jgibbs22

Hey Everyone:

Need some help with my EGR stuff. Went to smog the car here in CA, with all brand new cats, and I failed due to a faulty EGR system. I have two weeks to fix it and get it resmogged before they tag me as a gross polluter and basically make me pay more money to enjoy my car. But I digress. Here are some of my questions about this:

1) Is the EGR systems nothing more than a vacuum line running to the EGR solenoid valve, which in turn connects to the EGR valve. The solenoid valve recieves 12 volts from the computer under certain conditions (RPM, temp, vacuum, etc) and oepns the valve, allowing the manifold vacuum to operate the actual EGR valve? Can the solenoid valve be open, but there not be enough vacuum on the EGR valve to actually open?

2) Which connection point on the solenoid is the vacuum intake, and which side is the output vacuum?

3) When the solenoid is closed, what happens? Is it possible that the EGR valve is always open, and it pulls air through the solenoid valve air filter when the solenoid is closed? And when the solenoid opens it allows exhaust gas through? I know the basic idea of these things, just missing the little details to diagnose my problem.

4) Finally, what else will affect the EGR readings during a smog? I have heard BAC mentioned on other posts, but nothing specific that I recall. Anything you can offer would be great.

Oh, and whoever shows me the light and get this fixed, I can send some cash or some parts of my spare 88 car. Just let me know. Thanks guys! Keep those rx's on the road!

J

drftwerks

iTrader: (1)

what failed the EGR FUNCTIONAL TEST??? where he tried to stall the car by pulling vac on the egr??

jgibbs22

I dont know bro. But it looked like he did not even pull the vac line connection at the solenoid valve to test it. All they would say is EGR system failed, and wanted 80 bucks to diagnose the problem.

RotaMan99

The EGR valve bladder is often dried and cracked, leaking any vaccum applied by the engine. I would check that out and also make sure the ports on the engine block are not clogged up.

Also, look in the FSM and look for the EGR diagnosis so you can check the operation of system correctly.

jgibbs22

Thanks for the info bro. I pulled off the throttle chamber as the FSM says and checked out the EGR. I put a vacuum right up to it with the car off and I could not get it to hold a vacuum. Would you assume that it is bad then?

Secondly, if it is bad, can I do better then mazda trix for 260 bucks for a new EGR valve??

gross polluter

I got a good EGR on ebay for $25 shipped.

RX729

Just Rip Off all THose Emissions Crap and Pay Someone To Pass Your Smog...

tom0261

I just had this same problem recently. This is my first time trying to really help someone, so forgive me if I over do it.

The bottom line, for me, this time, was that the exhaust manifold gasket was installed the wrong way, thus blocking the the port that feds the EGR valve its exhaust gases. That was the previous owner's doing! If you can not confirm that YOU installed it right, you'll have to seriously consider checking it.

Here are a few things I dealt with over the 2-3 weeks I wrestled with this problem.

1. All the EGR's I worked with had leaky diaphragms. I ultimately determined that even with a leak, as long as it could hold at least 3" of vacuum, that was enough to open the valve. In my quest to solve this part of the problem, I smeared high temp silicone sealer over the diaphragm to reseal it. If you try this, applying vacuum to the valve during the process will probably get the sealer into the most leaking cracks better.

2. Make sure you don't have any vacuum leaks in this system.

3. Make sure the solenoid operates as it should. Mine had a broken nipple, so it probably wasn't sending vacuum to the EGR anyway. Per FSM, apply 12V to the valve to confirm that it opens and allows air to pass.

4. While you've got the manifold off, replace all the fuel lines and clamps with the best stuff you can get if they're more than a couple years old. Do the same with the vacuum and coolant lines. Consider the engine ground and Pulsation Dampener issues while you're in there.


Good luck.

jgibbs22

ARGH!! ok, so while I search for someone just to let me pass this smog crap, I THINK I have tracked down the problem. I have replaced the EGR valve, I have replaced the water thermo sensor on the back of the water pump, and I have verified the egr solenoid switch works properly. My problem now is that I can not get the switch to activate when it is plugged in. I know the connection is getting 12 volts, but the ecu never lets the signal through to the 2N pin. Any thoughts? New ECU? never heard of one pin going bad, but I guess anythings possible....

