mods sorry if this is a double post the original post shows a topic but no text.

Sooooooooo yeah been working on this FC for almost a month now and once again need some advice and comments. Gotta get it to pass smog and would also like a little more control on the fuel delivery because currently at idle this thing runs WAY too rich.
First off I was wondering if anybody has tried replacing the stock fuel pressure reg with an adjustable reg that would allow them to turn down the pressure behind the injectors.
Secondly I would like recommendations and a bit of an explanation as to the function and purpose of the stand alone fuel controllers. Would I be able to turn down the on time of the injectors to lean out the idle mixture? What product is really worth the money? What kind of time is involved in install and setup?
Thanks
-Pat

PS below are the latest analyzer test results/limits
Idle(300 -1200 rpm) tested at 850rpm
HC 1600/200
CO% 5.4/1.2

We have found that manually opening the air baffles leans out the mixture to well inside the limits but the RPMS kick up to outside the test limit. The variable resistor is turned to full lean and all the injectors are clean and properly operating. My thought at this point is find a way to either lower the on time for the injectors at a warm idle(safc?) or decrease the amount of fuel coming through the injectors(aftermarket reg?). This way the idle will be low enough and the air fuel mixture will be much better.

 

That would be an extremely bad idea, and would result in a dead engine very quickly. Reducing the fuel pressure with an adjustable FPR would result in lower pressure all the time, not just at idle. The first time you put the engine under load it would run lean and probably pop.

If you have a problem passing emissions, then something is wrong with the car. If everything's working as it should, it'll pass. Find the problem and fix it, don't start trying to modify your way around the problem.

 

I have the same problem with my '86. My numbers are almost identical.
Same deal, variable resistor cranked full lean, no leaking injectors.

Ironpanther, did you ever figure out what was causing the over-rich condition?

I'm getting burned out trying to find it.

 

Check out the ACV with a hot engine.

At idle little to no air should be blowing out the approx one inch hose at the bottom of the ACV.

The two small vacuum hose just above the ACV should both have a vacuum on them. Pull them off one at a time and feel for vacuum on each HOSE.]

The TPS must be set properly for the Relief and the Switching solenoids to work right. They have Blue and Grey connectors respectively. Those two items control the vacuum to the two vacuum hose I described just above.

Another thing to check is to have the engine OFF. Get a piece of vacuum hose about a foot to two feet long. Connect one end of the hose to one of the nipples of the two vacuum hose mentioned above. Suck on the other end of the hose. You should be able to hold a vacuum on the hose. If not, that particular diaphram is busted and the ACV needs replacement/fixing. Do both nipples the same.

ALSO: At the bottom of the radiator, on the left end, there should be a water temp switch. Make sure it is connected. If the switch is busted or missing, couple both wires for the switch together to make a circuit. This switch has an effect on the Blue (Relief) solenoid. A big effect if not connected or the wires coupled together.

Another thing mentioned in the fsm, is to take the bottom one inch hose off. Rev the engine to over 3500 rpm. Air should expell bigtime when over 3500 rpm out the one inch nipple at the bottom of the ACV.

Another is to have the one inch hose off the bottom of the ACV. Only a whisp of air should come out of the large nipple. Now pull the BLUE connector off the Relief Solenoid. Air should come out the one inch nipple big time now..

If all works right, then replace the catalytic converter.

 

First of all, why are you fingering high fuel rail pressure as the culprit?
Did you confirm this with a pressure gauge?


-Ted

 

I don't know about Ironpanther, but I know my fuel pressure's ok. Checked it. Running right around 35 psi at idle.

Maybe he was just guessing.

BTW, thanks Hailers. I've heard there are a lot of problems with those ACVs. I'll have to go over mine again.

 

Actually that's not okay. You should only see that much pressure with the engine off or running at full throttle. At idle it should only be 28psi. You may have a faulty FRP or more likely a broken FPR vac hose.

 

Really? Pressure spec. on the regulator's 29.00 - 37.68 psi. Seems ok to me...

 

Anyway, I just went over and checked it. FPR diaphragm holds vacuum, and there's vacuum at the FPR nipple.

ACV checks out. Even swapped over a known-good unit.

