respecttheseven

the check engine light keeps coming on, wondering what to do for this code?

hanknmorgan

I'm not really sure what you are asking. You got a code 16, meaning egr vavle failure and you want to know how to fix it? Did you buy your car in CA? I thought only CA cars had EGR valves. Anyway, from what I have read 90% of the time it actually the EGR sensor that goes bad, not the valve itself. So replace that and your usually good to go. There is an electrical deal you can do to trick the ecu into thinking the sensor works or something as well that I read before. Good luck.

BlueRex

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/question-about-12v-relay-fix-egr-345468/

That should be all you need to know to get rid of this pesky problem.

rotorhead333

So, one question,, will this also work with non-california emissions cars??
Another question, to put this all in laymens terms, you are just adding a relay in place of the vacuum solenoid and tricking the ECU into thinking it's operating? Also, after this "trick" will the car still have the loppy idle as it would with the check light on?
Thanks!

tt2323

It should work on any 93-95fd. yes your tricking the ecu. I had the egr light on and my idle was fine

BlueRex

Don't see why not, but I do remember reading that only the cali cars would through the CEL for a faulty EGR. Could be wrong on that one.

Not exactly true. Basically the EGR has an on/off switch that lets the ecu know it's working properly. Due to the small passages and pinhole gasket it doesn't take much for these things to get clogged and interfere with the operation of the EGR. The relay acts as the switch and sends a signal to the existing solenoid that fools the ECU into thinking everything is working.

I never experienced a loppy idle when my EGR was malfunctioning. That is most likely being caused by something else.

wstrohm

I hadn't planned on posting this yet, because the deed has not been done yet. But if anyone is interested, the EGR Function Sensor Bypass can be done (if you have a limber back) right at the PCME. And there are a couple of ways to do it, neither of which requires going into the engine compartment at all.

1) Transistor phase inverter (switch)
2) Relay

Here are a couple of possibilities. Keep in mind these have NOT been built or tested yet!!! Also, 1993 Federal (i.e. non-CA) cars do NOT need this mod since their EGR valve has no sensor connection to the ECU. This is applicable only to 1993 CA cars and 1994 - 95 cars (all).

BlueRex

'95s didn't have an EGR.

Interesting idea. Wiring in the relay really isn't difficult IMO, but let us know how your idea turns out.

wstrohm

"'95s didn't have an EGR."

Whoa, you're right! How did Mazda get away with that? Unbelievable that CARB actually removed an emissions equipment requirement. Never occurred to me that such a thing could happen. Sorry for the lack of research. (I did look at the parts diagrams for the '93 & '94, though.)

"Wiring in the relay really isn't difficult IMO..."

No, but taking off anything in the engine compartment below the throttle cable is.

BlueRex

It was unnecessary, which is why when people disable the EGR or use the 12v relay they are still able to pass the NOx emmissions part of the test. Even on the new CA load testing I had no trouble passing.

What your suggesting seems just as difficult to me, and since we all know what a pain it is to work on such a tight wiring harness maybe your should consider using one of these, it might make it a whole lot easier :

http://www.clubrx.org/default.asp?id...ntent=34&mnu=3

wstrohm

BlueRex,

That is a brilliant idea and I'm very lucky you read my post! Thanks heaps; that definitely makes the job easier. Now in fact, assuming the schematic(s) work(s), there is no reason to remove the UIM (again; I just did a vacuum hose replacement). YAAY!

scotty305

iTrader: (2)

That's a great idea using a transistor near the ECU; it's smaller and requires less wiring to be run through the chassis.


Assuming the signals are all 5V, you should be able to use a TTL logic gate (like a 7404 inverter or a 7400 NAND gate), and later use other pins of the same chip for tricking other switches too.

-s-

wstrohm

scotty305,

None of the signals are TTL-compatible. The 4O signal from the ECU to the EGR solenoid valve is a current sink, which grounds the cold end of the solenoid coil when it is active, while the other side of the coil is on a common +12V bus used by all the solenoids. I don't know whether the 4O signal is an open-collector transistor (like the one in the schematic) or an active pullup, but in either case, when it is not active in the stock configuration it would be at or close to +12V.

The 3J signal in stock configuration is an input to the ECU which is either connected to ground through the EGR sensor contacts when the EGR is not active, or open-circuit (floating) when the EGR is active.