HAILERS

&&&&&The solenoid valve recieves 12 volts from the computer under certain conditions (RPM, temp, vacuum, etc) and oepns the valve&&&&&&&&&&&

Close. Twelve volts is there any time the key is to ON. What operates it is a Ground FROM the ECU.

Just how did you determine the signal FROM the ECU isn't getting to the EGR solenoid? The gnd singnal isn't there all the time, you know.

To check it out, what I'd do is fully warm the engine up. Fully HOT. Then put a meter on the blue/white wire of the EGR solenoid plug. Back probe the wire with the connector on the solenoid. Rev the engine up and let off. The meter should have reacted when the ECU sent a signal to the solenoid. Voltage should have dropped.

pfsantos

iTrader: (1)

Do what HAILERS said...then once that is fine send power to the EGR valve at idle and see if it runs rough. This will tell you exhaust is going into the intake (assuming you don't have vacuum leaks between the source of vacuum and the EGR valve).

The emmissions guy may have noticed high NOX (oxides of nitrogen) in the exhaust, which indicate high combustion temperatures...the EGR system lowers these temps. by recirculating some exhaust into the intake above a couple of thousand RPM's. BTW, don't go crazy replacing parts; do a little more diagnostics.

HAILERS

Hmmmm. If you failed over NOX even a working EGR might very well not save you. Later models RX don't have a EGR at all. I pass a 87 turboii each year with no working EGR and pass very well.

I think it's the series five that don't have a EGR but series four do, turbo and non turbo.

jgibbs22

Hey guys, thanks for responding, we got to be close to the solution now! haha.

In a response to the last two messages, the car DID NOT fail any of the emmissions tests. It was free and clear on them all, probably partly due to three brand new cats. It only failed the EGR FUNCTIONAL test. I replaced the bad EGR valve (it was bad, held no vacuum and was quite cracked), tested the solenoind switch which turned out to be fine, and two days ago replaced the thero sensor switch on the back of the pump which had the connection piece broken off of it.


I am a little confused on this statement:

To check it out, what I'd do is fully warm the engine up. Fully HOT. Then put a meter on the blue/white wire of the EGR solenoid plug. Back probe the wire with the connector on the solenoid. Rev the engine up and let off. The meter should have reacted when the ECU sent a signal to the solenoid. Voltage should have dropped.

What do you mean back probe the wire with the connector on the solenoid? WHen I had the engine fully hot, when I put the probe from the B/W wire to the ground on the battery, it showed 14 volts. When I probe the B/W wire to the L/W wire while the car is HOT and at idle, i was reading 0.3 volts. WHen I reved up the motor, I would get a readong of about one volt. I pulled the ecu last night and it looked like someone had been in there before, but only obvious change was a new ground wire spliced into the center ecu connection.

HAILERS

Meters negative lead on a known ground. Like the batt neg terminal or alternators body.

Plug attached to the EGR solenoid.

Positive meter lead in the back of the wire that is not black/white. I forget the color right now.

Engine running and fully Hot. Rev the engine and let it return to idle. The meter should be on dcvolts and should have gone from say 12vdc to about 2vdc or less as you rev'd the engine, then returned to approx 12vdc.

The voltage drop would have been the ECU putting a gnd on the solenoid to operate the solenoid. Solenoid should have clicked when the engine was rev'd and returned to idle. Watch for the voltage drop.

jgibbs22

OK! I will try that this afternoon. Assuming that I dont get that voltage change, what are assumin is the problem? bad ecu?

HAILERS

Bad ECU or open wire b/t the ECU and EGR solenoid. BUT I doubt that is the case. I believe you'll see the voltage drop when you rev the engine. That means it is working for sure.

jgibbs22

Well, I worry then, because the switch never does let the vacuum through. When the car is warm and I get the revs up, I never get a vacuum on the outlet port of the valve. But like I said, I will do the voltage test u mentioned in a bit. Thanks again for all of the input, as much as I would love to just find a place to pass it, I really want it to work correctly, the car is just lovely!!