I've wired up a check engine light and O2 "Green Lamp" to the underhood diagnostic connector.

Green lamp is lit, RICH, under no load. (idle and free revving.)

Green lamp flashes, CLOSED LOOP, while cruising.

Green lamp goes out, LEAN, under decel.

Do 7's run closed loop at idle?

My guess is my injectors are NOT leaking. Fuel rail pressure does not bleed off when vehicle and fuel pump are not running. Also don't have any hot start issues (no flooding.)

This vehicle appears to have a rebuilt engine. My guess is 20k or less on the rebuild. Previous owner obviously couldn't get it to pass emissions either. Anyone know of any common oversights/bloopers when installing an engine in a 7 that could lead to fuel management issues?

I'm about ready to dump 2 gals of ethanol in the tank and run to the testing station...

 

You've misunderstood the spec. 37psi is the static fuel pressure, i.e. engine off. The job of the FPR is to keep a constant pressure differential between fuel pressure and manifold pressure. Vaccum in the manifold lowers fuel pressure and boost raises it. When the engine's idling the fuel pressure should be ~29psi. If it's higher than that with a stock pump, most likely the FPR has failed or its vac line is broken.

 

Something on your car is busted. A NORMAL RX-7 will read LEAN at idle. Why? Because IF the aircontrol valve is working, it will, at idle direct air from the airpump to the the exaust ports.

The exaust ports are located before the 02 sensor. THAT is why a RX reads LEAN at idle with a NORMAL car.

That's one reason I usually ask for a person to look at the acv's dump tube at the bottom of the acv to see if it's dumping air at idle. If it does, then that air is not going to the exaust ports where it should be.

You don't have one of those Waldo fuel pumps, do you? That could increase the mixture at idle. Even with a normal fuel pump, if you remove the ground coming from the ECU to the Fuel Pump Resistor and Relay you can, on a wideband, see a difference in the afr when at idle. That's just for Turbo cars though and some series five cars that are set up like that. If it's a 88 n/a ignore this paragraph.

If the car is a non turbo 88, then there is the possibility that someone has rebuilt the engine and when putting it back together put the front rotor housing where the rear rotor housing goes and thought it made no difference. It makes a difference because now there is no passage to the hole in the exaust ports for the air from the acv/airpump. Ignorance is bliss for those who think swapping places with the front and rear rotor housing makes no difference.

The rotor housings have a F or a R stamped on the top left side of the rotor housings. Somewhat difficult to see but can be seen.

 

Okay... here's the deal with my ACV. At idle, with relief hose disconnected, it kinda pulses air out. If I make it actually relieve, it's just a constant rush. Is that normal?

 

There will be some leakage at idle. If you rev the engine to above 3500 you should be able to tell a LARGE difference in the amount of air being expelled. I believe it's right at 3500 rpm the Relief solenoid closes and removes a vacuum signal from the acv. Memory here. NOTE: It should not expell air bigtime until you reach 3500 rpm.

OR...if you have a 88 non turbo, reach over on the other side of the engine and pull the BLUE plug off the Relied solenoid. Doing that should make the air relieve at the acv big time.

Another thing to check for SURE. Get a piece of vacuum hose about a foot long. Attach that hose to either one of the two metal nipples just above the acv. You'll have to remove the vacuum hose from the metal nipple first. Now suck on the vacuum hose. You should be able to hold a vacuum with your tongue covering the hose end. If you have to keep sucking to keep a vacuum going, then the diaphram inside the acv is busted.

Actually, with the engine idling, both vacuum hose above the acv should be pulling a vacuum. PUll one off at a time and see if that's so.

Also, if you pull the vacuum hose off one of the nipples, at idle, then the acv should relieve air big time at the bottom. Sorry, I forget which one right now. Your doing the same thing as pulling the BLUE plug off the Relief solenoid when you do that.

Do this with both of the two metal nipples above the acv. Both should hold vacuum.

Another little known fact of life.....make sure your series four's water temp switch at the bottom left side of the radiator is connected up or the two wires are jumpered together. One or the other. This switch effects the Relief Solenoid.

 

Doesn't that radiator temp switch also control the Accelerated Warm-Up function as well?

