemption for it
the third, and you need to be careful with this, is that the part is NLA, but they will make you buy a "rebuilt" one. this is very expensive, because at this stage you have no choice.

its maybe worth a phone call to see if the EGR is exempt in CA because its NLA, or not.

 

It's possible that I can repair the switch. The plastic of the switch body has become crumbly in parts. Crumbs (or crumb) likely fell back into the switch preventing it from closing. I could print a replacement, but that would take a lot of iterative design to get right. I can also probably patch the switch together long enough for it to pass smog using epoxy and silicone, but I doubt it would last and I'd be back in the same spot in two years. From what I can gather, using a relay to fool the ECU seems like the long term solution. The downside being that I have to remove the UIM. I'm okay with doing that, but I'm concerned that something else could get screwed up and I have a limited amount of time to get this thing to pass smog (I think about 30 days from today).

I'm not sure what California does in cases where parts are no longer available, but I'm not optimistic about them being flexible.

 

so they keep a list, and if the part is NLA and can't be found, then it becomes exempt. however they have to check each smog, so if they exempt you this time, they repeat the same process next time
(feel free to write your assembly person and tell them that the smog program did its job, and can be retired, its up for a vote like every year...)

if the part can be rebuilt, they make you buy it from their guy. the FC EGR valves are like this. if yours tests bad, you have to buy the one from the state rebuilder, and its very expensive, because you have no other option.
so its worth a phone call to see what the situation is before you're in it.

 

There is a fourth way to go about it...... leave California

 

I've never screwed around with the egr system on these cars so curious what this switch is that you guys are talking about... Is it one of the solenoids under the upper intake manifold?

 

California cars have a switch that senses when the EGR valve is opened. It's literally hooked up to the EGR valve and senses its motion. Depending on who you talk to, 49 state cars are not supposed to have this, but my car was first sold in Indiana.

 

interesting
my car is also originally from Indiana. This hasn’t been an issue for me. I'm going to take a look at it next time I have that area apart. You have me curious now.

 

Hey, that’s what I did—I left California—primarily to get my kid away from those woke California schools. But It works for the FD too.

So the egr on these cars is pretty useless: it doesn’t do much other than clog, stick and set off the CEL. I fashioned a transistor switch and located it near the ecu as a work around. It’s documented on the forums here, somewhere. Functionally, it is the same as a relay.

 

The "smart" EGR switch was on all '94s and supposedly only on California emissions spec FD's in '93. In '95 they got rid of EGR all together.

The smart EGR valves have a switch that, as stated, closes when the valve moves. So if the vacuum line is disconnected or the diaphragm tears so it can't open the ECU will see that and flag a CE light.

Also the EGR system is beyond useless in an FD. Mazda knew this, the gasket has a TINY pinhole for the gasses to go through that clogs almost instantly. It's just not something the rotary needs but federal law mandated it. Also later FC's (89-91) ditched EGR. I don't know if Mazda just had to make enough cars to satisfy the federal requirement or what.

Dale