HAILERS

Go here: http://wombat.sevarg.net/RX7/RX-7_Training_Manuals/

Download FUEL AND EMISSIONS.

Look at page 4-56.

Just a general overview.

jgibbs22

Thanks for the link bro! I have read this before and while it does a good overview job, it does not answer some of the specifics I had, but reminds me of some other questions.

1) It shows the ecu needing the crank angle sensor reading and the TPS, but the system only operates when the three condions are met (i.e rpm, temp, and vacuum). Why would the ecu need these readings for the egr system?

2) Do the three conditions need to be met for a certain amount of time before the system clicks on, or does it open the solenoid immediatly when the egr conditions are met?

I know, this has to be WAY more knowledge of EGR system then anyone wanted to know!

And I know this is off topic, but does anyone have electric diagrams for any, or even better, ALL, of the EGI computers?? Would love to see those!

HAILERS

Tell you what. I've watched the EGR output with a LED light sometime ago and watched it come and go. But I did this while driving. Then again I've looked at the EGR output on a RTEK2.0 on a turboii before, and if memory serves I saw that display come and go with the car at rest. Memory.

I'll take a look again but it might be after ten or so tonight or tomorrow. I've my 86 na with me now and it has a RTEK2.0, but unfortuantly the EGR output is being used as a switching device for another item right now. In other words is disfunctional for the EGR. But I'll go fetch my turboII later and watch the EGR output with the car at rest and OR put a N326 in the non turbo car tomorrow and monitor the EGR at 2N with the car at rest. That ought to put this to rest, but might be tomorrow or much later this day.

HAILERS

Also make sure you have vacuum at the EGR solenoid to operater the EGR when commanded.

HAILERS

Update: It only seems to work while driving the car. I tried it on the turboii and the na cars both. I only had a short time span to check it out, but I can guarantee it will come on in FIFTH gear while cruising down the hwy at 60 mph for sure. Both cars. Other times? Got me. I didn't see it come on other times. No time to really look further. Losing interest in a EGR I don't use anyway. Sorry 'bout the bad post earlier.

jgibbs22

Thanks bro, I appreciate all your help. Just tested the thing again, still no luck. To add info, I get no error codes on the computer, the tps is set right, new thermo switch, and the valve egr solenoid works fine. I hate to order a ebay N338 but it looks like its another option. GOD I WISH I WAS REGISTERED IN ANOTHER STATE!!!!!

I think I mentioned this, but the one thing I found when looking at the ECU connections is that the ground wire terminal had a serperate grnd wire attached and ran to a metal grounding point above the ecu on the mounting bracket. Other then that, everything looks stock

scrip7

iTrader: (6)

The egr system is designed to only open the egr valve on a warm engine, hence the need for a temp signal. The egr valve is only supposed to be open above idle, NEVER at idle, or the engine would stall, hence the need for the tps and rpm signal.

I see you have replaced the egr valve, We still need to test to see if the exhaust passages are clear. Run the engine at idle, and apply vacuum to the egr valve (if you don't have a hand-held vacuum pump, use a piece of vacuum hose long enough to connect to a vacuum nipple on the UIM that supplies vacuum at idle). With vacuum going to the egr valve at idle, it should start running like crap or possibly even die. This will confirm exhaust gas flow. If you have good flow, we need to confirm vacuum going TO the valve when you drive. Grab a 3 or 4 foot long vacuum hose and a cheap vacuum gauge from a parts store and connect the vacuum hose to it and to the vacuum pipe at the egr valve. Tuck the gauge under the driver's wiper blade so you can watch vacuum while driving. You should see anywhere from 3" to around 8" of vacuum while accelerating normally, and zero vacuum at idle, on decel, and at wide open throttle. If no vacuum at all, then start suspecting the solenoid or ecu or wiring. I had a split vacuum hose on my rat's nest behind the intake where i couldn't easily see it.

jgibbs22

scrip thanks for the post!! Well, something else has come up here. I get a good vacuum on my egr, however, when it is opened it does not make the car stumble terrible at all, it lowers the rpm slightly but is no where near killing it. How do I clear out the passage way you speak of?? I get the feeling I will not like the answer. Regardless though, it still does not solve the problem of the solenoid not opening either does it??