Yeah, my ACV's working right. I've done everything you've posted, HAILERS. Problem's gotta be somewhere else. 'Bout the only way I've been able to drop the 02 sensor reading at idle is to open the 6 ports manually. I've even opened the idle mixture screw and potted the variable resistor all the way to lean and it still runs rich.

Oh, and when I pull enough vacuum on the pressure regulator to drop the rail pressure to 29 psi, it still runs rich.

I checked the stampings on the rotor housings, they're in the right places. F in front, R in back.

Funny thing is, the car runs great.

I have another question... How much vacuum should I expect to see at idle? I'll have to check again, but I think I'm getting about 15 inHg. That'd be kinda low for a piston motor, but is it normal for a rotary?

 

On a completley stock non turbo car: The afr should read LEAN at idle. On that same car, IF you pull the BLUE connector off the Relief Solnoid at idle, the afr will now be RICH. I've never, ever seen it do otherwise on either of my stock n/a's (when all were stock n/a).

The reason for going from LEAN to RICH is as I described in an above post. Others have followed this advice and written back that their afr reading acted just as described in the above paragraph.

The o2 sensor is not used at idle.

GREEN LAMP: Is that the MAZDA code checker outfit? Nothing agains that, just asking. I'd no idea it measured afr at all. If set up right it WILL tell you if your 02 is working in conjunction with the ECU by making the GREEN light flash at several hertz per second. I think the setup is with the shifter in fifth or the plug off the neutral switch and reving the engine over 1700 or so. Memory here. It's in the fsm somewhere.

Measuring afr's: Do this, get your digital meter out. Put the negative on a known good ground. Backprobe the pin 2D on the ECU. Meter on DCV. Read the meter with the car warmed up and at idle. If the acv is working the reading will be LEAN, in the .02vdc or some other very lean range. Pull the Blue plug off the Relief solenoid. Immediatley the meter reading should go to the .6vdc or .7vdc or higher, proving the acv is functional. I've done this using the cheapest of the cheap RadioShack digital meters in the past.

If the meter does not go from LEAN to RICH doing the above, the acv is not functioning or the air cannot get past the checkvalve installed b/t the acv and the manifold (never seen that).

 

Ahhhh. I just looked at the 87FSM, the Digital Code Checker pages. At the top of the page that shows the Operation of the Feedback System there is a chart.

My interpertation of that chart is that the afr shown in the right of the chart is the results of what your about to do in the following paragraph called Operation of the Feedback System.
If the GREEN light does not flash during the test, then the afr is too rich. If the GREEN light is OFF then the afr is too LEAN. If the GREEN light flashes several times a second then things are just right.

Anybody that KNOWS differently can chime in if they want. Key word is KNOWS.

By the way, the GREEN lamp on the tester can be simulated with a single LED such as some people use to check codes on a series four. You just connect one wire of the LED to the six socket green connector to the Black/White socket and the other to the socket just below that black/white socket. Run the LED to the interior and go for a ride. When in closed loop the LED will flash several times a second. When not in closed loop it'll shine steady.

 

Any MAZDA Techies know anything about that Code Checker with the Green light? And the chart for it?

 

Yeah, I don't actually have the Mazda checker... I've got the LED in my dasboard.

And if you monitor the o2 voltage and watch the LED, the mimic each other. The "Green lamp" does show sorta whether the closed loop system is working or not, because it's just triggered by the o2 voltage and the ECU amps the signal up enough to drive a lamp. It basically works the same as an AUTOMETER AFR guage. Except with 1 led instead of a whole ring of them... in different colors... man I miss mine.

Anyway... getting back to the subject at hand... My o2 sensor runs pretty close to 1v at idle. Like .960v. Pulling the blue connector, which causes the relief valve to pop, doesn't really change it, cause it's so rich all the time anyway. And it's not relieving all the time either, cause the flow out of the ACV does change when I pull the blue connector. Sorry HAILERS, it's not that I don't believe the ACV can be a problem. I just think mine is rooted somewhere else.

I hooked an oscilliscope up to my ECM today and kinda watched it all the way home from work. Was monitoring my injectors firing. It was mostly OK, except that I have a HUGE voltage spike when the injectors close. Like 60v or so. I don't think that's right.

 

Okay, strike that... 60v spike on injector closing is normal. My mistake.

 

Nope, at .960 with the Blue plug on ...nothing is going to change if you pull it off. It shoulda been like ,1vdc with the plug on.

Airpump working? Had to ask. Sorry, I've no idea why your rich. If you drive the car with the voltmeter tapping into the 02 sensor output at pin 2D of the ECU, does the voltage drop down? Say your cruising at fifty, does it range on either side of .450vdc rapidly?

No WALDO pump, right? No patched in aftermarket FPR? Right?

It idles relatively smooth or not?

Are the two vacuum hose just above the ACV in their right spots?

And yes, that water temp switch at the bottom of the radiator does mess with the fast warm up when cold. The 3000rpm thing for 17 seconds. Also messes with the Relief solenoid a bit.

 

STUCK RECORD: Try this. Idle the car til fully hot.

Determine which of the two metal vacuum nipples just above the acv is for the Switching and which is for the Relief solenoid.

Pull the Switching vacuum hose off and plug it.

Install a spare piece of vacuum hose on the metal nipple above the acv that is for the switching diaphram.

Put you meter on the output of the 02 sensor at the ECU. Pin 2D.

Watch that reading on the meter and then suck on the vacuum hose. You should be opening the switching diapharm which in turn opens the path from the acv to the exaust ports.

When I do that on a car the 02 sensor reading falls from rich to waay lean.

If you know what your duty cycle is while idling and want to compare it with mine give notice. Either percent or ms.

I still would bet a twenty dollar bill your problem is ACV related.

 

Well, I'm not gonna rule out my ACV just yet.

But, my friend and I took a trip this weekend. He sat in the passenger seat and was checking my injector pulses with the scope. We found out that at idle, the injector pulse width is like 4 ms at idle. But under light cruising throttle, low speed, low load, we're seeing 2-3 ms.

Gonna do some more checking after work tonite. I'll let you know.

 

ACV's still looking ok.

Found something else funny. Driving home from work the other night, I had the scope plugged in, monitoring the injectors. I'd been noticing ever since I bought the car, that just before trailing throttle and fuel cut, the exhaust made this funny burbling noise. Well, I just happened to glance at the scope while it was doing it. The ECM was shutting of 1 injector.

And I can reproduce it. Every time, same injector, same throttle position, I can drive around with only one chamber firing.

I thought TPS at first. But if the TPS had a dead spot in it, the ECM should cut both injectors and I'd have a stumble during acceleration etc.

I'm starting to lean toward a bad ECM. I don't know about the 7's, but I've seen other manufacturers ECMs get weird little glitches in the before.

 

Which of the primary injectors is doing the cutout job?

Sometime take a look at the series five fsm that is online. Look in the Fuel section and towards the last pages. There's a page called OUTPUT DEVICES. It makes mention of fuel cut to the rear rotor when over 8500 rpm. On a series four it does the same thing.....but I THINK at a lower rpm.

That does not describe your problem exactly, but I thought you'd be interested in that OUTPUT DEVICES page because much of it should apply to a series four.

Also look at the FUEL INJECTION AMOUT and how during IDLE it uses the word RICH a lot. Take a look sometime.

I might take a look at my car during that period of barely letting off the throttle and see if I see the same thing. Sorry, I can only look at one injector at a time, that's why I asked which of the primary did you see that. Rear?

Usually, if I barely let of the pedal, the afr will go a full count in the rich direction. Say I was seeing 14.2 while just cruising along...then I barely let the throttle up a tash, the afr will go to the 13.2 range. And if I let up completely it will go full lean because the injectors shut off. I just thoght I'd mention how it went from 14.2 to 13.2. Just FYI. Same thing happens when going down a long downhill grade. None of this is with the 02 sensor connected up.

 

Oh, your pulse width at idle is contrary to what I see. At idle the percent duty cycle shows to be 4.0 percent and the pulse width is 3.1 ms. That's on a car fully warmed up, water temp 180, and been idling for over two minutes.

If you start up a fully warmed up car, the duty cycle will be higher for a minute or so. It'll ususally show something like 5.0 percent for a little while and finally fall down to 4.0 percent in a couple of minutes or less. That's what I see anyway.

And the idle is in the 750 range with the above.